A study of conditions of surface defects formation when bar rolling at a bar and wire mill and methods of their elimination

2021 ◽  
Vol 77 (10) ◽  
pp. 1053-1059
Author(s):  
I. A. Pankovets ◽  
V. I. Voznaya ◽  
A. V. Vedeneev ◽  
M. N. Vereshchagin
Keyword(s):  
Temperature Gradient ◽  
Surface Quality ◽  
Surface Defects ◽  
Temperature Deformation ◽  
Controlled Cooling ◽  
Wire Mill ◽  
The Core ◽  
Local Overheating ◽  
Rolling Production

Quality of long products surface is an important consumer property of it. In the process of measures elaboration aimed at the increase of long products surface quality, in particular of bars produced at the mill 370/150 of ОJSC “BMZ – managing company of holding “BMK”, studies were accomplished by metallographic laboratory. It was established that defects being revealed at the bars finishing, don’t relate to the quality of continuously casted billet (CCB), but formed in the process of deformation. Studies of the mechanism of surface defects formation on hot-rolled bar of rolling origin – deformation fissure and wrinkles were carried out. Results of numerical simulation of rolling in roughing group of stands at various temperature-deformation parameters presented. Regularities of formation of surface defects on the bar in the finished product were revealed. It was shown that the reason of the surface defects of rolling origin – deformation fissure and wrinkles was a high temperature gradient between the core and the surface of billet, originated from local overheating of surface in the angles zone of CCB resulted in nonuniformity of drawing out of different layers of the billet being deformed. To eliminate the defects, minimum possible temperature gradient between the surface and the core of a billet by controlled rolls cooling should be provided. By calculation, the maximum permissible temperature of the working surface of the rolls of the rough group of stands was established, and empirically the actual temperatures of the rolls with the current production technology, as well as the temperature of the rolls support bearings seats of the rolls were measured. The technical and technological possibilities for improving of rolling technology on a bar and wire mill in order to improve the surface quality of rolled bars were demonstrated. The existing technology was adjusted and new technological modes of rolling with controlled cooling of the rolls were established, which made it possible to significantly reduce the rejection of the finished product due to defects in rolling production. A device was proposed for the roughing group of stands, which enables to minimize the ingress of coolant onto the bar rolled.

Drilling of CFRP with an Electrodeposited Diamond Core Drill – Effects of Air Assistance and Tool Shape –

2016 ◽  
Vol 10 (3) ◽  
pp. 310-317 ◽  
Author(s):  
Yuto Kojima ◽  
◽  
Ryutaro Tanaka ◽  
Yasuo Yamane ◽  
Katsuhiko Sekiya ◽  
...  
Keyword(s):  
Cutting Force ◽  
Surface Quality ◽  
Cutting Forces ◽  
The Other ◽  
Twist Drill ◽  
The Core ◽  
Normal Core ◽  
Tool Shape ◽  
On Chip

This research was conducted to investigate the characteristics of electrodeposited diamond core drills when used to cut CFRP.An eccentric core drill was usedto improve cutting characteristics. First of all, the cutting characteristics of a normal core drill were investigated at a few different feed rates and compared with those of a diamond coated twist drill. The effect of air assistance on chip evacuation were also investigated. The cutting forces, surface roughness profile of the hole, and tool appearance were used for evaluation. At the same feed rate, more cutting force was necessary for the normal core drill than for the twist drill. When air was blown in, the cutting forces required by the core drill decreased drastically, but delamination was evident. When air was drawn out, the cutting forces of the normal core drill were almost the same as when there was no air assistance. On the other hand, when an eccentric core drill was used, the cutting force required was lower when air was drawn out than when it was blown in. Additionally, the surface quality of the hole when air was drawn out was greater than when it was blown in. When the eccentric core drill with slits was used while air was drawn out, the cutting forces, surface quality of the hole, and tool appearance were the same as when an eccentric core drill without slits was used. However, there was little core jamming. Therefore, the eccentric core drill with slits had the longest tool life.

Research Progress of Improving Surface Quality of Microcellular Foam Injection Parts

2011 ◽  
Vol 66-68 ◽  
pp. 2010-2016 ◽  
Author(s):  
Yue Wang ◽  
Guang Hong Hu
Keyword(s):  
Injection Molding ◽  
Surface Quality ◽  
Dimensional Stability ◽  
Surface Defects ◽  
Research Progress ◽  
Microcellular Foam ◽  
Counter Pressure ◽  
Foam Injection Molding ◽  
Application Scope

Microcellular foam injection parts have many advantages such as saving material and energy, reducing cycle time, and processing excellent dimensional stability. Despite these advantages, the low surface quality problems limit its application scope seriously. In this study, the microcellular foam injection molding principle and some surface defects were introduced, and the technologies to improve surface quality, such as Gas Counter Pressure (GCP), Rapid Heat Cycle Molding (RHCM), and Film Insulation were summarized in detail. Finally, the prospect of CAE technologies about microcellular foam injection molding was proposed.

Effect of cutting parameters on surface quality during diamond turning of micro-prism array

2016 ◽  
Vol 231 (3) ◽  
pp. 555-561 ◽  
Author(s):  
Dongxu Wu ◽  
Peng Zhang ◽  
Huiming Wang ◽  
Zheng Qiao ◽  
Bo Wang
Keyword(s):  
Surface Quality ◽  
Surface Defects ◽  
Cutting Speed ◽  
Side Surface ◽  
Cutting Parameters ◽  
Diamond Turning ◽  
Dominant Factor ◽  
Controlled Cooling ◽  
Cutting Depth ◽  
Ultra Precision

In order to achieve the high-quality roller mold used in roll-to-roll fabrication of optical prism films, this article investigates the effects of cutting parameters on surface quality during diamond turning of micro-prism array, and some cutting experiments are carried out on home-made ultra-precision drum roll lathe. The surface defects such as micro pits and burrs are presented and discussed at different cutting parameters. The experimental results show that, when the cutting depth is more than 4 µm, the plowing force becomes the dominant factor to remove material, which may cause the generation of micro pits on the side surface of micro prism. During multiple-step diamond turning of micro-prism array, the final cutting depth is recommended not to exceed 2 µm; in this case, there is no generation of micro pits and the height of burr is less than 13.6 nm. Moreover, the well-controlled cooling and chip evacuation can effectively improve the influence of cutting speed on surface quality. Finally, micro-prism array with pitch of 40 µm is successfully machined without apparent surface defects.

Research on Tribological Properties of Environment-Friendly Nano-MoS2 Water-Based Rolling Liquid

2020 ◽  
Vol 861 ◽  
pp. 349-353
Author(s):  
Yan Li ◽  
Ren Dong Liu ◽  
Lei Xia ◽  
Rong Sheng Sun ◽  
Jian Jun Zhang ◽  
...  
Keyword(s):  
Surface Quality ◽  
Laser Scanning ◽  
Surface Defects ◽  
Rolled Strip ◽  
Environment Friendly ◽  
Lubrication Performance ◽  
Water Based ◽  
The Coefficient Of Friction ◽  
Water Base

In this research, the four-ball tribometer was examined to evaluate the tribological behavior of environment-friendly nano-MoS2 water-based rolling liquid. This experimental method is used to measure the maximum non-seizure load (PB) and the coefficient of friction (μ). The newly introduced parameter ω can be combined with PB and μ to evaluate the tribological performances of the rolling liquid comprehensively. The rolling lubrication performance of nano-MoS2 water-base lubricant was investigated using a single stand 4-high reversing rolling mill. The surface morphologies and rolling textures of the samples were measured by laser scanning confocal microscope after cold rolling. The results show that when the concentration of nano-MoS2 is 0.4wt.%, the water-based rolling liquid has excellent tribological and lubricating properties. Meanwhile, compared with the surface quality of the rolled strip under other lubrication conditions, the surface quality of the cold-rolled strip using 0.4wt% nano-MoS2 rolling liquid as the lubrication condition is smooth without visible surface defects.

Design of Automatic Detection Device for Steel Bar Surface Defects

2012 ◽  
Vol 532-533 ◽  
pp. 390-393 ◽  
Author(s):  
Jian Chuan Zhang ◽  
Wu Bin Li ◽  
Chang Hou Lu
Keyword(s):  
Image Processing ◽  
Surface Quality ◽  
Automatic System ◽  
Surface Defects ◽  
Detection System ◽  
High Luminance ◽  
Linear Ccd ◽  
Steel Bar ◽  
And Performance

To inspect the surface quality of steel bar, we designed an automatic system including linear camera and laser. Through the comparison among kinds of cameras, we select linear CCD to our system. The laser is also chosen by us with its high luminance and performance. Through a series of computation, we select the appropriate camera lens to our device. At last, we draw the whole detection system. This device has been used well and provides a good foundation for prospective image processing.

Some Observations in Grinding Surface Quality of FRCMC

2013 ◽  
Vol 770 ◽  
pp. 198-201 ◽  
Author(s):  
Xiao Yan Cao ◽  
Bin Lin ◽  
Yan Wang ◽  
Shao Lei Wang
Keyword(s):  
Surface Quality ◽  
Fiber Orientation ◽  
Surface Defects ◽  
Optical Measurement ◽  
Orientation Angle ◽  
Decisive Role ◽  
Ceramic Matrix Composites ◽  
Obtuse Angle ◽  
High Tech

FRCMCs have potential applications in aerospace and other high-tech fields. According to FRCMCs anisotropic and non-homogeneous structure, the composites surface characteristics are different from metal material. Fiber orientations play the decisive role in grinding surface quality of woven ceramic matrix composites. This paper investigates the relationship between fiber orientations and grinding surface quality. Using a non-contact optical measurement instrument, the method was developed on 2.5D SiO2/SiO2 composite. Through a series of measuring experiments, it was found that greater grinding surface quality occurred at a fiber orientation 90, but poorer grinding surface took place at a fiber orientation 0. Meanwhile there were less surface defects at acute fiber orientation angle than at obtuse angle. The research obtained will be an important technical support on improving the processing quality of FRCMC.

scholarly journals Experimental Research on the Surface Quality of Milling Contour Bevel Gears

2021 ◽  
Author(s):  
Mingyang Wu ◽  
Jianyu Zhang ◽  
Chunjie Ma ◽  
Yali Zhang ◽  
Yaonan Cheng
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Surface Defects ◽  
Low Noise ◽  
Tooth Surface ◽  
Machining Accuracy ◽  
Machined Surface ◽  
Bevel Gears ◽  
Machined Surface Roughness

Abstract Contour bevel gears have the advantages of high coincidence, low noise and large bearing capacity, which are widely used in automobile manufacturing, shipbuilding and construction machinery. However, the quality of the tooth surface has a significant impact on the transmission accuracy of the gear, so it is of great significance to optimize the surface quality of the contour bevel gear. This paper firstly analyzes the formation process of machined surface roughness of contour bevel gears on the basis of generating machining method, and dry milling experiments of contour bevel gears are conducted to analyze the effects of cutting speed and feed rate on the machined surface roughness and surface topography of the workpiece. Then, the surface defects on the machined surface of the workpiece are studied by SEM, and the causes of the surface defects are analyzed by EDS. After that, XRD is used to compare the microscopic grains of the machined surface and the substrate material for diffraction peak analysis, and the effect of cutting parameters on the microhardness of the workpiece machined surface is investigated by work hardening experiment. The research results are of great significant for improving the machining accuracy of contour bevel gears, reducing friction losses and improving transmission efficiency.

Study on the surface quality of 60vol% SiCp/Al2024 composites with large-grained

2022 ◽  
pp. 095440622110607
Author(s):  
Po Jin ◽  
Qi Gao ◽  
Quanzhao Wang ◽  
GuangYan Guo
Keyword(s):  
Surface Quality ◽  
Surface Defects ◽  
Subsurface Damage ◽  
Micro Milling ◽  
Stress And Strain ◽  
Particle Removal ◽  
Multiple Particles ◽  
Cutting Velocity ◽  
Stress And Strain Distribution

In this paper, the finite element cutting simulation model with irregular distribution of multiple particles is established, the stress and strain distribution of SiC particles in the process of machining, as well as the material removal mechanism are analyzed. The effects of cutting velocity and feed per tooth on the surface quality of the material are also analyzed. The effect of feed per tooth on subsurface damage is revealed. The results show that in the micro-milling of SiCp/Al2024 composites, the particle removal form is mainly crushing and extraction. The surface defects of the workpiece mainly include pits, scratches, cracks, and extrusion damage. When the cutting velocity increases, the surface defects gradually change to crack, which can improve the surface quality of the workpiece. Increasing the feed per tooth will increase the surface defects of the workpiece and lead to poor surface quality. When the feed per tooth increased from 0.428 µm to 0.714 µm, the subsurface damage thickness increased from 35.2 µm to 47.3 µm.

Characterization of homoepitaxial diamond films by Electron microscopy

1991 ◽  
Vol 49 ◽  
pp. 880-881
Author(s):  
D.P. Malta ◽  
S.A. Willard ◽  
R.A. Rudder ◽  
G.C. Hudson ◽  
J.B. Posthill ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Surface Defects ◽  
Substrate Surface ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Large Degree ◽  
Rf Plasma ◽  
Semiconducting Diamond

Semiconducting diamond films have the potential for use as a material in which to build active electronic devices capable of operating at high temperatures or in high radiation environments. A major goal of current device-related diamond research is to achieve a high quality epitaxial film on an inexpensive, readily available, non-native substrate. One step in the process of achieving this goal is understanding the nucleation and growth processes of diamond films on diamond substrates. Electron microscopy has already proven invaluable for assessing polycrystalline diamond films grown on nonnative surfaces.The quality of the grown diamond film depends on several factors, one of which is the quality of the diamond substrate. Substrates commercially available today have often been found to have scratched surfaces resulting from the polishing process (Fig. 1a). Electron beam-induced current (EBIC) imaging shows that electrically active sub-surface defects can be present to a large degree (Fig. 1c). Growth of homoepitaxial diamond films by rf plasma-enhanced chemical vapor deposition (PECVD) has been found to planarize the scratched substrate surface (Fig. 1b).

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