scholarly journals Adaptive Stretch-Forming Process: A Computer Vision and Statistical Analysis Approach

Machines ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 357
Author(s):  
Cosmin Constantin Grigoras ◽  
Valentin Zichil ◽  
Bogdan Chirita ◽  
Vlad Andrei Ciubotariu

An industrial process is defined through its quality of parts and their production costs. Labour-intensive operations must be applied to produce high-quality components with inexpensive resources. Recent development in dedicated software allows the industrial sector to rely on more and more autonomous solutions to obtain an optimum ratio between part quality and cost. The stretch forming process is an operation that has a high degree of difficulty, due to the process parameters and the spring-back effect of materials. Our approach to solving several of the shortcomings of this process was to develop a self-adaptive algorithm with computer vision capabilities that adapts to the process in real-time. This experimental study highlights the results obtained using this method, as well as a comparison to a classical method for the stretch-forming process (SFP). The results have noted that the stretch-forming algorithm improves the process, while adapting its decisions with each step.

2011 ◽  
Vol 130-134 ◽  
pp. 2240-2244
Author(s):  
Jing Ling Wang ◽  
Zhong Yr Cai ◽  
Mine Zhe Li ◽  
Hui Yang

Multi-point stretch forming is a flexible manufacturing technique for three-dimensional shape forming of craft skin. Its die surface is constructed by many pairs of matrices of elements whose height is controlled by computer. It uses the curved surface of elements instead of the die surface. The element numberis an important parameter because it has great influence on the part quality. This paper simulates the forming process of paraboloid part and saddle-shaped part with different number of elements and studies the influence of element number on the shape accuracy of the part .That will provides guidance for the application of multi-point stretch forming.


Author(s):  
C. J. Prabhakar ◽  
S. H. Mohana

The automatic inspection of quality in fruits is becoming of paramount importance in order to decrease production costs and increase quality standards. Computer vision techniques are used in fruit industry for fruit grading, sorting, and defect detection. In this chapter, we review recent approaches for automatic inspection of quality in fruits using computer vision techniques. Particularly, we focus on the review of advances in computer vision techniques for automatic inspection of quality of apples based on surface defects. Finally, we present our approach to estimate the defects on the surface of an apple using grow-cut and multi-threshold based segmentation technique. The experimental results show that our method effectively estimates the defects on the surface of apples significantly more effectively than color based segmentation technique.


2018 ◽  
Vol 767 ◽  
pp. 212-219 ◽  
Author(s):  
Patrik Schwingenschlögl ◽  
Jennifer Tenner ◽  
Marion Merklein

Hot stamping is a well-established technology for producing safety relevant components. The use of hot stamped components in modern car bodies offers the possibility of improving the crash performance while reducing the fuel consumption by using thinner sheet thicknesses. Hot stamped components are mainly produced out of the boron-manganese-steel 22MnB5. To avoid oxide scale formation during the heat treatment and the subsequent forming process AlSi coatings are applied on the workpiece surface. Due to the high forming temperatures, the use of lubricants is not suitable for the hot stamping process. Consequently, high friction and severe wear occur during the forming process and affect the resulting quality of hot stamped parts as well as the tool wear. In order to improve the part quality and increase the efficiency of industrial hot stamping applications, measures for reducing the tribological load during the forming have to be found. Within this study, the tool-sided impact on the tribological conditions is analyzed. Three different hot working tool steels were characterized based on strip drawing experiments under hot stamping conditions. Based on these investigations the tool steel characteristics hardness, thermal conductivity as well as chemical composition have been identified as possible influencing factors on the tribological conditions. Furthermore, the influence of the surface finish on the tribological performance was investigated by analyzing tool surfaces with three different roughness values and two PVD coatings. The experiments indicate a significant reduction of friction and wear due to application of PVD coatings while the tool roughness did not affect the tribological behavior under hot stamping conditions.


2011 ◽  
Vol 291-294 ◽  
pp. 282-285 ◽  
Author(s):  
Hao Han Zhang ◽  
Ming Zhe Li ◽  
Wen Zhi Fu ◽  
Xue Chen

Multi-Roll Stretch forming process is a new flexible process which is used for forming hyperbolic-degree surface pieces. Using the Multi-point flexible floating clamping system, the metal sheet can be more easily formed, and the flexibility can be much higher, which the ordinary floating clamping cannot have. A series of finite element simulations and experiments have been done for the process of forming saddle-shaped parts using Multi-Point flexible floating clamping system, and ordinary floating clamping system. The results show that the quality of the part formed using flexible floating clamping system is better.


2016 ◽  
Vol 705 ◽  
pp. 126-130 ◽  
Author(s):  
Dewa Ngakan Ketut Putra Negara ◽  
Tjokorda Gde Tirta Nindhia ◽  
I Wayan Surata ◽  
Made Sucipta

Currently, the use of activated carbon (AC) increased significantly for the industrial sector, health, environment and agriculture. However, the commercial price of activated carbon is relatively expensive, especially for micro industries mainly due to high production costs. Additionally, it comes from non-renewable sources with limited availability. This prompted the researchers to study the production of AC from inexpensive precursors and renewable; one of which is made from bamboo. AC production can be done through a pyrolysis process followed by physical or chemical activation. Differences in raw materials and activation methods used can affect the characteristics and quality of activated carbon produced. This paper reviews the development and application of bamboo activated carbons in the life sectors and their potency for use as an adsorbent material for the absorbed natural gas (ANG).


2000 ◽  
Vol 123 (4) ◽  
pp. 496-503 ◽  
Author(s):  
D. E. Hardt ◽  
W. A. Norfleet ◽  
V. M. Valentin ◽  
A. Parris

The process of stretch forming is used extensively in the aerospace industry to form large sheet panels of mild curvature. This has traditionally been a low precision process requiring considerable hand-working at assembly. However, recent demands for faster, less wasteful production have placed new demands on the accuracy and consistency (quality) of this process. In this paper the various modes of control for this process are examined, from both an analytical and experimental point of view. It is shown clearly that the process is least sensitive to material and machine property variations if controlled to a target level of strain in specific areas of the sheet. This method is compared with the conventional methods of controlling either the force applied to the sheet during stretching or the displacement of the stretch jaws. A series of both lab scale and full production experiments concur with the analytical findings, demonstrating reduced process variation if strain feedback is used. Lab experiments and analysis indicate that far greater reductions are possible if a more precise form of strain control is used. In production trials forming wing leading edges, a manually implemented strain control showed a shape variation reduction of 50 percent over normal factory practice using force control.


Author(s):  
Ibtissem Jbira ◽  
Antoine Tahan ◽  
Mohamed Ali Mahjoub ◽  
Borhen Louhichi

Due to machine tool imprecisions during manufacturing, the actual product cannot be the same as the nominal model. The product’s geometric variations influence the geometrical requirements of functionality and assembly [6, 8]; this remains a problem of industrial performance and plays a major role in the quality and cost of products; hence the need for a reliable strategy to evaluate errors in the final inspection of part quality. Among all the geometric characteristics, the circular characteristic is very common on most parts. Therefore, the measurement and evaluation of circularity with a high degree of accuracy is of utmost importance. Size, form and orientation are the basic descriptors of the geometric quality of the objects. The recent publication of ISO 14405-1: 2016 defines the size as the fundamental geometric descriptor; it described a new set of specification tools for the size of part characteristics that directly apply to the ideal geometry of the component [13]. These tools present new challenges for an inspector using a coordinate metrology system. The study of the influence of form defects on the identification of dimensional and geometrical requirements seems necessary. This paper studies four modifiers ISO 14405-1:2016 (Minimum circumscribed size (GN), Maximum recorded size (GX), least squares size Minimum (GG) and Minimum area (MZ)) will be studied. This paper presents simple and effective algorithms for evaluating the circularity error of a large number of points using four specification modifiers of ISO 14405-1:2016, and a study on the influence of measurement system strategies on different algorithms for the evaluation of these new specifications. An analysis software was developed to compare the sensitivity of different parameters (number of points, noise amplitude and circularity defect) on ISO 14405-1:2016 modifiers.


2000 ◽  
Author(s):  
D. E. Hardt ◽  
W. A. Norfleet ◽  
V. M. Valentin ◽  
A. Parris

Abstract The process of stretch forming is used extensively in the aerospace industry to form large sheet panels of mild curvature. This has traditionally been a low precision process requiring considerable hand-working at assembly. However, recent demands for faster, less wasteful production have placed new demands on the accuracy and consistency (quality) of this process. In this paper the various modes of control for this process are examined, from both an analytical and experimental point of view. It is shown clearly that the process is least sensitive to material and machine property variations if controlled to a target level of strain in specific areas of the sheet. This method is compared with the conventional methods of controlling either the force applied to the sheet during stretching or the displacement of the stretch jaws. A series of both lab scale and full production experiments concur with the analytical findings, demonstrating reduced process variation if strain feedback is used. Lab experiments and analysis indicate that far greater reductions are possible if a more precise form of strain control is used. In production trials forming wing leading edges, a manually implemented strain control showed a shape variation reduction of 50% over normal factory practice using force control.


2018 ◽  
pp. 1627-1639
Author(s):  
C. J. Prabhakar ◽  
S. H. Mohana

The automatic inspection of quality in fruits is becoming of paramount importance in order to decrease production costs and increase quality standards. Computer vision techniques are used in fruit industry for fruit grading, sorting, and defect detection. In this chapter, we review recent approaches for automatic inspection of quality in fruits using computer vision techniques. Particularly, we focus on the review of advances in computer vision techniques for automatic inspection of quality of apples based on surface defects. Finally, we present our approach to estimate the defects on the surface of an apple using grow-cut and multi-threshold based segmentation technique. The experimental results show that our method effectively estimates the defects on the surface of apples significantly more effectively than color based segmentation technique.


Agriculture sets difficult problems for the engineer because, although it is a vast industry in many countries, it is frequently organized in comparatively small production units. Furthermore, much of the work on the farm has to be done for short periods. Thus, the economics of farming often dictate that the engineering products to be used must be low in capital cost. These factors are discussed in relation to future developments. The tractor is usually the source of power in many farm machines. Compared with other farm equipment, tractors are manufactured in large numbers in plants where capital investment is high and where radical changes in design are costly to introduce. In the last 30 years tractors have shown steady increases in power and sophistication which have enabled them to be used more productively. They are the outstanding example of versatility in farm equipment but their value could be increased in the future if research in progress on using the power of the tractor in different ways from the traditional for soil cultivation is successful. Consideration is given to the implications of this important aspect of husbandry practice. The early tractor-drawn combine harvesters for cereal crops soon became self-propelled. Over the years, they have become more powerful and more complex; attempts by the research worker to produce an alternative way of separating grain from straw and chaff have shown promise and may lead to simpler and lighter machines by the 1980s. At the other extreme, there are many valuable crops produced in relatively small quantities, but they are, nevertheless, an important constituent of the improving quality of life. The problems in harvesting such crops are often acutely difficult to overcome and a high degree of specialization in operation, and therefore of design, is essential. Attempts over many years to make some harvesting machines suitable for a wide variety of crops by successful and ingenious engineering design and development have, at best, enjoyed limited success and farmers will most probably require more and more special purpose machines for individual crops. However, it may prove possible to make economies in manufacturing and production costs by using common components and common sub-assemblies. In future, livestock farms will need to use much specialized engineering equipment to maintain production with a much smaller labour force. The dairy parlour will require data processing equipment to enable men to milk and feed large herds of cows. It will be necessary to provide improved means for transporting and weighing food, better control of the environment for stock, and less time-consuming and unpleasant means of treating farm wastes.


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