Flowdrilling: a Preliminary Analysis of a New Bush-Making Operation

Flowdrilling is a bush-making operation applied to thin walled products for joint engagement. Fastenings exhibit mechanical properties which depend largely on the shear strength of the parent material and the area of engagement. Flowdrilling is specifically designed to increase the latter. Developments during the last six or seven years have resulted in a number of industrial usefull applications. Previous attempts to use “rotary plunging methods” failed due to low tool life and the inability to obtain an acceptable finish. The paper describes the different process variables and gives the results of a preliminary analysis of the different mechanical and physical aspects. Manufacturing properties like cycle time and tool life are also dealt with

Design study of the geometry of a punching/blanking tool

The cost of tooling in sheet metal industries contributes a considerable part to the overall cost of manufacturing a component. It is therefore imperative to keep down this cost by ensuring that the tool works for a long period in production without interruption. One way of achieving this objective is to reduce the stress on the tool during punching/blanking.\ud \ud This paper deals with the study of this problem by using the finite-element technique. 3-D finite-element models of various type of punching/blanking tools have been developed, these models enabling the analysis of the effects of variations in tool geometry on the punching/blanking force and on the deformation of the punch, a parameter highly relevant to the assessment of tool performance in terms of the accuracy of the manufactured components. The model caters also for variation in the characteristics of the tool material, in the sense that a highly wear-resistant tool is normally composed of carbide tips around its cutting profile. Computed results by FE models are checked against design standards by American Society of Manufacturing Engineers (SME). Some suggestions are offered as to how the efficiency of a punching/blanking tool can be improved

Tolerancing and Sheet Bending in Small Batch Part Manufacturing

Tolerances indicate geometrical limits between which a component is expected to perform its function adequately. They are used for instance for set-up selection in process planning and for inspection. Tolerances must be accounted for in sequencing and positioning procedures for bending of sheet metal parts. In bending, the shape of a part changes not only locally, but globally as well. Therefore, sheet metal part manufacturing presents some specific problems as regards reasoning about tolerances. The paper focuses on the interpretation and conversion of tolerances as part of a sequencing procedure for bending to be used in an integrated CAPP system

Long-term wine consumption is related to cardiovascular mortality and life expectancy independently of moderate alcohol intake: the Zutphen Study

Background: Light to moderate alcohol intake lowers the risk of cardiovascular mortality, but whether this protective effect can be attributed to a specific type of beverage remains unclear. Moreover, little is known about the effects of long-term alcohol intake on life expectancy. Methods: The impact of long-term alcohol intake and types of alcoholic beverages consumed on cardiovascular mortality and life expectancy at age 50 was investigated in the Zutphen Study, a cohort of 1373 men born between 1900 and 1920 and examined repeatedly between 1960 and 2000. Hazard ratios (HRs) for total alcohol intake and alcohol from wine, beer and spirits were obtained from time-dependent Cox regression models. Life expectancy at age 50 was calculated from areas under survival curves. Results: Long-term light alcohol intake, that is =20 g per day, compared with no alcohol, was strongly and inversely associated with cerebrovascular (HR 0.43, 95% CI 0.26 to 0.70), total cardiovascular (HR 0.70, 95% CI 0.55 to 0.89) and all-cause mortality (HR 0.75, 95% CI 0.63 to 0.91). Independent of total alcohol intake, long-term wine consumption of, on average, less than half a glass per day was strongly and inversely associated with coronary heart disease (HR 0.61, 95% CI 0.41 to 0.89), total cardiovascular (HR 0.68, 95% CI 0.53 to 0.86) and all-cause mortality (HR 0.73, 95% CI 0.62 to 0.87). These results could not be explained by differences in socioeconomic status. Life expectancy was about 5 years longer in men who consumed wine compared with those who did not use alcoholic beverages. Conclusion: Long-term light alcohol intake lowered cardiovascular and all-cause mortality risk and increased life expectancy. Light wine consumption was associated with 5 years longer life expectancy; however, more studies are needed to verify this resul

Long-term lifestyle and dietary habits in relation to cardiovascular mortality and life expectancy: a prospective cohort study

Introduction: In prospective cohort studies, information on lifestyle and dietary habits is generally only assessed at the baseline examination, assuming that these habits are relatively constant over the entire study period. Repeated measures can take into account changes in these habits, reduce measurement error due to a reduction in within-subject variation, and can give more insight into the etiology of diseases. The main objective of this thesis is to assess the relationships of recent and long-term exposure to known lifestyle and dietary risk factors with cardiovascular mortality and life expectancy. Methods: We used data from the Zutphen Study, a prospective cohort study among 1373 men born between 1900 and 1920. These men were examined repeatedly in seven examination rounds between 1960 and 2000. In addition to hazard ratios (HR), we presented some of our results in terms of differences in life expectancy at age 50. Main findings on lifestyle factors: We found that both the number of cigarettes smoked and smoking duration were strongly associated with mortality risk. Compared to never or long-term former smoking, cigarette smoking decreased life expectancy by about 7 years and exclusive cigar or pipe smoking decreased life expectancy by about 5 years. Stopping smoking cigarettes at age 50 increased life expectancy by 3.3 years. Furthermore, we observed that long-term light alcohol intake, i.e. Main findings on dietary factors: We observed that average trans unsaturated fatty acid intake decreased from 7 to about 1 percent of energy intake between 1960 and 2000 and that each additional 2 percent of long-term energy intake from trans unsaturated fatty acids was positively associated with sudden coronary death (HR: 1.62 [1.01 to 2.60]). In contrast, long-term fatty fish consumption was inversely associated with sudden coronary death (HR: 0.46 [0.27 to 0.78]). The strength of the association between long-term total fish consumption and coronary heart disease (CHD) death decreased from age 50 (HR: 0.32 [0.13 to 0.80]) until age 80 (HR: 1.34 [0.58 to 3.12]). We observed no clear dose-response relationship between the intake of the n-3 fatty acids EPA and DHA, and (sudden) coronary death. Finally, we found that each additional 10 grams of recent dietary fiber intake was associated with a lower risk of CHD (HR: 0.83 [0.70 to 0.98]) and all-cause (HR: 0.91 [0.82 to 1.00]) mortality. Conclusions: The studies described in this thesis emphasize the importance of lifestyle and diet for public health. Our results suggest that non-smoking and a low level of wine consumption decrease the risk of (cardiovascular) mortality and will increase life expectancy at age 50. The long-term consumption of fatty fish and the reduction in long-term trans unsaturated fatty acid intake may prevent sudden coronary deaths, and a higher recent dietary fiber intake may reduce both CHD and all-cause mortality risk. <br/

A process model for air bending

A so called `three-section¿ model for air bending is presented. It is assumed that a state of plane strain exists and that Bernoulli's law is valid. The material behaviour is described with Swift's equation, and the change of Young's modulus under deformation is addressed. As compared with other models, the model described in the paper is capable of generating information such as required punch displacement and the unfolded blank size, very accurately. With in-process measurement of the spring-back angle, the punch displacement can be calculated even more accurately

The generation of bending sequences in a CAPP system for sheet-metal components

An important process-planning task in sheet-metal manufacturing is the determination of bending sequences for individual components. Computer-aided generation of these sequences, as part of a computer-aided process-planning (CAPP) system, can relieve the workload of process-planning departments, this being especially important in small batch manufacturing environments. This paper discusses the functions that have to be performed during the determination of bending sequences, focusing on accuracy aspects. The generation of bending sequences is also put into the broader perspective of an integrated CAPP system such as PART-S, which is under development presently in the author's laboratory

The functional independence measure used in a Dutch rehabilitating stroke population:a pilot study to assess progress

In contrast to the United States, the Functional Independence Measure (FIM) is seldom used in Dutch rehabilitation settings. The purpose of this study was to determine if the FIM could be used in a Dutch stroke population to assess progress during rehabilitation. Patients with a recent stroke who received inpatient treatment were included in this longitudinal pilot study, which used the standard error of measurement (SEM) to quantify progress. Mean (SD) age of the subjects (n =48) was 61.3 (10.5) and 25 (56%%) were male. Mean (SD) length of stay (LOS) was 141.3 (75.0) days. For 42 subjects, admission and discharge scores of the FIM were registered. The mean admission (93.0, SD=23.3), as well as the discharge (112.4, SD=11.0) scores were rather high. The mean FIM difference (SD) between admission and discharge was 19.3 (16.9). However, only 55% exceeded a difference score of 13 points, indicating progress. Results of this pilot study confirm the ceiling effect of the FIM in this population. Based on the findings of our pilot study we conclude that the FIM is not suitable to assess progress in a Dutch rehabilitating stroke population

Process planning for small batch manufacturing of sheet metal parts

The paper describes process planning for order-based small batch sheet metal part manufacturing. In this domain, general purpose CNC machinery and standard tools are being used. An example of a process planning system is given and some areas of special interest are discussed in more detail. Process planning for sheet bending and tolerance reasoning are important and intricate tasks within process planning, whereas abstractions in design and nesting are important due to their relations with other manufacturing functions. In general, manufacturing functions tend to become increasingly intertwined and traditional boundaries become blurred. Sheet metal industries, customers and suppliers alike, can benefit from this