Development of the sheared edge in the trimming of steel and light metal sheet, part 1 - experimental observations

Trimming experiments were conducted on sheet metals including two drawing steels, an aluminum alloy and a magnesium alloy, using a specially designed die in a mechanical press. The punch-die clearance was varied and data obtained on the rollover and burr height as a function of the clearance. Samples were also partially trimmed to examine crack initiation, the generation of the fracture surface profile and mechanism of burr formation. The results showed that while the burr height and rollover depth generally increased with increasing clearance for all examined materials, there were differences in the fracture surface profile shape, the burr shape, and the mechanism of burr formation, between the two steels and the two light alloys. The major cause of these differences appeared to be the rate of crack propagation through the sheet material.

Development of the sheared edge in the trimming of steel and light metal sheet, part 2 - mechanisms and modelling

The shearing behavior of a drawing-steel and aluminum alloy were investigated using hardness contours of partially deformed samples and a finite element model of the trimming process. Results showed that the stress and strain distributions within the work-piece were more strongly dependent on the punch penetration than the material properties of the work-piece. Differences in the final fracture surface profile and burr formation of the drawing-steel and aluminum alloy were a consequence of the shape of the stress and strain distribution when the crack in the sample became unstable, not when it was initiated. Results and existing literature suggest that a correlation may exist between the strain-rate sensitivity of the work-piece material and the burr mechanism and fracture surface profile of the trimmed part.

An autonomous trimming system of large glass fiber reinforced plastics parts using an omni-directional mobile robot and its control

This paper describes an automated trimming system of large glass fiber reinforced plastic (GFRP) using an omni-directional wheeled mobile robot (WMR) and its path control method. In trimming GFRP parts, much glass fiber and plastic powder dust occur and it becomes bad visible in environment. It is necessary to correct dead-reckoning errors of the WMR in order to control its moving path. We have discussed an external correction method of the dead-reckoning errors for the WMR using ultrasonic sensor.

Simulation of contact pressure in sheet metal trimming/blanking process

In the car body stamping process, trim/blank die cutting edges are subjected to very high tribological loads that result in loss of tool material from both the punch and die cutting edges. According to Archard’s wear model, normal contact force and sliding distance directly affects the wear. Therefore, knowledge of the acting forces on local contact areas has a pivotal role towards the prediction of tool wear. This paper presents a finite element modelling approach to determining the contact pressure distribution on the tool cutting edges during a trimming/blanking process. Characteristic areas on sheared edge profile, variation of punch force and high contact pressures affected areas have also been analysed.

Sheared edge quality in the trimming of sheet metals

Examines the sheared edge quality of different automotive sheet metals resulting from the trimming process using experimental tooling and finite element modelling. The significant differences in burr, sliver and edge profile formation have been explained in terms of the strain distribution and tensile properties of the materials.

The ADKnowl: identifying knowledge deficits in diabetes care

Aims To present the ADKnowl measure of diabetes-related knowledge and evaluate its use in identifying the nature and extent of patient and health professional knowledge deficits.

Method The ADKnowl was used in a large-scale study of 789 patients (451 treated with insulin and 338 treated with tablets and/or diet) attending for annual review at one of two hospital out-patient diabetes clinics

Results Knowledge deficits were apparent in the patients. For example, 57% did not recognize the inaccuracy of the statement `fresh fruit can be eaten freely with little effect on blood glucose levels'. Seventy-five percent of patients did not know that it is advisable to trim toenails to the shape of the toe. Knowledge deficits were identified for many other areas of diabetes management, e.g. prevention of hypoglycaemia, avoidance of ketoacidosis. Sixteen health professionals at the clinics answered the same items. Contrary to recommendations, 25% of health professionals thought that fresh fruit could be eaten freely. Seventy-five percent of health professionals did not know the current recommendations for trimming toenails. As expected, HbA1c did correlate with scores from two specific items, while HbA1c did not correlate with summed ADKnowl score.

Conclusions Patient knowledge deficits were identified. Some specific knowledge deficits among health professionals may be the cause of some patient knowledge deficits. The ADKnowl is a useful tool in assessing both patient and health professional knowledge deficits and is available for use in a context of continuing evaluation.