Q2. How could a 0.5mm thickness be formed into a cone?
65Cr2 sheets with a 0.5mm thickness could, for example, be formed into cones with slope angles up to 57° at room temperature without any cracks appearing before a 40mm depth was reached.
Q3. What is the effect of dynamic heating on the formability of a single point incremental forming?
Comparing elastic deformation during unclamping allows to conclude that appropriate settings of the local heating and cooling parameters leads to reduced residual stress levels.
Q4. What was the effect of the coating on the laser side of the blank?
A graphite 33 coating was applied to the laser side of the blank in order to improve the absorption (approximately 60% with coating).
Q5. What is the main reason for the deformation in the vicinity of the tool contact area?
in the surrounding zone, that needs to provide the necessary support for achieving an accurate incremental forming effect, a high yield strength and a strong hardening effect contribute to a welllocalised deformation and consequently a high accuracy.
Q6. What is the way to prevent thermal gradients?
Strong temperature gradients over the thickness of the sheet material and extreme gradients in the planar direction thus need to be avoided in order to prevent thermal gradient and buckling mode forming effects [12] to take place.
Q7. How much emissivity can be expected at a load of 1000N?
with some variation (due to toolpath related changes in robot configuration), at a load of 1000N an average deflection of the robot joints and structural elements in the direction of the tool axis of 1.23mm can be expected.
Q8. What was the thickness of the sheet used to compare with the test results obtained at ambient temperature?
TiAl6V4 sheets of 0.6mm thickness were used to compare the formability behaviour under dynamically heated conditions with test results obtained at ambient temperature.
Q9. What is the effect of dynamic heating on the forming of a part?
While for the left part (A) a 30° cone was created at ambient temperature conditions, for the part at the right a 50° cone was generated using dynamic local heating support.
Q10. What was the effect of the local heating on the process forces?
One of the experiments conducted to demonstrate the influence of a local temperature increase on the process forces consisted of forming a series of cones in Al 5182.
Q11. What is the effect of the temperature on the ductility of the material?
The elevated temperature can only contribute to an improved ductility of the material when achieved in the tool-workpiece contact zone.
Q12. What was the thickness of the backing plate?
A backing plate with 180mm diameter cutout was selected, resulting in a 10mm wide, unsupported, ring shaped area between the cone and the backing plate.
Q13. What is the effect of local, dynamic heating?
The preliminary test results presented in this paper illustrate the effectiveness of local, dynamic heating as a means to reduce process forces in single point incremental forming.
Q14. What is the effect of the reduced process forces on the toolworkpiece?
it can be expected that the reduced process forces, as illustrated in Section 3.1, will contribute to a reduction of unwanted plastic deformation in the vicinity of the toolworkpiece contact zone.
Q15. What are the main causes of the deformation in the vicinity of the tool contact zone?
As cause for the unwanted deformation in the vicinity of the tool-workpiece contact zone, a combination of the following factors can be listed [8,9]: - relatively high process forces, resulting in high stresslevels outside the contact zone - limited yield strength of the sheet material andhardening effects
Q16. What is the way to generate thermal fields?
Thermal fields thus need to be generated in such a way that the induced thermal stresses do not negatively affect the incremental forming process.
Q17. What is the forming effect of the laser supported cone?
The groove like geometry edging the unprocessed bottom of the cone (zone B) also illustrates the more localised forming effect when using local heat support.
Q18. What is the main reason for the inaccuracy of the process?
Analysis of the emergence of geometric inaccuracies in the consecutive stages of the process, based on experimental [4] and simulation results [5], unveil unwanted plastic deformation in the vicinity of the tool contact area and springback effects as major sources of inaccuracy (Figure 1).
Q19. What is the effect of the temperature rise on the emissivity of the sheet material?
As can be observed from the results summarised in Figure 3, even for a material with a high thermal diffusivity like Al5182, a systematic temperature rise through the thickness of the sheet material can be dynamically imposed.