Earlier research (in the 1960s) in the field of pipe end transformation focused on the identification of the main process parameters, especially pipe inversion methods. In this context, in the present thesis, splicing using pipe end forming and splicing pipe end forming (FSPed) is performed. In the first part, the behavior of forming the pipe end with mechanical joining operations was studied.
Further, the mechanical testing of the joints formed from the bottom (sheet-tube and tube-tube) was performed. Later, it was observed that SZ shows lower dislocation density compared to other zones for most of the cases. In the case of beads, the thickness of the base metal is more than the thickness of the FSPed zone in most cases.
Greater hardness and reduced ductility of the base metal compared to the FSPed zone is responsible for this.
Nomenclature
Contents
- Introduction, Literature Review, Significance and Objective of Work
- Joining of a tube to a sheet through end curling
- Chapter 3: Joining steel tubes of different diameters by end forming operations
- End forming behaviour of FSPed Al 6063-T6 tubes at different tool rotational speeds
- End forming behaviour of FSPed Al 6063-T6 tubes at different tool traverse speeds
- End forming behaviour of FSPed Al 6063-T6 tubes at different pin profiles
- End forming behaviour of FSPed Al 6063-T6 tubes at different tool plunge depths
- Conclusions and scope of future work
51 2.2.4 Influence of parameters on the load-displacement behavior 51 2.2.5 Influence of parameters on the evolution of the thickness strain 55. 89 3.2.3 Influence of parameters on the evolution of the load 91 3.2.4 Effect of parameters on the evolution of the thickness the end of.
7.11 (a) Load-displacement behavior of the FSPed pipes made at different diving depths, (b) maximum load for parent pipe and FSPed pipe, for pipe beading.
List of Tables
Introduction, Literature Review, Significance and Objective of Work
- Introduction
- Literature review
- Influencing parameters in tube inversion, curling and flange formation
- Influencing parameters in tube expansion and reduction
- Influencing parameters in tube axial compression and crushing
- Influencing parameters in joining by tube end forming
- Modeling and simulation in tube end forming
- Effect of tool rotational speed and tool traverse speed
- Effect of tool geometry and tool plunge depth
- Modeling and simulation in FSW/FSP
- Significance of work
- Objectives of thesis
- Organization of thesis
The main purpose of this work is to study the end-forming behavior of pipes. It is observed that, the larger the half angle of the blow, the larger the forming load due to the greater clamping effect of the tube. It is observed that the slenderness ratio (lgap/ro) of the tube and the inclination angle α of the covers play a vital role in the formation of sound tube-sheet joints.
Regardless of grain size refinement, all FSP samples exhibit a reduction in tensile strength in the following order: Base metal>. The comparison of the temperature history measured and calculated by the thermocouple was carried out at coordinate mm). The change in the angle of the tool pin causes hardening of the workpiece due to upsetting.
We discussed the importance and goal of the thesis in the last part of the chapter.
Joining of a tube to a sheet through end curling
- Methodology
- Proposed joining method and parameters
- Demonstration and validation of the proposed method at lab scale
- Results and discussion
- Validation for standardizing the FE simulation of end forming of tubes
- Influence of parameters on the load-displacement behaviour
- Influence of parameters on the thickness strain evolution
- Quality analysis of the formed joints
- Experimental demonstration and validation at laboratory scale
- Load-displacement behaviour and energy absorbed during pull-out tests During Pull-out tests of the end formed joints and welded joints, it can be
- FE simulation of pull-out tests of end formed joint .1 Variation in „D‟ for different cases
- Conclusions
In this case the neck is formed slightly above the sheet due to the greater length of the tube. During the pull-out test, the tube within the twisted zone emerges from the bent part of the sheet and the unbuckling phenomena starts in the region of the joint. During the Pull-out test simulation, it was observed that the initial distance between diametrically opposite sides of the inner surface of the tube.
The effect of the initial tube and plate mesh size on the load displacement behavior and total processor time was observed through a sensitivity analysis of the tube mesh (Figure 2.16) for a specific case – Case 28 (see Table 2.1). A similar behavior is observed for all FE simulation cases of the proposed coupling procedure. With a tube length of 70 mm, this tube length is not sufficient to form a full neck in the undeformed part of the tube.
The thickness noise evolution at the edge of the pipe for different pipe lengths is shown in Fig. It is observed that the thickness strain at the edge of the tube is not much affected by different tube lengths. This shows that the thinning at the end of the pipe increases with increasing friction coefficient.
In the first case, due to smaller die groove radius, the bent edge of the tube touches the lower flange of the. The demonstration of the proposed connection method on a laboratory scale was carried out for three cases described earlier in Table 2.4. The load-displacement behavior obtained from the experimental trials is compared with the FE simulation results (Fig. 2.31) of the demonstrated coupling method.
The fault is due to the tube failure at the bend region while it is being deformed in the die groove region. When the punch is given upward displacement, the curled part of the tube is pulled in an upward vertical direction. During simulation studies, complete uncoupling is defined where the sheet finally emerges from the curled part of the tube.
For effective process planning, a comprehensive CAE analysis of the proposed joining method was performed using FE simulations.
Joining steel tubes of different diameters by end forming operations
- Methodology
- Parameters and mechanics of the proposed technology
- Materials used
- FE simulation details
- Theoretical model for joining tubes
- Criteria to assess the quality of joint formed
- Mesh sensitivity analysis
- Load-displacement behaviour and thickness evolution of tubes during joining Different zones have been defined according to change in deformation behaviour
- Influence of parameters on the load evolution
- Effect of parameters on the thickness evolution at the end of the tube
- Joint quality analyses based on criteria
- Mechanical testing of joints
- Merits and demerits of the proposed joining method
- Conclusions
The influence of α on the design of the inner tube is shown in fig. The mechanical properties of the inner and outer tubes are shown in table 3.2. The inner tube should be almost horizontal in the convex part of the outer tube without overlap at the free end of the inner tube.
Inner tube must be fully compressed within the bulging area of the outer tube for good joint formation. The free area of the inner tube should not bend outwards or inwards for a proper joint formation. Length of inner tube entering the bulging region of the outer tube is denoted as.
In the last few steps, the outer tube becomes thinner due to compression between the punch, the inner tube and the die (Figure 3.4d). The inner tube hits the bottom of the unsupported area of the outer tube after leaving the curl zone. The effect of h is almost negligible on the development of inner and outer tube thickness for different values.
As a result, the inner tube is properly clamped in the bulging area of the outer tube. Even after the inner tube was bent, the inner tube entered the bulging region of the outer tube. The failure is observed in the freely supported region of the inner tube and the outer tube.
In successful cases (cases 15 and 29), the inner and outer tubes are dismantled in the joint area. In case 21 (failed case), the inner tube does not easily come out from the bulged region of the outer tube, and buckling is observed in the supported and unsupported region of the inner tube.
End forming behaviour of FSPed Al 6063-T6 tubes at different tool
- Methodology
- FSP of tube
- Hardness distribution, tensile properties and grain size evaluation
- Dislocation density measurement using X-ray peak profile analysis
- Details of end forming of tubes
- Specific energy absorption capacity evaluation
- FE Simulation of end forming
- Instability prediction during end forming
- Results and discussion
- Dislocation density measurement
- End forming behaviour
- Specific energy absorption
- Simulation of end forming
- Conclusions
The hardness of the machined zone after final forming has been measured so that it can be compared with that of raw base material. The decrease in strength (or hardness) of the treated zone compared to raw base material can be improved during end forming. Three different zones have been identified in the processed zone according to grain size.
The hardness distribution was used to represent the strength of the FSPed zone under discussion. As mentioned earlier, the hardness of the FSPed zone is measured before and after molding. The average hardness of the machined zone before and after forming at all rotational speeds for all final forming operations is shown in Table 4.6.
The grain size investigation of the FSPed zone was done at all the rotation speeds (Fig. The average grain size of different regions of the FSPed zone is shown in Table 4.7. The base metal has greater hardness compared to the processed zone and therefore requires greater load for deformation , regardless of the end shape operations.
In the case of pipe expansion, failure of FSPed pipes occurred in the center of the treated zone. This is mainly due to reduced hardness of the treated zone compared to the base material of the pipe. The location of cracks in the base metal of the FSPed tube is random and has no relation to the FSPed zone.
The effect of tool rotation speed on the hardness distribution and grain size of the FSPed zone is negligible. The initial thickness of the FSPed zone also determines the load requirement during end forming. The thickness of the FSPed zone and the base material of the FSPed pipe are controlled by hardness changes in case of pipe expansion and reduction.
The hardness of the FSPed zone approaches that of base metal after end forming operations.
End forming behaviour of FSPed Al 6063-T6 tubes at different tool
- Methodology
- FSP experiments
- Details of end forming of tubes
- Hardness, tensile properties and grain size
- Dislocation density measurement using X-ray peak profile analysis
- FE simulation of end forming
- Instability prediction during end forming
- Tensile behaviour and hardness distribution
- End forming behaviour
Reasonable spacing between traverse speeds has been maintained so that their effect on pipe processing and end formation could be easily identified. The methodology for assessing hardness, tensile properties of base metals and processed zones and grain size is described in chapter 4 in section 4.1.2. The method for evaluating specific energy absorption of processed and untreated pipes is mentioned in chapter 4 in section 4.1.5.
Then, a discussion on the dislocation density and microstructural changes in different regions of machined zones is presented. The tensile behavior of the machined zone at different traverse speeds is shown in Figure. It is observed that with the increase in traversing speed, the strength, ductility and strain hardening exponent of the machined zone increases.
A coarser grain size closer to that of the base metal grain size was noted in HAZ. Modified Williamson-Hall plot for different zones and velocities is shown in Fig. The TMAZ made at different through speeds exhibits greater slope (Fig. 5.7b) compared to the base metal except 125 mm/min.
It means that for different displacement speeds, TMAZ possesses greater or equal dislocation density compared to base metal. It suggests that the dislocation density in the base metal and the HAZ region is almost the same for different displacement rates. The hardening capacity (Hc) for the base metal and the machined zone at different travel speeds and their respective n values are shown in Table 5.8.
The load-displacement behavior during tube expansion, tube reduction and tube shrinkage is shown in Fig. The evolution of thinning of raw tube, FSPed zone and base metal in the FSPed tubes is shown in Fig.
