Automatic generation of cross sections from computed tomography data of mechanical joining elements for quality analysis

In this work, we present a methodology for shifting from a conventionally destructive, manual quality analysis for repetitive processes towards a non-destructive and largely automated process. The objects subjected to the quality analysis are mechanical joining elements like rivets or flow-drilling screws. We propose an algorithm that can automatically find and extract such joining elements from a computed tomography (CT) scan, rotate these elements to an upright orientation and eventually generate radial cross sections parallel to the elements’ longitudinal axis. The proposed algorithm was tested on five grayscale-based computed tomography volumes, with one synthetically generated volume. We will discuss both, cases in which the duo of CT and our proposed algorithm produces satisfying results, as well as cases in which it fails. Limitations of both the scan acquisition process and the proposed algorithm will be elaborated on and potential improvements will be mentioned.

Porównanie wyników metod pomiaru skuteczności usuwania osadu płuczkowego

The proper cleaning of the annular space before cementing is one of the most important factors affecting the proper sealing of the casing column. Inadequate or incomplete removal of the mud cake or residues of the mud may result in the formation of uncontrolled gas outflows (migration or exhalation) at the contact of the cement sheath with the rock formation and with the surface of run-down casing. It is related to the lack of compatibility in the contact of the mud and the cement. Additionally, the lack of proper cleaning of the annular space will reduce the adhesion value of the cement sheath to the contact surface. The result of the above may be the lack of adequate stabilization of the column of pipes due to its weakened connection in the lower part with the wall, and in the upper part with the previous column of larger diameter pipes. Therefore, to improve both the tightness of the borehole as well as the quality of the cementation condition, laboratory tests of the efficiency of cleaning the annular space are carried out by measuring the efficiency of washing mud removal. So far, measuring the efficiency of mud removal or the effect of washing utilization have been done using a rotary viscometer. During the test, a mud cake is produced on the rotor surface and then removed with washing liquid. Recently, the Oil and Gas Institute – National Research Institute developed a new method for measuring the efficiency of drilling mud removal by using a newly developed drilling fluid flow simulator (Patent P.423842). The device enables the simulation of the drilling fluid flow (drilling fluid, washing fluid, spacer) in the simulated annular space. It is possible to select the parameters of the flow (delivery rate) and the contact time of the liquid with the tested surface. Due to the different measurement principles during the tests with the viscometer and the simulator, it was decided to conduct a comparison and determine the degree of convergence of the discussed methods. The same rinsing liquids were tested to remove the same type of mud, but using different measurement methods. The obtained values of mud removal efficiency were subjected to the correlation analysis, which made it possible to compare the results of the analyzed measurement methods.

Fatigue failure analysis of HSLA steel sheets holed by conventional and flow drilling processes

ABSTRACT Flow drilling process produces bushes for removable joints that can be threaded by forming tapping process, reducing stages in production of components of automobile industry and in construction sheds. High strength and low alloy steels (HSLA) are employed on several applications in the processing industry. Benefits provided by these materials make them an efficient solution, since their high cold resistance allows reducing weight on structures, as well as maintaining the required mechanical properties. The present study evaluated the conventional and friction drilling processes in HSLA steel sheets with a thickness of 4.25 mm. Specimens were subjected to cyclic loadings, with no rework after holemaking, so the resultant characteristics of each process were maintained. Fractured surfaces were analyzed with a scanning electron microscope (SEM) to identify the fracture mechanism in different drilling processes. Fractographies obtained on both processes indicated that the failure mechanism occurred due to ductile fracture resulting from the nucleation, growth and coalescence of micro cavities.

Flow drilling technology and thread forming - an economical and secure connection in hollow sections and thin-walled components

Detachable and highly loadable screw connections can only be realized in thin-walled components and in particular hollow profiles with great effort. The flow drilling technology and subsequent thread forming represents an economical and technically interesting manufacturing alternative. With Flow drilling, a bush is generated by a fast-rotating carbide taper mandrel and a high resistant internal thread can be produced in a subsequent manufacturing process. Conventional weldor rivet nuts can be replaced in many application areas.

Identification of Drilling Parameters during the Flow Drill Screw Driving Process

The automobile manufacturing industry, until recent years, has been using steel for car body components and the main method for joining these components has always been Resistance Spot Welding. However, since the global trends toward CO2 reduction and resource efficiency have significantly increased, the importance and usage of lightweight materials has enhanced as well. New lightweight materials such as aluminum and magnesium alloys, carbon-fiber-reinforced plastics, etc., have become a reality, thanks to the new fastening technologies. Flow drill screw driving (FDS) is a one–sided thermomechanical assembly process based on heat generation by frictional force and plastic deformation. A special screw, known as hole forming and self-tapping screw, is used in this process as both fastener and tool. Moreover, rotational and translation movements are applied to the screw to create special friction conditions with the workpiece. Furthermore, unlike traditional drilling and thread milling processes, there is no chip or waste of material in FDS and the machining operations are realized through plastic deformation. This paper explores flow drilling steps and the parameters which influence heating and local softening of the aluminum sheet 5182-0. An experimental study has been carried out by varying process parameters (rotational speed, drilling force), coating and geometry of the screw. As a result, an increase of rotational speed and drilling force allows significant reduction in drilling time and introduce an important variation of the torque installation. In addition, a strong dependence is observed between drilling time and torque on the one hand, and related to the screw parameters geometry and coating on the other hand. Finally, an evaluation of the heating effect on the thread forming operation is also undertaken.