Browsing by Author "Wegert, Robert"

Now showing 1 - 3 of 3

Open Access
Development of a multi-sensor concept for real-time temperature measurement at the cutting insert of a single-lip deep hole drilling tool
(2022) Ramme, Johannes; Wegert, Robert; Guski, Vinzenz; Schmauder, Siegfried; Möhring, Hans-Christian
The mechanical energy resulting from cutting processes is turned almost completely in thermal energy, which encourages thermal procedures, such as diffusion, leading to higher wear in the cutting tool and thus to higher temperatures. Furthermore, high temperatures influence the properties of the marginal zones in the workpiece. In this presented work, the in-process temperature of a cutting insert during single-lip deep hole drilling (SLD) is investigated. Therefore, a sensor-integrated tool with resistance temperature detectors (RTD) placed beneath the cutting insert is developed. First, the thermal properties of the cutting insert are adjusted to fit the assembled tool. Afterwards, a CEL-Simulation is obtained to examine the temperature distribution at the cutting edge of the SLD-tool. The temperatures calculated by simulation can be compared to the in-process temperatures of the sensor integrated tool. Because of the usage of a cooling lubricant, simulated temperatures can be varied with a factor to fit the experimentally measured temperature curves. The highest temperature during the process appears at the outer edge of the cutting insert. By knowing the thermal properties, the maximum process temperatures for the deep hole drilling operation are to be calculated. The results represent a contribution to an interdisciplinary research project “Surface Conditioning in Machining Processes” (SPP 2086) of the German Research Foundation (DFG).
Open Access
In-process approach for editing the subsurface properties during single-lip deep hole drilling using a sensor-integrated tool
(2024) Wegert, Robert; Guski, Vinzenz; Schmauder, Siegfried; Möhring, Hans-Christian
Single-lip deep-hole drilling (SLD) is characterized by high surface quality and compressive residual stress in the subsurface of the drill hole. These properties depend significantly on the thermomechanical conditions in the machining process. The desired subsurface properties can be adjusted in-process via process monitoring near the cutting zone with a sensor-integrated tool and closed loop control when the thermomechanical conditions are maintained in the optimum range. In this paper, a method is presented to control the thermomechanical conditions to adjust the properties in the subsurface. The process model integrated in the controller is implemented as a soft sensor and takes into account the residual stresses, the roughness, the hardness and the grain size in the surface as well as in the subsurface depending on the process control variables, such as the feed rate and cutting speed. The correlation between the process variables, the thermomechanical conditions of the cutting process and the subsurface properties are investigated both experimentally and by finite element (FE) simulations. Within a justified process parameter range, characteristic fields for the soft sensor were established for each property. In addition, the procedure of controller design and the employed hardware and interfaces are presented.
Open Access
Simulation study on single-lip deep hole drilling using design of experiments
(2021) Fandino, Daniel; Guski, Vinzenz; Wegert, Robert; Möhring, Hans-Christian; Schmauder, Siegfried
Single-lip deep hole drilling (SLD) is characterized by a high surface quality and compressive residual stress in the subsurface of the drill hole. These properties are strongly dependent on the cutting parameters of the SLD process and the actual geometry of the insert and the guide pads. In the present work, full 3D FE simulations of the SLD process were carried out to analyze the thermo-mechanical as-is state in the drilling contact zone by evaluating the feed force, the temperature, as well as the residual stress in the drill hole subsurface. An extensive simulation study was conducted on the effect of the process parameters on the properties using design of experiments (DoE). For the simulations, the Johnson-Cook (JC) constitutive law and the element elimination technique (EET) were applied to represent the material behavior of the workpiece, including chip formation. In-process measurements as well as results from the hole-drilling method to determine residual stresses were conducted to verify the numerical results. By means of DoE and analysis of variance (ANOVA), regression models were developed to describe the effect of the feed rate, cutting speed, and guide pad height on the temperature, feed force, and residual stress in the subsurface.