EVALUATION OF MECHANICAL RESISTANCE BY THE FINITE ELEMENTS METHOD OF A MACHINING TOOL WITH INTERNAL COOLING CHANNELS

In this work, the strength of machining hardware for the modified turning process with internal channels that circulates water as a coolant through a closed system was studied. As output parameters, the mechanical strength at the cutting edge and in the grooves was studied. In addition, input parameters were considered different force and thermal flow conditions generated in the tool's cutting edge. All analyzes performed: Influence of temperature on tool stress, comparison of the maximum stresses in the tool channels with the cutting edge, and the influence of coolant stress in the internal channels were performed using the finite element method by the Ansys® Workbench software 19.2. The main conclusions were that the parameter that most influences the tension exerted on the tools is the force and that, according to the force exerted, the tool will not resist the tension efforts.

Evaluation of Different Tools of Precision Finishing for Cold Extruded Sun Gear With Internal-External Tooth Shapes

Due to the complex metal flow in the cold extrusion of sun gear, the teeth accuracy of formed sun gear is poor. In order to improve the accuracy of the extruded sun gear, a novel precision finishing method with different tools was proposed in this study. Finite element simulations were performed using DEFORM, and a new finite element (FE) prediction strategy was developed to obtain an in-depth understanding of the deviation distribution laws of the finished sun gear. Then, the influences of different finishing tools on tooth deformation, tool stress, forming load and tooth accuracy were examined. The investigation results show that the profile accuracy of external gear can be improved from ninth to seventh class, lead accuracy can be enhanced from tenth to eighth class, and total M value deviation of internal spline is reduced to 72.3 μm by the precision finishing method with interference mandrel. Therefore, the interference mandrel is recommended as the optimal reshaping tool for commercial production of sun gears. The simulation results are well agreed with the experimental results, which verifies the feasibility of the precision finishing method and the reliability of the FE prediction strategy.

Optimizing the Geometric Parameters of Cutting Edge for the Finishing Machining of 30CR Alloy Steel

In order to optimize the geometric parameters of cutting edge for the finishing machining of 30Cr alloy steel, a two-dimensional (2D) finite element (FE) model of orthogonal cutting was built with FE software AdvantEdge. The optimized methodology of the cutting edge geometric parameters was likewise proposed based on the simulated results. Thereafter, the geometric parameters of the cutting edge were optimized based on a comprehensive criterion that combines chip deformation coefficient and tool stress. The chip deformation coefficient indirectly determines the surface roughness, whereas tool stress determines tool wear, thereby affecting the dimensional precision of the components. The rake angle ranges from 12[Formula: see text] to 20[Formula: see text], while the cutting edge radius ranges from 12[Formula: see text][Formula: see text]m to 20[Formula: see text][Formula: see text]m in the optimization process. The optimal rake angle for the finishing machining 30Cr alloy steel is 16[Formula: see text], while the optimal cutting edge radius is 14[Formula: see text][Formula: see text]m with a given relief angle of 7[Formula: see text].

Lessons Learned: Feasibility of a Discussion Prompting Tool to Increase Fertility Risk Discussion Among Adolescent Oncology Families

The purpose of this study was to explore the feasibility of distributing a prompting tool (stress egg) in order to increase discussions about fertility risk and preservation (FP) among female adolescent oncology patients, parents, and healthcare providers (HCP). 200 eggs were distributed to four pediatric oncology centers. Qualitative interviews were completed with healthcare staff (N=7) after 6 months of distribution to newly diagnosed female oncology patients ages 12-18. Interviews showed that the main barriers to distribution of the prompt were: forgetting to distribute the eggs; uncertainty about the significance of fertility; and uncertainty about fertility issues in general for female adolescent cancer patients. The scientific community must continually explore effective avenues of communication to ensure such information is received. The stress egg has potential to impact a cancer survivor’s outlook on future partnering, family life, and self-concept when used in conjunction with policy.

Investigating the Effect of Ultrasonic Vibration on Hole Accuracy in Drilling of Metal Matrix Composites

Generally in the drilling of new engineering materials such as metal matrix composites, problems frequently occur in terms of poor finished surface, tool stress, tool wear, high drilling forces as well as low process reliability. A useful and promising method to overcome these problems is the use of ultrasonic vibration as an assistance, where high-frequency and low amplitude vibration are added to the conventional movement of cutting tools or workpieces. This research presents the new design of an ultrasonic assisted system and the experimental investigation of ultrasonically assisted drilling of Al/SiC metal matrix composites under different cutting conditions. The effect of cutting conditions and ultrasonic amplitude on the circularity, cylindericity, and hole oversize of the ultrasonically and conventionally drilled workpieces were investigated. The obtained results show that the ultrasonic vibration can improve the hole quality.

Frequency and chronological distribution of linear enamel hypoplasia (LEH) in the Late Neolithic and Early Bronze Age population from Żerniki Górne (Poland) – preliminary report

Linear enamel hypoplasia (LEH) is treated as a nonspecific indicator of stress, but even so, many authors consider it the most reliable tool stress in anthropological research. Its analysis allows the reconstruction of health related to the socio-economic status of the group. This study documents and interprets patterns of LEH in Żerniki Górne (Poland), a settlement which was functional in the Late Neolithic and the Early Bronze Age. We examined two successive cultures: the Corded Ware Culture (CWC; 3200-2300BC) and the Trzciniec Culture (TC; 1500-1300BC). In total, there were 1486 permanent teeth (124 adult individuals). The frequency of LEH in the examined cultures shows a small rising trend. In these series from Żernik Górne, males showed a higher occurrence of LEH (16.5%) than females (13.4%). The earliest LEH appeared at similar ages at about 2.0/2.2 years and the last LEH occurred at about 4.2 years of age in both cultures. However, it is worth noting that periods associated with physiological stress were more common but not very long (four months on average) in the CWC. Longer stress periods (nine months on average) were associated with the TC.

Experimental Primer Seating-Stamping Tool Study in Small Caliber Cartridge Production

In an effort to produce a more secure assembly fit between the primer and the cartridge case in 5.56 mm combat ammunition, variants of the conventional case stamping tool were developed and incorporated in the small caliber ammunition manufacturing process (or SCAMP). The challenge is to develop a tool that provides a secure cartridge case-primer assembly fit while maximizing tool life. Two concept tool designs were realized—a concept four-prong triangular stamping tool and a concept four-prong wave stamping tool. This work compares the results of SCAMP trials using a concept four-prong triangular stamping tool, a concept four-prong wave stamping tool and the conventional circular stamping tool. Comparison data include cartridge case material movement after stamping, stamping tool stress distribution, stamping tool life, and stamping forces required to achieve the objective primer seating depths. Although the SCAMP trials are still ongoing, the findings to date show that the wave stamping tool has consistently met the design challenges of improved cartridge case-primer assembly fit and maximized tool life and is currently the leading candidate for implementation in SCAMP.