Percussive-Abrasive Stone Tools from Chagyrskaya Cave: Results of Functional Analysis

This article presents a comprehensive study of percussive-abrasive active stone tools from Chagyrskaya Cave, using experimental use-wear and statistical methods, supplemented by 3D-modeling. Experiments combined with use- wear analysis allowed us to determine the functions of these tools by comparing the working surfaces and use-wear traces in the Chagyrskaya samples with those in the reference samples. As a result, we identified 19 retouchers, four hammerstones for processing mineral raw materials, and one hammer for splitting bone, which indicates the dominance of secondary processing over primary knapping in the Chagyrskaya lithic assemblage. Using statistical analysis, we traced the differences in the dimensions of the manuports and lithics under study. These artifacts are a promising and underestimated source of information for identifying working operations associated with stone- and bone-processing; moreover, they can provide new data on the functional attribution of sites and the mobility of early hominins.

Improvement in Hardness and Wear Behaviour of Iron-Based Mn–Cu–Sn Matrix for Sintered Diamond Tools by Dispersion Strengthening

The work presents the possibility of fabricating materials for use as a matrix in sintered metallic-diamond tools with increased mechanical properties and abrasion wear resistance. In this study, the effect of micro-sized SiC, Al2O3, and ZrO2 additives on the wear behaviour of dispersion-strengthened metal-matrix composites was investigated. The development of metal-matrix composites (based on Fe–Mn–Cu–Sn–C) reinforced with micro-sized particles is a new approach to the substitution of critical raw materials commonly used for the matrix in sintered diamond-impregnated tools used for the machining of abrasive stone and concrete. The composites were prepared using spark plasma sintering (SPS). Apparent density, microstructural features, phase composition, Young’s modulus, hardness, and abrasion wear resistance were determined. An increase in the hardness and wear resistance of the dispersion-strengthened composites as compared to the base material (Fe–Mn–Cu–Sn–C) and the commercial alloy Co-20% WC provides metallic-diamond tools with high-performance properties.

Percussive-Abrasive Stone Tools from Chagyrskaya Cave: Results of Functional Analysis

В статье представлены результаты комплексного исследования каменных ударно-абразивных орудий активного действия из Чагырской пещеры с использованием экспериментально-трасологического и статистического методов, дополненных 3D-моделированием. Проведенные эксперименты в сочетании с трасологическим анализом позволили определить функции этих орудий путем сопоставления рабочих зон и следов утилизации на инструментах в полученной эталонной и археологической коллекциях. В результате выявлено 19 ретушеров, четыре отбойника для обработки минерального сырья и один для расщепления кости, что свидетельствует о доминировании в каменной индустрии Чагырской пещеры вторичной обработки над первичным расщеплением. С помощью статистического анализа прослежены различия в размерности манупортов и исследуемых орудий. Указанные артефакты не только являются перспективным и недооцененным источником информации для идентификации хозяйственно-трудовых операций, связанных с обработкой камня и кости, но и могут предоставить новые данные о функциональной принадлежности стоянок и мобильности древних гоминин.

Results of petrographic research of new finds from the archaeological monument Tokivske-1

The purpose of the work was to determine the provenance of the raw materials of ancient stone products, found during the excavations of the Bronze-Early Iron Age monument Tokivske-1, with the aim to establish connections of the ancient population of the area with residents of other regions. The archaeological monument Tokivske-1, located in the northern outskirts of the village Tokivske, Apostolove Raion, Dnipropetrovsk Oblast, has been explored by the expedition of Dnipropetrovsk National Historical Museum named after D.I. Yavornytskyi since 2012. The authors of this article already carried out petrographic study of stone artefacts from this monument, which had been found during the first five years of excavations. However, over the past two years, a number of stone and other items were found that could expand our knowledge of the links of Tokivske-1 with ancient industrial centers of other regions. To carry out the petrographic analysis, six artefacts were taken, mainly those made from macroscopically different rocks. Most of them can be related to metalworking. The analyzed samples are represented by an amphibolite hammer for forging jewels or peening sheet copper, a dolerite anvil-prop for a specified hammer, a fragment of an abrasive stone made of ferruginous quartzite, a quartz tile, which is a fragment of an altar, and fragments of an anvil and a scepter-pestle made of sandstone. Petrographic analysis of artefacts allowed determining the probable provenance of their raw materials. Amphibolites are quite common in the territory of the Middle Dnipro area, but by the color of the hornblende, the predominance of epidotization processes over sericitization and macrostructural features, the studied rock is more similar to the amphibolites from the middle stream of the Bazavluk River. Dolerites, similar to the raw material of the anvil-prop, are also common in the area of excavations, and by the presence of the micropegmatite in its composition, its origin can be localized in the middle stream of the river Bazavluk or in the valley of the river Mokra Sura. Magnetite quartzite – the raw material of the abrasive stone – most likely comes from the territory of the city of Kryvyi Rih. Quartz tile – a fragment of an altar – is a quartz vein, similar to those that intersect granites of the Tokivskyi massif directly near the village Tokivske. Sandstones, from which the anvil and the scepter-pestle were produced, appeared to be very similar in their petrographic features. They are represented by quartz sandstones with fragments of rocks and polymineral cement with the predominance of quartz regenerative and porous sericite cement. Also, the relic chalcedony and, more rarely, clay cement are present in the pores. In the territory of Ukraine, the most similar to them, according to petrographic characteristics, are the sandstones of the Carboniferous system, which crop out in the Donbas. Thus, the obtained data testifies to the connection of the Tokivske-1 archaeological complex with other parts of the Middle Dnipro area, such as the middle stream of the Bazavluk River and the Kryvyi Rih area, as well as with more distant regions such as the Donbas. It should be noted that scepter-pestles, similar to the one studied by us, are associated with metalworking, and the Donetsk basin, where the raw material of the indicated tool originates from, was the copper production center of the Late Bronze Age.

Investigation of Abrasive Super Finishing under Various Paths with a 5-Axis Closed-Link Compact Robot and Fine Diamond Stone

To reduce the environmental impact of abrasive polishing, we investigated fixed-abrasive polishing using a compact robot. We used a five-joint closed-link compact robot with a fine diamond stone on the main axis to polish a glass plate and measured the polishing pressure and polishing force. We analyzed the stick-slip vibration of a glass polishing motion due to the low stiffness of the robot arm and estimated the influence of relative speed changes on the friction coefficient between the glass plate and the abrasive stone. We also used various paths to polish the workpiece to examine the characteristics of the polishing equipment. Based on the results, we proposed a method that can estimate a workpiece's surface roughness based on the friction coefficient. Using the compact robot and a fine diamond stone, the workpiece's surface roughness decreased and polishing processes on the glass plate were more stable.

Basic Study on Thermo Chemical Turning Method for Metal Bonded Diamond Wheels

In this paper, a new truing method is proposed instead of the conventional mechanical truing that has low truing rate for metal bonded diamond grinding wheels. In the proposed method, the metal-bond diamond grinding wheel is rubbed by a steel truer rotating at high speed. Generated frictional heat increases the oxidization and the diffusion of carbon into the steel truer, then diamond grains are thermally attrited on the wheel surface, so that the machinability of wheel is improved. Subsequently, high truing rate is achieved by mechanical truing with abrasive stones. These experiments are conducted using bronze bonded diamond abrasive stones and stainless steel truers, and the relation between truing resistance, truing temperature, and truing rate are investigated. The truing temperature is measured using the thermo couple embedded in the truer. The thermo couple consists of the steel wire embedded and the bronze which is the bonding material of the abrasive stone. The surface profiles of abrasive stones are measured by scanning stylus before and after truing, then the removal volume of abrasive stones is derived from these profiles. Truing rate is also obtained from the removal volume and the truing time. Experimental results for diamond abrasive stones are as follows: The waviness of bronze bond is decreased by proposed truing method. Truing rate is increased as truing resistance and truing temperature increase.

Study the Properties of Abrasive Stone for Aluminum Grinding

A doubled-sided lapping machine of grinding stone manufactured of a SiC as an abrasive, specific resin and other thermosetting resin were developed for grinding process of the substrate of hard disk drive (HDD) made up of aluminum since the conventional lapping machine cause the serious quality problem of the magnetic substrate. However, at certain parameter during the grinding process, the abrasive stone was clogging due to the agglomeration of debris from the substrate which cause scratches on the magnetic substrates and affect its performance. The samples were classified into four parts (soft spot, border spot, hard spot, and unused spot). Characterizations of the samples were done using XRF, SEM and FTIR analysis. Based on all the above analysis, it can conclude that the porosity of the stone were not homogeneous and the percentage of Al was highest at the border spot which shows that, the area at the border spot cause the clogging to occur thus produces the hard spot that will damage the magnetic substrate during grinding process.

Investigation of Glass Polishing Motion Based on Micro-Oscillating Pressing Force with a Compact Robot and Fine Diamond Stone

To reduce the environmental impact of abrasive polishing, we have investigated using a compact robot and fixed-abrasive polishing. We look at a five-joint closed-link compact robot with a fine diamond stone on its main axis to polish a glass plate. In this method, we measured the chatter vibration in glass polishing motion due to the low stiffness of the robot arm. Therefore, we estimated a dynamic characteristic of the robot arm by a hammering test and measured the friction coefficient between the glass plate and the abrasive stone. From these results, we attempted a novel polishing method to prevent its self-vibration using micro-oscillating pressing force with a voice coil motor. As a result, the proposed method of polishing a glass plate with a compact robot and a fine diamond stone was found to be effective.