The authors propose in this paper testing of materials used in dental constructions and dental cutters used for their processing on an electric stand, made by the authors. The stand will be equipped with a transmission that ensures variation of the rotation speed of the cutter from 3000 to 30000 rpm, variation of the sample rotation speed of the tested material from 10 to 300 rpm, vertical and horizontal plane and horizontal rotation mechanisms. The operation of the stand is considered to be simple. In order to carry out the tests, it is necessary and obligatory that the sample preparation operation is carried out in accordance with the validation standards, namely, the knowledge of the sample material, the mechanical properties, the dimensions and their weight. After mounting the samples and the cutter on the stand, the pressing force is established by adding additional weights, the rotation speed of the sample is set and the rotation speed of the cutter is also set to the horizontal movement speed to the cutter (measured in microns) by means of a micrometric screw mounted on the table stand acting on the sample holder.It measures the test time, determines the shape, dimensions and the weight of the samples after each period of time. Following the determinations we can observe the proportionality of the friction force with normal reaction, the connection between the coefficient of friction and the rotation speed during the test, the quality of the sample surfaces and the milling cutter subjected to the test.The study was conducted to determine the wear properties of dental cutters used in dental laboratories, where many materials with different mechanical and technological properties are used.
Population growth in the last 20 years and also diversifying people's food needs have led to an increased demand for products obtained from animals raised on zootechnical farms. For maintaining in the profile market, by providing quality products at the lowest price, the combined feed factories were equipped with modern work equipment and installations to ensure a high degree of mechanization, automation and computerization of the activities performed. This had favourable consequences in achieving high productivity with low specific consumption. The technological flow carried out in a combined feed factory involves performing several activities, such as: supply, transport, grinding, mixing, granulation, cooling, packaging and storage. Thus, a very important activity in a combined feed factory is the transport of raw materials from warehouses to work facilities. To ensure proper functioning of work facilities and an increase of labor productivity, the implementation of automated control of conveyor belts is recommended. The experimental investigations were based on the achievement of an electronic device, through which the operation of magnetic rotation and proximity sensors was monitored. These types of sensors equip the automatic control devices for conveyor belts used in a combined feed factory. The electronic assembly realized in own conception allowed to determine with accuracy the values of the response times, as well as the distances required for automatic shutdown of the transport system. In case of overload, this automatic shutdown command is of major importance in order to avoid the destruction of the transport system. The obtained results demonstrate the functionality of the designed command and control system, as well as the need for its implementation to ensure automated monitoring of the transport of raw materials between the work facilities.
In this work we make a comparative analysis of the dynamics for two variants of seedling planting machines equipped with distributors and articulated buckets respectively: with the seedlings being placed in the furrow opened by a coulter; with the seedling being planted directly into the ground. The dynamics of the seedling planting machine equipped with vertical distributors and articulated buckets is seen from the perspective of the working process involving the placement of the seedling in the ground, its release, its covering with earth and its additional compaction. In principle, furrow opening is performed by a coulter and the vertical distributor with articulated buckets places and releases the seedling in the furrow, in the first variant, and in the second one, the seedling is inserted and released directly into the ground. In the paper are written the mathematical relations describing the dynamics of the seedling planting machine, in the two variants, and we perform their testing, make recordings, interpret the results, reach conclusions and make recommendations on the optimum variant. The agro-technical parameters and tensile strength of the planting machine are analysed in the two functional variants. The experiments were performed under the same working conditions for both variants analysed.
The study carried out on the qualitative indicators of work for planting seedlings requires knowledge of the cyclogram of the operation of the cup of the planting device.This involves knowing and correctly setting the operational phases of the bucket at a full rotation of the distributor disc.The realization of the cyclogram takes into account the kinematic elements of the transmission that determine the peripheral speed of rotation of the cup and influence the time of placing the seedling in the cup by the user.Consisting of several sectors, namely the sector of placing the seedling in the cup, moving the seedling cup until it opens and leaving the seedling in the ground, moving the open cup without seedling, closing the cup for feeding the seedling by the user, mainly influences the distance between the plates at a time.At the same time, the peripheral speed of rotation and the times for completing the operational phases of the cup have an influence on the state of fatigue of the user, in the conditions where an experienced user can place 60-70 seedlings/minute.Following the conducted research, conclusions were drawn on the operation of the planter with different number of cups at different work speeds on the achievement of the respective work quality indices: the distance between plants in a row, the position of the plant in the soil. The obtained results led to observations for the optimization of the cyclogram.
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