The performance of MPPC 13360-6050PE SiPM matrices with parallel and series connections of elements under conditions of an experiment with a two-phase detector has been investigated, and theoretical calculations of the signal characteristics have been performed for these matrices. It is shown that the signal duration does not change with a high accuracy when SiPMs are connected in series but increases with the number of SiPMs in the matrix when SiPMs are connected in parallel. Within the measurement accuracy, the integral amplitude of the signal does not depend on the number of elements in a matrix in case of the parallel connection. For the series connection, the expected decrease in the amplitude is observed, and this decrease is inversely proportional to the number of elements in the matrix. Based on the results of this study, an SiPM matrix consisting of four parallel-connected elements has been selected for further use in a two-phase cryogenic dark-matter detector since reliable detection of single-photoelectron pulses by this matrix has been demonstrated at an acceptable signal duration.

Recent discovery of neutral bremsstrahlung (NBrS) mechanism of electroluminescence (EL) in noble gases in two-phase detectors for dark matter searches has led to a prediction that NBrS EL should be present in noble liquids as well. A rigorous theory of NBrS EL in noble liquids was developed accordingly in the framework of Cohen–Leckner and Atrazhev formalism. It has been recently followed by the first experimental observation of NBrS EL in liquid argon, which however deviates significantly from the previous theory. Given these results, we revise previous theoretical calculations of EL NBrS in noble liquids to be consistent with experiment. In particular, NBrS EL yield and spectra were calculated in this work for argon, krypton, and xenon with momentum-transfer cross section for electron scattering (instead of energy-transfer one) being used for calculation of NBrS cross section. The results for light noble liquids, helium and neon, are also reexamined.

The paper deals with improving the reliability and durability of parts of the cylinder-piston group of internal combustion engines. Strengthening of machine parts is possible through the use of special production processes. Modern materials and coatings must be able to meet high operating temperatures and loads.Chrome plating, boriding and ion-plasma spraying do not meet the established quality requirements. The aluminum piston suffers damage in the head area. This manifests itself in the accumulation of cracks, channels, and traces of alloy washout. In addition, due to heating, the strength of the aluminum alloy becomes worse more than 2 times.It is proposed to create and use a coating that would withstand operating temperatures of more than 2000°C, as well as shock-pulsating loads. A detonation-gas spraying method is proposed. It is characterized by the versatility of materials and can be applied to polymers and to refractory ceramics, as well as to any metals and alloys.The deposited particles have high kinetic energy. The coating is characterized by high strength, which reaches 180 ... 200 MPa, hardness HRCe 60, and minimal cracks. The temperature effect during spraying on the workpiece is negligible. A sequence of preparatory operations is proposed. The piston and glow ring on the UN-102 detonation-gas installation were to be strengthened. A manipulator was used that uses the energy of the installation shot.The resulting surfaces are characterized by a regular macrostructure (waviness). A nickel-aluminum alloy was applied. Coating thickness was about 150 ... 270 microns, hardness was of HV 550, adhesion to the base eas of 94 ... 100 MPa. The results of studies on the parts of the cylinder-piston group showed a decrease in operating temperatures due to the running-in of the coating and high-quality sealing of the combustion chamber.The durability of the rings is 1.6·106…2.3·106, which indicates a significant increase in fatigue resistance and service life. The proposed technology is suitable and recommended for implementation in mass production

The work is devoted to the establishment of design dependencies to determine the main optimal parameters of radial-rotary profiling, which provide quality indicators of manufactured products. The processes of rotary shaping of metals by pressure are becoming more and more widespread, since it can effectively solve the main problems arising in machine-building and metal-working industries. The economic efficiency of radial-rotary profiling can be ensured by development of a technological scheme based on the deformation process main parameter optimal values. Localization of the deformation zone significantly reduces the deformation forces, which makes it possible to process high-strength and low-plastic materials and to obtain products of various configurations on equipment with a relatively low power, for example, wheel rims of various transport vehicles (cars, light aircraft, etc.). The results of analytical studies of the regularities describing the technological scheme of radial-rotary profiling are presented. For this, the following parameters have been determined: maximum feed of the lower and upper rollers, conditional groove depth for a part with tapered caps; geometric dimensions of the imprints of the cap contact areas with the lower and upper rollers. It was found that when the profile depth changes, the feed rates of the upper and lower rollers change insignificantly, so the profile depth can be taken the same in both cases. It has been established that the concentrated nature of the specific pressure that the workpiece perceives does not reduce the tool safety margin. The rollers are made of steel 9ХС, withstand pressure 1600 ... 1800 MPa. During the workpiece shaping the values of the characteristics change. Therefore, it is recommended to determine the feed critical value for several values of the profile depth and take the smallest value. The calculated feed values have been confirmed by experimental studies. It was determined that when profiling without lubrication, the number of shell revolutions per unit time is 20% less than the number of shaft revolutions.

This work is devoted to experimental studies to determine the influence of technological factors on the process of intensification of pneumatic shock punching by drawing and accuracy of stamped products. The process of pneumatic shock extraction, as well as other impulse methods of extraction (explosive, electrohydraulic and magneto-pulse) is complicated by the high speed of deformation and, accordingly, by the occurrence of considerable inertial forces that counteract the movement of the flange of the extracted part. In the case of pneumatic shock reduction of the deformation rate can be achieved by adjusting the relative weight of the striker or by applying a two-stroke stretching. It is experimentally confirmed that the greatest influence on the limit values of the stamping ability in pneumatic impact stamping have the properties of the workpiece material, its surface properties, the scheme of the deformation process, the rate of deformation, the geometry of the matrix or punch, the value of contact friction and intensification techniques. Experiments have shown that the following factors have the greatest influence on the ultimate degree of drawing and the quality of the products: the condition of the surface and the physical and mechanical properties of the workpiece material; the radius of curvature of the working edge of the matrix; the relative thickness of the workpiece; workpiece loading rate (parameter α); the frictional properties of the matrix material and the workpiece; quality of greasing; technological scheme of operation. For two-stroke stretching, the stretching limit is increased by 8-10%. Also, when using two-stroke load, as shown by experiments, the amount of thinning in dangerous sections of the finished product is reduced. The reduction of radial deformation in the centre of the samples reaches 20-25%. The accuracy of pneumatic shock punching by a liquid is very high, since the deviation of the measured diameters does not exceed 0.1 mm. The surface quality of the pneumatic impacted products is determined only by the surface quality of the starting material. The pneumatic shock method of punching using a two-stage folded dash allows to increase the degree of drawing, accuracy and quality by means of a two-stroke loading, that is, to intensify the process of deep drawing of sheet products. The intensification is due to the successive double shock load for one cycle of the PUSH installation – the first blow is a formative, and the subsequent blow of the second stage is a calibration.

Нагнібеда М. М., Кухар В. В., Ткачов Р. О., Радушев О. О., Ясько С. Г., Фролов Є. А. Випробування на поперечний згин закритих армуючих профілів гнутого та гнутозварного виконання // Обробка матеріалів тиском. – 2019. – № 2 (49). - C. 156-162. Обґрунтовано необхідність удосконалення конструкцій та технологій виготовлення армуючих холодногнутих профілів для будівельної, машинобудівної та інших галузей промисловості, при цьому показано необхідність дотримання показників якості, що вимагаються умовами експлуатації профілів. Виявлено, що показниками експлуатаційної надійності армуючих профілів є характеристики жорсткості, які визначають шляхом випробувань на поперечний згин. Поставлено за мету визначити відмінності характеристик жорсткості армуючого профілю розмірами 40 мм х 50 мм холодногнутого виконання із формуванням напівзамкненого перерізу з зазором між кромками не більше 0,5 мм, сформованим вздовж боку, що має розмір 40 мм, та профілю, виготовленого багатовалковим формуванням сталевої штаби в профілезгинальному стані в замкнутий контур і наступним зварюванням кромок з формуванням поздовжнього зварювального шва по середині сторони, що має розмір 50 мм. Визначення проводили шляхом експериментального випробування на поперечне згинання на універсальній випробувальній машині. Випробовували зразки профілів довжиною 1000 мм по три зразка для кожного варіанту виконання профілю. Замірами та статистичною обробкою встановлено, що середня товщина стінки гнутого профілю становила 1,936 мм, а гнутозварного – 1,843 мм. Отримано графічні та аналітичні залежності величини прогину профілів від значення прикладеної сили при випробуванні. Виявлено, що, незважаючи на меншу середню товщину стінки, армуючий профіль гнутозварного виконання є більш жорстким у порівнянні із профілем гнутого виконання. Це підтверджено тим, що встановлена величина прогину для найбільш несприятливого випадку навантаження профілю на більшу сторону зменшується на 59 %, а при навантаженні профілю на меншу сторону прогин знижується на 0,7 %.

The article presents the results of experimental studies of the wear resistance of metals in order to select the most effective for the manufacture of guide elements of prefabricated universal readjusted stamps. To determine the effect of the material and chemical-heat treatment of them on the wear resistance of the guide elements, the optimal friction pair was selected and tested under conditions similar to the operating conditions of the stamps. Specimens for testing were made in the form of cuts of steel 20, 12ХНЗА (12HNZA), 40Х (40Н) and 38ХМЮА (38HMYUA). Laboratory tests were performed on the machine MИ-1M (МI-1M) under a load of 50, 75 and 100 kgf with a contact area of 243 mm2. The amount of wear was determined by the gravimetric method of I. Kragelsky. Before testing for wear resistance, the specimens were subjected to thermal and heat-chemical treatment: Steel 20 (cementation, normalization, quenching, tempering), 12ХНЗА (12HNZA) (cementation, high tempering, quenching, tempering), 40X (40Н) (quenching, tempering, nitriding) and 38ХМЮА (38HMYUA) (quenching, vacation, nitriding). Studies of the microstructure and microhardness of the test specimens have shown that the nitriding of 38ХМЮА (38HMYUA) and 40X (40H) steel specimen reduces its wear by 1...2 µm and 2...3 µm, and the microhardness of both materials decreases by 50...100 Nm. The analysis of the wear intensity graphs on the number of cycles have shown that for all specimens there are two periods of wear (1 – running-in of rubbing surfaces, 2 – steady wear). Also, studies have shown that the surface layer of nitrated specimens on 38ХМЮА (38HMYUA) steel has a higher wear resistance and a slight tendency to seizing and hardening, providing a high resistance of the part to wear in various friction conditions. The results of testing samples under various loads have shown that the linear wear value is proportional to the change in the specific pressure value established on the basis of the conducted studies that the most effective material for the manufacture of guide elements for PURS is 38ХМЮА (38HMYUA) steel with the following thermal and heat-chemical treatment (quenching – 940 ... 950°C, tempering – 650°C and nitriding – 540°C).

Tilted fiber Bragg gratings with different tilt angles have been inscribed in single-mode isotropic optical fiber with an increased photorefractivity using Talbot interferometer and KrF-excimer laser system. Their spectra are studied. Using a confocal laser scanning luminescent microscope the images of gratings in transmitted light were obtained. The calculated dependence of the slope angle of the grating recorded in the Talbot interferometer on the angle between the strokes of the interference pattern created in the interferometer and the transverse section of the optical fiber is experimentally verified.

To determine the accuracy of the readjustable punches for separating operations (perforation + punching out) of sheet-metal forming, the accuracy parameters were analyzed using the random balance method using the method of experiment planning. Analytical dependencies are obtained to determine the values of deviation of the outer and inner contour dimensions of perforated and punched out sheet parts. From the dependencies obtained, it is possible to estimate and predict the value of deviation in the dimensions of the resulting part at any time during the operation of the punch. Practical recommendations on the calculation of the actuating dimensions of the working elements (stamping punch, matrix) of readjustable punches are offered.

This work is devoted to experimental studies of the strength and accuracy characteristics of adhesive bonding guide elements with the basic elements of the stamp in the prefabricated universal readjusted stamps (PURS). The design of these stamps allows the installation of guide elements in the necessary from the technological and structural points of view, the points of the basic elements. A feature of this autonomous directional system is the method of its fixing, which determines the achievable accuracy and strength characteristics of the PURS. In contrast to the fixing of the guide elements on the press fit in special stamps in the studied structures of the stamps, a method of fixing and precise centring of the seating parts of the guide columns and bushings using glue materials based on epoxy resins was applied. This method of fixing significantly affects the accuracy of execution and installation of the guide block, since it plays a particularly important role in the system “press - guide block - cutting parts of the stamp”. Studies on the results of mathematical processing of experiments allowed us to determine the functional dependence of the strength of adhesive bonding based on epoxy resins of the guide column in the base plates of universal pre-adjustable re-dies. As variables, the force of extrusion was considered: the diameter and length of the nozzle portion of the guide elements in the base elements of the dies. Comparison of all the obtained results showed that the magnitude of the extrusion effort and the length of the nozzle portion at fixed diameter values are interconnected by such dependence that the function can be taken as proportional. The change in the force of extrusion with increasing diameter and fixed values of the length of the nozzle portion has a low intensity. It was established that the theoretical results on the definition of the functional dependence of the strength of adhesive bonding differ by no more than 5%, and the strength of adhesive bonding is 2.2 – 2.4 times higher than the press head of the guide columns and the accuracy of their installation in basic slabs.

The determination of the deformation parameters for high-speed extraction of axisymmetric thin-film blanks that ensure the shaping of parts without distortion of the shape of the relief and destruction of metal by the method of pneumatic impact punching is performed. On the basis of the conducted researches the technological possibilities of manufacturing of quality axisymmetric thin-walled details by the method of pneumatic impact punching are established. The conditions for the stability of the workpiece when forming the axisymmetric elements of a non-spherical shape are similar to the conditions for the stability of the workpiece during the shaping of spherical elements, and the results can be extended to the drawing of elliptical, shallow conical and other similar parts. Pneumatic impact punching allows you to pull dome-shaped parts without the use of hanging thresholds, two-transversal stamping and other special techniques with a relative billet thickness of two to four times less than allowed when drawing a punch.

The results of investigations of the spectral characteristics of chirped fiber Bragg gratings induced in an optical fiber using a Talbot interferometer and a KrF excimer laser system of the master oscillator-power amplifier type with enhanced coherence are presented. Dependences of the full width of the reflection spectrum at half maximum and the reflectivity of chirped fiber Bragg gratings on their length are obtained and analyzed. Through the inscription of seven superimposed chirped fiber Bragg gratings, a diffraction structure with a spectral width of 32 nm was obtained. In addition, a chirped fiber Bragg grating whose spectral response shape is almost rectangular is presented. (C) 2018 Optical Society of America

С использованием интерферометра Тальбота и KrF

In this paper, we showed a technique for the formation of phase-shifted fiber Bragg gratings. The analysis of the efficiency of the obtained structures was carried out with the help of an optical spectrum analyzer with the subsequent calculation of the full width at half maximum of a bandpass in reflection spectrum. Fiber Bragg gratings inscription was performed on the Talbot interferometer, the KrF excimer laser system was used as a UV radiation source, and a phase shift was introduced by the electrical discharge of an arc fusion splicer. The experimental dependence between the length of the obtained structure and the full width at half maximum of a bandpass in reflection spectrum of a phase-shifted grating was presented, the value of the last parameter varies in the range from 24 pm to 96 pm.

Buildings and constructions located on the territory of the enterprises of chemical and petrochemical profile require works on the maintenance of the basic bearing elements in working condition. When carrying out expert examination of industrial safety is drawn a conclusion on the degree of technical state of individual elements of constructions and buildings in General. Also identifies the main factors causing the destruction of the main building material and the refusal of the work of construction.

Physical-probabilistic models of formation and breaking of adhesive bonds between the metal blade cutting tool and workpiece material are offered. Use of these models for an estimation of dynamics of major flank wear surface of the cutting tool is considered. Results of calculation of wear of the cutting tools in comparison with the results of experimental studies published in the open press are presented.