APPLICABILITY EVALUATION AND SHAPE OPTIMIZATION OF THE ELASTIC VALVE STATIONARILY INSTALLED IN PNEUMATIC IMPACT MACHINES

The possibility of using construction design with a stationarily installed conical ring-shaped elastic valve in pneumatic impact machines is considered. Using a simulation model of the contact interaction of the striker with the valve, the shape of the valve was optimized and its applicability was proved for sealing the return strike chamber.

DESIGNING ANNULAR ELASTIC VALVE THAT CONTROLS AIR EXHAUST FROM WORKING CHAMBER OF PNEUMATIC IMPACT MACHINE

The paper considers one of the promising shut-off and control elements of the air distribution system of pneumatic impact machines - an annular elastic valve (CUV). This element allows you to reduce the energy consumption of pneumatic devices. Unfavorable combinations of factors that hinder the movement of the valve necessary for sealing the working chamber are considered. The paper presents a method for calculating the elastic valve that controls the release of energy from the return chamber of the pneumatic impact machine, which allows determining the main geometric dimensions of the valve device at the design stage, which provides a stable self-oscillating cycle of the pneumatic impact machine with the specified energy characteristics. The developed technique was used in the modernization of the air distribution system of the ring impact machine (KUM), designed for immersion of rod elements in the ground. Tests of the resulting sample in production conditions confirmed the increase in energy performance compared to previously produced machines of a similar type.

ТЕХНОЛОГІЧНІ АСПЕКТИ ЗАБЕЗПЕЧЕННЯ ЯКОСТІ ДЕТАЛЕЙ ПРИ ПНЕВМОУДАРНОМУ ШТАМПУВАННІ ВИРУБУВАННЯМ-ПРОБИВАННЯМ

The paper considers the issues related with technological capabilities and features of the process of cutting-punching of sheet-metal parts with an elastic medium of pneumatic impact stamping, taking into account the indicators of their quality and accuracy, and also suggests effective ways to improve them. One of the promising methods for producing high-precision parts, including those with a complex profile, is a shaping method based on the technology and equipment of pneumatic shock stamping with an elastic medium on the TA-1324 in-stallations. The advantages of this method are environmental cleanliness, safe operation, wide technological capabilities, mobility and versatility, low labour and energy costs. At these installations it is advisable to perform formative operations of separation (cutting-punching) and shallow shaping both as a separate operation and together with cutting-punching. As a workpiece for the study the sheet material of the following grades was used: steel 08kp, aluminium alloy AMG-M, steel 12X18H10T. The thickness varied within the range from 0.5 to 2.5 mm. Dies and copier punches were made of U8A steel, followed by heat treatment to a hardness of HRC 56-62. An analysis of the experimental studies of punching-cutting processes allows us to conclude that with an increase in the number of stamped parts, there is an increase in size deviations from their nominal values. This increase is due to the wear of operating elements (copier punches and dies). At the same time, the sizes of the copier punches are reduced, and the sizes of the matrices are increased. The absolute values of deviations do not depend on the type of operations; their values, both during cutting and punching, are almost the same in each of the samples taken. The process of pneumatic impact stamping, where a hammer with a bevelled end was used, has a similar character. The paper also proposed and tested ways to improve pneumatic impact stamping, providing cutting, punching of parts from sheet copper, aluminium alloys with a thickness of 0.3 to 3 mm and mild steel up to 3 mm thick. The roughness of the cutting surface is in the range Ra = 0.3 to 0.6 μm, and in the case of high-strength materials up to 2.5 mm thick, the roughness of the cutting surface is Ra = 0.6 to 1.0 μm, depending on the contour configuration that is cut down or punched.

ТЕХНОЛОГИЧЕСКИЕ ВОЗМОЖНОСТИ ПНЕВМОУДАРНОЙ ШТАМПОВКИ ВЫТЯЖКОЙ ТОНКОЛИСТОВЫХ ДЕТАЛЕЙ

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.