RU2014206C1 - Method for hydraulic rotary part working - Google Patents

Abstract

FIELD: mechanical engineering. SUBSTANCE: fluid-abrasive mass with workable parts positioned in a working chamber are periodically subjected to compressed air jets through forward and reverse direction nozzles. The air feed nozzles are circumferentially equidistant on the chamber bottom. The amount of abrasive, fluid and parts loaded into the chamber is determined from a mass ratio 1:2 - 3:1 - 1,5 respectively, the total amount of abrasive, fluid and parts by volume is set within 10-20% of the working chamber volume. The duration of the compressed air jet effect in the reverse direction is set to be within 10-80% of the effect duration in forward direction. The fluid-abrasive mass with the parts is subjected to compressed air jets equidistantly circumferentially fed by additional nozzles located in the central part of the chamber, the pressure of the air fed to the additional nozzles is lower than the air pressure in the main nozzles by a factor of 1.5-2. EFFECT: improved working intensity, uniformity and stability. 2 cl, 2 dwg

Description

 The invention relates to mechanical processing production, in particular to the finishing and cleaning treatment (OZO) of parts in mechanical engineering (deburring, rounding of sharp edges, stripping, preparation for coatings, etc.) and can be used in mechanical, galvanic and other machine-building (instrument-making) workshops ) enterprises to perform OZO operations.

 Known devices with which hydrotreatment processing can be implemented.

 However, these devices do not allow for a sufficiently high processing intensity.

 A known finishing installation for hydrotreatment treatment, in which vibration is additionally used to increase the processing intensity.

 This complicates the equipment, reduces its reliability. Additional vibration under certain conditions can worsen the process, as it violates the formation of a stable operating state of the abrasive-liquid medium.

 The prototype of the invention is a method of abrasive processing of parts and a device for its implementation. According to this method, the abrasive mass with parts is affected by jets of compressed air. The direction of these jets cyclically change the direct to the opposite and vice versa.

 However, when implementing this method, the formation of stagnant zones, zones with different processing intensities and other phenomena that reduce its effectiveness are observed. In addition, the method does not determine the optimal process parameters.

 The purpose of the invention is to increase the intensity of processing by creating the most favorable conditions for the impact of abrasive mass on the treated surface and ensuring uniformity and stability of processing.

 This is achieved due to the fact that the number of abrasives, liquids and parts loaded into the chamber is selected in a ratio by weight, respectively: 1: 2-3: 1-1.5, while the total amount of abrasive, liquid and parts by volume is set in the range from 10% to 20% of the volume of the working chamber, and the duration of exposure to compressed air jets in the opposite direction is assigned in the range of 10-80% of the duration of exposure in the forward direction, and also due to the fact that the liquid-abrasive mass with parts is affected by compressed jets air feed uniformly around the circumference of the additional nozzles located in the central part of the chamber, while the pressure of the air supplied to the additional nozzles is set 1.5-2 times less than the air pressure in the main nozzles.

In FIG. 1 shows the dependence of the removal rate of metal g on the content in the working mixture of the amount of abrasive A, liquid Zh and parts D; in FIG. 2 - dependences of the metal removal rate g on the specific loading of the chamber V _beats , on the relative duration of the action of compressed air jets in the opposite direction t _arr and on the air pressure in the additional nozzles P _add .

 The working chamber of the installation for hydrotreatment processing is a container formed by two truncated cones connected by large bases. In the bottom of the chamber, nozzles for supplying compressed air jets are equally spaced around the circumference; as a result, a continuous stream of liquid air-abrasive mixture is created, which ensures transportation of parts from the jet to the jet. Since abrasive particles and parts differ in density and drag, they acquire different speeds. The combined dynamic effects of high-speed air and liquid flows carrying abrasive particles, provides processing and intensive mixing of parts.

 In the nozzle exit zones, abrasive ejection occurs; continuous stream of air prevents the ingress of abrasive particles into the nozzles, which determines the durability of the latter. A layer of rotating fluid protects the inner surface of the working chamber from direct exposure to air-abrasive jets, thereby preventing the wear of the rubber lining.

 To ensure a high intensity of hydrotreatment treatment in the installation chamber, it is necessary to observe certain mass ratios between the abrasive, the liquid, and the workpieces. To identify this optimal ratio, experimental work was performed. Parts made of various materials, various in weight, configuration and size, were processed, and the mass of the loading components — abrasive, liquid, and parts — changed. The processing intensity was determined by the amount of metal removed, measured by weighing the parts on special analytical scales. As a result, it was established (Fig. 1) that the ratio between the mass of the abrasive and the liquid should be from 1: 2 to 1: 3. A relative increase in the amount of abrasive to a certain limit contributes to an increase in processing intensity. However, an increase in the abrasive beyond the permissible level results in attenuation of the air jets. This is due to the fact that the specific gravity of the abrasive is 2-3 times greater than the specific gravity of the liquid, and the very structure of the abrasive particles requires considerable energy to “float” and disperse. As with a relatively small amount of abrasive (insufficient number of cutting elements), and when it is increased above the permissible (insufficient energy of air jets to disperse a large amount of abrasive), the processing intensity decreases. The volume of liquid should be minimal, but necessary to create an abrasive-liquid medium that evenly covers and "flows around" the workpiece. An increase in the relative volume of the liquid leads to the fact that the energy of the air jets works as if idle, since there is little abrasive in it, useful work is reduced.

 The loading volume of the machined parts plays a large role in the formation of an effective processing environment. An increase in the volume of parts to a certain limit increases the intensity of processing, since there is an active mutual influence of the parts with the abrasive particles surrounding them. The limit of the relative volume of parts is determined by the energy capabilities of the air jets and the required specific amount of abrasive that falls on each part and during which intensive processing takes place. Therefore, if the batch of workpieces in production conditions is small for optimal loading, then it should be artificially increased with samples of parts (ballast) to maintain a high processing intensity.

 As a result of the experiments, the total loading volume, which is optimal relative to the volume of the entire working chamber, was also established — abrasive + liquid + workpieces, which amounts to 10-20% of the volume of the entire working chamber (Fig. 2). If the relative volume of the load is less than 10%, then there is not enough mass to form a normal process, i.e. a rarefied atmosphere is created in the chamber, resulting in reduced productivity. With an increase in the relative load of more than 20% of the chamber volume, the processing efficiency decreases sharply due to the fact that the energy of the air jets is no longer enough to organize a normal process.

 Due to the noted features of hydrotreatment processing, the working mixture with parts tends to occupy the space adjacent to the wall of the working chamber. And in the central part of the chamber a "dead" zone is formed in which there is no movement of the working medium and no processing. To reduce this phenomenon, a conical rod is introduced into the central part of the chamber, which fills this zone and, to a certain extent, excludes the entry of parts there.

 It is impossible to exclude the indicated phenomenon completely. In an unfavorable combination of processing parameters and conditions, parts are grouped around and above the cone, the processing intensity of which drops sharply. The indicated phenomenon can nevertheless be completely eliminated if compressed air is fed uniformly through the cone along the circumference. At this pressure, the supplied air should be 1.5-2 times less than the pressure of the air supplied through the main nozzle. It was experimentally established that if the air pressure in the additional nozzles is the same as in the main ones, or less than 1.5 times, then these additional nozzles seem to “clog” the main nozzles and do not allow them to provide a normal hydrotational process. If the air pressure in the additional nozzles is more than 2 times less, then the efficiency of these nozzles decreases sharply.

 As an example of the use of the method, processing at one of the optical-mechanical factories is considered of small stamped parts having, after cutting, burrs 0.5-0.8 mm in size with a thickness of 0.1 mm at the base, the material of the parts is steel 10, weight 1 pc . - 4-5 g.

 Processing is as follows.

2.4 l of the working fluid, which is a 1% solution of trisodium phosphate, is poured into a working chamber with a capacity of 27 l, then 1.3 kg of workpieces and 0.92 kg of abrasive are loaded into the chamber (grinder 63 with N 40, GOST 3647- 80). The total volume of loading is 3.1 liters, i.e. 0.115 volume of the working chamber. Set the pressure of 0.31 MPa in the working nozzles, the pressure of 0.01-0.03 MPa in the nozzles with boost and the pressure of 0.15 MPa in the additional nozzles. The time relay sets the processing time of 15 minutes and the cycle time of 40 s (35 s are nozzles of the forward direction and 5 s are nozzles of the opposite direction). They turn on the installation and process the parts. After setting the sleep via its neck is discharged onto the mesh separator contents of the processing chamber by rotating the chamber at ^about 150-180. Parts are washed, at the same time separating them from the abrasive, which goes through the mesh cells into the lower pan and is collected there. Idling for 10 s, rinse the working chamber. Separated from the abrasive and washed parts are loaded into the container and the installation is ready for processing the next batch of parts.

 Machined parts are thin-walled and delicate. Their cleaning by other mechanized methods (vibration-abrasive, jet-abrasive, etc.) is impossible, since the parts are deformed, packaged, intertwined, etc. Therefore, they were previously processed manually by friction on an abrasive skin; labor input - 0.5 min per 1 part. 260 units are processed simultaneously at the installation. parts, the general processing cycle - 20 min.

= 0,077 мин. Экономическая эффективность Э_г от данного способа за год составляет Э_г=(Т₁-Т₂)N x C x K, Т₁ и Т₂ - старая и новая трудоемкость на 1 деталь, мин;
N - программа выпуска деталей в год;
С - стоимость 1 мин рабочего времени, руб.;
К - коэффициент учитывающий капитальные затраты.The complexity of one part is

= 0.077 min. The economic efficiency of E _g from this method per year is E _g = (T ₁ -T ₂ ) N x C x K, T ₁ and T ₂ - old and new laboriousness for 1 part, min;
N - program for the production of parts per year;
C - the cost of 1 min of working time, rubles .;
K - coefficient taking into account capital costs.

Claims (2)

 1. METHOD OF HYDROTORATIVE PROCESSING OF PARTS, in which a liquid-abrasive mass with parts is placed in the working chamber and is exposed to equally spaced compressed air jets around the chamber bottom cyclically in the forward and reverse directions, characterized in that the number of abrasive, liquid and parts loaded into the chamber choose in a mass ratio, respectively, 1: 2 - 3: 1 - 1.5, while the total amount of abrasive, liquid and parts by volume is set within 10 - 20% of the volume of the working chamber, duration of exposure to jets of compressed air in the opposite direction is assigned in the range of 10 - 80% of the duration of their effect in the forward direction.  2. The method according to claim 1, characterized in that the liquid-abrasive mass with parts is exposed to additional jets of compressed air, which are supplied uniformly around the circumference, while the pressure of the air supplied to the additional jets is set 1.5 to 2 times less air pressure in the main jets.

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