RU2381889C1 - Sand-sprinkler tool with local water curtain - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: tool contains casing, cylindrical element for feeding of pneumatic abrasive mixture, discharge jet in the form of convergent-divergent channel with device for axial movement, branch, reciprocal displacements facilities and fixation and swirler for formation of local water curtain around abrasive jet. Discharge jet is installed open coaxial-to cylindrical element from its other end with formation in casing of annular groove. Branch is connected to cavity of annular groove. Swirler is provided for formation of local water curtain around abrasive jet and is installed at the end of cylindrical element. Output cross-section swirler is open to convergent tube of convergent-divergent channel, and input - to mentioned annular groove. Branch is connected to water source. External diametre of cylindrical element is more than dimension of critical section of convergent-divergent channel.

EFFECT: there is provided settlement of products of abrasion in working area.

2 cl, 2 dwg

Description

The invention relates to sandblasting and can be used when cleaning surfaces of products with pneumatic abrasive media.

Various sandblasting devices are known in which the sandblasting nozzle is surrounded by the suction circuit of the used abrasive and the associated dust fraction (see, for example, US 4993200, 02.19.1991; RU 2312759, Kolomin et al., 20.12.2007; RU 2314907, Grechishkin and et al., January 20, 2008). Such devices incorporate a screen contour, prevent air pollution and regenerate used abrasive, but are complex, require powerful vacuum systems and, in addition, due to inevitable losses in the pumping lines cannot be removed for a considerable distance. At the same time, in some cases, it is generally impossible or impractical to suck off the processed products, for example, when cleaning concrete or plastered surfaces, however, it is necessary to prevent the spread of dust fractions into the environment from the workplace of the sandblasting operator. The prior art it is known to use various curtains of sprayed water (see, for example, RU 2278272, Bot, 06/20/2006) as an independent tool for protection against dust emissions.

The closest analogue is the sandblasting tool according to patent RU 2222420, Grechishkin, 07.23.2002, comprising a housing, a cylindrical element for supplying an air-abrasive mixture, fixed at one end in a fixing sleeve associated with the housing, an output nozzle with axial displacement means, mounted with a clearance coaxially cylindrical element at its other end with the formation of an annular cavity, as well as a pipe connected to the annular cavity.

However, this device does not provide means for protecting airspace from spent abrasive.

The present invention is the development of a sandblasting nozzle with a local water curtain in the shape of a cone, which makes it possible to precipitate the abrasive products directly in the work area.

The sanding tool comprises a housing, a cylindrical element for supplying an air-abrasive mixture, fixed at one end in a fixing sleeve connected to the housing, an output nozzle of an abrasive jet in the form of a Laval nozzle with axial displacement means, mounted with a gap coaxially with the cylindrical element at its other end to form in the housing annular groove, pipe connected with the cavity by an annular groove, means of mutual movement and fixation.

The tool is characterized by the fact that a swirl is introduced to form a local water curtain around the abrasive jet, mounted on the end of the cylindrical element so that its output section is open to the Laval nozzle confuser, and the input section to the aforementioned annular groove, with the pipe connected to a water source and the external the diameter of the cylindrical element is larger than the critical section of the Laval nozzle. Means of mutual movement and fixation are made in the form of fixing and regulating nuts interacting with the sleeve and the housing.

The technical result consists in the implementation of an annular curtain of sprayed water around the treatment area with an abrasive jet using the same tool. An additional technical result consists in increasing the service life of the exhaust nozzle of the air-abrasive mixture and giving additional thrust to the abrasive jet.

The invention is disclosed in the drawings, where

figure 1 schematically shows the principle of formation of a local water curtain in the instrument;

figure 2 is a variant of the design of the tool.

The principle underlying the functioning of the tool is to create an external circuit from sprayed water, inside of which a working area for abrasive-jet processing is provided. Figure 1 schematically shows the process of forming an annular curtain 1 on the treated surface 2. The tool contains two input channels: a channel 3 for supplying air-abrasive mixture formed in the axial direction by means of a tubular element 4 and an exhaust nozzle 5. Another channel - channel 6 of the water supply - is formed by an annular groove 7 in the tool body. The groove 7 is communicated through a swirl 8 with a cavity 9 formed by the gap between the conical surface of the outlet end 10 of the tubular element 4 and the exhaust nozzle 5. The exhaust nozzle 5 is made in the form of a Laval nozzle, the confuser of which is located on the side of the swirler 8, and the diffuser is directed towards the work surface 2. As a result, when the tool is working around the spray zone of the working pneumoabrasive jet 11, an annular curtain 1 is formed in the form of a conical local screen 12 of sprayed water.

Figure 2 shows one of the possible tool designs. In the housing 14, a fixing sleeve 15 is installed, in which a tubular element-nozzle 16 is fixed, an element 17 with through spiral slots, performing the functions of a swirl 8 of the water flow. The exhaust nozzle 18 is mounted in the housing 14 by means of a nut 19. The nuts 15, 19 provide adjustment of the clearances during adjustment and fixation of the elements 16, 18 relative to each other. Water for the formation of the curtain is fed through the pipe 20 into the annular gap 21 between the housing 14 and the tubular element-nozzle 16.

The device operates as follows. The pre-prepared air-abrasive mixture is fed through the tubular element 4 to the confuser part of the Laval nozzle 5, where it is accelerated and ejected in the form of a high-energy air-abrasive jet 11 onto the treated surface 2. At the same time, under pressure, water flows through the channel 6 through the annular groove 7 to the input of the swirler 8, in which is twisted and in a twisted form is injected into the gap 9 in the zone of the critical section of the Laval nozzle 5. Further, in the form of a thin film, water is distributed over the inner surface of the nozzle 5 and is thrown out, forming a conical local curtain 12 of sprayed water. As a result, the spent abrasive, together with the cleaning products (sludge), is inside the shielding circuit, it is moistened and precipitated and can be easily removed. This makes it possible to improve the environment in terms of dust content in the treatment area. Tests have shown that at a distance of 0.5 m from the surface to be treated, the diameter of the base of the cone of sprayed water is about 0.2 m, while the actual mixing of the air-abrasive medium and water in the nozzle practically does not occur until sandblasting is performed. Water consumption at a critical section of 8–9 mm of the Laval nozzle depends on dustiness and averages 300–400 ml per 1 sq. M of the treated surface.

As a concomitant technical effect, there is a decrease in wear on the inner surface of the Laval nozzle due to a decrease in direct contact with abrasive particles.

Claims (2)

1. A sandblasting tool comprising a housing, a cylindrical element for supplying an air-abrasive mixture, fixed at one end in a fixing sleeve connected to the housing, an output nozzle of an abrasive jet in the form of a Laval nozzle with axial displacement means, mounted with a gap coaxially with the cylindrical element at its other end with the formation in the housing of an annular groove, a pipe connected with the cavity of the annular groove, means of mutual movement and fixation, characterized in that it is equipped with a swirl for formed I have a local water curtain around the abrasive jet mounted on the end of the cylindrical element so that its output section is open to the Laval nozzle confuser, and the inlet to the aforementioned annular groove, the pipe being connected to a water source and the outer diameter of the cylindrical element is larger than the critical section of the nozzle Laval. 2. The tool according to claim 1, characterized in that the means of mutual movement and fixation are made in the form of locking and adjusting nuts that interact with the sleeve and the housing.

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