RU2310554C2 - Apparatus for abrasive-jet treatment of surfaces - Google Patents

Abstract

FIELD: abrasive jet treatment processes and apparatuses, possibly manufacturing processes including surface treatment.

SUBSTANCE: apparatus includes housing where nozzle unit, discharging duct and duct for supplying abrasive containing mixture are arranged. Nozzle unit includes inner and outer envelopes and it has annular nozzle with flow-through portion. Mean surface of said flow-through portion is in the form of cone whose apex is outside nozzle unit. Inner envelope of nozzle unit and housing of apparatus are made with possibility of forming annular ejection duct between them.

EFFECT: improved evacuation of waste abrasive out of treatment zone, lowered dust separation to environment, reduced noise level.

4 cl, 2 dwg

Description

The invention relates to techniques for exposing a material to a surface with high-energy abrasive jets and can be used in technological processes for surface treatment, for example, to clean them from contaminants or old coatings.

A device is known for abrasive-jet surface treatment, comprising a conical body with a nozzle block located therein, made in the form of a sleeve (having the shape of a cylindrical chamber) for supplying an abrasive, and a fitting for supplying compressed air; the sleeve is made in the form of a diffuser with a generatrix of the inner surface making an angle with the axis of rotation of the diffuser 1.5-5 °, while the housing is 3/4 of the length made in the form of a cone with a generatrix making an angle of 15-20 ° with its axis of rotation, the diffuser outlet is made at the nozzle exit (see RF patent No. 2146997, class B24C 5/04, op. March 27, 2000).

A disadvantage of the known device is the insufficiently active evacuation of spent abrasive from the working area, as well as high dust emission into the environment and high noise of the device during its operation.

Closest to the claimed one is a device for abrasive-jet surface treatment, containing a nozzle block and an abrasive-containing flow supply channel (see RF patent No. 2224647, class B28D 1/00, op. February 27, 2004).

A disadvantage of the known device is also insufficiently active evacuation of spent abrasive from the working area, high dust emission into the environment and high noise of the device during its operation.

The technical result achieved by the present invention is to improve the evacuation of spent abrasive from the working area by using the energy of an abrasive-containing mixture (for example, air-abrasive) while reducing dust emission into the environment and reducing noise during operation of the device.

The specified technical result is achieved by the fact that in the device for abrasive-jet surface treatment containing the nozzle block located in the housing, the channel for supplying the abrasive mixture, the nozzle block includes an annular nozzle with a flow part, the middle surface of which has the shape of a cone, the apex of which is outside the nozzle block, the inner shell of the nozzle block forms a confuser nozzle, and the nozzle block and the body form an annular ejection channel, while the body is equipped with a discharge channel.

The specified result is also achieved by the fact that the housing is equipped with a limiter of its axial displacements.

The specified result is achieved by the fact that the housing is equipped with a sealing element.

The indicated result is also achieved by the fact that the annular nozzle is made supersonic.

Figure 1 shows a structural diagram of a device for abrasive-jet surface treatment (in section).

Figure 2 shows a structural diagram of a device for abrasive-jet surface treatment (in section) in a specific form of its implementation, which involves the placement of the supply system of the abrasive mixture directly in the nozzle block.

The device for abrasive-jet surface treatment contains a housing 1, for example, a bell-shaped with a wide part open to the side of the work surface 2, as shown in figures 1 and 2. However, the bell-shaped shape of the body is not the only possible within the framework of the present invention and is given solely as one of the possible forms of concrete implementation. In the cavity of the casing there is a nozzle block 3 formed by the outer 4 and inner 5 shells. The nozzle block 3 includes an annular nozzle 6, which, at its input, is connected to the supply channel of an abrasive-containing (e.g., air-abrasive) mixture, made, for example, in the form of a pipe 7, which is hermetically inserted through the wall of the housing 1 into the cavity between the outer 4 and inner 5 by the shells of the annular block 3. The annular nozzle 6, with its outlet (cut), faces the work surface 2. The inner shell 5 of the nozzle block 3 forms a confuser nozzle 8. The fastening elements of the nozzle block 3 to the housing 1 and the shells 4 and 5 to each other for hours rtezhah not shown. The nozzle block 3 and the housing 1 form an annular ejection channel 9. The housing 1 from the side of its tapering part is equipped with a discharge channel 10. The exhaust channel 10 is connected to the housing 1 outside (upstream) of the annular ejection channel 9 and can be made constructively in the form of any a known element that allows connection with a discharge pipe (not shown), for example, in the form of an opening (including a threaded one) in the housing, a pipe (including welded to the housing or made integrally with the latter), a fitting, a flange, etc.

The housing 1 can be equipped with a limiter 11 of its axial displacements. In the particular case, the limiter 11 can be made in the form of a system of adjustable roller or ball (spherical) bearings (at least three), mounted on the housing and, mainly, evenly spaced along the perimeter of its end part facing the work surface 2. Such the axial displacement limiter is one-way, i.e. in the operating state of the device, it restricts the axial movement of the housing 1 with the nozzle block 3 towards the work surface 2 and, at the same time, does not prevent the removal of the housing 1 with the nozzle block 3 from the work surface. At the same time, a two-way axial displacement limiter, for example, a vacuum or magnetic clamp, can be used. The housing 1 in its end part facing the work surface 2 can be equipped (mainly around its perimeter) with a sealing element 12. It is most preferable to use an elastic sealing element, for example a brush-type sealing element. Roller or ball (spherical) bearings, it is advisable to place on the outside of the housing and, at the same time, on the outside of the sealing element 12, so as not to subject them to erosion wear.

In the particular case of execution, the annular nozzle 6 can be made supersonic.

In the specific embodiment of the device shown in FIG. 2, the abrasive mixture supply channel is located directly in the nozzle block between its outer 4 and inner 5 shells and includes an annular abrasive supply chamber 13 with an abrasive supply pipe 14 into this chamber, an annular chamber 15 feeding the abrasive carrier (for example, air) with a supply pipe 16, an annular chamber 17 for mixing the abrasive and the abrasive carrier (air). The annular abrasive feed chamber 13 communicates with the annular mixing chamber 17 via an annular channel 18.

The geometry of the annular nozzle 6 is selected so that the middle surface 19 of its flowing part has a cone shape, the vertex 20 of which is outside the nozzle block 3 (i.e., outside the volume of the nozzle block 3 and outside the truncated cone formed by the conical cut-off surface 21 of the annular nozzle 21 6), and the angle at the apex of the indicated conditional cone can be from 5 to 85 degrees. Moreover, the term "middle surface" refers to a certain conditional surface, which is the geometrical location of points equidistant from the outer and inner surfaces of the walls of the annular nozzle 6. The concept of "middle surface" is widely used in technology and, in this case, gives an exhaustive characteristic of geometry flow part of the annular nozzle 6. When the device is operating, the best effect is achieved when the vertex 20 of the cone is located on its axis. However, deviations of the position of the top 20 of the conical median surface 19 are quite acceptable, lying within the generally accepted tolerances for the manufacture and assembly of such structures. In the examples of a particular embodiment of the device shown in FIGS. 1 and 2, the conditional median surface 19 of the flow part of the annular nozzle 6 is the surface of a circular cone (in particular, a straight circular cone).

The claimed device operates as follows.

The device for abrasive-jet surface treatment is brought to the surface to be treated 2 and, by pressing it to the latter (for example, manually or using known mechanical devices), is positioned relative to it by a limiter 11 (for example, adjustable) so as to ensure approximately the same distance between the end edge of the housing and the machined surface around the entire perimeter of the housing. In the presence of an elastic sealing element 12 around the entire perimeter of the end part of the housing, this task is greatly facilitated, since such a sealing element contributes to the self-alignment of the housing 1 with respect to the treated surface 2.

When positioning the device relative to the machined surface 2, the distance "L" between it and the reference plane 22 drawn through the outer edge of the conical surface 21 of the cutoff of the annular nozzle 6, they try to minimize, while respecting the ratio:

L = H-A and 0 <A <H

where H is the design (calculated) for a given conical annular nozzle 6, the distance between the top 20 of the conical median surface 19 and said conditional plane 22;

A is the distance between the top 20 of the conical median surface 19 and the work surface.

After that, the device is ready for operation.

When performing the device according to the scheme shown in figure 1, the abrasive stream (consider the example with an air-abrasive mixture) from an external source (made, for example, in the form of a metering mixer with a fluidized bed, as described in RF patent No. 21118587, class B24C 1/00, op. 10.09.1998, or in the form of an injector, as described in RF patent No. 2070507, class B24C 3/06, op. 1995.06.20) through the feed channel of the abrasive mixture, made, for example, in the form pipe 7, under excess pressure is fed into the space between the outer 4 and inner 5 shell nozzle block, from where it enters the annular nozzle 6. In the annular nozzle 6, the air-abrasive mixture accelerates and increases its kinetic energy, and then flows out of it in the direction of the treated surface 2.

Particles of abrasive having high kinetic energy break off microparticles of dirt or old coatings from the treated surface and most of them, reflected from the treated surface, are carried away by the air flow through the confuser nozzle 8 into the exhaust channel 10, associated, for example, with a passive dust collection system (air cyclone). At the confluence of the confuser nozzle 8 and the annular channel 9, an ejection effect occurs, due to which the particles of spent abrasive and microparticles of contaminants or coatings, for some reason not entrained by the air flow in the annular nozzle 8, enter the annular ejection channel 9 and, thus, nevertheless, they are also evacuated from the working area to the discharge channel 10. The presence of the “confuser channel - annular ejection channel” pair in the inventive device allows evacuating from RA without additional energy sources (additional suction) In the working zone, limit the amount of contaminated spent abrasive and minimize dust emission into the environment, which is most important when working with toxic coatings (deposits) or radioactive contamination on the treated surface. The enclosure closure and the presence of the sealing element 12 significantly reduce not only the dust emission into the environment, but also the noise of the device.

When executing the device according to the scheme shown in figure 2, the operation of the device proceeds similarly except that the preparation of the air-abrasive mixture occurs not outside the device, but inside its body. This allows to reduce hydraulic losses when feeding the air-abrasive mixture into the annular nozzle 6. Along the nozzle 14, the abrasive is fed into the annular chamber 13 for feeding the abrasive. Through the pipe 16, air is supplied to the annular chamber 15 for supplying the abrasive carrier. Through the annular channel 18, the abrasive particles enter the annular mixing chamber 17, where they are captured by the air flow and entrained in the annular nozzle 6. The remaining processes are similar to those described above for the device according to the circuit shown in Fig. 1.

The implementation of the annular nozzle 6 supersonic allows you to significantly increase the kinetic energy of the flow of air-abrasive mixture when it is fed to the work surface.

Claims (4)

1. Device for abrasive-jet surface treatment, comprising a housing in which the nozzle block is located, and an abrasive mixture supply channel, characterized in that it is provided with a discharge channel placed in the housing, the nozzle block is made in the form of inner and outer shells and has an annular nozzle with a flowing part, the middle surface of which has the shape of a cone, the apex of which lies outside the nozzle block, the inner shell of the nozzle block is made in the form of a confuser nozzle, and the nozzle block and the housing are made They are capable of forming an annular ejection channel between them. 2. The device according to claim 1, characterized in that it is equipped with an axial displacement limiter located in the housing. 3. The device according to any one of claims 1 or 2, characterized in that it is equipped with a sealing element located in the housing. 4. The device according to claim 1, characterized in that the annular block is made with a supersonic annular nozzle.

Images