RU2084327C1 - Method of and device for machining of parts in fluidized abrasive - Google Patents

Abstract

FIELD: mechanical engineering and other industries; finishing of parts such as bearing races, axles, bushings. SUBSTANCE: in known method of machining of parts in fluidized abrasive air stream is delivered to surface to be machined under action of which abrasive particles act onto part surface air stream is divided into separate streams which are uniformly distributed around the part and are directed to surface to be machined at angle equal to angle of cutting of abrasive grains. Device has housing and working chamber with holes to let in air stream and layer of abrasive particles. Part to be machined is installed in working chamber which has circular shape and is formed by surface of machined part and inner cylindrical groove of ring installed in housing. Ring has holes uniformly spaced over circumference which communicate working chamber with ring groove of housing intended for delivery of compressed air. Slots are arranged at angle relative to radial direction. EFFECT: increase machining capacity , simplified design of processing equipment. 2 cl, 3 dwg

Description

 The invention relates to finishing methods for processing parts such as rings of bearings, axles, bushings with a free abrasive and can be used in mechanical engineering, instrumentation and other sectors of the economy.

 A known method of processing parts with a free abrasive [1] in which the rotatable workpiece is placed in a fluidized bed of a free abrasive, which is mounted due to the impeller installed in the chamber and kinematically connected with the drive of the part.

 The disadvantage of this method is the uneven removal of material over the entire machined surface and the complexity of the regulation of technological processing parameters.

Device for processing parts in a fluidized abrasive, in which the workpiece is exposed to a stream coming through inclined channels made in a cone-shaped chamber [2]
The disadvantage of this device is the limited technological capabilities due to the low speed and irrationality of the angle of impact of the grains under the influence of air flow on the treated surface, as a result of which high processing productivity is not ensured.

 The objective of the invention is to increase processing productivity while simplifying the design of process equipment.

 The problem is achieved in that in the known method for processing parts in a fluidized bed of an abrasive, in which an air flow is supplied to the surface to be treated, under the action of which the abrasive particles act on the surface of the part, the total air stream is divided into separate air jets, they are evenly distributed around the part and sent to the treated surface at an angle equal to the angle of cutting of abrasive grains.

 In the known device for processing parts, comprising a housing and a working chamber mounted thereon, having openings for air flow and containing a layer of abrasive particles in which the workpiece is installed, the working chamber has an annular shape and is formed by the workpiece surface and the inner cylindrical groove of the ring, installed in the housing, the ring has holes evenly spaced around the circumference, connecting the working chamber with the annular groove of the housing, designed to compressed air flow, slotted holes are located at an angle to the radial direction.

 Since the total air flow is divided into separate jets, the speed of air movement increases and the kinetic energy of the abrasive grains entering the air jets increases, as a result of which they hit the surface to be treated with greater force and more effectively remove the stock. And since air jets are directed to the surface to be machined at an angle equal to the cutting angle, all the energy of the impact of grains on the surface of the part is spent on individual chips, which further increases the rate of metal removal. In addition, the location of the air jets at an angle to the work surface provides a circular movement of the abrasive around the part and rotation of the part itself, which eliminates the need to use a special rotation drive, simplifies the implementation of the method.

 The invention is illustrated by drawings, where in FIG. 1 shows a device in axial section AA; in FIG. 2 the same in cross-section BB; in FIG. 3 diagram of the impact of abrasive grain on the treated surface.

 A ring 4 is pressed into the housing 1 having a radial hole 2 (FIGS. 1 and 2) and an inner cylindrical groove 3, having an inner cylindrical groove and a slot 5 evenly spaced around the circumference of the ring 4, and inclined at an angle to the radial direction. In the hole of the ring 4 with a guaranteed clearance, part 6 is installed in the form of an inner ring of a roller bearing. The inner groove of the ring 4 together with the workpiece surface 6 forms a working circular chamber 7, into which the abrasive is filled. Using the discharge tube 8, the working chamber 7 is connected with the atmosphere.

 Before processing, the abrasive is poured into the annular groove of the ring 4 and the part 6 is installed. Through the hole 2, compressed air is fed into the groove 3 of the housing 1. The air flow generated in this case passes through the slotted openings 5 of the ring 4, is divided into separate jets entering the chamber 7 at a high speed. The abrasive particles in the chamber 7 are rotationally rotated around the workpiece surface 6. Part 6 under the action the abrasive also gets a little rotation. The air entering chamber 7 is freely vented into the atmosphere through device 8. Device 8 has a mesh (not shown) to prevent abrasive particles from being emitted from chamber 6.

где P_т тангенциальная сила резания,
P_н нормальная сила резания.The inclination angle β of the slotted holes 5 of the ring 4 to the radial direction is determined from the condition of ensuring the most effective angle a of the impact of abrasive particles that have fallen into the air stream about the surface to be treated, equal to the cutting angle:

where P _{t is the} tangential cutting force,
P _n normal cutting force.

отсюда

Так как

где d диаметр обрабатываемой поверхности
D диаметр проточки кольца 4,
то

Технико-экономическая эффективность предложенного изобретения состоит в следующем:
увеличивается производительность снятия припуска, так как абразивная частица, попадая в отдельные струи воздуха, приобретают значительную кинетическую энергию и со значительной силой ударяются об обрабатываемую поверхность под рациональным углом;
упрощается конструкция устройства для обработки, так как отпадает необходимость иметь специальный, как правило, очень сложный привод для перемещения деталей.If the angle of impact of the particle on the surface to be treated is significantly greater than α, the particle will mainly slide along the surface without separating the chips. If the angle of impact is much smaller than a, then the abrasive particle will predominantly plastically deform the surface, rather than cutting chips. The maximum productivity of removing the allowance is ensured when particles hit the workpiece at an angle a The value of the angle a depends on the material of the abrasive and the material of the workpiece and is usually in the range tgα = 0.4 ÷ 0.6
In FIG. Figure 3 shows the moment of impact of an abrasive particle on the workpiece surface 6 under the action of an air stream entering the working chamber 7 through the slot 5 of ring 4. From ΔAOC by the sine theorem

from here

Because

where d is the diameter of the surface to be treated
D the diameter of the groove of the ring 4,
then

Technical and economic effectiveness of the proposed invention is as follows:
the productivity of removal of the allowance increases, since an abrasive particle, falling into individual air jets, acquires significant kinetic energy and with a considerable force hit the surface being machined at a rational angle;
the design of the processing device is simplified, since there is no need to have a special, usually very complex drive for moving parts.

Sources of information
1. Autosvid. N 818828 Device for processing parts in a fluidized abrasive.

 2. Autosvid. N 455838 Device for parts in a fluidized abrasive.

 3. Turbo-forming machining of complex profile parts. Methodical recommendations M. Minstankoinstr. prom USSR, 1987, 53 p.

 4. Korolev A.V. Novoselov Yu.K. Probabilistic theory of abrasive processing. Part 2. The interaction of the tool and the workpiece during abrasive processing. From Sarat. University, 1989, 160 pp.

Claims (2)

 1. A method of processing parts in a fluidized bed of an abrasive, in which an air flow is supplied to the surface to be treated, under which the abrasive particles act on the surface of the part, characterized in that the air flow is divided into separate air jets, they are evenly distributed around the part and sent to the workpiece surface at an angle equal to the cutting angle. 2. A device for processing parts in a fluidized bed of an abrasive, comprising a housing carrying a working chamber, designed to accommodate the workpiece and abrasive medium, connected to a source of compressed air by means of inclined channels of an additional tool, characterized in that the additional tool is made in the form of a ring with a cylindrical a groove on the side surface, and the inclined channels are evenly spaced around the circumference and made slit-like, while the working chamber is formed by the machined surface ited part and the cylindrical bore of the ring, wherein the channels are arranged inclined at an angle to the radius of the ring which is selected from the formula

where d is the diameter of the part;
D is the diameter of the inner cavity of the ring;
α cutting angle.

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