RU2411118C1 - Method of centrifugal treatment by surface-impact straining with pneumatic buffer - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming, in particular, to method of pulse-impact surface plastic deformation (SPD) treatment, and can be used for finishing and hardening processing. Proposed device comprises disk-like casing accommodating straining balls, ring-like separator with holes arranged on disk periphery and pneumatic chamber. Casing can rotary and has flange arranged on its face. Pneumatic chamber is fixed in bearing arranged on casing face flange. Radial holes bottoms have holes to communicate with pneumatic chamber. Pneumatic chamber wall adjoining the casing face has sector-like slot to allow access of compressed air into several radial holes with straining balls arranged in processing zone and nearby it.

EFFECT: expanded process performances, higher durability of tools, higher machining precision and reduced roughness of processed surface.

6 dwg, 1 tbl

Description

The invention relates to the processing of metals by pressure, in particular to the manufacture of equipment for processing by pulse-impact surface plastic deformation (PPD), and can be used for finishing and hardening processing.

A known method of finishing surfaces with deforming balls and a device for its implementation, made in the form of a housing and mounted on pins with the possibility of rotation in the drum casing with nests for balls, made in the form of a tube with rolled ends, while the rotation drive is connected to one of the pins, and the device housing is located on ball bearings for movement [1].

The disadvantages of the known method and device are: rapid wear of the balls, their spalling, failure of the nests for the balls, especially the rolled ends of the tubes, which limit the movement of the balls - all this reduces the tool life, dramatically reduces productivity, accuracy and quality of the processing process.

A known method of centrifugal treatment by surface plastic deformation, implemented by a tool with deforming elements (balls or rollers) located in the radial grooves of the disks [2]. During operation, the elements can be shifted in the radial direction, an interference is created due to the high speed of rotation of the disk with the elements, the latter inflict numerous blows on the surface of the workpiece, plastically deforming the surface, and instantly bounce off of it, floating reflectors are installed under the balls to extend the tool life or motionless.

The disadvantages of the known method and tool are: quick wear of the balls, their chipping, failure of the sockets for balls and reflectors, which limit the movement of balls and separators - all this reduces the tool life, dramatically reduces the productivity, accuracy and quality of the processing process.

The objective of the invention is the expansion of the technological capabilities of centrifugal treatment by surface plastic deformation, reducing the wear of deforming ball elements, nests for deforming elements, separators, as well as increasing the tool life as a whole, increasing productivity, accuracy and quality of the processing process.

This is achieved using the proposed device for centrifugal treatment by surface plastic deformation (PPD), comprising a housing in the form of a disk with radial blind seats, in which there are deforming balls and a separator in the form of a ring with holes mounted on the periphery of the disk to limit the radial movement of deforming balls, while it is equipped with a pneumatic chamber with a fitting for supplying air to it, the housing is rotatable and a flange is located at its end, The chamber is mounted on the end of the housing in the flange using a bearing from the condition of ensuring its immobility during rotation of the housing, holes are made in the bottom of the radial disc seats for connecting them to the air chamber, in the wall of the air chamber adjacent to the housing end, a groove is made in the form of a sector for providing access for compressed air from the pneumatic chamber to several radial sockets with deforming balls located in the processing zone and close to it.

Features of the design and operation of the device for centrifugal processing of PPD with pneumatic buffer are illustrated by drawings.

Figure 1 shows the design of the proposed device for centrifugal processing of PPD with pneumatic buffer, a longitudinal section; figure 2 is a cross section along a - a in figure 1; figure 3 is a transverse section along B - B in figure 1; figure 4 is an end view of in figure 1; figure 5 is a General side view; Fig.6 is a diagram of the process of centrifugal processing of PPD balls of the workpiece of a rotor blade of a helicopter made of titanium alloy.

The proposed device is designed for centrifugal treatment by surface plastic deformation (PPD) of critical, heavily loaded metal parts with high parameters of surface roughness and hardness.

The device consists of a housing 1 in the form of a disk with radial blind sockets 2 for deforming elements-balls 3. Housing 1 has a central hole for mounting it on a mandrel or spindle, for example, a grinding, turning or milling machine.

A separator ring 4 with holes restricting the radial movement of the deforming ball elements 3 is installed on the periphery of the housing 1. The dimensions of the holes in the ring separator 4 affect the amount of deformation of the deformation elements above the surface of the separator ring, i.e. the amount of interference h (see Fig.6). Under the deforming elements-balls 3 in the bottom of the radial sockets 2 holes 5 and 6 are made, connecting the sockets 2 with the pneumatic chamber 7.

Compressed air under pressure P is supplied into the pneumatic chamber 7 from the outside through the nozzle 8. The pneumatic chamber 7 floating through the bearing 9 mounted in the flange 10 and secured by the cover 11 is mounted on the end face of the housing 1. The mounting design of the chamber 7 allows it to remain stationary on the rotating housing 1. In the wall adjacent to the end of the camera body 7, a groove 12 is made in the form of a sector. Groove 12 allows access of compressed air P to several radial sockets 2 ^P with deforming balls 3 located in and around the workpiece processing zone 13, and the compressed air is closed to other slots. In FIG. 2, groove 12 allows access of compressed air P into three radial sockets in which the deforming ball elements 3 are under pressure. Thus, a pneumatic buffer is created, which allows avoiding impacts of deforming elements about the bottom of the radial nests during their bounce and increasing the resistance of deforming elements.

During operation, the elements are shifted in the radial direction under the action of centrifugal force and additional force P. Due to the value of h, an interference is created during processing. The case with elements rotates at high speed.

At the same time, the elements inflict numerous blows on the surface of the part, plastically deforming the surface, and do not instantly bounce from it, but are pressed by the force P to the treated surface, preventing the elements from striking the bottom of the nests.

As a result of plastic deformation of microroughnesses and the surface layer, the surface roughness parameter rises to Ra = 0.1 ... 0.32 μm with the initial value Ra = 0.8 ... 3.2 μm. The surface hardness increases by 30 ... 80% with a riveted layer depth of 0.5 ... 3 mm. Residual compressive stresses reach 400 ... 800 MPa on the surface.

Preliminary processing of a part: grinding to a roughness parameter value Ra = 0.4 ... 1.6 μm, as well as finishing turning or boring of surfaces with a roughness Ra = 3.2 μm.

Centrifugal impact treatment with a pneumatic buffer is used in the manufacture of parts from non-ferrous metals and alloys, titanium and stainless steel, as well as cast iron with a hardness of up to HRC 58 ... 64. In addition to the external and internal surfaces of rotation, planes are machined with this device, and shaped surfaces are used with a copier. You can also handle intermittent surfaces and mating surfaces.

The conditions of centrifugal impact treatment with pneumatic buffer are as follows. The hardness of the surface layer, the hardening depth and the surface roughness depend on the impact force, the pressure value P of the pneumatic buffer and the number of strokes per 1 mm ^{2 of the} surface. These parameters, in turn, depend on the peripheral speed of the disk, the interference fit h, the size of the elements, their number in the disk, rotation frequency, feed rate per revolution of the workpiece and the number of passes.

The length l of the socket where the deforming element is located provides a complete repayment of the rebound speed of the deforming element. The value P of the pressure of the compressed air in the socket ensures the repayment of the rebound speed, the more P, the more effective the repayment of the rebound velocity of the deforming element. The pressure P also affects the amount of deformation of the workpiece. Modes of centrifugal-shock surface treatment with balls with a diameter of 7 ... 10 mm with pneumatic buffer are shown in the table.

The process of riveting balls with pneumatic buffer has been little studied. In specific cases, experimental testing of the regimes is necessary.

If the mode is selected incorrectly, surface ripening may occur and tensile residual stresses may occur in the surface layer.

To obtain good results, the following processing conditions must be observed. It is necessary to provide a constant interference value h. Permissible radial runout of balls (in the state pressed to the separator), shape deviations and radial runout of the workpiece should not exceed 0.03 ... 0.05 mm.

Processing with high tightness leads to an increase in surface roughness, but at the same time the hardening effect is somewhat increased. To obtain a surface of high quality, the parts are cleaned from corrosion and degreased before processing. Processing is carried out using COTS. Elements are lubricated with a mixture of industrial oil (60%) and kerosene (40%), the surface of the part is kerosene.

Leave no allowance for processing should not be, as the size change is very slight (1 ... 5 microns). After processing with this device, the accuracy of the parts corresponds to 7 ... 9th qualifications.

During industrial testing of a device installed in a special electromechanical device, a workpiece, item 13 (see Fig. 6), rolled from a pipe that underwent the formation of a helicopter rotor blade profile made of a titanium alloy was processed.

The initial roughness parameter Ra = 3.2 μm, achieved - Ra = 0.63 μm; deforming elements - balls with a diameter of 10 mm from steel ШХ15, hardness HRC 63 ... 65 are located in a housing with a diameter of 2R = 200 mm.

Impulse-impact PPD were conducted in the following modes: circumferential speed of the body - V _И = 1500 min ^-1 ; blade rotation speed - V _З = 5 min ^-1 ), transverse tool feed S _pop = 50 mm / min, number of passes (i.e. the number of workpiece revolutions) - 3, interference - h = 0.2 mm; longitudinal S _pr supply was carried out manually during adjustment; the value of the break-in force was set to 170 ... 175 N; the height and width of the workpiece profile changed after rolling in 0.02 mm (0.01 mm per side); the depth of the riveted layer was in the range of 0.15 ... 0.20 mm; hardness increase by 25 ... 30%; when running in, the deforming elements were lubricated with a mixture of industrial oil (60%) and kerosene (40%), the surface of the part with kerosene; tool life increased by 45 ... 55%. The control was carried out by an indicator bracket with an indicator ICh 10 B, class. 1, GOST 577-68 and on the profilometer mod. 283, type AN, GOST 19300-86. No defective parts were found in the processed batch (equal to 10 pcs.). The deviation of the shape of the rolled surface from the required was no more than 0.02 mm, which is permissible.

The use of the proposed device for centrifugal treatment of PPD with a pneumatic buffer allowed us to expand the technological capabilities of centrifugal processing of PPD, reduce the wear of deforming elements - balls, nests for deforming elements, separators, increase tool life, processing productivity, ensure high accuracy, reduce the roughness of the processed surface and reduce cost of processing.

Information sources

1. Auto USSR 667391, MKI V24V 39/04. A device for treating metal surfaces with balls. Zhebelev Yu.K. and Rubin I.L. Application No. 2564489 / 25-08, declared 01/06/78, publ. 06/15/79. Bull. Number 22.

2. Reference technologist-machine builder. In 2 vols. T 2. / Ed. A.G. Kosilova and R.K. Meshcheryakova. - 4th ed., Revised. and add. - M.: Mechanical Engineering, 1985. S. 412-414.

Claims (1)

A device for centrifugal treatment by surface plastic deformation, comprising a housing in the form of a disk with radial blind seats, in which the deformation balls and a separator in the form of a ring with holes are located, mounted on the periphery of the disk to limit the radial movement of the deformation balls, characterized in that it is equipped with a pneumatic chamber with a fitting for supplying air to it, the housing is rotatable and a flange is located on its end, the pneumatic chamber is mounted on the end of the housing in the flange using a bearing from the condition of ensuring its immobility during rotation of the housing, holes are made in the bottom of the radial seats of the disk for connecting them to the pneumatic chamber, a groove in the form of a sector is made in the wall of the pneumatic chamber adjacent to the end face of the housing to provide access for compressed air from the pneumatic chamber to several radial sockets with deforming balls located in the processing zone and close to it.

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