RU2542214C1 - Method of parts flaring by ball tool - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: deforming element is indented in the processed surface, and it moves over the processed surface. The deformed tool indentation is performed by the contact pressure P_c, its value is determined by the equation: P_c=9σ_sD(h_e+h_p), where σ_s is yield strength, D is ball diameter, h_e is elastic strain, h_p is plastic strain.

EFFECT: increased quality of part surface layer.

1 dwg

Description

The invention relates to finishing and hardening of parts by surface plastic deformation (PPD), in particular to rolling holes in parts, shafts, bushings, etc., and can be used in aircraft engine building, turbine construction, shipbuilding, automotive and other technical fields in the manufacture and repair of cylindrical hollow parts and parts with holes.

By rolling is meant the rolling of a tool (ball) on the inner surface to be machined [L. Odintsov Hardening and finishing of parts by surface plastic deformation. Directory. - M .: Mechanical Engineering, 1987, p.13].

A known method of rolling parts with a ball tool, including the introduction of a deforming element into the work surface with a contact pressure P _to provide the necessary penetration depth, and its movement along the work surface, while the normal force value P _n is determined by the formula

Where

P _to - contact pressure;

R is the radius of the deforming tool;

α is the angle of indentation, depending on the properties of the material, the dimensions of the part and tool (see Papshev D. D. Finishing and hardening by surface plastic deformation. M .: Mashinostroenie, 1978. 14, 15, 147 pp.).

It is known that operational properties depend on a correctly set contact pressure P _k ; an unsuccessful choice of this parameter can cause partial destruction of the surface (peeling) and reduce the durability of the part (product) as a whole (see Papshev D.D. Finishing-hardening treatment by surface plastic deformation. M .: Mashinostroenie, 1978. 14, 15 p.) .

The magnitude of the contact pressure P _k , which is included in formula (1), for each particular product is determined experimentally using several batches of prototypes, despite this, the magnitude of the contact pressure P _k is approximate, which reduces the quality of the surface layer and, as a result, negatively affects on the operational properties of the part (product) as a whole.

The technical result of the claimed invention is to increase operational properties by improving the quality of the surface layer of the part.

The quality of the surface layer is understood as the roughness, depth and degree of hardening, the nature and magnitude of the residual stresses (see Papshev D. D. Finishing and hardening by surface plastic deformation. M .: Mashinostroenie, 1978, 144 pp.).

The specified result is achieved by the fact that in the method of rolling parts with a ball tool, including the introduction of a deforming element into the work surface with contact pressure P _to provide the necessary penetration depth, and its movement along the work surface, according to the invention, the contact pressure P _to is determined by the formula

Where

σ _s - yield strength;

D is the diameter of the ball;

h _y - elastic deformation;

h _p - plastic deformation.

This formula takes into account the physicomechanical properties of the material of the parts and the processing parameters, which allows it to be used for each specific case, excluding the experiment.

The drawing shows a diagram of the introduction of a deforming element in the form of a ball in the surface of the part.

The drawing shows: ball 1, the workpiece - shaft 2, d _OTP. - imprint diameter, h _у - value of elastic deformation; h _p - the value of plastic deformation.

The implementation of the method is considered on the example of rolling the inner diameter of the compressor shaft of an aircraft gas turbine engine with the required depth of the deformed layer δ _n = 1 mm from material EI961Sh.

As a spherical tool, an elastic single-ball coil is selected. The device for rolling (rolling) and the method of its operation are standard (see, for example, L. Odintsov. Hardening and finishing of parts by surface plastic deformation. Reference book. - M.: Mashinostroenie, 1987, p. 57). Depending on the specified depth of the deformed layer, the size of the deforming device is selected - a ball with a diameter D of 15 mm, a treatment mode is assigned, the contact pressure P _{k is} calculated by formula (2) and the normal force value is determined depending on the contact pressure P _k .

The magnitude of the contact pressure P _to calculated as follows.

According to the well-known formula

Where

δ _n - the specified depth of the deformed layer;

d _TNA. - diameter of the print.

(Odintsov L.G. Hardening and finishing of parts by surface plastic deformation. Handbook. - M.: Mechanical Engineering, 1987, p. 18) determine the diameter of the print:

d _TNA. = δ _n : 1.5 = 1.0: 1.5 = 0.666≈0.7 mm

The known formulas determine:

elastic strain h _y

Where

D is the diameter of the ball;

σ _s - yield strength; in a specific example, σ _s = 85 kG / mm ² E is the elastic modulus;

in a specific example, E = 20,000 kgf / mm ²

h _y = 2.4 (D: 2) (2σ _s : E) ² = 2.4 × (15: 2) × (2 × 85: 20000) ² = 0.0013 mm = 1.3 μm

- the value of plastic deformation h _p

Where

r _Otp. - radius of the print;

D is the diameter of the ball.

h _p = (r _sp. ) ² : D = (0.35) ² : 15 = 0.008 mm = 8.0 μm

Calculate by the formula (2) the magnitude of the contact pressure:

P _k = 9σ _s D (h _y + h _p ) = 9 × 85 × 15 (0.0013 + 0.008) -106 kG

The magnitude of the contact pressure or calculate the magnitude of the normal force P _n , or this value is determined from the table data.

Next, the rolling operation is carried out.

Part 2 (shaft) is fixed in the spindle of a horizontal lathe and gives it a rotational movement. Using auxiliary elements of the rolling mill (rod, spring, transfer balls, rotary nut) and a deforming device - ball 1 (made, for example, of bearing steels ШХ15, ШХ20СТ, etc.), the value of the normal force P _n is determined in accordance with the calculated value of the contact pressure R _to . Then, the roller with the ball 1 is brought to the rotating part 2, the ball 1 is introduced into the workpiece surface of the part 2 (shaft) to the penetration depth H = 0.009 mm to provide the required depth of the deformed layer δ _n = 1 mm, and the ball is longitudinally moved along the treated surface. In this case, when moving the deforming element - the ball - on the surface to be treated, the normal force value is controlled within P _n ± 5% (P _n plus or minus 5%), avoiding going beyond this limit by means of a change.

Otherwise, it is impossible to ensure the proper quality of the processed surface.

At the end of the rolling process, the rolling unit is returned to its original position, and the part is removed from the machine.

Claims (1)

The method of rolling parts with a ball tool, including the introduction of a deforming element into the work surface with a contact pressure P _to provide the necessary penetration depth, and its movement along the work surface, characterized in that the contact pressure is determined by the formula
P _k = 9σ _s D (h _y + h _p ), where
σ _s - yield strength;
D is the diameter of the ball;
h _y - elastic deformation;
h _p - plastic deformation.