SU1220881A1 - Method of working holes - Google Patents

Description

The invention relates to metal cutting, in particular, the processing of holes with a tool, such as a countersink.

The purpose of the invention is to increase the life of the tool.

The drawing shows a scheme for implementing the method.

The part 1 is fixed in the fixture, the tool 2 is installed in the spindle of the machine, the rotation of which is communicated from the engine 3 through the 4-speed gearbox.

In the process of machining parts, for example, in the process of dimensional wear of the tool, there is a decrease in the diametral size of the holes being machined. When the hole size comes out of the tolerance field, which is fixed by the gauge 5, the control is made, in this case in the direction of increasing the amplitude of the tool oscillation by increasing the cutting speed (increase the number of tool turns Pcn) Example. It is necessary in billets 1 of steel 45 with a pre-processed hole with a diameter of 29.5 mm to ensure the size of holes with a diameter of 30 + 0.05 mm.

The following initial data is selected: countersink diameter (30 mm of steel R18 with number of teeth cutting speed V 9 m / min; feed S 1.0 mm / / rev; given tool mass, 0 kg, radial rigidity of the tool Cyprus 1320 kg / mm; the mass of the cutting part of the tool 300 g

Initially, an unbalanced radial force is determined by the formula

iP

2; Sr-yn-cfp- 2. Mr-S (| -) Mp,

Wg

(I)

at Cfp 355, Cug 2.2 (y 0), Ksur 2.26 ((f 15 °), K, 0.82 (g 10 mm), YP, - 0.75, n 0.51 For these values get

drr 416 N.

the limit are amplitude amplitude V

BUT

Tmv

uPr k 2mV

tjop W

(2)

In the above data, the total oscillation amplitude of the tool is 2A 0.05 mm.

With a tool diameter of 30 mm, this makes it possible to achieve the required diametrical hole machining accuracy S30 + 0.05 mm, since 30 + 0.05

 30.05 mm is the maximum resulting hole size in the tolerance range.

As the instrument is blunt, it is ground around the front and back surfaces and again

process holes. Due to the inverse taper, the diameter of the countersink after several registers can become, for example, 29.94. Processing such a countersink with the original value

a vibration of 0.05 mm does not provide the required accuracy of the diameter, since the maximum size of the holes obtained is 29.94 + 0.05. 29.99 mm out of range

hole clearance.

The proposed method should be adjusted in the direction of increasing the amplitude of oscillation of the tool. For this case, the amplitude

The oscillation of the tool should be 0.11 mm, since 29.94 +0.11 30.05 mm.

An increase in the amplitude of oscillation of the instrument can be carried out.

by increasing the reduced mass of the tool.

The reduced mass depends on the mass of the cutting part of the tool (sr.) And the mass of the mandrel reduced to the free end (SOR).

:

 33

14. + T50 (3)

Therefore, by increasing the mass of the mandrel, you can increase the reduced mass of the tool.

To provide an oscillation amplitude of 0.11 mm, it is necessary to have a reduced tool mass of 4 kg. To obtain such a mass, it is necessary to increase the mass of the mandrel.

With a given mass of 2.4 kg, the oscillation amplitude of the tool is –0.11 mm and the holes drilled by a countersink with a diameter

 29.94 mm is again in the tolerance field, since 29.94 +0.11 - 30.05 mm. An increase in the amplitude of oscillations of a tool can be achieved by reducing its radial rigidity.

In order to provide an oscillation amplitude of the tool O, 11 mm

it is necessary that the rigidity of the tool is 25 kg / mm.

With a tool stiffness of 25 kg / mm, the oscillation amplitude of the tool is 0.11 mm and the holes machined by a countersink with a diameter of 9 $ 29.94 are in the tolerance range, since 29.94 +0.11 30.05 mm.

The increase in the amplitude of oscillations of the tool can be achieved by increasing the rake angle of its teeth. The initial rigidity of the KU tool is 360 kg / mm.

In order to provide a tool oscillation amplitude of 0.11 mm, it is necessary that the unbalanced force be 200 N. To obtain such a value of DFR, the coefficient is changed, which takes into account the magnitude of the transferable angle. At 20 ° K5 1.0.

Editor I. Casard

Compiled by G. Sirotovsk

Tehred I. Veres Proofreader M.Samborska

Order 1526/16 Circulation 1001Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

 Branch ShSh Patent, Uzhgorod, st. Project, 4

At D Pf, 200 N, the oscillation amplitude of the tool is " 0.11 mm and the holes machined by a countersink with a diameter of 29.94 are in the tolerance field.

An increase in the amplitude of oscillations of a tool can be made by increasing its angle in plan.

In this case, they take 5 ° C, K (|, 1.0. At these values, H and the amplitude of vibration 0.11 mm are obtained.

In the case of an increase in the radius at the point of transition of the intake cone and the calibrating part of the tooth of the tool, take 0.25 g, Kjr 0.4. At these values, LR is obtained, - 200 N and an oscillation amplitude of 0.11 mm.

In the case of a decrease in the feed rate, S 0.04 mm / rev is taken. With

these values are obtained with a Pg of -200H and an amplitude of oscillation of 0.11 mm.

Claims (1)

METHOD OF HOLE TREATMENT with a multi-blade tool, in which the parts and the tool communicate relative rotation and axial movement with superimposed vibrational movements, characterized in that, in order to increase the life of the tool, the amplitude of the vibrational movements is assigned to the tool wear size according to the following relationship IN Kpr-r / Λη ^ P | ^> ' ^g ' in ^{,, G} · P 2 k ₊ ^k ynp l (l-3 _Pr ) mV _Mh m where V _MH is the cutting speed; g _in - the radius of the tool; Ku _P p - the radial rigidity of the tool; . w - reduced mass of the tool; Y _pr - coefficient taking into account the processing method; η is a coefficient depending on the number of teeth, the parameter U _Pg and the ratio of the machining allowance to the tool radius t ₀ / g _in , ^k Ph ' ^C p'? where C _p - coefficient taking into account the processing conditions; K. - coefficient depending on the value of the front angle of the tooth of the tool; K ^ - coefficient depending on the magnitude of the angle in terms of the tool; K ₂ is a coefficient depending on the radius at the junction of the intake cone and the calibrating part of the tooth of the instrument; ^to m ~ coefficient taking into account the properties of the processed material; S is the feed rate; Z is the number of cutting teeth of the tool. >