SU1294490A1 - Method of determining rigidity of machine tool - Google Patents

Abstract

The invention relates to the field of machine tools. The aim of the invention is to increase the accuracy of determining the quasistatic and dynamic rigidity of the machine. To implement the method, it has been proposed to use mandrels with the same rigidity, each of which has cylinders. The drike and conic surfaces intended for the treatment, while processing one of the mandrels is carried out with a tool having known quasi-static or dynamic rigidity of its attachment. Before treating the conical surface of each mandrel, its cylindrical surface is machined, and the error of treatment of each of the mandrels is determined on a diameter equal to the diameter of the outgrowed cylindrical surface, and the rigidity of the machine is determined by the fit j. (lu y,) Jij Y, Dv Jp machine rigidity; j. - rigidity of fastening of the tool; lu - machining error on the first mandrel; Lou - processing error on the second mandrel, 5 Il.

Description

FIELD: machine tool industry.

The purpose of the invention is to increase the accuracy of determining the quasistatic and dynamic rigidity of the machine.

FIG. 1 shows a mandrel with cylindrical and conical surfaces intended to be processed during the implementation of the method} in FIG. 2-t cylindrical and conical surface of the mandrel before and after processing, section; in fig. 3 is a device for adaptive control of machining accuracy, used as a device with known quasistatic and dynamic rigidity of machine tools; in fig. 4 is a schematic diagram of the device; in fig. 5 - device operation diagram ..

The proposed method is carried out as follows.

For the case of determining the quasistatic rigidity of a machine in the Y direction for the sake of simplicity, the rigidity calculation is performed through compliance.

To determine the quasistatic stiffness, two mandrels of the same stiffness are turned (Fig. 1 B. In the first case, the turning is carried out with a simple cutter, in the second, with a special device having a specific quasistatic or dynamic stiffness. Geometrical parameters and material of the mandrels, geometrical parameters and material of the cutting wedge and modes cuttings (S and V) are the same in both cases. The cutter's overhang is provided the same, and if this is impossible for some reason, then the size-force coefficient.

Consider the case with the same cutter reach.

During machining, the cylindrical surfaces of the mandrel (hereinafter referred to as rings) in both cases, the allowance increases from t to t. The pressing of the technological system changes

 I ° Umax of the diameter of the treated surfaces varies from aa „„ „to d ,.

Despite the fact that the actual diameters obtained after processing with a simple cutter and with the device are different, they are located on the first and second rings

You can always find the section I and II (Fig. 2) with two equal pre-specified allowances (for example, t, 0.5 mm, t, 1 mm). Then (Fig. 2) you can

 -g

write down

lu

where 4 y

t and d - h t.

d, - d ,,, (1) processing error; diameter of the ring processed at depth

and t

soot

cutting t, legally, or for the first and second rings (the first ring is machined with a simple cutter, the second with a device)

 d, t, - d, t, f .t ,;

djti (2) (3)

20

The exodus of FIG. write:

2, can Tatore for

d,

+ +

 yt; yt

five

or for the first ring

d, t, d, t.

 d.

2 4 y, t

for

n y, the second ring

1 J

-four

0

d, t,

 d, + 2 fty.t, d .. +

2 & y.t.

five

and - -fj 7

For a process system that has sufficient rigidity, the equality

Ay P,,

where Ru and Yt.e are respectively the radial component of the cutting force and the flexibility of the technological system.

0

It is known that "

,

Where

RF

five

t, s, v

 P

s h

0

W

a constant characterizing the material being processed;

depth, feed, cutting speed, respectively;

respectively, exponents at t, S and V.

4i: H - t, + + i

where 1l) e, and

m

and)

.

five

- compliance of the machine, tool, tool and parts, respectively.

The main component of the technological system that determines compliance

is a machine. Taking into account that the flexibility of the fixture and parts in the first and second cases does not change and enters the compliance of the machine, and the compliance of the tool in the first case enters the compliance of the machine (taken into account by the value J.), in the second it is determined by the flexibility of the special mechanism and) (Can be written for the first case)

n}

-T-C.1

and).

(five)

for the second case

c, + H- (6) f5

for the first section (at t

t) is determined by the formula

P g. t s, fi / 1 l second cross section (with t

 V

g

t. . v

 tz)

  f4 -2

Taking into account the conditions of processing rings the same processing modes and material rings), you can write

A t de A pic

 Si

9 a ""

A t -;

")

but.

TOYAI

(7) (8)

ina determined

product C,

,

V

PV

From the specified equation for two rings and two sections, you can write (taking into account equations 5-8) for the first ring in the first section

to

& Y,

A t, uJ

st

for the first ring in the second section & y, t, A

for the second ring in the first section

UV t And t (Zet + t). ), 40 if necessary, the value at Jf about 1

Start can be set to 5 mm or more. After installing the Vernier, the cylindrical part of the mandrel is processed by nursing (at least 6-7 times), the tuning diameters (dj,) and the conical part of the mandrel (before processing) are measured every 1 mm of the conical part. mandrels by any method known in metrology, for example, using a UIM universal instrumental microscope. The measurement results are entered in a table. After the ring is measured, it is processed. The cutting conditions are assigned based on the purposeful definition of quasistatic or dynamic stiffness.

A second ring in the second section

A t

(2)

.

Then write the equations in the form:, + 2 А t.

(,

and (3) you can

+ J,)

ay (d

-f 1 Xj H

2 A t

and"

"J,

 u "

+ 2 A

);

2 A t

tr

“JCT) - d“ +45 (iZet +)) 3

(tJct +,

X 1

 2 Aui ,, (t; - t,); (9)

cT -a 2 A (u) c-, + u

and

lou

meadow

t, m. Dividing equation e (10), get

do lu luh .t-,

) (tr (9)

(10) on the equation (11)

+ lu, oo., - lu

.

 about

and),

or.

chim

and), - AZj

(- & yj)

Enter the sign (-) in brackets, half a number, oJ.,

st

Insofar as

(ftu, - lu7u

 -t-, we get

or

Jc.

20

25

thirty

35

(12)

To determine the rigidity of the machine, it is necessary to have two mandrels with a conical (15 mm thick) and cylindrical (5-5 mm thick) surfaces (FIG. 1). The mandrel is installed in the centers of the machine, for example turning, and clamped with a lead. the cutter (the cutter tips should meet the cutting edge of the device with a known stiffness, with which the second ring is machined) and, along the vernier, the transverse movements of the caliper are set in such a way that The knowledge began on a conical surface at a distance of about 1 mm from the right end of the ring (the size of the ring cone and the installation of the cutter on the size to be made should ensure an increase in the allowance from t 0 to t 1 mm).

Start can be set to 5 mm or more. After installing the Vernier, the cylindrical part of the mandrel is processed by nursing (at least 6-7 times), the tuning diameters (dj,) and the conical part of the mandrel (before processing) are measured every 1 mm of the conical part. mandrels by any method known in metrology, for example, using a UIM universal instrumental microscope. The measurement results are entered in a table. After the ring is measured, it is processed. The cutting conditions are assigned based on the purposeful definition of quasistatic or dynamic stiffness.

machine, based on the specific conditions of further use of the machine, as well as the basis of the conditions for ensuring sustainable cutting. The treated conical ring was again measured at a diameter equal to the diameter of the leached cylindrical surface. The measurement results are tabulated.

After machining the first mandrel with a simple cutter and measuring it, the second mandrel is machined using a device with known stiffness, and the diameter (d) should correspond to the diameter of the adjustment when machining the first ring. The measurement results of the second ring are tabulated. The processing and measurement of the second ring is carried out in the same follower element. In the middle part of planarity, as the first, in this case, the quasistatic or dynamic rigidity of the device should be known. Then, using the interpolation method, determine the diameter of the machined rings for given values of the allowance, for example t, 0.5 mm and mm, determine the machining error y and ddu, at given equal allowances and machine rigidity by the formula

 -,;

J

lu

As a device having

known quasistatic or dyn-35 mechanism.

Mechanical rigidity, a device for adaptive control of machining accuracy is used.

The device consists of front 1 (Fig. 3) and rear 2 bars. On the strap 1, there is a T-groove on the front side, which is necessary for fastening the cutter 3, on the back side there are protrusions 4 for mounting the axis 5 of the rolling support 6 and the protrusion 7, which serves to fix the initial position of the front strap relative to the rear. The cutter 3, equipped with a mechanically secured mineral-ceramic plate 8, is mounted in a T-slot on the front plate 1 with movement for adjustment to the required height of the centers with screws 9 and crackers 10. On the bar 2 there is a shank 11 on one side used for fixing it in the tool holder, on the other hand - a wedge 12, fixed

An adjustable plate can be changed with the help of a lining 13 with screws 14. In the upper part of the strap 2 there is fixed a plate 15, which is used for locating the stop screw 16 and leaf springs 17. The plate 15 is attached to the strap 2 with the possibility of changing the distance between the slats required for length measurement

the active part of the plate springs, which occurs due to the varying thickness of the gasket 18. The stop screw 16 is locked by a screw 19. In the upper part, both strips are joined

two plate springs 17c of varying length of the active part. The springs 17 serve to keep the front and rear bars in contact state and are used as an elastic

0

The ki are in contact through the rolling support 6 and the wedge 12, and due to constructive refinement, the rolling support 6 can move along the wedge only in the Y and g directions, excluding the movement along the X axis. In the lower part of the column, they are connected by a helical spring 20 reinforced at one end and the back plate 2 with the aid of a ring 21, others in the front with the possibility of changing the tension, which is produced by means of a screw 22. A screw spring is necessary for sampling the gaps in the contact members

0

five

0

five

As mentioned in the implementation of the method, one of the conical mandrels is treated with a device having a known quasistatic or dynamic stiffness, i.e. with the described device, which operates in the case of incomplete compensation of deformations, as most frequently encountered as follows.

With a gradual increase in the allowance (since the ring is conical), the cutting forces increase. When the tangential component of the cutting force (P) increases (Fig. 4), the front plate 1 with the cutting element 3 moves down the Z axis by an amount proportional to the change in cutting forces. Moving down along the Z axis, the bar 1 with the cutting element with a positive value of the wedge angle 12 (FIG. 4, shows the positive wedge angle),

the raid on the wedge 12, moves simultaneously forward along the Y axis, partially compensating for the elastic deformations of the machine’s technological system. Since the allowance during machining of the conical ring constantly increases, the position of the tip of the cutting element shifts down along the Z axis and forward the Y axis, and partially compensates the elastic deformations the size of the machined ring constantly increases by the difference in the double value of the elastic deformations of the technological system and the double value of the comp Moves the movement of the front panel. The total divided motion of the tool tip is shown in FIG. 5, where AB is the elastic deformation of the support group of the machine; BC - compensating movement of the front panel; 00 - elastic deformations of the spindle group.

Thus, at any values of adjustable ACS parameters providing stable cutting, the device has additional compliance (rigidity), which is determined (for specific values of wedge angle and plate spring thickness) during the cutting process (for any real V, S and t) using a universal dynamometer, such as the UDM-600, and an inductive displacement transducer required to measure displacements (from cutting forces) of the front panel relative to the rear in the Y direction.

L4908

Claims (1)

Invention Formula The method for determining the rigidity of a machine, according to which two mandrels fixed in the machine are sequentially processed with a cutting tool, the processing error of each of them is measured, and the stiffness is determined, characterized in that To improve the accuracy of determining the quasistatic or dynamic rigidity of the machine, mandrels with the same rigidity are used, each of which has cylindrical and taper surfaces designed for processing, while processing one of the mandrels with a tool having its known quasistatic or dynamic rigidity fastenings, moreover, before processing the conical surface of each mandrel, its cylindrical surface is inserted, and the machining error of each of the mandrels is determined eaten on a diameter equal to the diameter of the outgrowed cylindrical surface, the rigidity of the machine is determined by the expression Ja , , J . Where five J "T j. (iy, Hh - rigidity of the machine; - rigidity of fastening of the tool; - processing error on the first mandrel; - processing error on the second mandrel. 22W 15 18 physical PhieA Editor N. Margolin 5 Compiled by V.Semenov Tehred L.Opeynik Proofreader T. Kolb Order 422/10 Circulation 976 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4