SU1426677A1 - Method of expanding cylindrical thin-walled shells and die for effecting same - Google Patents

Abstract

The invention relates to the processing of metals by pressure, in particular sheet metal forming. The goal is to increase the degree of deformation and quality by creating additional circumferential efforts directed to the most thinned areas of the collar. At the first stage of distribution, the two sliders (П) 8, mounted on each expansion valve (PC) t, are brought together by the action of n-pYKHii 10, and the lever () 12 mechanisms of forced circular movement P 8 that are fastened together with P 8 together with PC 1 After deforming the shell 2 to a mean circumferential deformation of 10.,. 20% of the limiting f, the common axis 13 of the K 12 pair of pairs rests against the wall of the radial groove. Due to the subsequent rotation of P 12 around the axes 13, P 8 acquire an additional one. circumferential speed, is active on the inner surface of the shell 2 by friction forces. After the distribution of the latter to an average circumferential deformation of 40–60% of the limit, the directions of the circumferential speeds of each П В along with the directions of actions of the circumferential forces change to the opposite 2 s. f-ly, 11 ill. P lvgyu

Description

ft

.five

114

The invention relates to the processing of metals by pressure, and more specifically to sheet metal forming, and can be used to calibrate cylindrical thin-walled shells by dispensing an internal diameter.

The aim of the invention is to increase productivity by increasing the limiting degree of deformation, quality and the increase in the utilization rate of the metal.

Figure 1-3 shows a follower

the process of distribution of thin-walled

15

shells in the initial, intermediate and final moments; figure 4 - stamp, top view; figure 5 is a section aa in figure 4; Fig. 6 shows a fixed plate at the time of the end of the second distribution stage; Figures 7-10 show the section 20BB in Figure 5 (the initial moment of distribution, the end of the first stage of distribution, the end of the second stage of deformation, the final moment of distribution); FIG. 11 is a schematic diagram for calculating its design parameters.

The method is carried out as follows.

At the first stage, by means of expanding sectors 1, radial forces of shell 2 are distributed to an average circumferential deformation equal to 10–20% of the limiting one.

At the same time, there are parts of the connector (the number of which is equal to the number of expansion sectors 1), in which the wall of the shell 2 has a minimum thickness. The areas of the shell 2 with the greatest wall thickness along the perimeter are located along the central (in cross section) axes of the expanding sectors 1.

After the first stage of distribution, additional circumferential forces (active friction forces) are applied to the inner surface of the shell 2 in the second stage of deformation, which are directed to the most thinned areas. As a consequence, the circumferential velocities of the material particles of the shell 2 are also directed from the thickened sections of the last 50 to the most thinned. By the end of the second distribution stage (after reaching the shell 2 of the average circumferential deformation, 40-60% of the limit), the most 55 thinned after the first distribution stage the shell 2 sections now have a maximum (along the last perimeter)

25

thirty

40

45

Q

five

0

thickness. Correspondingly, the largest thickness of the shell 2 after the first stage becomes by the time of the end of the second distribution stage the most thinned.

At the third stage of distribution, the directions of actions of additional district forces (active friction forces) are reversed (relative to their directions at the second stage of deformation). As a result, the circumferential speeds of the material particles of the shell 2 are again redistributed so that, simultaneously with the radial movement, the material flows from the thickest parts of the shell to the thinnest parts of the shell,

When the material is moved from the thickened to the thinned sections, the altitude deformations are also aligned, g since the thinned areas of the shell 2 have the smallest (along the last perimeter) height.

By the time of distribution of the shell 2 to the desired degree of average circumferential deformation, the wall thickness and the height of the finished product 3 are uniform along the perimeter of the latter. As a result, the quality of the finished product 3 is improved, the utilization rate of the metal is increased, and the degree of deformation increases in parallel.

Example. Shell 2 of steel. 08 kp is made of sheet (by means of bending into a cylinder and butt welding) and has the following initial dimensions, mm: thickness, 0, height HO 150, diameter. The number of sections of the expanding tool is 8.

0

The required largest diameter after the meeting is .235 mm, i.e. Required level of distribution

m

  llax

Ps

 1.175,

required average circumferential deformation boron, 16.

Under conditions of cold linear stretching, the limiting average circumferential deformation for a shell of 08 kp steel is equal to

e.

P,

.ii (limit) problems, jjT deformation

).

D

krt.

v

., 248 mm. O. "Gdelna) the degree of time- y.z

l, 24,

m

.

degree of distribution and deformation of the cr

During the distribution stage, the envelope to the average circumferential deformation 6, amounted to 10–20% of

marginal

R

those.

h-

14266774

and at the same time, additional circumferential forces directed to the thinning areas of the shell 2 (forces are created by moving the expanding sectors 1 at the same time and in the circumferential direction), while the surface of the expanding sectors 1 in contact with the inner surface of the shell 2 is sufficiently rough R 80.

The amount of additional circumferential forces depends on the surface area of the shell contact. with a single unwrapped sector 1 (i.e. it depends on the number of the latter and is determined for one slider approximately by the formula

ten

15

20

-DSP

 fuKS,

s -1 umoks o 91 (- l 9 C -i-n - ;; U, / il-U, it,

D

1.ms, ks 204-208 mm.25

After the first distribution stage, connectors appear between the expansion sectors 1, each of which has a width 1 along the perimeter of the shell 2, determined from the expression (Fig. 1)

1 g, "

1 h sin-tt-,

where "i- is the angle of the solution of the expanding sector-, h, is the stroke of the latter, ie

h,

The thickness and height of the shell 2 after the first stage of distribution in places A (Fig. 1), determined experimentally, constitute

s J 0.94 N

143 mm.

a on the central axis B of the cross section of the expanding sector 1

S 0.95 N 144 mm.

At the second stage, the workpiece 2 is distributed to an average circumferential deformation of 40-60% of the limit, i.e.

er

 0,084-0,126,

five

0

five

Where

(C - plastic coefficient

friction (0.15-0.35) K is the plasticity constant S is the contact surface area of the expanding sector 1 with the shell 2.

After the second stage of distribution 217-225 mm.

At the same time, the place of the connector; when the adjacent expanding sectors 1 shift to point B. At this point, the thickness and height of the shell 2 (experimentally determined) minima-pzt along the perimeter of the latter

, 6

S 0.91

H 136 mm.

40

At point A, the thickness and height of the shell 2 are greatest along the perimeter.

S, j 0.92

H, 138 mm.

45

At the third stage of distribution, shell 2 is distributed to the required average circumferential deformation cf 0.16.

At the same time, at each contact point of the inner side Surface of the shell 2 with expanding sectors 1, the direction of action is additional

circumferential efforts are opposed to the effects of additional actions of circumferential efforts at the same points in the second distribution stage.

After the third distribution stage is completed and the finished product 3 is obtained at points A and B, the thickness and height of the last are as follows, mm:

one

sj. 0.87 S 0.87.

When dispensing shell 2 to the desired degree of distribution, 175 according to the method used as a prototype, the reject rate is very high due to the destruction of the shells 2 after the loss of the STABILITY of deformation,

With the degree of distribution, 12 (Od, (, cs 225 mm) at points A and B, respectively, the thickness and height are as follows, mm:

, 88, 90.

. Thus, due to the distribution proposed by the proposed method, the quality of the finished product is improved, the utilization rate of the metal is increased due to a decrease in the heterogeneity of deformations (and the corresponding elimination of additional trimming operations on the ends of the finished product), and the labor productivity due to an increase in the limiting degree of deformation,.

A stamp for carrying out the proposed method, designed to be installed on a press with a simple action, includes an expanding tool in the form of expanding sectors 1, mounted for movement in radial grooves made in the fixed plate 4,

Each expanding sector 1 has a cleaved surface 5, interacting with a corresponding face of the pyramid-made central wedge 6, which is attached to a press slider (not shown),

The surface 7 of each expanding sector is made circularly cylindrical and is a support for the mounted sliders 8 on it. The latter are placed in the transverse laser guide 7 made on each surface by means of the shanks 9.

Two sliders 8, mounted on the same expanding sector 1, are interconnected by the base 10, the working surfaces 11 half- 3ymei t 8 are made circular cylindrical with a radius equal to the radius of the finished product 3,

Each expandable with.

enforcement mechanism

the displacement of the located studs 8, which is made. two royagov 12, install fy movable plate 4 with the possibility of a pulling on a common axis 13, Each 12 ° by means of a pin 14 hinge. fastened with the corresponding flag 8,

In addition, each axis 13 and its levers 12 have the possibility of radial movement in the grooves 15 inserted in the fixed plate 4. The length of the groove 15 is equal to the radial movement of the expansion sectors 1 in the first stage of distribution. The springs 16 spring expanding sectors

1k fixed plate 4 in the radial direction,

The stamp works as follows.

In the upper position of the press ram and the central wedge 6, the expandable sectors 1 under the action of the springs 16 are in their initial position, which is closest to the die axis. The axis 13 of each mechanism of forced circumferential movement of the sliders 8 is located at the transverse wall of the corresponding radial groove 15 closest to the punch axis. Shell 2 is mounted on a fixed plate 4,

Under the action of the press ram, the central wedge 6 goes down and after the contact of its faces with the wedge surfaces of the 5 expanding sectors 1, the latter begin to move in the radial grooves from the punch axis, while discharging the shell 2,

Together with the expanding sectors 1, the mechanisms of forced displacement oKpjOKHoro of the slider 8 move, the latter at the first distribution stage are brought together by springs 10, and therefore the working surfaces 11 of each pair of sliders 8 (mounted on any expanding sector 1) form a single surface, in the center of the longitudinal axis of which (at the junction of two sliders 8) the shell material

2examines the smallest deformation (wall thickness and height of the shell 2 in this place at the first stage of distribution - the greatest along its perimeter),

Between the expanding sectors 1, as well as between the slider 8, there is a uniformly increasing gap (connector). In the center of the connector between the slider 8, the deformation of the shell material 2 is the greatest along the perimeter of the Latter (respectively, the wall thickness and the height are the smallest).

 At the end of the first distribution stage (when the casing 2 achieves an average circumferential deformation of 10-20% of the limit) axis 13 of the mechanisms for forced circumferential movement of the sliders 8 abut against the peripheral walls of the grooves 15 and stop.

With further expansion of the expansion sectors, the levers 12 begin to rotate in pairs around a common axis 13 and, as a result, the sliders 8 also move in the radial direction of the scientific research institute. Here, the frictional forces acting on the inner side surface of the shell 2 change direction. opposite, i.e. directed at the second stage from the most thickened areas of the shell 2 to the most thinned (during the first stage of distribution). This direction of friction forces prevents further intensive thinning of the shell 2 in places of the connectors and helps to level the deformations along its perimeter.

The second stage of distribution ends when the levers 12 are rotated by an angle equal to half the angle of their full rotation in the process of distribution. In this case, the lateral faces of adjacent non-interconnected springs 10 of sliders 8 are close to each other (or in contact), and after the first stage of distribution, the thickest and most thick sections of the shell 2 become the thinnest by the end of the second stage of distribution.

After the second stage of distribution, with further rotation of the levers 12 around the respective axes 13, the direction of the radial movement of each slide is reversed. The directions of the friction forces are also redistributed and directed from the most thickened (after the second stage of distribution) sections of the shell 2 to the most thinned, due to which gradual alignment of the deformations along its perimeter occurs. As a consequence, the utilization rate of the metal increases, since it becomes possible to eliminate the final operations.

machining. In addition, the marginal level of distribution increases, and as a result, labor productivity rises.

At the end of the distribution and receiving the finished product 3, the central wedge 6 is retracted upward by the press slider, the expansion sectors 1 are retracted by the springs 16 to the initial position. In this case, the levers 12 perform the reverse (idle) rotation on the axes x 13 after the latter are pressed into the walls of the corresponding grooves 15 that are closest to the die axis.

To determine the structural dimensions of the stamp that meet the conditions of the method, the analytical dependencies found were used.

The number of initial data (specified values) are (11):

r,, R.j3 are the radii of the workpiece and the finished part, respectively, and the radius of the working surface 11 (sliders 8) with the center at the initial moment of distribution at the point O is R.J ..,;

v is the angle of the half-solution of the expansion sector 1 (the angle between the straight line OM and 00 at the initial moment of distribution, i.e. “with, while the point O is the center of the stamp; M is the extreme point of the working surface 11 of the sliders 8, 0 is the center of the axis 13 at); Jo is the angle between straight and 0.0 at (S is the center of the pin 14),

g is the length of the lever 12 (i.e. the length of the segment 805 in FIG. 11); R is the length of the segment L is the movement of each expanding sector 1 during the first stage of distribution.

In the calculations, it was assumed that the cylindrical surface of the expanding sector 1 is coaxial with the working surface 11 of the slider 8, therefore the value of Rg during the dispensing process remains unchanged.

Given the initial data determined:

tf is the angle between the MO and .O with the

cf arcsin (- sinu /.).

(one)

S, is the length of the segment 0,0, with

S,, (2)

and Sj is the length of the segment with

lr

gSin

(3)

In the coordinate system in which the axis OX is directed along the central axis of the connector between the sections (Fig. 11), the point M of the slider 8 moves along the curve MoM, M, jM5. In this case, the straight forward MDI segment corresponds to the first distribution stage, i.e.

,,

(4) 20

the curve MiMj corresponds to the second distribution stage, and the curve to the third.

The coordinates Yf of the points M, and Mj must be equal to zero (or close to zero):

U, (Ma) U (M,) 0

(five)

In the moving coordinate system moving together with the expanding sector 1 (Fig. 11), the coordinates of the points M as it moves (depending on the stroke H of the expanding sector 1 in the second and third stages of distribution) are defined by the expressions

(6)

(7)

where the magnitude of the angle, the current angle between the straight lines SO, and 0.0, is from the USO, 0 according to the cosine theorem:

cos

(eight)

Now, in the fixed coordinate system of the HOU formed by the axes of the scale, we have the point M for the coordinates

 ,

Y -V with; 4-T-4-P m th, -i-tl,

(9)

(io)

one . The method of distribution of cylindrical thin-walled shells, including the continuous application to the inner side of the coordinates of point M in the system of the coordinate surface of the shell of radial dinat, is given by known transformations by means of expansion joints:

, X, „X soB + Ud 81pog, y, -X sinoi + y cosei.

(11) (12)

Given the initial data g ,,: y Jo 9 RS L, the values of q, S, and Sj were determined, then, depending on the stroke H, the angle J. After that, we found the coordinates of point M in the coordinate system X, OU, using formulas (6-7) and (9-12).

Then, the initial data, the magnitude of which is from constructive considerations (i.e. r, R or o), was changed until condition (5) was satisfied,

With rj values of 100 mm, R 118 mm, & 30 °. the value of L is mm and in this case we get

0

, mm, 20 °.

The use of additional circumferential efforts during the distribution by expanding sectors directed at the second stage of distribution to the most thinned (at the first stage) areas of the workpiece, and the change in the third stage of distribution of the direction of actions of additional „red” forces to opposite, favorably distinguishes the proposed method of distribution cylindrical thin-walled shells and a stamp for its implementation from the specified prototypes due to the reduction of the deformation inhomogeneity along the perimeter of the finished product, which improves the quality the latter, and also allows you to increase the maximum achievable degree of distribution and increase through this labor productivity.

The advantages of the proposed method and the stamp for its implementation in comparison with the prototypes are the shading of the heterogeneity of deformations.

5 of the finished product and an increase in the maximum achievable degree of distribution, and also an improvement in the quality of the finished product and an increase in labor productivity.

Claims (1)

Invention Formula tr Fi.2 (Rig.z W FIG. If . B-5 FIG. 7 (Puz. 6 5 B FIG. eight Editor Yu, Sereda FIG. 11 Compiled by I. Aynetdinov Tehred M. Didyk Proofreader M. Demchik