SU1227496A1 - Method of forming pneumatic tyre casings - Google Patents

Description

The invention relates to the manufacture of tires for pneumatic tires - and is intended for forming a billet of a radial tire into a tire assembly production device.

The aim of the invention is to improve the quality of the moldable pokryshki.

FIG. Figure 1 shows a scheme for calculating the rate at which the flanges of the drum approach each other in the proposed method; in fig. 2 - experimental dependence of the non-uniformity of the rarefaction of the cord in a moldable billet of the radial casing on the degree of deformation at different rates of deformation of the billet for the 4L22 steel cord cut by the mixture 2 E2179; FIG. 3 shows the equatorial strain rate of a billet of a radial tire 18.00-25R as a function of its deformation at the equator — with a constant rate of convergence of flanges and experimental dependence (&) that deforms the workpiece material below the tensile strength of the transverse gap during the entire molding process with a constant non-uniformity of the rarefaction of the cord; Fig. 4 shows the dependence of the speed of convergence of the flanges of the forming drum V on their movement.

The molding of single-layer skeletons of radial pockets of rubberized 4L22 metal cord rubber-wrapped with a mixture of 2 E2179 and rubber from this mixture was carried out on an assembly drum with a rubber diaphragm. The strips of rubberized steel cord, cut at an angle O, are superimposed on the rubber diaphragm of the assembly drum at the maximum distance of the flanges from each other; they join the edges of the bands in the form of a bracelet, which the clamp is attached to the flanges. Then, the forming pressure P 0.06 MPa is fed into the diaphragm cavity and the flanges of the forming drum begin to close together at an initial velocity of m / s, which drops to zero as the flanges move closer.

The molding time is measured and, at the end of the molding, the unevenness of the cord vacuum is evaluated (by a known method), which is characterized by the deviation of the thread position from a uniform distribution (see table).

Molding method

Spreading the cord at the equator of the moldable billet at the end. molding,%

Forming time, with

Known (at constant speed form-, 002m / s)

Known (at a constant mold speed, 004 m / s) Offered (at a variable rate of flange approach, 0.01 - O m / s)

120

18

60

50

As can be seen from the table, the molding according to this method ensures uniformity of the cord vacuum in the molded workpiece of the radial joint and, at the same time, the molding time is reduced.

When deriving the calculated calculated dependence of the speed of movement of the flanges of the forming drum on the distance between them, it was possible to describe the shape of the meridian profile of the moldable billet 1 (Fig. 1) fixed on the flanges of the assembly drum 2, with a circular arc, then the current radius of the equator of the moldable billet

.

(one )

de

R is the radius of the equator of the billet radial tire in the molding process, m; RO is the radius of the side ring of the moldable billet radial pokryshki ki, m;

C is the length of the thread of the cord from side to side of the moldable billet of a radial tire, MJ

H is the distance between the sides.

formable billet radial tires, m

The greatest circumferential deformations of the radial tire billet are exposed at the equator, then from the front, and the formulas for it will be given by the expression for the equatorial deformation

.

R,

but)

Hence the equatorial strain rate

de en

/ з н Эн

dt th

FIG. 1 shows the position of the forming drum flange at an arbitrary point in time, and the dotted line shows its positioning in terms of the time interval At. The change in the distance between the flanges of the DN-UD, then -y and for the strain rate at the equator we get

TTN V

3HV

16, e

(3)

For a tire of 18.00-25P, if the speed of movement of the sides of a molded tire is 0.0002 m / s, then this dependence is represented by curve 1 in FIG. 3, and curve 2 is the dependence of the equatorial strain rate f on equatorial strain 6, obtained from the graph of FIG. 2, if we choose the nonuniformity of the vacuum cord vacuum during the whole process of forming a constant and equal to 4% (dotted line right in Fig. 2). The intersection of this line with the family in FIG. 2 gives the optimal law of change in the deformation rate due to the deformation in the process of forming the billet radial, which ensures high quality of the billet, since the NDT is equal to the specified value during the entire molding process.

From FIG. 3 it can be seen that the dependence () - curve 1 in the moldable billet is far from the optimal law (4) of curve 2. At the initial stages of the molding process, with a circumferential deformation of the workpiece equator 40%, you need to increase the speed of its deformation, and then in comparison with the real.

So at 20% speed should be increased approximately 2.5 times.

Yu

15

20

25

thirty

five . YU

At the same time, a significant increase in speed at the beginning of the molding process and a slight decrease at the end of the process compared to the actual speed allows an increase in the speed of the molding process. In addition, a reduction in the rate of convergence of the flanges at the end of the process improves the uniformity of the distribution of the cords.

Thus, for high-quality molding of the radial tire blank, it is required that the equatorial strain rate changes with increasing strain according to the law, described. Curve 2 in FIG. 3. As can be seen from formula (3), the equatorial strain rate E depends on the rate of convergence of the flanges of the forming drum V. Assuming in (3) the speed of movement of the flanges, depending on the degree of deformation of the moldable workpiece 6, we find the law of variation V (), which ensures the transition of curve 1 to curve 2 in FIG. 3

Let curve 2 of FIG. 2 be optimal. 3 is described by law

((f-l). (H, From the condition that at the final deformation of the molding 100% molding speed g is equal to O, the constant C is represented in the form of the charger „Н

oi

16 R

where V is the initial rate of convergence of the flanges during molding, determined from the real curve 2 of FIG. 3 specifically for the size of the tire and material, ala billet, m / s.

The initial velocity V is determined from the following considerations. If it is assumed that the rate of convergence of the flanges Y decreases evenly from V to O and the productivity of the process remains the same, then the average speed of the process with an equally slow movement of the flanges H) / 2 should be equal to the speed V used in the known method about

Assuming in (3) V V () and demanding that (3) and (4) match, we have

3-N „Н

(...

(f-).

or, substitute instead of the equatorial deformation f its expression (2), we get, -

, /)

where V is the speed of movement of the flanges, m / s;

 initial speed of movement of flanges, m / s;

radius of the side of the ring

thin tires, m; cord length from side

before the board, pokryshki, m; distance between sides

formable billet pokryshki, m.

 0.0001 8 0.003

Yu 20 30 40 50 80 70 80 90 100. kVatoriapna on deformation C,%

(Reg. 2

No. Jc

-f

 0.0001 s 8 0.003 s

О20W6080

Ecbatorial de (rormaci, / o

Fig.Z

100

About w 80 t t 200

Interleave (rpansV drum, mm Fy

2kQ

Editor L.Avramenko

Order 2252/19

Circulation 640 Subscription

VNIIPI USSR State Committee

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

Production and printing company, Uzhgorod, Projecto st., 4

Compiled by E. Krieger

Tehred I.Popovich Proofreader E.Sirohman

Claims (1)

METHOD FOR FORMING PNEUMATIC TIRE TIRE TIRES, in which the sides of the tire blank are fixed on the flanges of the drum, compressed air is supplied under pressure into the forming cavity of the drum and axial movement of the sides of the blank is carried out, characterized in that, in order to improve the quality of the formed tire, the axial the movement of the sides of the workpiece is carried out with a monotonously decreasing speed as they approach each other, determined by the formula where V is the speed of movement of the flanges, m / s; V is the initial displacement velocity of the flanges, m / s; R _o is the radius of the side ring of the tire blank, m; E is the length of the cord thread from the side ΰ to the side of the tire blank, m; N is the distance between the sides of the moldable tire blanks, m 96 ^ 221 PE