CS272817B1 - Method of rubber product's cure course determination - Google Patents

Abstract

For the process of vulcanisation it is necessary to know the temperature of the point, where the rubber product is heated in the slowest manner. Determining vulcanisation process in rubber product (1) consists in the fact that at first the point (A), where the rubber product (1) is heated in the slowest manner, is defined. This point is in the distance of (Lmin) from the point (B) on the mould form (2) surface, in which temperature (φ) is measured in constant time intervals (Δ τ) from the beginning of the process. Concurrently the temperature (Tj) in the point (A) of the rubber product (1) is defined according to the following relation:<IMAGE>According to the temperature measured in the point (A) of the lowest heating speed according to modified Arrhenius' equation the process of incubation and vulcanisation is defined. After achieving the required degree of vulcanisation the whole process is terminated.<IMAGE>

Description

The invention relates to a method for determining the vulcanization process of a rubber product by measuring the temperature of the mold surface in contact with the rubber product.

The vulcanization of rubber products can be classified as a complicated chemical reaction. Cross-linked spatial macromolecules are formed! structures; ' which shows through improvement of mechanical and physico-chemical properties. The course of vulcanization is divided into two basic stages of incubation and actual reacoeing. Their duration is directly proportional to the temperature of the rubber product. It is important to achieve the desired degree of vulcanization over the entire cross-section of the rubber product; even in the slowest heated place.

On the other hand; longer duration of vulcanization means not only energy loss; but also the deterioration of product properties due to the breakdown of some bonds. At present, efforts to determine the temperature course at the slowest heated location of the rubber product are by means of needling sensors; which do not yet provide the desired results.

These disadvantages of the prior art are overcome by the method of determining the vulcanization process of the rubber article of the invention; the nature of which is to determine the slowest heated location of the rubber product; which is a certain distance from a point on the mold surface; in which the temperature is subsequently measured at constant time intervals from the beginning of the vulcanization process. At the same time, the temperature at the slowest heating point of the rubber product is determined according to the following equation: ^T J ^{= A} jk

AFo where index j denotes successively the first; second to general nth time interval. Fo is a dimensionless Fourier number, e is the base of natural logarithms / k is the addition index and C ^: ^A j 'k 3 ^S0U equation coefficients. Based on the observed temperature in the slowest heated area, the course of incubation and vulcanization is determined according to known relationships based on the modified Arhenius equation. After reaching the required degree, the whole process is completed.

An advantage of the method of determining the vulcanization process of a rubber product according to the invention is that, in an easy method of measuring the surface temperature of the mold in contact with the rubber product, the temperature in the slowest heated location of the rubber product is also detected.

Then, the optimal vulcanization time can be determined, avoiding the empirical techniques used so far, as well as needling sensors, which are subject to considerable stress and the development of the latter has not given satisfactory results. A simple and reliable method has all the prerequisites for use in automatic process control; thereby saving energy while creating optimal product properties.

The accompanying drawings illustrate a method for determining the vulcanization process of a rubber product according to the invention; FIG. 1 is a cross-sectional view of a portion of the rubber article having the slowest heating point and a portion of a mold; Fig. 2 shows the course of temperatures on the mold wall and at the slowest heated point versus time intervals; and Fig. 3 is a temperature table for the example.

In determining the vulcanization process of the rubber product, the slowest heated spot at point A of the rubber product 1 / which is spaced by L _min from point B on the mold surface 2 is determined. Subsequently, temperature temperature $ at point B is measured at constant time intervals. In this process, the temperature T at point A of the rubber product 1 is calculated by the following formulas:

^TJ % ⁺ £ ^A 5 / k mm where index 2 denotes the first; second to general nth time interval. ^ Individual terms in the relationship have the following meaning »The fourier number zsFo is in the form:

A. Fo = r.. L

CS 272 817 Sl λ ~ · 2 -1 where Δ t is the time interval in seconds,'a is the thermal conductivity in m. s, distance of points A, B in meters and roots of the transcendental equation —— ·

0,5 · ^ (2k - 1), where · $ is the Ludolf number, _e the basis of natural logarithms, _k is the addition index and the coefficients have the form

C, =>

0.5 - _{( i} ) / AFo 2 B. ^C

A.. = 2 Π. ·, +

Jrk 1 J, k (t where the integral value 1 ^^ is

(a) for the first time interval j = 1: TJ sin> k (iCk where Τθ is the temperature of the rubber product at the start of the process, ^- in the same units as the temperatures T ^,

(b) for all other time intervals j - 2;

.2 = 3-1 ' ^C 3-J η fi and _ρ “Λ ^ΔΡ ° ₊ ^Sin ^ k j-ΙΛ

From this temperature Tj at the slowest heated location A of the rubber article JL, the incubation and vulcanization process is also determined according to known relationships based on a modified Arhenius equation. Once the desired degree of vulcanization is reached, the process is complete.

Example:

When the tire was vulcanized, the L _rain value was 0.0195 m, the mold surface temperature measurement interval was Δ / · β 120 s, the initial temperature of the tire at point A was 31 ° C, the temperature conductivity of the tire was _a ® 1) 77.10 “ ιη s ”. Fig. 3 shows the measured mold surface temperatures and the calculated tire temperatures at the slowest heated point A. After the last time interval j = 11, the prescribed degree of vulcanization was reached and the process was terminated.

Claims (1)

OBJECT OF THE INVENTION Method for determining the vulcanization process of a rubber product, characterized in that the slowest heated spot at the point (A) of the rubber product (1) is spaced a distance ( ^L rai _n ) from the point (B) on the mold surface (2) , the temperature (ý ² ) at point (B) is then measured at fixed time intervals from the beginning of the process, and the temperature (T) at point (A) of the rubber product (1) is calculated by the following formulas k = 1 where j) denotes the first) second to general n-th time interval »where the dimensionless Fourier number (AFo) is in the form CS 272 817 Bl Δ Fo ~ 2Xt »* .min. · Qkde ( ^Δ ·) is the time interval in seconds, (a) is the thermal conductivity of the rubber product in m ² .s ^_1 , the distance between points (A) / (B) in meters and the roots of transcendent ce expresses the dependence of »O; 5 ^ (2k - 1) where (št) is the Ludolf number, '(e) is the basis of natural logarithms; and the factors have a shape Bj. 0, B (/ j -fj.p ZAF) - 4where the value of the integral (I. ..) is for J » ^K sin a) first time interval j = 1: T _Q where T _Q is the temperature of the rubber product at the beginning of the process in the same units as the temperatures TL, * (b) all other time intervals j - 2: θ (“ ² ΔΡο ^sin / ^z -k ° ' ^SA jI; k ⁺ (“ k ^k Γ ² 1 - L (1- £ 2) BH! ₊ ; at the same time, the incubation and vulcanization process is determined according to the relationships based on the modified Arhenius equation, and when the desired degree of vulcanization is reached, the process is terminated.