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Calculation of pressure during vulcanization of raw rubber. Calculation of the technological regime of overlay and vulcanization

When choosing a vulcanization mode, one should take into account the influence of the main technological factors on this process, i.e. medium properties, temperature and pressure.

1.3.1 Wednesday. Since rubber products are vulcanized not only in metal molds, but also directly in a coolant medium, when choosing the latter, it is necessary to know not only its thermophysical properties, but also the effect on the properties of rubber products in contact with it. Thus, during vulcanization in a hot air environment, oxygen causes rubber oxidation, which significantly worsens their properties. During vulcanization in an environment of saturated water vapor, due to the condensation of vapors on the surface of the product, the conditions for heat transfer change, therefore, uneven vulcanization of the product is possible.

When choosing a vulcanization medium, the type of product, the composition of the rubber compound, the equipment used, the features of the process, and other factors are also taken into account.

1.3.2 Temperature. Basically, the vulcanization temperature of rubber products is 140 - 170 °C, in some cases - 190 - 260 °C. With an increase in temperature, the duration of vulcanization is reduced, but for thick-walled products, the possibility of overvulcanization of products from the surface and the unevenness of vulcanization in thickness increases. This leads to deterioration in the quality of products.

When intensifying vulcanization processes, it should be remembered that sometimes the properties (quality) of rubber deteriorate with increasing temperature. Thus, rubbers based on natural and isoprene rubbers at vulcanization temperatures above 140°C are characterized by a sharp deterioration in mechanical properties. With an increase in the vulcanization temperature of rubber-fabric products, a deterioration in the quality of the rubberized fabric is observed, as well as a decrease in the strength of its bond with rubber.

During vulcanization, the temperatures on the surface and in the center of thick-walled products are not the same. If the duration of the process is determined by the conditions necessary to ensure a given degree of structuring in the center of the product, then the surface layers will be strongly overvulcanized. To reduce the heterogeneity of properties during vulcanization of thick-walled products, they should not be vulcanized at a very high temperature. When determining the duration of vulcanization of such products, it must be taken into account that structuring continues for some time after the end of heating due to the absorbed heat. Therefore, in the process of heating, one should not achieve complete vulcanization of the workpiece in thickness. To reduce the inhomogeneity of heating, stepwise heating is carried out or the rubber mixture is preheated. When vulcanizing massive products, programs are used that automatically maintain the required mode.

1.3.3 Pressure. Vulcanization of rubber products is possible without pressure and under pressure. Most products are vulcanized under pressure (0.5 - 5 MPa), which contributes to the deterioration of the physical and mechanical properties of vulcanizates, while eliminating the porosity of products and improving their appearance.

When heated, internal pressure arises in the rubber mixture due to the evaporation of moisture and the release of gaseous substances formed during the decay of accelerators (especially ultra-accelerators) or during the interaction of acids with carbonic salts with the formation of volatile substances (carbon dioxide from chalk or magnesium carbonate in the presence of stearic and other acids) , as well as desorption of absorbed and mechanically absorbed air. To obtain high-quality products, rubber compounds must be vulcanized at a pressure that exceeds the internal pressure in the rubber compound.

In order to prevent the appearance of porosity, water- and gas-absorbing substances (gypsum and calcium oxide) are introduced into the rubber mixtures, which absorb the moisture contained in the mixture, forming sufficiently stable chemical compounds.

Preliminary evacuation of rubber compounds during the molding process in worm machines dramatically reduces porosity and allows pressureless vulcanization.

The correct choice of the mode of applied pressures is especially important for the vulcanization of multilayer products. For example, in the case of a premature decrease in pressure in the cooking chambers during the vulcanization of tires, rejection is possible due to the formation of sponge rubber and delamination of the carcass.

When vulcanizing rubber fabric products, pressure has a great influence on the depth of penetration of the rubber mixture into the fabric; with an increase in the penetration depth, the endurance of products to multiple bends increases. The depth of penetration of the rubber mixture into the fabric depends on the ability of the mixture to spread when heated, which in turn is determined by the properties of the original rubber and its components.

With the existing technology, the vulcanization mode is usually developed in advance by calculation and experimental methods, and a program is set for the vulcanization process in the manufacture of products. For the punctual implementation of the prescribed mode, the process is equipped with control and automation tools that most accurately implement the prescribed strict program for the vulcanization mode.

The disadvantages of this method are the instability of the characteristics of manufactured products due to the impossibility of ensuring full reproducibility of the process, due to the limitation of the accuracy of automation systems and the possibility of shifting modes, as well as changes in the characteristics of the rubber compound over time.

A control method has been developed that eliminates the disadvantages of the above. A method for controlling the process of vulcanization of rubber products by controlling the vulcanization time, characterized in that the vulcanization time of rubber products is corrected depending on the time to obtain the maximum shear modulus of the rubber mixture during vulcanization of samples of the processed rubber mixture in laboratory conditions on a rheometer and the deviation of the tensile modulus of rubber in manufactured products from set value .

There is a method that allows you to determine the parameters of vulcanization at the initial stage of the process. It is characterized by the fact that it provides for the process of vulcanization of the rubber compound, sampling during the implementation of the process, preparation of samples for analysis.

Initial data for calculations

The initial data for the calculation is the technical documentation for the frame vulcanizing press type 250-600 4E with the following parameters:

1. Dimensions of heating plates, mm - 600 x 600;

2. Nominal force, kN - 2500;

3. Number of floors, pcs. - 4;

4. Distance between plates, .mm - 160;

5. Plate heating - electric;

6. Temperature control range, 0 С - 20 to 250;

7. Accuracy of maintaining the temperature of the plate, 0 C - + 5.0;

8. Duration of vulcanization, min - 1 30;

9. Pressure in the hydraulic system, MPa

a) low - 5;

b) high - 32;

10. Power of the electric motor of the hydraulic installation, kW - 5.5;

11. Power of electric heating plates, kW - 4;

12. The duration of the closing of the plates, s - 12;

13. Duration of plate opening, s - 8;

14. Number of prepresses - 2;

15. Molded product rubber cuff from rubber compound 7-51 - 3060(B)-1 (MUP "VNTK") with dimensions, mm:

a) height-45;

b) inner diameter - 209;

c) outer diameter - 240;

16. Dimensions of the workpiece strip of rectangular section, mm - 16x46x740

Calculation of vulcanization time

Initial data: for the manufacture of a V-shaped cuff 45x240x209 mm, a rubber compound 7-51-3060(B)-1 is used. for molding the cuff, blanks are made by extrusion in the form of a strip with a section of 16x46, which is cut into measured lengths of 740 mm. The workpiece thickness is O = 2h = 16 mm. According to the MUP "VNTK" data, the measurement of the kinetics of vulcanization on the Mojanto volcameter and the determination of the optimum vulcanization on standard plates o = 2 mm at 143 °C was t = 7 min. .

According to the heating time of a plate made of a rubber compound with a thickness of 2 mm, it is 10 s. With a part thickness of more than 2 mm, it is necessary to take into account the time required to warm up the workpiece with an accuracy of its alignment in the middle of ±2 °C.

The temperature of the workpiece before laying in the mold t = 25 °C;

Billet heating temperature t = 143 °С;

The coefficient of thermal conductivity of the rubber compound ?= 0.1 W/m °C.

Thermal diffusivity

The heat transfer coefficient of the rubber compound? \u003d 23 W / ° C.

The total vulcanization time of the cuff is equal to the sum of the warm-up time and the vulcanization time of the standard plate

The heating time of a workpiece with a thickness of 2h = 16 mm is determined for the non-stationary mode of heating a long workpiece with a section of 16 x 46 mm, according to using graphs that allow calculating the temperature in time on the surface and in the middle (and other points) of the workpiece section:

In expressions

where is the Biot criterion - a dimensionless complex that characterizes the ratio of thermal resistances of heat transfer of the rubber compound on the surface to its thermal conductivity inside the workpiece during heating.

Bi \u003d 23 * 0.008 / 0.1 \u003d 1.84

F0 - Fourier criterion - a dimensionless complex that characterizes the change in the temperature field in the workpiece during heating over time.

the relative temperature of the workpiece is found by the formula

Where 0x=(tx=o - relative and absolute temperature in the center of the workpiece.

= (145-143)/(145-25) = 0.017

According to the schedule for the calculated values and? we find the value of the criterion F0=3.7.

Knowing the value of the Fourier criterion, we calculate the time required to warm up the middle of the workpiece with an accuracy of temperature equalization of ± 2 °C

3 \u003d 0.0082 * 3.7 / 2.1 * 10 "7 \u003d 1128 \u003d 18.8 min

the dimensionless (relative) temperature on the workpiece surface is determined from the graph at F0 = 1.84 and Bi = 3.7

The surface temperature will be

The heating process is a non-stationary process, since the temperature field changes with time. Further, after the temperature equalizes to ±2 °C along the thickness of the workpiece, the process approaches the stationary one.

The total curing time will be the same.

1. Depending on the size of the model, choose a holder, taking into account that in the finished mold, the distance from the model to the edges of the mold must be at least 8 mm.

2. Use a stiff brush with soapy water to clean the inner parts of the clip and metal liners that come into contact with raw rubber, dry the clip and liners

3. Rinse and dry the master model before molding

4. put the vulcanizer on heating up to a temperature of 150°C. The heating temperature should not exceed 163°C.

5. Heat the two rubber blanks in contact with the model on the vulcanizer plate to soften for 5-8 minutes.

6. lay all the cavities of the model, complex bends with pieces of raw rubber, crush with a spatula and warm up together with the blanks

7. put the model between two softened blanks, while the sprue cone should be flush with the end of the rubber blanks, carefully crimp to avoid molding

8. put the prepared rubber bag with the model into the holder. In this case, the sprue cone of the model must fit snugly against the holder

9. cut rubber blanks according to the size of the clip. The number of rubber layers depends on the height of the clip and the thickness of the rubber plates (3.2mm). Molds are used with a height of 18mm - 6 layers of rubber, 20mm - 7 layers, 30mm - 10 layers.

10. fill the clip with metal liners 5-7 mm above the edges, then lay gasket metal plates on top and bottom and install in the press

11. if necessary, warm up without clamping the press for several minutes, then compress the clip with the press completely. Program the press timer for the required time, based on the calculation of 10-15 minutes for 1 layer of rubber

12. Pre-vulcanize for 6-8 minutes. Set the pressure of the final deformation on the regulator at the rate of 28-30 kg/cm surface of the molds. However, it must not exceed 100,000 N to avoid damage to the mechanical parts of the press.

13. If molded correctly, the excess rubber should come out of the cage.

14. after the expiration of the molding time, remove the clip from the press and cool in water, then in air for 20 minutes.

15. disassemble the cooled clip, rinse with water, remove adhering remains of raw rubber, cut off the flash

16. After cooling, the rubber mold with the model sealed in it is cut in such a way (zigzag) that there is no displacement of the two halves of the mold when receiving wax models. In some cases, inserts are additionally cut out, which facilitate the extraction of stencils, cuts (bulges) are made from the front surface to improve the filling of thin sections of the mold cavity with the model composition.

Distinguish between open and closed cuts. When cutting the rubber mold open in half, the model partially protrudes in one of the halves. With closed cutting, after cutting, the model is under a thin layer of rubber in one of the halves.

Cutting is carried out in the following sequence:

1. Having determined the position of the model in the mold by the notch on the sprue and using the sketch of the model, make cuts from the sprue along the perimeter in both directions, cutting out fixing teeth with a height and frequency of up to 5 mm. To facilitate the cutting of the mold with a scalpel, it is necessary to use expanding pliers.

3. carefully release the model from the rubber

4. in the mold cut in half, several cuts should be made, starting from the model to the edges of the mold, to release air during waxing and to prevent deformation of the waxes when they are removed

5. Clean the mold with a stiff brush and talcum powder.

Tools, equipment, materials used:

Rubber molds are made in metal vulcanizing clips Rectangular shape made of a material that quickly heats up, does not oxidize in water and does not stick to raw rubber (aluminum alloy). The design of the cage must meet the following requirements: quickly and conveniently assemble and disassemble, provide sufficient tightness when curing raw rubber, must have wide walls to ensure sufficient strength under the pressure of the rubber mass from the vulcanizer.

metal cone

Ladder Vulcanizing Rubber
Silicone rubber
ladder cover

A. Hole in the ladder

B. Cone reference font

Rice. 1 View and components of the assembled clip ready for vulcanization

Vulcanizing press used for pressing and vulcanizing raw rubber, which is installed in a cage between two heated plates.

Technical parameters of the vulcanizer EV 40N: (if the vulcanizer is different, then do not write it !!!) - supply voltage .............................. .....220V, 50/60 Hz - external dimensions……length 310mm; width 250mm; height 550mm - working plane .............................................. ..170x240mm - maximum distance between plates.............80mm - power consumption.................................. .............825W; - the weight................................................ .......................35 kg; - vulcanization temperature range…… from 50 to 200° С - vulcanization time range…………….from 1 to 99 min

The temperature and curing time are set and controlled by a digital programmer. Two aluminum plates are heated evenly, which leads to high-quality sintering of rubber. The maximum mold size is 85x70 mm. Time and temperature are controlled by digital components to closely match the parameters specified by the rubber manufacturers. A special fan is built into the control panel, which allows you to quickly cool the stamp in automatic mode, and thereby quickly remove the finished matrix from the vulcanizer. Square shaped heating plates provide maximum heat distribution, a feature that allows the vulcanizer to be used with round, rectangular or square dies.

Molded scalpel- This is a knife with surgical-type blades with a steel or plastic handle, which has grooves for attaching replaceable blades. For cutting the form, 3 types of blades are used: - straight, sharpened on one side; straight, sharpened on both sides, and curves.

Silicone based hot vulcanized paste rubber sheetEconosil F.E. Knight Castaldo (USA). These are silicone compositions specially designed for investment casting technology for the production of high quality jewelry castings. Traditional methods and equipment are used to work with such rubbers. Pasty rubbers easily fit into the mold, never give bubbles and fill all the voids when tightly packed, because. increase in volume during vulcanization. Forms after vulcanization are easily cut with a scalpel blade. The rubbers do not interfere with the material of the model, which greatly improves the surface quality. No silicone spray is required to separate the waxes from the rubber mould, the mold already contains components that help the waxes to be easily separated from the rubber. A possible disadvantage that is characteristic of some technical rubbers that are not specially adapted for hand-laying into a form characteristic of jewelry production is an increased sensitivity to fats. The sebum, which is always present on the hands, can lead to delamination of the finished form at the point of contact. Vulcanization temperatures 140 -177°C at the rate of 10-15 minutes per one layer of rubber to be laid.

Christmas tree assembly

After the wax models are made, they proceed to the assembly of the wax tree, for which they use sprues - wax risers, which are made from the waste of the model composition from smelting models or a special (gating) wax, which, when burned out, burns out faster than other waxes of this "Christmas tree". This facilitates the free flow of wax molds from the flask. The sprue must be thick enough (5...7mm in diameter) so that the liquid metal can reach the thin parts of the model cavity before it hardens. It is intended: for soldering wax models, removing wax during melting, annealing, movement of molten metal into a separate cavity, feeding castings during crystallization, reducing melt turbulence. To better fill the mold, save precious metal and reduce the weight of the gating system, it is recommended to use a conical shape of the riser.

The path of the metal in the herringbone must be of the correct form, without kinks, with large radii of curvature, this will help to avoid turbulence in the flow and favor the release of wax from the hardened form. Metal particles move in different directions, which can cause the capture of foreign particles, uneven flow and the consequence of this - porosity. The formation of porosity contributes to the increased fluidity of the metal, i.e. its temperature is too high.

The size of the feed channels should be sufficient to fill the model with metal.

If the model has different thicknesses in different places, it is necessary to provide several feed channels attached to the parts of the model with the greatest thickness - the liquid mass must pass from the thicker to the thinner areas, and never vice versa.

Fig.1 Fig.2 Fig.3

Fig.1 - incorrect location of the sprue.

Fig. 2 and 3 - the correct location of the sprues.

The metal begins to harden in places with the smallest thickness. The product becomes incomplete and porous if the mold and metal temperatures are too low. Feeding channels should go to the largest parts of the model.

When assembling the Christmas tree, 3 conditional options for arranging waxes are used:

- vertical rows;

- horizontal rows;

- in a checkerboard pattern.

The choice of the stenciling option depends on the range of stencils, taking into account the possibility of the most dense stenciling. In this case, waxes should not touch each other. The distance between the nearest points of the model must be at least 3 mm. When placing the stencil on the riser, it is necessary to take into account the possibility for air to escape during vibration vacuuming of the "Christmas tree" from the recesses in the stencil.

To assemble models into a block, the wax riser is fixed in a special device - a holder. The holder is designed so that when assembling the wax tree, the sprue with the seal can be rotated around several axes. Then, with a thin blade of an electric spatula, touch both the feeder of the model and the seat at the same time. After that, the knife is quickly removed, and the parts to be joined are lightly pressed against each other until the wax hardens at the place of soldering. The operation is repeated, turning the "Christmas tree" as necessary, until the riser is completely filled.

A wax tree should be assembled from wax models of approximately the same wall thickness in sections, because the temperature of the metal pouring is set depending on the wall thickness of the models.

If it is necessary to cast models with different wall thicknesses in one flask, then thin models should be placed at the top of the tree and closer to the barrel, and thick ones closer to the outside, because the temperature is higher in the center of the flask.

Thick wax models should not be placed close together with their large surfaces. It is desirable to place large surfaces of some models next to small surfaces of others.

Wax models should be placed at an acute angle to the riser (60° - 80°), this facilitates wax burning and promotes smoother pouring of metal in all parts of the model cavity.

The distance from the top of the sprue bowl to the bottom row of wax models should be at least 10 mm, due to the possible formation of underflows in the bottom row of the wax tree.

Technologically, the vulcanization process is the transformation of "raw" rubber into rubber. As a chemical reaction, it involves the integration of linear rubber macromolecules, which easily lose stability when exposed to external influences, into a single vulcanization network. It is created in three-dimensional space due to cross chemical bonds.

Such a kind of "cross-linked" structure gives rubber additional strength characteristics. Its hardness and elasticity, frost and heat resistance improve with a decrease in solubility in organic substances and swelling.

The resulting mesh has a complex structure. It includes not only nodes that connect pairs of macromolecules, but also those that unite several molecules at the same time, as well as cross chemical bonds, which are like “bridges” between linear fragments.

Their formation occurs under the action of special agents, the molecules of which partially act as a building material, chemically reacting with each other and rubber macromolecules at high temperature.

Material properties

The performance properties of the resulting vulcanized rubber and products made from it largely depend on the type of reagent used. These characteristics include resistance to exposure to aggressive environments, the rate of deformation during compression or temperature rise, and resistance to thermal-oxidative reactions.

The resulting bonds irreversibly limit the mobility of molecules under mechanical action, while maintaining high elasticity of the material with the ability to plastic deformation. The structure and number of these bonds is determined by the method of rubber vulcanization and the chemical agents used for it.

The process is not monotonous, and individual indicators of the vulcanized mixture in their change reach their minimum and maximum at different times. The most suitable ratio of physical and mechanical characteristics of the resulting elastomer is called the optimum.

The vulcanizable composition, in addition to rubber and chemical agents, includes a number of additional substances that contribute to the production of rubber with desired performance properties. According to their purpose, they are divided into accelerators (activators), fillers, softeners (plasticizers) and antioxidants (antioxidants). Accelerators (most often it is zinc oxide) facilitate the chemical interaction of all ingredients of the rubber compound, help reduce the consumption of raw materials, the time for its processing, and improve the properties of vulcanizers.

Fillers such as chalk, kaolin, carbon black increase the mechanical strength, wear resistance, abrasion resistance and other physical characteristics of the elastomer. Replenishing the volume of feedstock, they thereby reduce the consumption of rubber and lower the cost of the resulting product. Softeners are added to improve the processability of processing rubber compounds, reduce their viscosity and increase the volume of fillers.

Also, plasticizers are able to increase the dynamic endurance of elastomers, resistance to abrasion. Antioxidants stabilizing the process are introduced into the composition of the mixture to prevent the “aging” of rubber. Various combinations of these substances are used in the development of special raw rubber formulations to predict and correct the vulcanization process.

Types of vulcanization

Most commonly used rubbers (butadiene-styrene, butadiene and natural) are vulcanized in combination with sulfur by heating the mixture to 140-160°C. This process is called sulfur vulcanization. Sulfur atoms are involved in the formation of intermolecular cross-links. When adding up to 5% sulfur to a mixture with rubber, a soft vulcanizate is produced, which is used for the manufacture of automotive tubes, tires, rubber tubes, balls, etc.

When more than 30% sulfur is added, a rather hard, low-elastic ebonite is obtained. As accelerators in this process, thiuram, captax, etc. are used, the completeness of which is ensured by the addition of activators consisting of metal oxides, usually zinc.

Radiation vulcanization is also possible. It is carried out by means of ionizing radiation, using electron flows emitted by radioactive cobalt. This sulfur-free process results in elastomers with particular chemical and thermal resistance. For the production of special rubbers, organic peroxides, synthetic resins and other compounds are added under the same process parameters as in the case of sulfur addition.

On an industrial scale, the vulcanizable composition, placed in a mold, is heated at elevated pressure. To do this, the molds are placed between the heated plates of the hydraulic press. In the manufacture of non-molded products, the mixture is poured into autoclaves, boilers or individual vulcanizers. Heating rubber for vulcanization in this equipment is carried out using air, steam, heated water or high-frequency electric current.

For many years, automotive and agricultural engineering enterprises have been the largest consumers of rubber products. The degree of saturation of their products with rubber products is an indicator of high reliability and comfort. In addition, parts made of elastomers are often used in the production of plumbing installation, footwear, stationery and children's products.

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Ministry of Education and Science of the Russian Federation

Federal Agency for Education

Perm State Technical University

Department of KTEI

Settlement work No. 2

Calculation of the technological regime of overlay and vulcanization

rubber outaboutlation

Completed by: student gr.KTEI-04-1:

Murzina O.A.

Checked: teacher of the department of CTEI

Popov O.A.

Perm 2008

cable brand: GOST 6598-73

conductor cross section: S=6mm 2

Rated voltage: U=3 kV

steam temperature in the vulcanization tube: T P=195°C

1. d pr \u003d 0.4 mm - wire diameter;

n=280 - number of wires in the core;

N=7 - number of strands; (strand twisting system 1+6);

D from = 1.8 mm - the thickness of the rubber insulation;

d w =3.98 mm - core diameter;

2. Rubber type RTI - 1 according to OST 16.0.505.015-79; brand of rubber compound TSSh - 35A.

3. Consumption of materials per 1 m of insulated core:

d etc - wire diameter, mm;

n - number of wires in the core;

n 1 - number of strands in the core;

G- specific gravity of the core metal, r=8, 890kg/withm 3 ;

to 1 ,to 2 - coefficients taking into account the twisting of wires into a core and cores into a cable, to 1 =1,0 34 , to 2 =1 ,034 .

d- core diameter;

to 5 - coefficient taking into account technological factors (uneven overlap, filling of voids between the wires), to 5 =1, 17 ;

s- insulation thickness.

4. We choose the equipment ANV - 115;

Vulcanizing tube length l T= 100 m;

5. Calculation of the sag of the product in the pipe

where R- weight of 1 m of insulated core, kg/m,

g m/s 2 ,

l T- pipe length, m,

T- allowable tensile force, Pa

where S is the cross section of the conductive core, m 2 ,

Tensile strength of the core material, Pa,

To- safety factor, K \u003d 2 + 3;

d uh- product diameter, m.

The condition is not met, therefore we take an inclined line.

6. Temperature regime of rubber processing on the press:

7. Tool dimensions:

8. Press performance - Q= 5 kg/min

Pressing speed:

R from- rubber consumption per 1 m, kg/m .

To T- technological coefficient, To T=0,7 ? 0,8

vulcanization insulation power cable

9, Thermophysical characteristics of condensate at a given temperature:

Heat of vaporization - r= 876 10 3 j/kg,

Density - =876 /m 3 ,

Thermal conductivity - \u003d 0.67 W/m°C,

Kinematic viscosity of condensate

at steam temperature (set) - =0,16 6 10 -6 m 2 /with.

10. Heat transfer coefficient on the surface of the insulated core -, W/m 2 With(horizontal pipe)

where To n- coefficient taking into account the roughness of the insulation surface To n=0,80 ? 0,85 ;

T with is the average wall temperature,

where T p is the temperature of the rubber coming out of the head, With;

g- acceleration of gravity, m/s 2 ,

E t- coefficient taking into account the dependence of the thermophysical characteristics of the condensate on temperature

Specific thermal conductivity of condensate at T n and T with respectively, W/m With; =0,685W/m°C

MM with- absolute viscosity of condensate at T n and T to respectively, M=140, M with=201 ,

11. To determine the vulcanization time, we will use numerical methods. The calculation is made in the program (Appendix 1).

12. The intensity of vulcanization of the outer layers of rubber does not depend on time and is determined from the expression

where T uh- temperature of the beginning of intensive vulcanization.

E max maximum allowable vulcanization effect ( 36000 s),

Let's find the maximum allowable time for the insulation to stay in the vulcanization pipe

14. Calculation of the dependence of the intensity of vulcanization at a point with a radius r- U r(t) from time:

where To in=2 - temperature coefficient of vulcanization of rubber.

For most rubbers T uh=143 With- temperature of the beginning of intensive vulcanization.

Then the vulcanization effect is determined by the formula

N - number of intervals along the axis t,

Where To 0 =1,16 - coefficient taking into account the additional vulcanization of rubber in the initial period of cooling (on the inner surface of the insulation, the temperature during cooling decreases to 143 With over time).

15. The speed of passage of the insulated core through the vulcanization pipe:

16. Specify the dimensions of the receiving drum and calculate the length of the insulated core on the drum ( L, m).

The drum is used with the dimensions of the take-off drum for the general laying machine (3+1) AVM -2400/1800

where d w- drum neck diameter, mm;

d- diameter of the insulation (screen), mm;

l- drum neck length, mm;

D 1 - diameter by winding the product on the drum, mm;

D 1 = D sch- (4 ? 6) d=1 200 - 4 7,58 = 2370 mm,

Where D sch- drum web diameter,

.

Routing:

Developer organization code KTEI-04-1

Map of sketches of the technological mode of isolation and vulcanization

Cable brand

Document code

Developer

Settlement work No. 2

Kanyukova Yu.I.

Name

material

Material Grade

material

Name of equipment

Equipment brand

Performance

pipe length,

Steam pressure, MPa

Take-up drum number

OST 16.0.505.015-79

Continuous Vulcanizing Cable Line

Core construction

Insulation

Tool diameter

Linear speed m/min

Steam pressure, MPa

Length on the take-up drum,

wires

core diameter,

insulation

* Note: Temperature regime for rubber processing:

1 press. 1 zone - 60 With

2 zone - 80 With

Head temperature - 90 With

TPG temperature - 80 °C

Steam temperature - 195 ° С

Hosted on Allbest.ru

Calculation of pressure during vulcanization of raw rubber. Calculation of the technological regime of overlay and vulcanization

Initial data for calculations

Calculation of vulcanization time

Material properties

Types of vulcanization

Send your good work in the knowledge base is simple. Use the form below

Settlement work No. 2

Calculation of the technological regime of overlay and vulcanization

rubber outaboutlation

Completed by: student gr.KTEI-04-1:

Murzina O.A.

Checked: teacher of the department of CTEI

Popov O.A.

Perm 2008

Where D sch- drum web diameter,

.

Routing:

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