橡胶的热空气硫化

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Hot air vulcanization of rubber profiles.

Elastomer elastomer (ĭlăs`təmər), substance having to some extent the elastic properties of natural rubber. The term is sometimes used technically to distinguish synthetic rubbers and rubberlike plastics from natural rubber.  profiles are deployed in quantity by the automobile industry automobile industry, the business of producing and selling self-powered vehicles, including passenger cars, trucks, farm equipment, and other commercial vehicles.  as seals and waterproofing in coachwork coachwork
Noun

the body of a car . The high standards demanded by the industry; improvement in weather protection, noise reduction, restriction of tolerances, together with the powerful demand for EPDM EPDM Ethylene-Propylene-Diene-Monomer
EPDM Enterprise Product Data Management
EPDM Ethylene Propylene Dimonomer (industrial/commercial piping/plumbing components)
EPDM Engineering Product Data Management  force the rubber processing industry into development, particularly of elastomers.

Complex proofing systems must also be achieved with extremely complicated profile forms. All too often such profiles have an extremely large surface together with a low cross-section density. They frequently consist of two or three rubber compounds and are steel reinforced. Sometimes they are flocked and coated with a low friction finish. Such high-tech seals require an adjustment of the vulcanization vulcanization (vŭl'kənəzā`shən), treatment of rubber to give it certain qualities, e.g., strength, elasticity, and resistance to solvents, and to render it impervious to moderate heat and cold.  method.

The consistent trend in the nineties towards lower quantities of elastomer per sealing unit and the dielectric dielectric (dī'ĭlĕk`trĭk), material that does not conduct electricity readily, i.e., an insulator (see insulation). A good dielectric should also have other properties: It must resist breakdown under high voltages; it should not  factor, especially with EPDM, has brought an old fashioned n. 1. A cocktail consisting of whiskey, bitters, and sugar, garnished with with fruit slices and often a cherry.

Noun 1. old fashioned - a cocktail made of whiskey and bitters and sugar with fruit slices  vulcanization method once more to the fore, a method developed over the past years to an extremely high standard, namely the hot-air method.

Curing methods and their importance

Autoclave autoclave

Vessel, usually of steel, able to withstand high temperatures and pressures. The chemical industry uses various types of autoclaves in manufacturing dyes and in other chemical reactions requiring high pressures.

Curing in an autoclave (steam-bath) is a very old method and has no relevance to todays manufacture of sealing profiles.

It does still have a place in the manufacturing of profiles with a woven constituent such as cables, pressure hoses and manifold manifold

In mathematics, a topological space (see topology) with a family of local coordinate systems related to each other by certain classes of coordinate transformations. Manifolds occur in algebraic geometry, differential equations, and classical dynamics.  pipes for vehicles.

The inner construction of such products should not be required to be absolutely free of moisture and air inclusion, as one is working with a high steam pressure. In this process a peroxide peroxide (pərŏk`sīd), chemical compound containing two oxygen atoms, each of which is bonded to the other and to a radical or some element other than oxygen; e.g.  vulcanization system is possible.

The curing is very labor-intensive and thus very expensive. It is barely possible with modern profile-geometries to hold the profile shape while packed in the autoclave as the curing time In the annealing procedure could be divided into 3 stages:heating to a particular temperature, keeping for a period of time and cooling to room temperature. The curing time is the hold time of the 2nd stage.  is very long. In most cases twenty minutes or longer.

Fluid bed

This method of vulcanization is totally outmoded out·mod·ed
adj.
1. Not in fashion; unfashionable: outmoded attire; outmoded ideas.

2. No longer usable or practical; obsolete: outmoded machinery. . Hot air is blown into a vortex - the speed of this air must be stringently controlled so that the glass beads which make up the bed of the vortex are not expelled.

The profile glides on moving glass beads and is heated simply on the facets. A surface impression develops. The glass beads imbed im·bed
v.
Variant of embed.

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imbed
Verb

[-bedding, -bedded] same as embed

Verb 1.  themselves easily in the surface depressions of the fine-lipped profiles and cleaning is very difficult.

The curing uses large amounts of energy as enormous quantities of air must be heated. Due to this necessary environmental protection measures are difficult to achieve. Also, among other things, the recirculation Noun 1. recirculation - circulation again
circulation - the spread or transmission of something (as news or money) to a wider group or area  of surplus energy is made extremely difficult due to the condensation of the softening steam. This is certainly the dirtiest of all curing methods. Only limited running speeds can be attained.

Infra-red installation

These plants are seldom used nowadays to heat up rubber profiles. They are subject to the great disadvantage that the profile can almost never be heated up evenly, because of the known problems of energy dissipation Dissipation
See also Debauchery.

Breitmann, Hans

lax indulger. [Am. Lit.: Hans Breitmann’s Ballads]

Burley, John

wasteful ne’er-do-well. [Br. Lit.  over distance. Thus this method is now also rarely used for adhesive-drying of flocked profiles. Energy consumption is relatively low, but unfortunately this is also true of the throughput speed.

LCM (Liquid Crystal Monitor) A flat panel display that uses the liquid crystal (LCD) technology. See flat panel display.  installation

Vulcanization in molten salt Molten salt may refer to:
Molten salt battery, a class of primary cell and secondary cell high temperature electric battery that use molten salts as an electrolyte
Molten salt reactor, a type of nuclear reactor where the primary coolant is a molten salt

is very common even today. The excellent heat transfer properties between the salt and the vulcanizate make peroxide curing possible even when a saltdrizzling oxygen is achieved on the profile surface.

Heating up of the profile is extremely even, as the molten salt contacts all surfaces equally. As this contact occurs within seconds one can reckon on a very smooth surface for sponge-rubber.

The energy required to maintain the molt at 240 to 248[degrees]C is not very great, although one should bear in mind that salt baths are usually electrically heated and so can carry quite heavy operating costs operating costs npl → gastos mpl operacionales  in spite of this. These costs are noticeably increased by the tremendous consumption of salt.

Together with the obvious advantages of the system the following disadvantages must be taken into consideration.

Large cross-sections of sponge rubber sponge rubber
n.
A soft, porous rubber used in toys, cushions, gaskets, and weather stripping and as a vibration dampener.  are difficult to manufacture as the cell structure deteriorates and loses its uniformity as it nears the center. If a metal conveyor belt conveyor belt

One of various devices that provide mechanized movement of material, as in a factory. Conveyor belts are used in industrial applications and also on large farms, in warehousing and freight-handling, and in movement of raw materials.  is used one must be prepared for an alteration in the lip-placement of the profile because of the buoyancy buoyancy (boi`ənsē, b`yən–), upward force exerted by a fluid on any body immersed in it. Buoyant force can be explained in terms of Archimedes' principle. .

The admittedly excellent heat transfer can scarcely be varied over the length of the plant, due to the very narrow running speed tolerances.

If sulfur is used for curing it is almost impossible to prevent the dangerous buid-up of nitrosamines nitrosamines

highly hepatotoxic compounds formed in the rumen by the combination of amines and nitrite. They do not appear to occur naturally in large quantities. Nitrosamine poisoning has also been caused by feeding nitrite-treated fishmeal and Solanum incanum. .

Purification of the used salt in accordance with the present environmental requirements can only be achieved with an enormous capital outlay capital outlay

See capital expenditure. .

LCM vulcanization will be of less and less importance as time goes by. It will become practically impossible to fulfill the always stricter environmental requirements.

Shear head vulcanization

This curing method was publicized pub·li·cize
tr.v. pub·li·cized, pub·li·ciz·ing, pub·li·ciz·es
To give publicity to.

Adj. 1. publicized - made known; especially made widely known
publicised  in 1979 and has in the meantime Adv. 1. in the meantime - during the intervening time; "meanwhile I will not think about the problem"; "meantime he was attentive to his other interests"; "in the meantime the police were notified"
meantime, meanwhile  earned its place in the industry.

Electrical energy is converted from the motor to the rotation of the shear head mandrel mandrel /man·drel/ (man´dril) the shaft on which a dental tool is held in the dental handpiece, for rotation by the dental engine.
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man·drel or man·dril
n.
1.  directly in front of the extrusion die. The elastomer is processed through the extruder barrel into the shear head space, which has been created from the space between the rotating mandrel and the static and centered cylinder.

The amount of electrical energy transformed into molecular frictional heat is regulated by altering the rate of revolution of the mandrel.

The elastomer temperature can therefore be much higher than typical extrudate temperatures and be maintained while exiting the die.

These facts produce an important advantage for the user; the vulcanization begins to take place immediately before the forming process. Thus with the reduced viscosity and the compound partially cross-linked, a high degree of form definition and stability in sealing profiles can be achieved.

There is little or no wastage wastage

a loss of product or productivity; in terms of animal production includes losses due to deaths of animals, lowered production from survivors, including reproduction, and lost opportunity income.

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wastage Fetal wastage, see there  in the electrical energy used for heating and, because of the low consumption, costs are relatively low.

As with every curing method there are some disadvantages to be considered when deploying this method.

Adjustment of the elastomer compound can be problematic as the scorch point of the compound can only be established after the exiting of the rubber from the die. For reasons dictated by compound technology it is often only possible to work with low exit temperatures which once again places the onus of the greater part of vulcanization on the following, compulsory, hot-air channel.

Production of reinforced multi-component seals and sponge rubber is possible but the same problems still persist.

A particular drawback is the swelling of the elastomer when subjected to a variable temperature. Because of this, this curing method requires special extrusion dies which cannot be used with ordinary extruders. On the other hand, of course, profile-tooling from previous extruders cannot be used with shear head systems.

And yet for the majority of rubber sealing profiles where variations in form and compound are unimportant, shear head vulcanization appears to offer an advantageous technology.

UHF (Ultra High Frequency) The range of electromagnetic frequencies from 300 MHz to 3 GHz. In the U.S., analog television has used UHF channels 52 to 69 in the 700 MHz band.  installations

Vulcanization using UHF energy at 2.45 GHz is widespread. If it is possible to set the dielectric loss or polarity (1) The direction of charged particles, which may determine the binary status of a bit.

(2) In micrographics, the change in the light to dark relationship of an image when copies are made.  of the compound high enough, then the microwave energy can be directly transformed to heat within the vulcanizate.

Unfortunately, however, the physical properties of EPDM formulas often do not lend themselves well to UHF. Polarities can be low due to the fillers or other agents in the compound recipe. This can, however, be overcome by the addition of special agents that will cause the formula to be more receptive to UHF. The drawback to this is that it makes the rubber compound more expensive.

The high technical requirements of, above all, the automobile industry leads to the ever declining deployment of UHF plants. Also, however, because the modern elastomer seals demand only limited quantities of raw rubber per unit and at the same time maximize the profile-seal surface. The applied heat is reflected back extremely quickly because the radiation emission factor An emission factor can be defined as the average emission rate of a given pollutant for a given source, relative to units of activity. Emission factors can be used to derive estimates of gas emissions (for instance, greenhouse gas emissions) based on the amount of fuel combusted  is 0,95 W/m*d 253* K*d 253* and the total radiation grows to the power of four of the profile temperature.

The already installed, following, hot-air-channel tends increasingly to take over the task of heating the profile, a task which naturally demands of it specific qualities.

It then must be noted here that UHF machines can only be sensibly deployed if the compounds have a high polarity and the profiles have a small surface in relationship to the cross-sectional mass.

The operating costs of microwave installations are, however one may attempt to prove the contrary, relatively high. For example: With a rated power of output of 24 kw UHF, the total electrical requirement (including the far too weak support hot air) is 80 kw. This does not include the energy for the hot-air-channel in line after the microwave.

Taking into account only the UHF section - in United States United States, officially United States of America, republic (2005 est. pop. 295,734,000), 3,539,227 sq mi (9,166,598 sq km), North America. The United States is the world's third largest country in population and the fourth largest country in area.  alone for example - over a year's operation, running three shifts a day, one can expect the energy for the UHF alone to cost $35,000 ($.05/Kw). Additives to increase polarization to the rubber compound will increase your compound cost by an average of $0.05 per kilogram kilogram, abbr. kg, fundamental unit of mass in the metric system, defined as the mass of the International Prototype Kilogram, a platinum-iridium cylinder kept at Sèvres, France, near Paris. . With an extrusion rate of 300 kilograms of compound per working hour we have an additional cost of $131,400 per annum Per annum

Yearly. . The electrically heated post curing channel uses another $63,000 in energy costs, so that with the most favorable calculations and excluding the cost of maintenance, the yearly costs are in the neighborhood of $229,400.

Were we to compare this with the 180 kW natural gas requirements of a hot-air-channel of equal performance we would find an immediate saving of $205,700, the latter having an energy cost of $23,700 per annum ($0.015/Kw). This calculation has very similar results when applied to our European neighbors.

An extra, economically calculated, saving - nay nay
adv.
1. No: All but four Democrats voted nay.

2. And moreover: He was ill-favored, nay, hideous.

n.
1. A denial or refusal. , "profit" of $205,000 per installation per annum. This should be reason enough to think about vulcanization methods.

Hot-air vulcanization

Thirty years ago rubber was already being vulcanized vul·ca·nize
tr.v. vul·ca·nized, vul·ca·niz·ing, vul·ca·niz·es
To improve the strength, resiliency, and freedom from stickiness and odor of (rubber, for example) by combining with sulfur or other additives in the presence of heat  by the continuous hot-air-method. Success, however, was restricted as the machine development was not such as to overcome the well known inferior heat exchange between a gas and the vulcanizate.

The firm Gerlach Ltd., involved in the hot-air process particularly for the past 18 years, has, in the last seven years, improved this procedure to such a high technical standard that in most cases it outperforms the methods described above both technically and economically.

Not only high production standards recommend hot-air vulcanization. As already discussed, nowadays the user of elastomer profile seals demands compounds and forms which can simply be better produced by the hot-air method.

The aim to transfer heat to a rubber profile as quickly as possible, depends on three criteria:

* The temperature difference between the heat-transferring air and the rubber profile should be as great as possible. Technically it is easy to achieve this "delta T."

* The hot air must be as heavy as possible in order that it can store and give out large quantities of heat. It should also be as damp as possible.

* The heat absorbing elastomer profile should be exposed to the air in such a way that the high energy air molecules come into contact with its surface as much as possible.

Lastly, the heat exchange should be linearly fashioned over the whole period spent in the hot-air-channel, difficult to attain because the dela T sinks, owing to owing to
prep.
Because of; on account of: I couldn't attend, owing to illness.

owing to prep → debido a, por causa de  the warming up of the profile.

Possible working principles and their effects

Figure 1 shows a very old method in which cold air is extracted from the working channel and is then reintroduced through the electric air heater An air heater (also referred to as air preheater or regenerative air heater) is a common component of large boilers with the purpose of increasing its overall efficiency. It can be used alone, in replace of a recuperative air heater, or in conjunction with a steam coil, all three . The air-stream direction is at a ninety degree angle to the profile axis.

[ILLUSTRATION OMITTED]

The effect with regard to the profile warming and the temperature constancy con·stan·cy
n.
1. Steadfastness, as in purpose or affection; faithfulness.

2. The condition or quality of being constant; changelessness.

Noun 1.  is very limited. The profile can, as is shown in the illustration, only be heated weakly on one side and simultaneously gives off a great part of the acquired energy (see UHF installations). The air is permanently contaminated contaminated,
v 1. made radioactive by the addition of small quantities of radioactive material.
2. made contaminated by adding infective or radiographic materials.
3. an infective surface or object.  with softening agents, and these condense con·dense
v. con·densed, con·dens·ing, con·dens·es

v.tr.
1. To reduce the volume or compass of.

2. To make more concise; abridge or shorten.

3. Physics
a.  or coalesce co·a·lesce
intr.v. co·a·lesced, co·a·lesc·ing, co·a·lesc·es
1. To grow together; fuse.

2. To come together so as to form one whole; unite:  in the working channel and in the supply routes, leading to an obvious deterioration in the quality of the process.

This so-called cross-current recycling principle comes from the textile industry and was originally developed for fabric drying.

It is totally unsuitable for the vulcanization of rubber profiles but is, unfortunately, used again and again for that purpose.

Figure 2 shows a similar principle. Here cold air is drawn from the working channel and finally fed through a weak electric air heater.

[ILLUSTRATION OMITTED]

Then the heated process air is returned to the working channel passing infra-red rods, which complete the heating up process, immediately before its re-entry RE-ENTRY, estates. The resuming or retaking possession of land which the party lately had.
   2. Ground rent deeds and leases frequently contain a clause authorizing the landlord to reenter on the non-payment of rent, or the breach of some covenant, when the .

The infra-red heating rods are situated behind long drawn out and narrow meshed performated plates which, understandably, barely allow the infra-red energy access to the working channel. The air is led over a relatively long course, parallel to the axis of the the diameter of the sphere which is perpendicular to the plane of the circle.

See also: Axis  profile, and is recirculated. With every in and ou-ttake of air, however, a quantity escapes onto the factory floor and this must be dealt with.

The improvement in efficiency of this method over the previous one described is noticeable. In spite of this the heating up efficiency is still too limited. Of the criteria previously listed, only the first point is covered. At its best, therefore, this machine can only be deployed as an after-heater for UHF plant, should the desired profile temperature be attainable with UHF.

This is, however, exactly where the problem lies (see UHF installation) and there is no reason to suppose it will become any easier with time.

The convenience is restricted by the soiling of the installation. In order to combat this problem the installation of heat-exchange plates in which the emollient emollient /emol·li·ent/ (e-mol´yent)
1. softening or soothing.

2. an agent that softens or soothes the skin, or soothes an irritated internal surface.

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e·mol·lient
adj.  can partially condense has been tried. This has failed to achieve total success, however, since maintenance now concentrates on daily cleaning of the exchange plates. This also brings problems as the cleaning is done with compressed water which creates environmental problems.

Hot-air installations which work on this principle are sadly still deployed, although seldom. The method has been extant for more than twenty years TWENTY YEARS. The lapse of twenty years raises a presumption of certain facts, and after such a time, the party against whom the presumption has been raised, will be required to prove a negative to establish his rights.
   2. , and in this time it has never met the expectations of the profile producer.

The Gerlach hot-air concept

This concept meets the criteria as listed previously. An optimum delta T is reached and the air is damp. The heat carrying air molecules provide an optimum heat exchange directly on the profile surface through their extremely high crossmotion.

A linear heat transfer over the total length for the complete duration is achieved by a modification of the molecular movement.

As in figure 3, process air is forced into the air/air heat exchanger heat exchanger

Any of several devices that transfer heat from a hot to a cold fluid. In many engineering applications, one fluid needs to be heated and another cooled, a requirement economically accomplished by a heat exchanger.  through the ventilator ventilator /ven·ti·la·tor/ (ven´ti-la-tor)
1. an apparatus for qualifying the air breathed through it.

2. a device for giving artificial respiration or aiding in pulmonary ventilation. . Here it absorbs a large proportion of the exhaust warmth and is fed via pipes 3 and 4 to the burner unit, 5. This gas heating can be effected with natural or propane propane, CH3CH2CH3, colorless, gaseous alkane. It is readily liquefied by compression and cooling. It melts at −189.9°C; and boils at −42.2°C;.  gas.

[ILLUSTRATION OMITTED]

The air is fed further into the working channel 6. An intake booster jet every three meters is foreseen.

The air is removed in varying amounts at stages 7, 8, 9 and 10 and led to heat exchanger 2. Here it is cooled to a temperature of 65[degrees]C with emollient containing exhaust air.

Through the cooling of the air on one side, and the air diversion-separation effect, so-called, on the other, a large quantity of the condensation separates out and can be led away.

The still contaminated air is fed through pipe 11 into a cooler and intensive separator. Here it is further cooled and another portion of emollients Emollients
Petroleum or lanolin-based skin lubricants.

Mentioned in: Ichthyosis  can be condensed con·dense
v. con·densed, con·dens·ing, con·dens·es

v.tr.
1. To reduce the volume or compass of.

2. To make more concise; abridge or shorten.

3. Physics
a.  and led away. Then the air is chanelled further into a centrifugal filter Cen`trif´u`gal fil´ter

1. A filter, as for sugar, in which a cylinder with a porous or foraminous periphery is rapidly rotated so as to drive off liquid by centrifugal action.  where 99.7% of the remaining impurities are removed. A special feature of this filter is that it is self-cleaning.

Lastly, the air is fed into the exhaust ventilator, 14, from whence whence
adv.
1. From where; from what place: Whence came this traveler?

2. From what origin or source: Whence comes this splendid feast?

conj.  85% returns to the individual burner.

The burner, 5, is constructed in such a way that it can burn off the remaining impurities.

The efficiency of the hot-air concept can be summed up as follows: The system is virtually closed and environmental protection is totally integral. As the individual burners are fed relatively cold air there is a strong pressure difference between the burner in-take and outlet, which makes it possible to modify the air in the working channel in such a way that here also differing pressures can be attained.

Figure 3 shows extremely clearly that the pressure values, delta p, are greater at the end of the installation.

The Gerlach hot-air system establishes that parallel to the increase in pressure there is an increase in the cross-motion of the molecules immediately in contact with the profile surface. Due to the decreasing delta Ts between the air temperature and the profile temperature a huge increase in the heat exchange values is achieved.

The heat transfer runs from beginning to end of the channel, parallel to the pressure curve.

The burner units are constructed in such a way that they can release large quantities of water into the working channel. Thus, as explained above, the air becomes particularly heavy and the heat transfer properties are once more improved.

Purely theoretically, the working temperature can be increased to 500[degrees]C. For safety reasons it is regulated to a maximum of 340[degrees]C.

The Gerlach hot-air concept offers a modular system in which software can be modified so that hardware can be processed as desired. For the user this offers the possibility of growth, both in the area of special elastomers and also of specific profiles, for years to come.

The hot-air installation concept

When we are absolutely clear about the product range to be cured by means of a hot-air vulcanization plant, then it is simple to create a working concept for the installation.

Figure 4 shows a selection of hot-air installations with the average running speeds and the projected energy consumption.

[ILLUSTRATION OMITTED]

Each installation presupposes a vacuum extruder preceding and a regulating and measuring unit Noun 1. measuring unit - a unit of measurement
measuring block

unit, unit of measurement - any division of quantity accepted as a standard of measurement or exchange; "the dollar is the United States unit of currency"; "a unit of wheat is a bushel"; "change  following, the latter capable of measuring the profile and regulating the raw material feed to the extruder. It must be pointed out, however, that where a coextrusion is present, regulation of the material in this way is not possible.

After the measuring and regulating unit, a high-speed-hot-air channel is basically always deployed which serves to heat up the rubber temperature from the extrusion temperature to the desired vulcanization temperature.

The running speeds "V" shown in the table are compiled from the operating records of customers who have installed Gerlach hot-air channels. To establish the values, EPDM profiles - as used overall in the automobile trade - were used.

In cases where the rubber profile is rigid because of its steel reinforcement, two hot-air channels in sequence are often deployed. In such cases the second machine invariably in·var·i·a·ble
adj.
Not changing or subject to change; constant.

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in·vari·a·bil  consumes less energy than the first.

It is often possible to divert steel reinforced profiles over corresponding minimum radii ra·di·i
n.
A plural of radius.

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radii
Noun

a plural of radius . In this case the second machine should be a triple-banked hot-air channel with integral cooling system cooling system: see air conditioning; internal-combustion engine; refrigeration.
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cooling system

Apparatus used to keep the temperature of a structure or device from exceeding limits imposed by needs of safety and efficiency. . This machine is shown in the illustration; marked 114.

The most compact installation, worldwide, in deployment, is a combination of types 109 and 114.

Elastomer seals for the automobile industry are frequently cured on the systems indexed in figures 5, 6 and 7.

The installation 9 is very commonly used for the production of high volume profile seals for the building industry.

Due to the compact construction of the machine, extremely good running speeds can be attained, as in a total length of 25 meters, a heating channel of 50 meters and a cooling plant of 25 meters are combined.

The throughput figures given are an average and are easily adjusted heavily upwards or downwards if the relationship of the surface area of the profile to the cross section is altered.

Special requirements are not included in the installations illustrated. There are, however, because of the modular construction, virtually no special orders which cannot be fulfilled.

Which compounds and profiles can be cured with a hot air vulcanization

installation?

Here we can give a very simple answer: All profiles which consist of a sulfur-cured compound and are heat-curable can be vulcanized with a hot-air channel.

Sealing profiles with a silicon base can be cured extremely fast with a hot-air channel type 109.

Textile or metal reinforced low- middle- and high-pressure hoses can be vulcanized extremely efficiently in a hot-air channel. Special aggregates are available which make it possible to control these supported forms and to adjust the air content, for example, to eliminate damp.

If, in the broadest sense, we can consider a fire-hose, with or without polyester sheating, as a profile, then it must be a perfect example for warming by hot air.

Peroxide curing with hot air

Unfortunately, peroxide curing in hot air cannot be achieved without assistance, because of the affinity between the peroxide particles on the surface of the profile and the oxygen in the process air vulcanization is virtually impossible.

Vulcanization in inert atmospheres is also impractical as the unavoidable traces of oxygen find the undercured profile surface and thus lead to a volatile surface.

Past attempts to distance the oxygen from the profile surface by powdering the latter have failed.

Recently a chemical treatment of the surface has been developed which among other things accelerates the curing process.

We are involved in the research project and believe that the results will be ready for publishing for the technical market within a few months.

Can transport marks on the surface be eliminated?

The elastomer profile is lying on the conveyor belt when it reaches its highest plasticity and the contact surface acquires any irregularities inherent in the above belt.

These unwanted irregularities can be eliminated by the use of an absolutely smooth conveyor belt. Unfortunately the market does not yet offer such a belt, which at the same time is resistant to extremely high temperatures.

This surface marking can also be reduced by the use of a coating for the profile - with talcum tal·cum
n.
See talc.

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talcum

talc, talcum powder.  for instance - this however, as is known, creates other problems.

Profiles with especially balanced cross-sections can indeed be suspended on a cushion of air, but handling is very difficult.

An excellent result can be obtained with the deployment of conveyor belt consisting of rollers. The development of this solution is complete and is being met with great interest. This new approach not only removes belt marking but it also helps aid in a more uniform heating around the part. Without the hinderance of the belt, more direct heating of the underside can be achieved.

The curing of sponge rubber by means of hot air

It is essential when curing sponge rubber to achieve a good cellular construction over the whole cross section and also to produce a surface area which is as smooth as possible. Naturally, to a large extent, both of the foregoing criteria are dependent on the compound used. However, it is also a question of the type and adjustment of the installation.

Index 9 in figure 4 shows a typical hot-air plant for sponge rubber. Here the rubber profile is fed through a high speed channel, type 109, with a length of 12,000 mm. The channel is set up in such a way that an extremely large heat transfer from the air to the rubber profile takes place in the first channel zone, so that the surface can be heated up and vulcanized as quickly as possible.

After approximately 3.5 meters the heat transfer rate is then, once more, raised in the third and fourth channel zones in order to initiate the foaming process.

In such an installation the blowing point is set at the end of the machine and the expansion of the profile can be balanced by raising the conveyor speed of the following machine. This subsequent machine is, incidentally, a type 114 twelve meter long, triple banked machine with an integral cooling plant built under.

This manufacturing process ensures that the profile has a uniform honey-combing over the whole cross section and that the surface is equivalently smooth. The relatively large cooling plant under the machine (requiring no extra floor space) provides a good cooling of the product, and this, as is well known, cannot be achieved with sponge rubber without a correspondingly long stay in the cooling medium. In a twelve-meter machine the cooling plant is twenty-five meters long.

With large cross sectioned profiles it is effective to station a very short UHF machine with a low output, possibly 3kw, between the high speed channel and the following triplebanked appliance or straight single pass ovens. It is now possible to integrate such a UHF back-up in a high-speed installation.

This type of low KW microwave is possible due to the extreme high energy that can now be put into the profile through the surface.

The addition of the new super jet air channel can now greatly improve the surface of the sponge profile due to the rapid skin cure that can be achieved.

Further possibilities for the deployment of hot-air plants

It is not only vulcanization which requires a heating of the elastomer profile, but also, often, drying out of primers of rubber coated steel reinforcements. For such applications very short installations are required, situated in line before the extruder. Optimally they are gas heated and the temperature of the process air can be set up to 400[degrees]F (248[degrees]C).

Coachwork seals are frequently flocked with a polyester fiber Noun 1. polyester fiber - a quick-drying resilient synthetic fiber consisting primarily of polyester
polyester - any of numerous synthetic resins; they are light and strong and weather resistant . For safety reasons it is best to use an adhesive which dries particularly fast providing it is subjected to a temperature of 170[degrees]F 248[degrees]C, and that the surrounding air is damp.

A high-speed channel, type 109, can fulfill all expectations, and at the same time it can polymerize polymerize /po·lym·er·ize/ (pah-lim´er-iz) to subject to or to undergo polymerization.
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pol·y·mer·ize
v.
To undergo or subject to polymerization.  the adhesive faster and more evenly than can be achieved with infra-red installations. More evenly because the hot air is fed equally to all surfaces, even in deep crevices, where infra-red radiation has particular problems, (also, the intensity of the infrared rays sinks in cubic proportion to the radiation distance, which results in assorted degrees of polymerization polymerization

Any process in which monomers combine chemically to produce a polymer. The monomer molecules—which in the polymer usually number from at least 100 to many thousands—may or may not all be the same.  at different levels). Production is faster because of the better heat transfer and because air humidity is extremely high.

The fact that the process air is clean allows to be removed through evaporation evaporation, change of a liquid into vapor at any temperature below its boiling point. For example, water, when placed in a shallow open container exposed to air, gradually disappears, evaporating at a rate that depends on the amount of surface exposed, the humidity  the adhesive solvents. Although very high air turbulence is available in a channel, the flock-fiber remains very stable.

Hot-air installations as a back-up to a UHF machine

UHF machines, such as shearhead extruders, need hot-air installations as back-ups so that the achieved heat can be held constant for the necessary time. Overall, however, it is a fact that simply to maintain the heat is not enough and that extra heating is required. This has already been explained heretofore. At high throughput speeds hot-air installations like those in figure 4, index 9, are recommended. If high volume profiles are cured, then installations of the type 114 are sufficient - with an overall length of twelve meters, a heating length of thirty-eight meters and a cooling length of 25 meters, as the extrusion speed is already governed by the extruder.

The hot-air channel - often only one unit in a long line

Often the hot-air vulcanization plant is only one small unit in a very long production line. Even more then, it must be fashioned in such a way that it is compatible with other machines and its performance approaches 100%.

For instance, universally compatible computer controls are now offered which can identify and deal with a problem before this leads to a breakdown of the entire plant. Here we must not forget that a breakdown in the hot-air curing installation can bring the whole production line to a halt.

In our hot-air vulcanizing installation we measure not only the temperature but also what the rubber profile is actually experiencing - and nothing less is acceptable for successful vulcanization. The Siemens SPS (Standby Power System) A UPS system that switches to battery backup upon detection of power failure. See UPS.
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SPS - Symbolic Programming System. Assembly language for IBM 1620.  Control can be spliced into the main computer via a RS-interface. The application of the stored data-values occurs automatically.

Filtering of the exhaust air

We believe one can no longer ignore one of the most basic human requirements - clean air to breathe. Therefore, Gerlach is developing at the moment a collecting filter which it is envisioned will mechanically remove all but .3% of the contaminants and return these to the burners to be incinerated.

The piece de resistance of this centrifugal filter unit is that an aerosol aerosol (âr`əsōl,–sŏl): see colloid.
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aerosol

System of tiny liquid or solid particles evenly distributed in a finely divided state through a gas, usually air.  phase is generated and the fine spray Noun 1. fine spray - precipitation in very small drops
downfall, precipitation - the falling to earth of any form of water (rain or snow or hail or sleet or mist)  is then mechanically collected. However, because the whole filter unit has a centrifugal centrifugal /cen·trif·u·gal/ (sen-trif´ah-gal) efferent (1).
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cen·trif·u·gal
adj.
1. Moving or directed away from a center or axis.

2.  motion, the collected vapor can be expelled immediately after its entry to the filter layer. The filter unit is therefore largely self-cleaning and thus works to maximum efficiency.

Energy costs - a savings concept

Naturally, we will pay less for energy if we use less; and if we can achieve a saving in energy then this is obviously very positive. If, however, at the same time as these energy savings the production rate falls, then the process has usually already degenerated into inefficiency.

We maintain that energy should never be squandered squan·der
tr.v. squan·dered, squan·der·ing, squan·ders
1. To spend wastefully or extravagantly; dissipate. See Synonyms at waste.

2. , and that the primary energy used in our process must be that which is the cheapest on the market and over and above that the cleanest. So, we come to natural gas. As we use direct and not indirect heat we find it particularly easy to meet the emission requirements laid down by law.

For most countries of the world, the cost of natural or propane gas is only ten to twenty-five percent of that of electricity. The small side effect, namely, the extremely fast heating of the process air from 20 to 340[degrees]C inside 30 to 60 seconds, is often almost ignored in comparison to the cost advantages. As shown previously, the investment costs Those program costs required beyond the development phase to introduce into operational use a new capability; to procure initial, additional, or replacement equipment for operational forces; or to provide for major modifications of an existing capability.  of a well thought-out vulcanization installation can be recouped by the savings in energy costs over a comparatively short period of time.

Waste heat must be recycled

We do this in that we let if flow into our heat exchanger, and this in its turn provides for it to be carried over, in a most sophisticated fashion, to the clean process air.

Obviously, condensation is formed. This, however, can be allowed to run off freely, and cleaning, necessary perhaps only every 6-12 months, demands only about 30 minutes.

Future developments

The trend to the introduction of EPDM sealing profiles with limited elastomer quantities per unit and the future demand for complex sealing units force the pace of integration of hot air processing units into industry.

In order to be more flexible with the future's complex seals, the Gerlach company is working on supporting the high speed hot-air channel with additional UHF. In this concept the polarity of the compound plays a less important role as the dielectric loss is usually increased considerably by the heating with hot air. The electromagnetic fieldelectromagnetic field

Property of space caused by the motion of an electric charge. A stationary charge produces an electric field in the surrounding space. If the charge is moving, a magnetic field is also produced. A changing magnetic field also produces an electric field.
..... Click the link for more information. can be shifted over the channel cross section by computer control so that an optimal adaptation to the profile is possible.

Only very low powered UHF units of about 2.4 kw are required for the most part as the primary heating is still achieved by the hot-air installation.

Our use of the superjet su·per·jet
n.
A supersonic jet airplane.  air oven eliminates belt marking and plays a great roll in better sponge surface conditions. It also reduces line length requirements which can be of big concerns in many older plants.

fwt820623 · 发表于 2009-3-26 08:53:44

有没有中文的啊，

arron_mao · 发表于 2009-3-26 08:59:02

大哥，你这个资料是概论类的吧，权且看看吧

julun · 发表于 2009-3-26 09:04:29

有中文吗？。。。。。。。。。。。。。。。

qbinli · 发表于 2009-3-26 09:56:04

LZ你这个帖子不应该发到问吧！

梦已随风 · 发表于 2009-3-26 10:06:09

楼主，你在搞什么？请提出你的问题，不是把问题甩给别人！！！

kennygu · 发表于 2009-3-26 10:19:34

:@ :@ :@ 我没有问题，提供解决问题方法

contender · 发表于 2010-4-8 11:21:19

看着费劲！！！！！！！！！！！！！！！！

davidzhao · 发表于 2010-4-8 15:30:28

放在问吧不合适吧。

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