DE2849349A1 - METHOD FOR DETERMINING THE OPTIMUM COOLING WATER TEMPERATURE OF THE ROLLS OF A RUBBER ROLLER - Google Patents

Description

^ R.-ING. WALTER ABITZ DR. DIETER F. MORF DIPL.-PHYS. M. GRITSCHNEDER

Patent attorneys

mn ***,

2649349

November 1978

Postal address Postfach 8Θ0109, SOOO Munich 8β

Pienzenauerstrasse 28

Telephone 98 32 22 '

Telegrams: Chemlndus Munich

Telex: COJ 5 23992

GT-1290

THE GENERAL TIRE & RUBBER COMPANY Akron, Ohio, V.St.A.

Method for determining the optimal cooling water temperature for the rolls of a rubber mill

909830/0578

GT-1290 tons

The invention relates to a method for determining the optimum flow rate to be used in a rubber rolling mill or rolling mill and optimal water temperature and the application of these optimal conditions in the operation of the rolling mill.

When producing rubber or rubber products, the ingredients are first mixed in a Banbury mixer or rubber kneader. Until recently, the Banbury mixer was operated with cold water flowing through it during the winter months and
Hot water cooled during the summer. The
Cooling by hot water passed through the Banbury mixer throughout the year, which means a higher throughput of the
Banbury mixer compared to the earlier methods with cold water cooling.

After mixing the ingredients in the Banbury mixer
the mixture obtained is rolled on a rubber mill having two rollers. The rollers are cooled by means of cold water passed through them. The processed rubber has a "memory" of its "heat history". If the rubber is held too long at too high a temperature (total heat history), it will be vulcanized. Problems of scorching have hitherto been solved by the applicant by using colder water for roller cooling. The applicant has even gone so far as to cool the cooling water flowing through the rollers with Freon (eg monochlorodifluoromethane) as. Install mechanical cooling units that work with cooling gas. The other manufacturers have presumably not followed the applicant's example in this regard.

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The use of chilled water in the applicant's rolling mills has caused great costs and a high energy requirement for the operation of the cooling units. The extreme cooling also has increases the stiffness of the rubber being rolled, which in turn has made the mill motors work harder and therefore used more energy. In some cases where abundant and inexpensive cold water from boreholes was available, large amounts of cold water were used and disposed of. The water treatment to prevent a However, corrosion of the rolling mill has proven to be quite costly in these cases.

Surprisingly, it has now been found that by Varying the temperature of the cooling water in the rolling mill the temperatures of the rubber compound can be lowered if the cooling water temperature is reduced at a constant flow rate. It was also found that the temperature the rubber mixture can be reduced considerably by increasing the flow rate at constant temperature. This phenomenon of a decrease in the temperature of the rubber compound occurs only in selected areas of the graph Functions between the temperature of the rubber compound and the temperature of the roll surface as well as between the temperature the rubber mixture and the flow rate.

It is desirable to achieve the minimum difference between the temperature of the rubber mixture and the temperature of the Roller surface or working in that area of the graphic Relation in which the temperature of the rubber mixture decreases with an increase in the temperature of the roll surface, to to and slightly beyond the point at which the mixing temperature increases with an increase in the temperature of the roll surface increases.

A brief explanation of the accompanying drawings follows.

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90983 0/0578

Fig. 1a is a flow diagram (partially in cross-section) of a two-roll rubber mill in combination with a variable volume water pump and variable water supply Temperature. There is also a water loop, which limits the total volume of water pumped through the system;

Fig. 1b is a top view of the device shown in Fig. 1a?

Fig. 2 is a graph showing the change in the temperature of the rubber compound with an increase in the through the rolling mill illustrates flowing volume of cooling water; and

Fig. 3 is a graph showing the change in rubber compound temperature in the case of gradual Increase in the cooling water temperature at constant flow rate illustrated by the rolling mill; the shape of the curves depends on the rubber compound being rolled different .

The following is an explanation of the preferred ones according to the invention Embodiments.

The device used according to the invention and its operation are explained in more detail below with reference to the drawings.

Figures 1a (side view) and 1b (top view) show a water-cooled rubber rolling mill with two rollers 3 and 5. Die Rollers are each 68.59 cm (27 in.) In diameter and 213.36 cm (84 in.) Long. Located on the reels an unvulcanized or uncured rubber compound

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se 7. The rolling mill is operated from the inside with the help of a water spray device 9 chilled. The water is fed into the water by a variable volume pump 13 via line 11 Pumped rolling mill. The water 15 collects in the bottom of the rollers and is returned to a cooling tower 18. A changeable one Valve 20 is arranged so that the cooling tower 18 is bypassed.

Figure 2 shows the effect of changing the cooling water flow rate while maintaining a constant cooling water temperature. The optimal flow rate will be determined at constant water temperature. The water temperature becomes arbitrary for the first flow rate determination chosen. In the present case, a flow rate of 113.55 l / min (30 gpm) ensures the best cooling for the examined volume range.

According to FIG. 3, the cooling water temperature is varied by actuating the valve 20, which allows a partial return of hot water flowing in from the rolling mill, while the volume of water pumped through the rolling mill is kept constant at 113.55 l / min (30 gpm) with the aid of the pump 13. is held. As the rubber compound temperature curve of Figure 3 shows, the compound temperature increases from 93.3 ° C (200 ° F) to 105.6 ° C (222 ° F) when the water temperature rises from 21.1 ° C (70 ° F) ° F ^{) rises to 29.4 0} C (85 ° F). The rubber mixture is subjected to the rolling rubber 7. When the water temperature of 29.4 ° C (85 ° F) to 32.2 ° C (90 ⁰ F) increases, the temperature of the rubber mixture of 1O5,6 ° C (222 decreases ° F) drops to 97.8 ° C (2O8 ° F) and then stabilizes, with a slight increase in temperature as the water temperature goes from 32.2 ° C (90 ° F) to 37.8 ° C (100 ° F ) is increased. If the water temperature is 32.2 ° C (90 ° F), the temperature of the rubber compound will be 97.8 ° C (2O8 ° F) '. The difference between the temperature of the water and that of the rubber compound is

_ 4 _
909830/0578

65.6 ° C (11 8 ⁰ F). This is the beginning of the area of the minimum difference that can be read from the graph. When the water temperature at 37.8 ⁰ C (100 ⁰ F) increases, the temperature of the rubber mixture increased to 94 ₇ 4 ° C (211 ⁰ F), which means a difference of 56.6 ⁰ C (111 ° F).

The curve above the mixture temperature curve is the heat curve, which illustrates the amount of heat dissipated by the rolled rubber. The amount of heat dissipated reaches with one Water temperature of about 32.2 C (about 90 ° F) is also a maximum. The temperature of the front and rear rollers is also shown graphically. You can see that the roller temperature increased at temperatures above the minimum difference between the mixture temperature and the water temperature is.

The diagrams of FIGS. 2 and 3 show the results which are achieved with a particular rubber compound would. Other rubber compounds would produce graphs which are believed to be different but a similar one Would have shape.

After determining the optimal cooling water flow rate and optimal cooling water temperature, the rolling mill is operated at this cooling water temperature and at this flow rate, to achieve the required energy savings. If necessary, one can determine the flow rate check at the determined optimal temperature, which is where a check of the optimal Temperature can connect.

Since most of the water is circulated, the method according to the invention also enables considerable water savings compared to traditional methods or facilities based on a single pass system. energy

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909830/0578

is saved because lukewarm water has a higher flow rate used than would normally be the case. In addition, compared to the conventional use of Chilled water achieved an energy saving because in the latter Trap for the cooling a high amount of energy was required and the rolling of the rubber mixture also a higher amount Energy demand.

The rollers used are preferably drilled, i.e. they are cast as a solid roller, after which water channels are built into the roller be drilled. The rollers can also be cast around a sand core, with the rough interior machined if necessary will. Suitable rolling mills are brought onto the market by Steward Boiling and Farrel, among others. With the exception of Temperature and the flow of the cooling water, the rolling mills are operated in a conventional manner.

The variable volume pump used is a commercially available one Centrifugal or centrifugal pump.

The variable bypass valve used is also a commercially available valve. Also the cooling tower is a conventional water evaporation cooling tower. The cooling tower capacity depends on the volume of water used away. The heated water draining from the rolling mill can also be achieved by exchanging heat with cold air or the cold water supply be cooled during operation.

The origin of the aforementioned components is not decisive. The ingredients are usually made by a professional selected to fit specific rolling mills or a particular facility. Changes, for example in the amount and quality of the water supply, water temperature, etc., play a decisive role in the choice of device.

End of description

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909830/0 57 8

AS

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Claims (13)

PATENT CLAIMS Process for reducing the energy requirement for rolling an unvulcanized rubber mixture on a rolling mill, which has one or more roller (s) with internal water cooling, characterized in that that he a) the flow rate of the material flowing through one or more roller (s) at a specified temperature The cooling water varies to determine the rate at which further increases make the difference do not decrease between the temperature of the rubber compound and the cooling water temperature, b) stage a) for one or more other specified ones Temperature (s) repeated to determine the temperature at which further temperature reductions do not significantly reduce the difference between the rubber compound temperature and the cooling water temperature , c) selects the water temperature and the flow rate which has the smallest difference between the temperature 909830/05 7 ~ 8 ensure the rubber mixture and the cooling water temperature - 20 C / and d) operates the rolling mill at the selected water temperature and flow rate. 2. The method according to claim 1, characterized in that the selected water temperature is the minimum difference between corresponds to the temperature of the rubber mixture and the cooling water temperature - 10 C. 3. The method according to claim 1, characterized in that the Temperature of the rubber mixture determined by the required physical properties of the rubber after it Vulcanization is a predetermined temperature. 4. The method according to claim 1, characterized in that the selected water temperature is the maximum temperature - 10 ° C within a temperature range in which the Temperature of the rubber mixture with an increase in the water temperature at a constant water flow rate decreases. 5. The method according to claim 1, characterized in that the selected range of the temperature of the rubber mixture that The range is in which the temperature of the rubber compound increases with an increase in the water temperature at a constant flow rate decreases. 6. Method of reducing energy consumption for rolling of unvulcanized rubber on a rolling mill, which has several rollers with internal water cooling, thereby marked that one a) the temperature of the at a predetermined flow rate flowing through at least one roller - 2 - 909830/0578 2843349 GT-1290 n Water varies and b) an unvulcanized rubber mixture at different Water temperatures rolls to the slightest difference between the temperature of the rubber compound and the To determine the water temperature, which is the energy consumption by the roller drive motor and the cooling water requirement reduces to a minimum and prevents premature vulcanization. 7. The method according to claim 6, characterized in that the optimum temperature of the rubber mixture is the minimum temperature the mix is. 8. The method according to claim 6, characterized in that the temperature of the rubber mixture based on laboratory data and / or is an experimentally predetermined temperature which has the required physical properties of the rubber after its vulcanization results. 9. The method according to claim 8, characterized in that the optimal water temperature is the maximum water temperature, which maintains the temperature of the rubber compound. 10. Method of reducing energy consumption for rolling of unvulcanized rubber within a predetermined temperature range on a rolling mill which has several Has rollers with internal water cooling, characterized in that one a) the flow rate and temperature of the water flowing through the rollers varies, b) the temperature of the unvulcanized rubber mixture at different flow rates and water temperatures measures to determine the relation between the temperature of the rubber compound, the flow rate and the water - 3 909830/0578 to determine the temperature, and c) the flow rate and water temperature selects which the least amount of energy for the operation of the Rolling mill and pumping the water through the rolling mill. 11. The method according to claim 10, characterized in that the processing temperature of the rubber mixture for improvement the physical properties of the mixture can be reduced without reducing the production rate. 12. The method according to claim 10, characterized in that the Temperature of the rubber mixture corresponds to the temperature range which is determined by the required physical Properties of the rubber is determined after its vulcanization. 13. The method according to claim 10, characterized in that the optimal temperature of the rubber mixture with regard to the water temperature / mixture temperature relation at + 10 ° C the value after which the mixture temperature, which has decreased with increasing water temperature, begins to rise with a rise in water temperature at constant water flow rate. -A- 909830/0578