JPS6218325B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for determining optimum flow rates and optimum water temperatures for use in rubber rolling mills, and the use of such optimum conditions in rolling mill operations.

In the manufacture of rubber products, the ingredients are first mixed in a banbury. Until recently, Bambari was cooled by running cold water during the winter months and hot water during the summer months. Current Bambari is cooled through hot water throughout the year. As a result, Banbari's throughput has increased compared to the previous cold water method.

After the ingredients are mixed in the Banbury, the ingredients are rolled in a two-roll rubber mill. The rolling mill rolls are cooled by passing cold water through them. The rubber being treated has a memory of its thermal history. If the rubber is held at too high a temperature for too long (total heat history), the rubber will scorch. When faced with the problem of scorching, the solution at the General Tire and Rubber Company has historically been to use cold water on the mill rolls. The General Tire and Rubber Company has also installed mechanical refrigeration systems that use Freon refrigerant gas to cool water running through the rolling mill. We do not believe that our competitors will follow our lead in this regard.

The use of frozen water in rolling mill rolls has resulted in high water costs and energy consumption in operating the refrigeration equipment. Extreme cooling also increases the stiffness of the rubber being rolled, which causes the rolling mill motor to work harder, thus consuming more energy. When cold water from wells is plentiful and cheap, large amounts of cold water are used and discharged. However, water treatment to prevent rolling mill corrosion was extremely expensive in these cases.

By changing the cooling water temperature inside the rolling mill,
It has been unexpectedly discovered that material temperature can actually be lowered by increasing the cooling water temperature at a constant flow rate. It has also been discovered that by increasing the flow rate at a constant temperature, the material temperature can be significantly lowered. These phenomena of material temperature reduction occur only in selected areas of the graph of material temperature vs. rolling mill surface temperature and the graph of material temperature convection rate.

What is desired is to obtain the minimum temperature difference between the material temperature and the rolling mill surface temperature, or to increase the material temperature as the rolling mill surface temperature increases in the graph section where the raw material temperature decreases as the rolling mill surface temperature increases. The point is to operate up to and slightly beyond this point.

The apparatus of the present invention and its operation will be described below in connection with the drawings.

Figures 1a (side view) and 1b (top view) relate to a water-cooled rubber rolling mill. The rolling mill has two rolls 3 and 5. The roll is 27 inches (68.6 cm) in diameter and 84 inches (213 cm) long. A mass 7 of unvulcanized rubber is positioned on the roll. The rolling mill is internally cooled by water spray 9. A variable displacement pump 13 pumps water through conduit 11 into the rolling mill. water 1
5 collects at the bottom of the mill rolls and is returned to the cooling tower 18. The variable valve 20 is positioned so as to bypass the cooling tower 18.

FIG. 2 shows the effect of varying the cooling water flow rate while maintaining the cooling water at a constant temperature. Optimal flow rate is established at constant water temperature. The water temperature is chosen arbitrarily for the first flow rate measurement.

As shown in FIG.
This valve allows partial recirculation of the hot water coming from the rolling mill. On the other hand, the amount of water pumped through the rolling mill is pump 1
3 held constant at 30 gallons per minute. As shown by the material temperature graph in Figure 3, as the water temperature increases from 21.1°C (70〓) to 30°C (86〓), the material temperature increases from 93°C (200〓) to 103°C.
(217.4〓). The material is rolled rubber 7. The water temperature is between 30℃ (85〓) and 32℃ (90〓).
〓), the material temperature increases from 103℃ to
It decreased to 97°C and then stabilized with a slight temperature increase when the water temperature was changed from 32°C to 37°C. water temperature
The material temperature was 97°C at 32°C. The difference between the water temperature and material temperature was 48°C. This is the beginning of the minimum temperature difference range obtained from the graph. As the water temperature increased to 37°C, the material temperature increased to 100°C, resulting in a temperature difference of 44°C.

Graph 41 above the material temperature graph is a thermal graph that outlines the amount of heat removed from the rolled rubber. The amount of heat being removed also reaches a second peak at a water temperature of about 32°C. The temperatures of the front and rear mill rolls are also shown on the graph. It can be seen that above the minimum temperature difference between the material temperature and the water temperature, the mill roll temperature is increased.

The graphs (Figures 2 and 3) show the results obtained with specific rubber materials. In other rubber materials,
This will yield graphs that are expected to be similar in shape to different degrees.

After the optimum cooling water flow rate and optimum cooling water temperature within the range of material temperature and flow rate specified in the claims are obtained, when the rolling mill is operated at the cooling water temperature and flow rate, The required water cooling energy will be saved.

If necessary, the flow rate determination can be remeasured at the established optimum temperature, and the optimum temperature can be remeasured if necessary.

Because most of the water is recycled, there are also significant water savings compared to what was previously used in plants that used flush-through systems. Energy is saved because hot water is used hot at a higher flow rate than would normally be the case. Energy is saved since when prior art freezing water was used, a large amount of energy was required for freezing and more energy was required for rolling the rubber material.

The rolling mill used is preferably perforated, ie cast as a solid roll and then the channels are perforated in the roll. The roll may be cast around a sand core with or without internal machining of the roughened surface. Rolling mills are commercially available from companies such as Steward Balling and Farrel. Other than cooling water temperature and flow, the mill is operated in a conventional manner.

The variable displacement pump used is a commercially available centrifugal pump.

The variable bypass valve used is also a commercially available valve. The cooling tower is also a conventional water evaporative cooling tower. Cooling tower capacity depends on water usage. The heated water exiting the rolling mill can also be cooled by heat exchange with the cooling air or chilled water supply entering the mill.

The manufacturing source of the above ingredients is not critical.
Typically, the components are selected by the engineer to suit a particular rolling mill or a particular plant. Variables such as the quantity and quality of the water supply, water temperature, etc. are determining factors in equipment selection.

[Brief explanation of the drawing]

FIG. 1a is a schematic partial cross-section of a two-roll rubber rolling mill in combination with a variable capacity water pump and a variable temperature water supply. A water recirculation loop is also included to limit the total amount of water pumped into the system. FIG. 1b is a top view of the device of FIG. 1a. FIG. 3 is a graph showing the change in material temperature when the flow rate through the rolling mill is constant and the cooling water temperature is gradually increased. The shape of the graph changes depending on the rubber compound being run on the rolling mill. In the lower graph 43, the solid line represents the forward roll,
The dotted line represents the backward roll. FIG. 2 is a graph showing the change in material temperature as the cooling water capacity through the rolling mill is increased.

Claims (1)

[Claims] 1 (1) At a temperature of 20°C or higher, the flow rate is 0.0159 m ³ water/m ³ internal mill surface area to 0.1233 m ³ /m ² internal mill surface area (or 0.0111 m ³ water per minute) / ^m2 external mill surface area ~ ^0.0855m3 / ^m2 external mill surface area) to optimize the cooling water flow rate, and even if the water flow rate is increased further, it will still be 74℃~121℃
(2) then establish one or more additional at least 20
At different fixed temperatures of ℃, the cooling water temperature is increased at the above optimal constant flow rate to establish a temperature at which the difference between the material temperature and the cooling water temperature does not substantially decrease even if the temperature is further increased, and the temperature is 74℃. Obtaining the optimum cooling water temperature for material temperatures in the range of ~121°C, (3)
operating at said optimum cooling water flow rate and said optimum cooling water temperature at a material temperature in the range of 121°C to 121°C to compound said material and save energy, said water flow being turbulent; An energy-efficient method for compounding rubber material on the rolls of a rubber mill in a compounding zone on an internally cooled rubber mill, characterized in that