MXPA98003204A - Roller of molding and support with rodi - Google Patents

Abstract

The present invention relates to a molding roll and a roll support therefor, comprising an internal core and an outer layer of the roll, and cooling channels to allow the liquid refrigerant to flow through the roll to cool the same during the molding, the outer layer is in intimate contact with the core and removably attached thereto by a press fit of at least 0.5 mm per meter in diameter of the inner core and the cooling channels are located within the outer layer of the roller. The cooling medium can be introduced at one end of the roller and travels axially along the length of the roller and exits at the other end. The channels for cooling can be arranged or distributed in the core of the roller at least 20 mm from the interface of the outer layer / core, being grouped and connected to a supply of refrigerant so that the flow direction of the refrigerant can be inverted.

Description

ROLLER OF MOLDING AND SUPPORT WITH ROLLER Field of the Invention This invention relates to a molding roll and a roll holder, in particular, to an improved design of the molding rolls.

Background of the Invention Twin roll molding is an established technology for the production of metal bands. In the case of aluminum alloys, it is usual for the thickness of the cast strip to be in the range of 6-10 mm. In this molding process, the molten metal is fed by a refractory nozzle in the occlusion or depth of penetration of a pair of rollers that rotate in opposite directions, cooled internally. Because of the use of the tip or refractory feeder nozzle, the band does not cover the total width of the roller, causing this location of heat, which causes thermal distortions in the roller that make it difficult to control the dimensions of the band being molded and also leads to defects in the roller, which means a relatively short working time for the roller and therefore frequent roller changes are required. The shaping rollers typically comprise a core and an outer layer which is commonly compressed on the core with a snap fit. The cooling channels, which can be circumferential or axial, are machined on the surface of the core or roller center and are connected to the water supply and return lines. The outer layers for molding are typically 50-100 mm thick and it is normal to periodically remachine the surface to remove defects, for example defects known as thermal shrinkage cracks. Thermal shrinkage cracks are characterized by the generation of a large number of fine cracks which result from contact with the molten metal and the cyclic mechanical and thermal loading cycle that the roll surface undergoes. The molten metal solidifies in contact with the molding rolls and then typically suffers a hot reduction before leaving the moulder as a solid web. A major problem of the aforementioned process is the tendency of the metal strip to adhere to either or both of the molding rolls. It is known that the application of a separating agent, such as a suspension of colloidal graphite in water, to the molding rolls on the output side of the machine, is beneficial in reducing this adhesion tendency. The separating agent is usually applied to the molding rolls as an atomized spray. During the last ten years, considerable efforts have been made to reduce the thickness of the metal band and this has led to a fundamental change in the design of the molding machines. It is well known that during molding by means of rollers, the molding rollers deform under the action of the separation forces developed between the metal strip and the molding rolls. "When the thickness of the molding is reduced, the separation forces generated by the metal band are significantly increased.These increased separation forces can be accommodated either by increasing the diameter of the molding rolls and the necks or the rollers of the roller or preferably by supporting the molding rolls with backing rolls With this preferred solution, the molding rolls are dimensioned to meet the requirements of the process and the backing rolls are sized to accommodate or adapt the separating forces and the torques generated during molding.

As already mentioned, there is a tendency for the metal band to join or adhere to either or both of the molding rolls. This is a particular problem with 4 raised moulders because there is a possibility that the material that is adhered to the molding rolls can pass through the depth of penetration of the backing roll / molding roll and be rolled or rolled. If this happens, considerable forces are generated and these forces can cause damage to both the molding rolls and the backing rolls. This damage has several effects. The most visible effect is the formation of depressions located both in the molding roll and in the backing roll in the immediate vicinity of the bonded or bonded material. This damage is easily repaired by polishing the rollers. A more serious problem occurs at the interface between the outer layer or shell of the molding roll and the core or center of the molding roll. If the material in this interface is damaged, it is possible that the intimate contact between the outer layer and the core is locally diminished with the result that the outer layer is not adequately supported. Furthermore, if the intimate contact is reduced, the heat transfer between the outer layer and the core and between the outer layer and the cooling water will be adversely affected. The combined effect of these various factors is the presentation of localized defects of the sheet or sheet. This problem is not always evident immediately but becomes more noticeable when the thickness of the outer layer for molding is reduced and is characterized by the gauge variations located in the molded metal sheet in the vicinity of the regions of the outer layer where the material has been previously adhered. US Patent No. 5469909 describes a typical molding roll used in roll molding of steel, with a core and a relatively thin outer layer, with cooling channels in the outer layer, and intimate contact at the core interface and of the outer layer, however this intimate contact can only be achieved by the diffusion bonding of the outer layer to the core., by means of a specialized process which is time consuming and very expensive, and does not allow the outer layer be easily removed to be replaced in close proximity to the molding line. Such a way of bonding the outer layer to the roll may not be able to withstand the loads during molding of the aluminum. Because the method of operation used is different, when alloying aluminum alloys are applied much larger loads are applied and the outer layer could be separated from the roll and fail or decompose after a short period of time. The present invention is primarily directed to overcoming the problems caused by the rotary drive of the backing rolls on any material passing through the molding roll / penetration depth of the backing roll, but it is applicable to all roller shapers. It is also an object of the invention to provide a molding roll with a relatively thick outer layer for the molding of the aluminum, with a strong bond between the roll and the core, but also allowing the removal and adaptation in a facilitated and economical manner of the layer external to the nucleus. According to the invention there is provided a molding roll and a molding roll holder comprising an inner core and an outer layer of the roll, and cooling channels to allow the liquid refrigerant to flow through the roll to cool the same during the molding, the outer layer is in intimate contact with the core and removably attached thereto by a snap fit, characterized in that the snap fit is at least 0.5 mm per meter of the inner core diameter and the cooling channels are located inside the outer layer of the roller.

The cooling channels may be located additionally or alternatively in the core of the roller. In a further aspect of the invention, the cooling channels are rearranged or redistributed axially along the length of the roller. The cooling channels can be grouped together and connected to a refrigerant supply so that the direction of the refrigerant flow can be reversed. Various embodiments of the invention will now be described in greater detail with reference to the appended figures, in which: Figure 1 is a longitudinal cross-section of a known molding roll, for the molding of aluminum; Figure 2 is a cross-section through the molding roll according to a first embodiment of the invention; Figure 3 is a longitudinal cross section through a segment of the circumference of a molding roll according to a further aspect of the invention; Figure 4 is a cross section through the molding roll according to a further embodiment of the invention; Figure 5 is a cross-section through a cooling channel of a molding roll according to a further aspect of the invention; Figure 6 is a longitudinal cross-section through the end of a molding roll of the embodiment shown in Figure 2, Figure 7 is a longitudinal cross-section through the end of a molding roll of the embodiment in the Figure 4, and Figure 8 is an enlarged longitudinal cross-section through the end of a molding roll of the embodiment in Figure 4.

Detailed description of the invention As previously described, the continuous molding rolls for aluminum are composed of an outer layer or shell 1 and a core or center 2, and the cooling channels 3 are machined within the surface of the core or center. This is shown schematically in Figure 1. In this example the cooling channels are arranged or distributed circumferentially on the surface of the core or center. The outer layer 1 is typically arranged to be relatively thick compared to a steel molding roll to withstand the mechanical loads during molding of the aluminum. The cooling channels 3 are in the form of channels of square cross-section, which are easy to machine in the core or center 2 before the outer layer or shell 1 is press-fitted on the core to form the roll. In a first embodiment of the invention, a plurality of cooling orifices 13 are provided, which are of circular section and which are located in the outer layer or shell 11 as shown in Figures 2 and 7. The holes of Cooling 13 are provided longitudinally in the outer layer or shell 11, spaced equidistantly around the circumference of the outer layer or shell and at a constant distance from the inner surface of the outer layer or shell. The outer layer or shell 11 is fixed or secured to the core 12 by means of a snap fit. Preferably the press fit is of the order of 1 mm per meter of the diameter of the roll to provide a sufficiently secure press fit of the core 12 and the outer layer 11 to withstand the high loads and torque experienced in particular in the molding of aluminum. If the outer layer 11 is not securely secured to the core, mechanical and thermal, cyclic loading can lead to movement of the outer layer with respect to the core. This relative movement is sometimes referred to as a "walk". The only means of effectively preventing this effect or reducing it to an acceptable degree is by a pressure adjustment of the order of 1 mm per meter of the diameter of the roller. If there is any value lower than this and if the reduction of the walk effect is not prevented sufficiently, permanent damage to the roller could occur. It will be appreciated that although in this embodiment the cooling channels are located conveniently away from the interface between the outer layer and the core, the same could also be located at the interface. In this case, the cooling channels could conveniently have a rectangular cross-section or some other preferred shape. By way of example, the molding roller of this first embodiment has the following dimensions: External diameter of the roller 600 mm External diameter of the core 440 mm thickness of the outer layer 80 mm cooling holes holes 20 mm diam. on a p.c.d. of 480 mm Spacing of the cooling holes 20 mm Adjustment to pressure 0.44 mm With the above example, the thickness of the outer layer between the holes and the outer diameter of the outer layer could be 50 mm and as with conventional aluminum mold rolls, they could have a usable thickness of about 25 mm. The axial cooling holes 13 are conveniently machined along the entire outer layer 11 and are connected to a cooling water supply and to return lines 16 by means of a plenum chamber 14 at each end of the roller as shown in FIG. Figure 8. On this basis, the cooling water could be introduced to the roller at one end and exit at the other. In an alternative arrangement the cooling orifices 13 could be arranged or distributed in groups in such a way that the flow direction of the cooling water is reversed. This is shown schematically in Figure 3. A further embodiment of the invention for the construction of the molding roll is shown in Figures 4 and 6 in which the cooling channels 23 are located in the roll core 22 and in this case it is preferred to locate the cooling holes 23 which are conveniently in the form of a series of axial holes, at some distance below the surface 22a of the core 22. The dimensions of the molding roll according to the embodiments of the roller of the invention they must be included within the following intervals: External diameter of the roller 550 to 1200 mm External diameter of the core 310 to 1100 mm Thickness of the outer layer 50 to 120 mm Cooling holes holes of 10 mm to 30 mm diam. on a p.c.d. 20 to 60 mm from the interface. Spacing of the cooling holes 10 to 30 mm Adjustment to pressure 0.5 to 1.5 mm per meter of the diameter of the roller.

The above interval for the location of the cooling holes of 20 to 60 mm from the interface of the core and the outer layer, is for the cooling orifices arranged or distributed in the core. For cooling holes arranged or distributed in the outer layer, the range is from 0 to 60 mm. It has been well established that the greater the velocity of the cooling water through the cooling channels, the greater the heat removal rate. The water velocity in the cooling channels can be conveniently increased by reducing the effective cross section of the cooling channels. This can be achieved, for example, by inserting suitably dimensioned rods 31 into each of the cooling holes 13, 23 as shown in Figure 5. The precise location of the rods and, if necessary, the diameter of the rods can be selected. to optimize the heat transfer in the cooling water.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates.

Having described the invention as above, the content of the following is claimed as property

Claims (8)

1. A molding roll comprising an inner core and an outer layer of the roll, and cooling channels to allow the liquid refrigerant to flow through the roll to cool it during molding, the outer layer is in intimate contact with the core and fixed removably thereto by a snap fit, characterized in that the snap fit is at least 0.5 mm per meter in diameter of the inner core and the cooling channels are located within the outer layer of the roll.

2. A molding roll comprising an inner core and an outer layer of the roll, and cooling channels to allow the cooling medium to flow through the roll to cool it during molding, the outer layer is in intimate contact with the core and removably attached thereto by a snap fit, characterized in that the snap fit is at least 0.5 mm per meter in diameter of the inner core and because the cooling medium is introduced at one end of the roller, it travels axially along the the length of the roller and comes out at the other end.

3. A molding roller according to claim 1 or claim 2, characterized in that the cooling channels are grouped and connected to a supply of refrigerant so that the direction of the refrigerant flow can be inverted.

4. A molding roller according to claim 1, characterized in that the outer layer incorporates a plurality of cooling channels arranged or distributed along the axis of the outer layer at least 20 mm from the interface of the core of the moulder / outer layer of the moulder.

5. A molding roll comprising an inner core and an outer layer of the roll and cooling channels to allow the cooling medium to flow through the roll to cool it during molding, the outer layer is in intimate contact with the core and fixed removably thereto by a snap fit, characterized in that the snap fit is at least 0.5 mm per meter in diameter of the inner core and because a plurality of cooling channels are arranged or distributed along the axis of the outer layer and placed in the core at least 20 mm from the internal diameter of the outer layer.

6. A molding roll according to any preceding claim, characterized in that the speed of the cooling water is adjustable to provide the optimum heat transfer.

7. A molding roller according to any preceding claim, characterized in that a cooling chamber or plenum chamber is provided on at least one end of the roller for feeding and withdrawal of cooling water from the molding roll.

8. A molding roll holder comprising a pair of molding rolls, each molding roll comprises an inner core and an outer layer of the roll and cooling channels to allow the cooling medium to flow through the roll to cool the roll during the molding, the outer layer is in intimate contact with the core and removably attached to it by a snap fit, characterized in that the snap fit is at least 0.5 mm per meter of the internal core diameter and because the cooling medium It is introduced at one end of the roller, travels axially along the length of the roller and exits at the other end.