Method of producing coils of sheet metal and the spacer designed to implement said method

Abstract

The invention relates to a method of producing coils of sheet metal consisting in coiling the sheet metal (1) following a hot-rolling, cold-rolling or cleaning operation. The inventive method is characterised in that it comprises the following steps, namely: coiling a part of said sheet metal (1) fixing a spacer (2) to one edge of the non-coiled part of the sheet metal (1) and coiling the rest of the sheet metal (1), thereby creating a coil (7) comprising a space (6) between two of the wraps thereof, with the possibility of fixing said spacer (2) either with or without interrupting the coiling; said coil (7) is then disposed in a heat treatment installation; a heat measuring device (8) is inserted in the space (6) created between the wraps of the coil (7) which is fitted with a spacer (2); the coil (7), which is fitted with a heat measuring device (8), is subsequently heat treated. The invention also relates to a spacer that can be used in order to implement said method.

Description

[0001] The present invention concerns a method of manufacturing spools of metal sheet, and a spacer device suitable for implementing said method.

[0002] In the steel production cycle, the slabs of steel, generally obtained by continuous casting, undergo a first hot rolling to obtain sheets of medium thickness that are rolled into spools, then unrolled for pickling and cold rolling to obtain sheets with the desired final thickness. Upon completion of the cold rolling, the sheets are again rolled into spools, and for many types of steel, these spools are given a heat treatment such as annealing in order to obtain the desired mechanical characteristics.

[0003] In the case of steels with high carbon content, a first heat treatment is given to the spool after hot rolling, before cold rolling.

[0004] The purpose of these annealing heat treatments is to modify the structure of the steel in order to adjust its mechanical properties. This is a delicate operation, because effort must be made to ensure that the correct temperature has been reached and held long enough at all points of each spool, regardless of its position in the heat treatment furnace.

[0005] Furthermore, if the spools are removed from the furnace too soon, before their temperature has lowered sufficiently, the steel oxidizes in the air and takes on an unacceptable coloring. All parts of the coil having this coloring or not attaining the required mechanical characteristics will have to be cut off, resulting in significant losses of material.

[0006] Control of this annealing operation can be accomplished by means of mathematical models that are not very accurate, or by means of temperature measuring devices such as those described in the patent FR 2 703 780 (Sollac). This device comprises a plate made of heat-conducting material that is inserted by manually or pneumatically hammering it between the coils of the spool. This plate has a slot in which a thermocouple is then inserted, making it possible to measure the actual temperature at the core of the spool.

[0007] However, the insertion of such a device between the coils of spools of steel sheet that is too stiff because it is too thick, or because of a carbon content that is too high, for example, is impossible. Moreover, this insertion is a relatively difficult operation and requires additional tools.

[0008] Another solution to this problem has consisted of treating in the same annealing furnace a number of spools between the coils of which thermocouple holder plates cannot be inserted, such as spools of high carbon steel (more than 0.3% by weight), for example, and one spool of steel of sufficiently low rigidity, such as a mild steel, so that said type of plate can be inserted therein. The heat treatment suitable for the first type of spools is then controlled by means of the data furnished by the spool having a thermocouple. However, the duration of the heat treatment that the spools not having a thermocouple must undergo is not suitable for the spool having the thermocouple. Indeed, the heat treatment of the spools of high carbon steel is twice as long as what is used for the spools of mild steel, which results in a significant loss of productivity.

[0009] The purpose of the present invention therefore is to remedy the disadvantages of the methods of the prior art by providing a method of manufacturing spools of metal sheet, which is adapted to all types of spools, regardless of their stiffness, which would be easier to implement and would allow to increase productivity.

[0010] To this means, a first objective of the present invention is a method of manufacturing spools of metal sheet, comprising a spooling of said metal sheet at the outlet of a hot rolling operation, of cold rolling and pickling, characterized in that said method comprises the steps consisting of:

[0011] coiling a part of said metal sheet, then

[0012] attaching a spacer device on one edge of the uncoiled part of said metal sheet, and coiling the rest of said metal sheet, thus creating a spool having a space between two of its coils, the attachment of said spacer device being performed with or without interruption of the coiling, then

[0013] placing said spool in a heat treatment facility, then

[0014] inserting a heat measuring device in the space created between the coils of the spool having the spacer device, then

[0015] causing the spool with the heat measuring device to undergo a heat treatment.

[0016] The invention can also have one or more of the following characteristics, taken alone or in combination:

[0017] the space created by the spacer device corresponds appreciably to the volume of the heat measuring device to be inserted therein,

[0018] the spacer device is made of one or more thermodegradable materials most of which decompose at the temperatures reached during the heat treatment,

[0019] the spool of metal sheet is a spool of steel sheet having more than 0.3% by weight of carbon,

[0020] the spool of metal sheet is a spool of sheet having a thickness of more than 1.2 mm,

[0021] the heat treatment is an annealing treatment carried out at a temperature of between 600 and 750° C.,

[0022] the spacer device is attached to said edge of the metal sheet with an adhesive.

[0023] The metal sheet can be selected, for example, from among mild steels, high carbon steels (more than 0.3% by weight), or any other metal or alloy that can be formed into spools, whether the thickness of the sheet is less than or more than 1.2 mm.

[0024] A second purpose of the present invention is a spacer device intended to be used during the implementation of the method according to the invention in all of its forms of embodiment, said spacer device being comprised of two appreciably identical parallelepiped parts made of compression resistant material, connected by a junction part so that a space is made between the two parallelepiped parts, said space corresponding appreciably to the volume of the heat measuring device to be inserted therein.

[0025] In a preferred form of embodiment, the spacer device according to the invention is also composed of one or more thermodegradable materials, selected from the group formed by wood, cardboard, and paper.

[0026] The present invention will now be illustrated by the detailed description of one form of embodiment of the method according to the invention given by way of non-limiting example, and with reference to the appended figures in which:

[0027] FIG. 1 represents the step of installing a spacer device during the implementation of the method according to the invention,

[0028] FIG. 2 represents a view in perspective of a spacer device according to the invention,

[0029] FIG. 3 represents the step of inserting a heat measuring device in the core of a spool of metal sheet,

[0030] FIG. 4 represents a part of the heat measuring device of FIG. 3.

[0031] FIG. 1 shows a sheet of steel 1 of thickness equal to 1.2 mm containing more than 0.3% by weight of carbon, having just been pickled after hot rolling, and which is coiled by means not shown. After having coiled part of the sheet 1, the first step of the method according to the invention consists of attaching a spacer device 2 on one edge of the sheet 1.

[0032] The spacer device 2, shown in FIG. 2, is here composed of two identical parts 3 and 4, made of wood, connected by a junction part 5 made of heavy cardboard. Each part 3 or 4 is a parallelepiped shaped block the thickness of which decreases slightly as it goes away from the junction part 5. This junction part 5 is U-shaped, each of the parts 3 and 4 being symmetrically glued to one of the arms of this U. The parts 3 and 4 are thus separated by a space 6 the width of which is determined by the distance between the arms of the U of the part 5, and the length of which is equal to that of the parts 3 and 4. These parts 3 and 4 are made of wood, which has the advantage of ensuring the disintegration of the spacer device 2 during the last heat treatment, while guaranteeing sufficient compressive strength to ensure the existence of the space 6 during the coiling of the spool. The lower face of the device 2 is also provided with an adhesive strip of the double face type of adhesive.

[0033] In order to be able to attach the spacer device 2 to an edge of the sheet 1, the speed of coiling is decreased, or the line is stopped for a few moments. However, it is quite possible to maintain the speed of coiling by providing for the installation of a robotized handler for putting the device 2 in place. In the present case, the coiling is completed as soon as the spacer device 2 is put in place.

[0034] A spool 7 as shown in FIG. 3 is thus obtained, said spool 7 having been transported and placed on edge in a heat treatment facility. As can be seen, the insertion of the spacer device 2 has separated the two coils of the spool 7 between which it is located as a result of the coiling. The space 6 between the parts 3 and 4 is thus left free. The junction part 5 has been folded over onto the edge of the spool 7 so as not to hinder the insertion of a heat measuring device 8.

[0035] This device 8 comprises a section of metal plate 9, shown in FIG. 4, which has a longitudinal slot 11 in which a thermocouple 10 is inserted. This thermocouple 10 is made to remain in the heat facility because of its great fragility, making it necessary to limit its movements and handling in general. The section of plate 9 is identical to the one covered by the French patent 2 703 780, to which reference may be made for a more detailed description.

[0036] The heat measuring device 8 in this instance is installed twice. The operator first inserts the section of plate 9 in the space 6 between the two parts 3 and 4 of the spacer device 2. Then he inserts the thermocouple 10 in the slot 11 of the section of plate 9.

[0037] The space 6 created between the parts 3 and 4 of the spacer device 2 corresponds to the volume of the heat measuring device 8, so that the temperatures picked up by the thermocouple 10 are as close as possible to the actual temperatures of the steel sheet 1.

[0038] Other spools of the same steel can then be placed in the heat facility, followed by the annealing heat treatment, for example. Because the spacer device 2 is made of materials that are thermodegradable at these temperatures, there is nearly nothing left of it when the annealing is completed. All the operator has to do, therefore, is remove the section of plate 9 from the spool 7, which spool is then taken to a cold rolling mill. It should be noted that the extraction of the device 8 is much easier in comparison to the same operation performed in the methods of the prior art, because the space made between the coils of the spool 7 has not varied at all between the beginning and end of the annealing, in a way that is quite surprising, and this is in spite of the disintegration of the spacer device 2.

[0039] Furthermore, the edge area of the spool 7 on which the spacer device 2 had been attached shows no trace of the operation, which has the additional advantage of being able to carry out the cold rolling with no risk of damage to the cylinders of the rolling mill.

[0040] Although the method according to the invention is particularly advantageous when it is used to control the annealing of spools of metal sheet too stiff to have an appropriate heat measuring device inserted directly therein, it is obvious that it can also be used to control the annealing of any spools of metal sheet, regardless of their stiffness and thickness. Indeed, its use is also advantageous there because the insertion of the heat measuring device is much easier compared to the methods of the prior art. The same is true for its extraction when the spacer device 2 self-destructs during the heat treatment.

Claims

1. Method of manufacturing spools of metal sheet, comprising a spooling of said metal sheet (1) at the outlet of a hot rolling, cold rolling, or pickling operation, characterized in that said method comprises the steps consisting of:

coiling a part of said metal sheet (1), then

attaching a spacer device (2) on one edge of the uncoiled part of said metal sheet (1), and coiling the rest of said metal sheet (1), thus creating a spool (7) having a space (6) between two of its coils, the attachment of said spacer device (2) being performed with or without interruption of the coiling, then

placing said spool (7) in a heat treatment facility, then

inserting a heat measuring device (8) in the space (6) created between the coils of the spool (7) having the spacer device (2), then

causing the spool (7) with the heat measuring (8) device to undergo a heat treatment.

2. Method according to claim 1, characterized in that the space (6) created by the spacer device (2) corresponds appreciably to the volume of the heat measuring device (8) to be inserted therein.

3. Method according to either of claims 1 or 2, characterized in that the spacer device (2) is made of one or more thermodegradable materials most of which decompose at the temperatures reached during the heat treatment.

4. Method according to claims 1 to 3, characterized in that the spool (7) of metal sheet (1) is a spool of steel sheet having more than 0.3% by weight of carbon.

5. Method according to claims 1 to 4, characterized in that the spool (7) of metal sheet (1) is a spool of sheet having a thickness of more than 1.2 mm.

6. Method according to claims 1 to 5, characterized in that the said heat treatment is an annealing treatment carried out at a temperature of between 600 and 750° C.

7. Method according to claims 1 to 6, characterized in that the spacer device (2) is attached to said edge of the metal sheet (1) with an adhesive.

8. Spacer device (2) intended to be used during the implementation of the method according claims 1 to 7, characterized in that it is comprised of two appreciably identical parallelepiped parts (3, 4) made of compression resistant material, connected by a junction part (5) so that a space (6) is made between the two parallelepiped parts (3, 4), said space (6) corresponding appreciably to the volume of the heat measuring device (8) to be inserted therein.

9. Spacer device (2) according to claim 8, characterized in that it is composed of one or more thermodegradable materials, selected from the group formed by wood, cardboard, and paper.