Metal sheet for a container for granular materials
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- CONSTELLIUM ISSOIRE
- Filing Date
- 2024-07-17
- Publication Date
- 2026-06-10
AI Technical Summary
Existing dumpsters for granular materials experience significant abrasion wear, particularly at the bottom near discharge openings, due to the pressure and rheological characteristics of the materials being transported, leading to costly solutions like using expensive abrasion-resistant materials or optimizing geometry, but these methods are not economically viable for aluminum alloy bins.
A process for manufacturing an aluminum alloy laminated product with specific heat treatment and rolling stages to achieve an abrasion-resistant sheet without the need for relief patterns or costly materials, using alloys from the 6xxx series, which are then used to line the bottom of dumpsters to enhance abrasion resistance.
The process results in dumpsters with improved abrasion resistance equivalent to or slightly better than current techniques, while maintaining mechanical properties and reducing manufacturing costs, with a mass loss under Taber test conditions less than 470 mg after 4000 cycles, compared to traditional alloys.
Smart Images
Figure FR2024050987_06022025_PF_FP_ABST
Abstract
Description
[0001] Description
[0002] Title of the invention: Sheet metal for a skip for granular materials
[0003] Field of the invention The invention relates to sheets for bins for granular materials which have improved abrasion resistance.
[0004] State of the art
[0005] A skip for granular materials most often comprises a base, typically a flat or curved base 1, and a plurality of side walls 2, 4 intended to confine the granular material to be transported; typically, a skip has a rectangular shape and comprises two sets of side walls, at least one of which 2 can be opened to unload the granular material by tilting the skip using a jack 3 (see figure 1). Another method of construction is the so-called "half-moon" shape comprising a curved base and side walls, of which the one which can be opened to unload the granular material can have a more or less complex curved shape. There are other shapes of skip, in particular those which allow unloading via the base. These skips may comprise, in addition to the base and the walls, external stiffeners or frames.The parts of the walls and bottom that come into contact with the granular material are usually smooth, so that the granular material slides well when unloading.
[0006] Granular material skips are typically unloaded by tipping: the skip is tilted, and the granular material flows out through an opening. This opening may be a side hatch. The flow may also occur through an opening in the bottom of the skip. In all cases, during this flow, the granular material slides along the bottom of the skip. This leads to abrasive wear. This wear of the skip bottom is greater near the opening through which the skip is unloaded, because the pressure is higher there. Wear depends on the material used for the bottom of the skip and the granular material. It also depends on the tilt speed of the skip, as well as the rheological characteristics of the granular material.These rheological characteristics may depend, for example, on the humidity level: we know that dry sand flows as the bucket rises, while wet sand, which is more sensitive to compaction, flows in several blocks that detach from the main mass. The term "granular material" here includes any granular material, whatever its origin and nature, mineral or organic, which is usually transported in buckets, such as: sand, gravel, pebbles, stones, topsoil, backfill soil, seeds, etc.
[0007] The flow conditions encountered on steel skips lead to significant abrasion of the skip bottom. Several remedies have been proposed. The skip bottom can be covered with a rubber sheet or strip. More abrasion-resistant sheets, such as Hardox® 400 or 500, have also been used; these sheets typically exhibit a weight loss of 200 to 300 mg after 4000 Taber test cycles. Skip geometry can also be optimized to minimize the pressure exerted by granular material on the skip surfaces; the dumper-type skip is an example of such a geometry.
[0008] These products are quite expensive. Furthermore, we would like to have abrasion-resistant skips that can be made of aluminum alloy, because with equivalent performance, they are lighter than steel skips.
[0009] Patent application WO2006 / 035155 describes a container for transporting, storing or handling granular material comprising a base and side walls, characterized in that at least part of the base comprises a sheet having been printed by rolling with one or more relief patterns on one face, said sheet being arranged so that during transport or during unloading of the granular material, said pattern is in contact with said granular material. The alloys used for the relief sheets can be steel or, preferably, an aluminum alloy, such as an alloy of the 5xxx series, the copper-free Al-Zn-Mg type alloys of the 7xxx series, such as 7020, and the alloys of the 6xxx series, such as 6061. The printed sheets, however, have two disadvantages: on the one hand, they are more expensive and on the other hand, the granular material is retained and only begins to slide with a high angle of incidence.
[0010] Patent application WO2018 / 104004 relates to a method for manufacturing an abrasion-resistant aluminum alloy rolled product comprising the steps of: (a) providing an aluminum alloy rolling material having Mg 4.20% to 5.5%, Mn 0.50% to 1.1%, Fe up to 0.40%, Si up to 0.30%, Cu up to 0.20%, Cr up to 0.25%, Zr up to 0.25%, Zn up to 0.30%, Ti up to 0.25%, unavoidable impurities and remainder aluminum; (b) heating the rolling material; (c) hot rolling the rolling material to an intermediate thickness in a range of 15 mm to 40 mm;(d) hot rolling the rolling material from an intermediate thickness to a final thickness in a range of 3 mm to 15 mm and wherein the exit temperature of the hot rolling mill is in a range of 130 to 285°C; (e) cooling the hot rolled material to room temperature.The present invention aims to provide an improved rolled product made of aluminum alloy, intended in particular for the production of skips for the transport of granular materials, resistant to abrasion, having satisfactory mechanical properties for this application and whose manufacturing process is economical. Object of the invention.
[0011] A first subject of the invention is a method for manufacturing an abrasion-resistant rolled product made of aluminum alloy, comprising the following successive steps:
[0012] (a) casting a 6XXX series aluminium alloy into a rolling plate,
[0013] (b) heating the rolling plate to a temperature of 450°C to 580°C, (c) hot rolling the rolling plate thus heated in one or more rolling steps to a sheet of intermediate thickness of 12 to 40 mm, preferably 15 to 30 mm, the inlet temperature of the hot rolling mill preferably being 450°C to 560°C and the outlet temperature of the hot rolling mill preferably being 380°C to 530°C, (d) hot rolling the sheet of intermediate thickness in one or more rolling steps to a sheet of hot rolling outlet thickness of 3 mm to 15 mm, the temperature of the sheet of intermediate thickness when step (d) begins being 330°C to 460°C, and the outlet temperature of the hot rolling mill being 170°C to 320°C,
[0014] (e) cooling the hot rolling outlet thickness sheet from the hot rolling mill outlet temperature to room temperature,
[0015] (f) optionally cold rolling the hot rolling output thickness sheet with a reduction rate of 10% to 40% and / or carrying out heat treatment at a temperature of 150°C to 200°C, wherein, after hot rolling and cooling to room temperature the aluminum alloy rolled product is not subjected to solution treatment / quenching and is not printed with a relief pattern.
[0016] A second subject of the invention is a method of manufacturing a bin for granular material in which an abrasion-resistant rolled product is obtained by the method according to the invention, said abrasion-resistant rolled product is shaped and / or assembled to form a bin for granular material comprising said abrasion-resistant rolled product.
[0017] A third subject of the invention is a bin for granular material comprising an abrasion-resistant rolled product obtained by the method according to the invention. A fourth subject of the invention is the use of an abrasion-resistant rolled product obtained by the method according to the invention for manufacturing a bin for granular material.
[0018] A fifth object of the invention is the use of a skip according to the invention for the transport of granular material.
[0019] Description of figures
[0020] [Fig. 1] Figure 1 shows a bin for granular material made of sheet metal and profiles.
[0021] [Fig. 2] Figure 2 shows the relationship between the yield strength in the TL direction and the abrasion measured by the Taber test. Description of the invention
[0022] All aluminum alloys mentioned hereinafter are designated according to the rules and designations defined by The Aluminum Association in the Registration Record Series which it publishes from time to time, unless otherwise stated.
[0023] The metallurgical states referred to are designated according to European standard EN-515 (1993) unless otherwise stated.
[0024] All alloy compositions are provided in % by weight (wt%).
[0025] Unless otherwise stated, the static mechanical characteristics, i.e. the ultimate tensile strength Rm, the tensile yield strength Rp0.2, and the total elongation, also called elongation at break, are determined by a tensile test according to standard NF EN ISO 6892-1 (2016), the location of the gripping of the parts and their direction being defined in standard EN 485 (2016).
[0026] Unless otherwise stated, the definitions in EN 12258 (2012) apply.
[0027] The applicant realized that it is possible to improve the wear resistance of the bottom of the skips by developing more abrasion-resistant alloys or materials from the 6XXX family, without increasing the manufacturing cost thanks to a process that does not include solution treatment and quenching after hot rolling. Contrary to what the skilled person thought, the modification of the metallurgy resulted in a very significant improvement in abrasion resistance, without using alloys or materials that are unusual in the construction of industrial vehicles and / or much more expensive than the materials usually used and without using a relief sheet on the bottom of the skip.
[0028] The inventors have found that, surprisingly, alloy sheets of the 6XXX family which have not undergone solution treatment and quenching after hot rolling and which are not in the form of relief sheet, but whose processing conditions have been carefully chosen, have excellent abrasion resistance. According to standard EN 12258-1, the skilled person understands by "relief sheet" a "sheet having been printed with a relief pattern on one side, by rolling".According to the invention, the method for manufacturing an abrasion-resistant rolled product made of aluminum alloy comprises the successive steps of casting, heating, hot rolling to a sheet of intermediate thickness, hot rolling to a sheet of hot rolling exit thickness and cooling to room temperature, optionally cold rolling and / or heat treatment at a temperature of 170°C to 320°C, but does not include a solution treatment / quenching after hot rolling and is not printed with a relief pattern.
[0029] In step (a), a 6XXX series aluminum alloy is cast in the form of a rolling plate.
[0030] Preferably the alloy of the 6XXX series has the composition, in% by weight, Si 0.2-1.3
[0031] Mg 0.5- 1.4
[0032] Fe <= 0.7
[0033] Cu <= 0.9
[0034] Mn <= 1.0 Cr <= 0.4
[0035] Zn <= 0.25
[0036] Ti <= 0.15 unavoidable impurities: each <= 0.05%, total <=0.15%, remainder aluminum.
[0037] The Si content is preferably at least 0.3 or 0.4%, and / or at most 0.9% or 0.8%. In one embodiment the Si content is 0.4 to 0.8%. In one embodiment the Si content is 0.7 to 1.3%.
[0038] The Mg content is preferably at least 0.6 or 0.7%, and / or at most 1.3% or 1.2%. In one embodiment the Mg content is 0.8 to 1.2%. In one embodiment the minimum Mg content is 0.9%. The Fe content is preferably at most 0.6%. In one embodiment the Fe content is 0.3 to 0.7%. In one embodiment the Fe content is 0.1 to 0.5%.
[0039] The Cu content is preferably at most 0.8% or 0.7%. In one embodiment the Cu content is 0.1 to 0.4% or 0.2 to 0.4%. In one embodiment the Cu content is at most 0.2%. The Mn content is preferably at most 0.9% or 0.8%. In one embodiment the Mn content is at most 0.4% or at most 0.3% or at most 0.2%. In one embodiment the Mn content is 0.4 to 1.0%.
[0040] The Cr content is preferably at most 0.35% or 0.30%. In one embodiment the Cr content is 0.05 to 0.25%. In one embodiment the minimum Cr content is 0.06%.
[0041] The Zn content is preferably at most 0.30% or 0.25%. In one embodiment the Zn content is 0.01 to 0.20% or 0.06 to 0.19%.
[0042] The Ti content is preferably at most 0.12% or 0.10%. In one embodiment the Ti content is 0.01 to 0.10%.
[0043] The other elements are unavoidable impurities, the maximum content of which for each is 0.05% and 0.15% in total.
[0044] In an advantageous embodiment, the 6XXX series alloy has the composition, in weight %, Si 0.2-0.8
[0045] Mg 0.9- 1.4
[0046] Fe <= 0.7
[0047] Cu <= 0.9
[0048] Mn <= 0.4 Cr 0.06 - 0.4
[0049] Zn <= 0.25
[0050] Ti <= 0.15 unavoidable impurities: each <= 0.05%, total <=0.15%, remainder aluminum.
[0051] In one embodiment the 6XXX series alloy is selected from AA6061, AA6063 and AA6082 alloys, as designated by The Aluminum Association.
[0052] The chosen composition makes it possible in particular to obtain improved abrasion resistance and satisfactory mechanical properties for producing skips and to use an economical manufacturing process, not requiring solution treatment after hot rolling. In a step (b) the rolling plate is heated to a temperature of 450°C to 580°C. In one embodiment, the heating temperature of the rolling plate is at least 510°C, or is at least 520°C, or is at least 530°C, or is at least 540°C, or is at least 550°C, or is at least 560°C, and / or is at most 570°C, or is at most 560°C, or is at most 550°C, or is at most 540°C, or is at most 530°C, or is at most 520°C. In one embodiment, the heating is a homogenization, the duration of which is 4 to 48 hours. In one embodiment, the heating is a treatment to reach the hot rolling start temperature.In a step (c) the rolling plate is hot rolled in one or more rolling steps to a sheet of intermediate thickness of 12 to 40 mm, preferably 15 to 30 mm, the inlet temperature of the hot rolling mill preferably being 450°C to 560°C and the outlet temperature of the hot rolling mill preferably being 380°C to 530°C. In one embodiment, the inlet temperature of the hot rolling mill for the at least one rolling step to an intermediate thickness sheet is at least 460°C, or is at least 470°C, or is at least 480°C, or is at least 490°C, or is at least 500°C, or is at least 510°C, or is at least 520°C, or is at least 530°C, or is at least 540°C, and / or is at most 550°C, or is at most 540°C, or is at most 530°C, or is at most 520°C, or is at most 510°C, or is at most 500°C, or is at most 490°C, or is at most 480°C, or is at most 470°C.
[0053] In one embodiment, the outlet temperature of the hot rolling mill for the step(s) of rolling to an intermediate thickness sheet is at least 390°C, or is at least 400°C, or is at least 410°C, or is at least 420°C, or is at least 430°C, or is at least 440°C, or is at least 450°C, or is at least 460°C, or is at least 470°C, or is at least 480°C, or is at least 490°C, or is at least 500°C, or is at least 510°C, and / or is at most 520°C, or is at most 510°C, or is at most 500°C, or is at most 490°C, or is at most 480°C, or is at most 470°C, or is at most 460°C, or is at most 450°C, or is at most 440°C, or is at most 430°C, or is at most 420°C, or is at most 410°C, or is at most 400°C.
[0054] In a step (d) the intermediate thickness sheet is hot rolled in one or more rolling steps to a hot rolling exit thickness sheet of 3 mm to 15 mm, the temperature of the intermediate thickness sheet when step (d) begins being 330°C to 460°C and the exit temperature of the hot rolling mill being 170°C to 320°C.
[0055] In one embodiment, the inlet temperature of the hot rolling mill for the at least one rolling step to a hot rolling outlet thickness sheet is at least 340°C, or is at least 350°C, or is at least 360°C, or is at least 370°C, or is at least 380°C, or is at least 390°C, or is at least 400°C, or is at least 410°C, or is at least 420°C, or is at least 430°C, or is at least 440°C, and / or is at most 450°C, or is at most 440°C, or is at most 430°C, or is at most 420°C, or is at most 410°C, or is at most 400°C, or is at most 390°C, or is at most 380°C, or is at most 370°C, or is at most 360°C, or is at most 350°C.
[0056] In one embodiment, the exit temperature of the hot rolling mill for the at least one rolling step to a hot rolling exit thickness sheet is at least 180°C, or is at least 190°C, or is at least 200°C, or is at least 210°C, or is at least 220°C, or is at least 230°C, or is at least 240°C, or is at least 250°C, or is at least 260°C, or is at least 270°C, or is at least 280°C, or is at least 290°C, or is at least 300°C, and / or is at most 310°C, or is at most 300°C, or is at most 290°C, or is at most 280°C, or is at most 270°C, or is at more than 260°C, or is at most 250°C, or is at most 240°C, or is at most 230°C, or is at most 220°C, or is at most 210°C, or is at most 200°C, or is at most 190°C.
[0057] In a step (e) the hot rolling output thickness sheet is cooled from the hot rolling mill output temperature to room temperature, In an optional step (f) the hot rolling output thickness sheet is cold rolled with a reduction rate of 10% to 40% and / or a heat treatment is carried out at a temperature of 150°C to 200°C. In an embodiment of step (f) the reduction rate of the optional cold rolling step is at least 15%, or is at least 20%, or is at least 25%, or is at least 30%, and / or is at most 35%, or is at most 30%, or is at most 25%, or is at most 20%.In one embodiment of step (f), the heat treatment temperature is at least 155°C, or is at least 160°C, or is at least 165°C, or is at least 170°C, or is at least 175°C, or is at least 180°C, or is at least 185°C, or is at least 190°C, and / or is at most 195°C, or is at most 190°C, or is at most 185°C, or is at most 180°C, or is at most 175°C, or is at most 170°C, or is at most 165°C, or is at most 160°C. In one embodiment of step (f), the heat treatment time is at least 1 hour, or at least 2 hours or at least 3 hours or at least 4 hours and / or at most 12 hours or at most 11 hours or at most 10 hours or at most 9 hours.
[0058] According to the invention, after hot rolling and cooling to room temperature the rolled product made of aluminum alloy is not subjected to a solution treatment / quenching and is not printed with a relief pattern. If one or more optional steps of cold rolling and / or heat treatment at a temperature of 150 ° C to 200 ° C are carried out, the rolled product made of aluminum alloy is of course also not subjected to a solution treatment / quenching and is not printed with a relief pattern before or after these steps.Thus, a method in which, after hot rolling and cooling to room temperature, the aluminum alloy rolled product is subjected to a solution treatment / quenching treatment and is not printed with a relief pattern, or in which the aluminum alloy rolled product is not subjected to a solution treatment / quenching treatment and is printed with a relief pattern, or in which the aluminum alloy rolled product is subjected to a solution treatment / quenching treatment and is printed with a relief pattern, does not reproduce the invention.
[0059] The abrasion-resistant product obtained by the process according to the invention is typically in a metallurgical state F, if it is not cold rolled, or H if it is cold rolled.
[0060] The surface of the abrasion-resistant rolled product according to the invention can be described as the rough rolling surface; rolling lines parallel to the rolling direction can be distinguished, which correspond to peaks and valleys parallel to the rolling direction.
[0061] Surprisingly, although the abrasion-resistant rolled product according to the invention generally has a lower mechanical strength than products in a T state, cold-rolled and subjected to a solution treatment / quenching and tempering, its abrasion resistance is equivalent or slightly lower. The abrasion-resistant rolled product according to the invention also has a higher abrasion resistance than products made of 5XXX alloy according to the current state of the art.
[0062] Advantageously, the mass loss in mg under Taber test conditions of 60 rpm, number of revolutions 4,000 applied force 10 N, room temperature, type of movement: rolling, friction radius: 31.75 mm (U = 200 mm), friction roller H-22, is less than 470 mg, preferably less than 420 mg, or 410 mg and more preferably 400 mg.
[0063] The invention also relates to a method of manufacturing a bin for granular material in which an abrasion-resistant rolled product is obtained by the method according to the invention and said abrasion-resistant rolled product is shaped and / or assembled to form a bin for granular material comprising said abrasion-resistant rolled product.
[0064] The invention also relates to a bin for granular material comprising an abrasion-resistant rolled product obtained by the method according to the invention.
[0065] According to the invention, the abrasion-resistant rolled product is arranged at the bottom of the bucket, so as to be in contact with the granular material when the bucket is loaded. The abrasion-resistant rolled product may be arranged over the entire surface of the bottom of the bucket, or only on the part which is located close to the hatch through which the granular material is discharged. In the context of the present invention, the term "bottom" should be understood as meaning the part of the bucket on which the granular material exerts a downward force (when the bucket is in a horizontal position (transport position), while the term "wall" should be understood as meaning the part of the bucket on which the granular material exerts a rather horizontal force. The bottom and the walls may be separate parts (assembled for example by welding or bolting), or represent a single curved shape (assembled or not).What is important is that at least a part of the bottom of the skip, namely the part on which the granular material slides during its unloading, is covered with abrasion-resistant laminated product according to the invention. In one embodiment, the skip according to the invention is characterized in that the abrasion-resistant laminated product covers the entire surface of the bottom of the skip, or only a part of the surface of said bottom on which the granular material slides during its unloading.
[0066] In the following examples, advantageous embodiments of the invention are described by way of illustration. These examples are not limiting in nature.
[0067] Example
[0068] In this example, the mechanical properties and abrasion resistance of alloy sheets according to the invention, obtained according to the process of the invention or not (A-6 and B-1), were compared and compared with sheets according to the prior art made of alloy of the 5XXX series (C, D, E and F).
[0069] Table 1 discloses the composition of the alloys cast in rolling slab form, in wt%.
[0070] [Table 1] - Chemical composition (% by weight) The rolling plates were processed by hot rolling and optionally by cold rolling. The processing conditions are given in Table 2. [Table 2] Processing conditions
[0071] The mechanical properties of the obtained sheets were characterized. The results are provided in Table 3.
[0072] 5 [Table 3] - Mechanical properties In an abrasion resistance test, the samples were tested using a standardized setup according to Taber in which two abrasive wheels with a specified surface area are rotated with a defined force on a rotating material sample. The two abrasive wheels rotate in opposite directions, which means that the abrasion of the material takes place transversely. The weight loss is measured after 4000 revolutions and is referred to as the number of cycles (revolutions) as mass loss per revolution (mg / revolution). The applied test parameters were: 60 rpm, number of revolutions 4000 (resulting in a sliding path of 800 m), applied force 10 N, room temperature, type of motion: rolling, friction radius: 31.75 mm (U = 200 mm), friction roller H-22, for each test series, new friction rollers were used. The results are shown in Table 4
[0073] [Table 4] - Taber test results
[0074] The relationship between the yield strength and the mass loss during the Taber test is given in Figure 2. The samples according to the invention, A-1 and A-5 and G1-1, G-2 and G-5, show after 4000 cycles a mass loss of less than 470 mg despite a mechanical resistance lower than that of the other samples.
Claims
Claims 1. A method of manufacturing an abrasion-resistant rolled product made of aluminum alloy, comprising the following successive steps: (a) casting a 6XXX series aluminium alloy into a rolling plate, (b) heating the rolling plate to a temperature of 450°C to 580°C, (c) hot rolling the thus heated rolling plate in one or more rolling stages to a sheet of intermediate thickness of 12 to 40 mm, preferably 15 to 30 mm, the inlet temperature of the hot rolling mill preferably being 450°C to 560°C and the outlet temperature of the hot rolling mill preferably being 380°C to 530°C, (d) hot rolling the intermediate thickness sheet in one or more rolling steps to a hot rolling exit thickness sheet of 3 mm to 15 mm, the temperature of the intermediate thickness sheet when step (d) starts being 330°C to 460°C, and the exit temperature of the hot rolling mill being 170°C to 320°C, (e) cooling the hot rolling outlet thickness sheet from the hot rolling mill outlet temperature to room temperature, (f) optionally cold rolling the hot rolling output thickness sheet with a reduction rate of 10% to 40% and / or carrying out heat treatment at a temperature of 150°C to 200°C, wherein, after hot rolling and cooling to room temperature the aluminum alloy rolled product is not subjected to solution treatment / quenching and is not printed with a relief pattern.
2. Method according to claim 1 in which the alloy of the 6XXX series has the composition, in % by weight, If 0.2-1.3 Mg 0.5- 1.4 Fe <= 0.7 Cu <= 0.9 Mn <= 1.0 Cr <= 0.4 Zn <= 0.25 Ti <= 0.15 unavoidable impurities: each <= 0.05%, total <=0.15%, remainder aluminum.
3. A method according to claim 1 or claim 2 wherein the 6XXX series alloy is selected from AA6061, AA6063 and AA6082 alloys, as designated by The Aluminum Association.
4. A method of manufacturing a bin for granular material in which an abrasion-resistant rolled product is obtained by the method according to any one of claims 1 to 3, said abrasion-resistant rolled product is shaped and / or assembled to form a bin for granular material comprising said abrasion-resistant rolled product.
5. A bucket for granular material comprising an abrasion-resistant rolled product obtained by the method according to any one of claims 1 to 3.
6. A bucket according to claim 5, characterized in that the abrasion-resistant rolled product covers the entire surface of the bottom of the bucket or only a part of the surface of said bottom on which the granular material slides during its unloading.
7. Use of an abrasion-resistant rolled product obtained by the method according to any one of claims 1 to 3 for manufacturing a bucket for granular material.
8. Use of a skip according to any one of claims 5 to 6 for the transport of granular material.