Mastering the trimming knife position

Abstract

1. A trimming device (7) for metal sheets, comprising: an upper knife (8) mounted on an upper shaft (10) and having a central circular surface (9) with a diameter D1 and a thickness T1; and a lower knife (11) mounted on a lower shaft (13) and having a central circular surface (12) with a diameter D2 and a thickness T2, the upper and lower knives being vertically shifted with an overlap to define a shear in the metal sheet, at least one of the upper shaft (10) or the lower shaft (13) being vertically movable, and the trimming device (7) comprising: a first distance sensor (14) capable of measuring a vertical distance (V1) to an upper edge of the upper knife; a second distance sensor (15) capable of measuring a vertical distance (V2) to a lower edge of the lower knife; and calculation means (16) capable of calculating the overlap.

Description

[Technical field]

[0001] The present invention relates to a trimming device, a trimming method and a method making it possible to assess the wear of a trimming device. [Background technology]

[0002] After undergoing pickling operations in the cold rolling line or annealing treatment, the steel strip is generally trimmed. Such trimming has several advantages. First, trimming allows obtaining the desired width for the strip. Second, trimming ensures edge quality by removing irregular defects on the strip edge caused by upstream processes.

[0003] Side trimming is performed by a pair of trimming knives, an upper knife and a lower knife, on each side of the steel strip. The knives have a thickness generally comprised between 20 mm and 40 mm. The pair of knives defines a shear having two main process parameters, namely the gap and the overlap. The gap is the horizontal distance between the two knives, while the overlap is the vertical distance between the uppermost point of the lower knife and the lowermost point of the upper knife.

[0004] Trimming equipment processes a variety of steel grades, from mild steels such as interstitial-free steels to hard steels such as AHSS steels. However, depending on the steel grade and format, the overlap and gap distances must be adjusted. For example, too much overlap can result in excessive force on the trimming knives, stress on the trimmed material, and speed differences between the trimming knives, all of which can cause greater friction that accelerates the wear of the trimming knives.

[0005] Overall, if trimming is not properly controlled, it can have a detrimental effect on strip edge quality, line productivity, trimming equipment life, and downstream processes.

[0006] The overlap and gap are usually calibrated offline, however, it is desirable to measure these distances online in order to more efficiently control the trimming process.

[0007] China Patent No. 102489772 discloses a system that allows online control of the overlap of a trimming device. The system, as shown in Figure 1, comprises an upper trimming knife 1 mounted on an upper shaft 2, a lower trimming knife 3 mounted on a lower shaft 4, an upper shaft position detection sensor 5, and a lower shaft detection sensor 6. The overlap is measured by using the positions of the upper shaft 2 and the lower shaft 4 detected by the sensors (5 and 6). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Chinese Patent No. 102489772 Summary of the Invention [Problem to be solved by the invention]

[0009] The object of this invention is to accurately measure the overlap of two knives during the trimming of metal sheets.A second object of the invention is to accurately position the trimming knives during the trimming of metal sheets and to detect wear of the trimming device. [Means for solving the problem]

[0010] This is achieved by providing a trimming apparatus as claimed in any one of claims 1 to 4. This is also achieved by providing a trimming method as claimed in any one of claims 5 and 9.

[0011] Other features and advantages will become apparent from the following detailed description of the invention.

[0012] For the purposes of illustrating the present invention, various embodiments will be described with particular reference to the following figures. [Brief description of the drawings]

[0013] [Figure 1] 1 shows a trimming device known in the prior art. [Diagram 2] 1 illustrates one embodiment of a trimming device disclosed in the present invention. [Diagram 3] 1 illustrates the effect of a bent shaft on measurements known in the prior art. [Figure 4] 2 shows a second embodiment of the trimming device disclosed in the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] As shown in FIG. 2, the invention relates to a trimming device 7 for metal sheets, which trimming device 7 comprises: an upper knife 8 with a central circular surface 9 having a diameter D1 and a thickness T1, attached to an upper shaft 10; a lower knife 11 with a central circular surface 12 having a diameter D2 and a thickness T2, attached to a lower shaft 13; Equipped with - the upper knife 8 and the lower knife 11 overlap (D OVERLAP ) and shifted vertically with at least one of the upper shaft 10 or the lower shaft 13 is vertically movable; And the trimming device 7 is a first distance sensor 14 capable of measuring the vertical distance V1 to the top end of the upper trimming knife; a second distance sensor 15 capable of measuring the vertical distance V2 to the lower end of the lower trimming knife; - calculation means 16 capable of calculating said overlap; Equipped with.

[0015] The trimming device can trim metal sheets having a thickness of 1 mm to 10 mm. The trimming device can be used at any step of the process. The trimming device is preferably located downstream of the pickling line or the annealing device.

[0016] As shown in figure 2, the upper and lower trimming knives (8, 11) are disks attached to a shaft such that rotation of the shaft results in rotation of the trimming knives. For example, the trimming knives can be placed under pressure by a screw after insertion on the shaft. In figure 2 the means allowing the trimming knives to be fastened to the shaft are not represented. The trimming knives are preferably made of a material according to standard EN1.2344 or EN1.2343, with a diameter (D1, D2) of 300 to 500 mm and a thickness (T1, T2) of 20 to 60 mm.

[0017] Calculation means are connected to the sensors and have access to the measured vertical distances V1 and V2 and also have access to the diameters of the first trimming knife and the second trimming knife.

[0018] The upper trimming knife 8 and the lower trimming knife 11 define a shear. The shear is usually defined by the distance between the bottom end of the upper trimming knife and the top end of the lower trimming knife, i.e. the area of ​​contact with the trimming piece during trimming. Thus, in FIG. 2, the shear distance is between the bottom right of the upper trimming knife and the top left of the upper trimming knife. The vertical component of the shear is the overlap (D OVERLAP ), and the horizontal component is the gap (D GAP ) is defined.

[0019] The upper shaft 10 and / or the lower shaft 13 can be moved vertically to set the desired overlap. The upper shaft and / or the lower shaft can be moved horizontally to set the desired gap distance.

[0020] The position of the first sensor relative to the second sensor is known. The first and second sensors are preferably fastened to a trimming device.

[0021] A first distance sensor 14 is positioned above the upper knife 18 to measure the vertical distance to the top end of said upper knife. A second distance sensor 15 is positioned below the lower knife 11 to measure the vertical distance to the bottom end of said lower knife. The inventors have realised that such a positioning is advantageous since it allows a direct measurement of the knife position without the shaft undergoing deformation. On the other hand, the measurement of the knife position through the shaft position is less reliable since during trimming the shaft tends to bend, resulting in a vertical displacement of the shaft closer to the trimming knife compared to the shaft closer to the motor (opposite the knife). This is shown in Figure 3, where the shafts (2', 4') are aligned with the trimming knife (D KNIVES ) and the opposite shaft (D MOTOR ) is bent to provide a gap difference between the

[0022] The solution of the present invention is therefore more reliable than the prior art solutions since it is not adversely affected by bending of the shaft.

[0023] Preferably, as shown in FIG. 4, in the trimming device 7, The upper knife and the lower knife have a gap distance (D GAP ), at least one of the upper shaft 10 or the lower shaft 13 is horizontally movable; - said calculation means is capable of calculating said gap distance; The trimming device is a third distance sensor 17 capable of measuring the horizontal distance H1 to the upper knife; a fourth distance sensor 18 capable of measuring the horizontal distance H2 to the lower knife; It further comprises:

[0024] The position of the third sensor 17 relative to the fourth sensor 18 is known. The third and fourth sensors are preferably fastened to the trimming device.

[0025] A third distance sensor 17 is arranged next to the upper knife 8 to measure the horizontal distance to the upper knife. A fourth distance sensor 18 is arranged next to the lower knife 11 to measure the horizontal distance to the lower knife. During trimming, for each pair of knives consisting of a lower knife and an upper knife, two sides can be defined: a product side and a shaft side. The product side is the side on which the product runs and the shaft side is the side on which the shaft lies. Preferably, the third and fourth distance sensors are arranged on the shaft side.

[0026] Preferably, the first and second sensors are inductive sensors. Preferably, the third and fourth sensors are inductive sensors.

[0027] Preferably, the first, second, third and fourth distance sensors are inductive sensors.

[0028] Preferably, the first and second distance sensors are laser sensors because such sensors have a wider measurement range than inductive sensors, e.g. because they can measure larger variations in overlap. Preferably, the third and fourth sensors are laser sensors.

[0029] Preferably, both the first shaft and the second shaft are vertically movable.

[0030] The invention also relates to a method for trimming a metal sheet by means of a trimming device as already described, said method comprising the steps of: - measuring a first vertical distance V1 between said first distance sensor 14 and said central circular surface 9 of said upper knife 8; - measuring a second vertical distance V2 between the second distance sensor 15 and the central circular surface 12 of the lower knife 11; -Overlap L MEASURED based on the first and second vertical distances, the upper knife diameter (D1) and the lower knife diameter (D2), and a position of the first distance sensor relative to a position of the second distance sensor; Equipped with.

[0031] Preferably, the present invention relates to a method for trimming a steel sheet.

[0032] Preferably, in the method, L MINIMUM From L MAXIMUM An overlap operating range is defined, the method comprising: -L MEASURED L MINIMUM and L MAXIMUM and comparing -L MEASURED L MINIMUM If it is smaller than MEASURED L MINIMUM vertically moving at least one of said movable shafts (10, 13) to set the distance at least equal to -L MEASURED L MAXIMUM If it is greater than MEASURED up to L MAXIMUM vertically moving at least one of said movable shafts (10, 13) to set Equipped with.

[0033] L MINIMUM and L MAXIMUM can be defined as a percentage of the thickness of the metal sheet being trimmed.

[0034] Preferably, the overlap operating range is 4-25% of the thickness of the metal sheet.

[0035] Preferably, the method comprises: - measuring a first horizontal distance H1 between said third distance sensor (17) and said upper knife (8); - measuring a second horizontal distance H2 between the fourth distance sensor (18) and the lower knife (11); -Gap distance G MEASURED based on the third and fourth distances, a thickness (T1) of the upper trimming knife and a thickness (T2) of the lower trimming knife, and a position of the third distance sensor relative to a position of the fourth distance sensor; It also has.

[0036] Preferably, in the above-described method, G MINIMUM From G MAXIMUM A gap operating range is defined up to, and the method comprises: -G MEASURED G MINIMUM and G MAXIMUM and comparing -G MEASURED G MINIMUM If it is smaller than G MEASURED G MINIMUM horizontally moving at least one of the movable shafts to set the at least equal -G MEASURED G MAXIMUM If it is greater than MEASURED up to G MAXIMUM horizontally moving at least one of the movable shafts to set Equipped with.

[0037] The invention also relates to a method for assessing the wear of a trimming device as previously described, said method comprising the steps of: - while the trimming knife is stationary, overlap L is removed in the manner already described. STILL and measuring - the overlap L between the two rotating trimming knives according to the method already described ROTATING and measuring - the two measured values ​​L STILL and L ROTATING and comparing -LSTILL and L ROTATING The difference between DANGER issuing an alert if the Equipped with.

[0038] The inventors have found that worn trimming devices tend to show "jumps" in overlap when the trimming device is moving or stationary, e.g., turned on or off. Displacements of 10 to 40 μm are noticeable. Apparently, these jumps are due to wear and mechanical clearances in the bearings that clamp the knives when the trimming device is turned on. As a result, the jumps cannot be assessed by either off-line measurements or by measurements of the position of the knives through the shaft.

Claims

1. A method for trimming a metal sheet by means of a trimming device (7) for metal sheets, said trimming device comprising: - an upper circular trimming knife (8) having a diameter D1 and a thickness T1, attached to an upper shaft (10); - a lower circular trimming knife (11) having a diameter D2 and a thickness T2, attached to a lower shaft (13); Equipped with - the upper knife and the lower knife overlap (D) to define a shear cut in the metal sheet ＯＶＥＲＬＡＰ ) and shifted vertically, - at least one of said upper shaft (10) or lower shaft (13) is vertically movable; And the trimming device (7) a first distance sensor (14) capable of measuring the vertical distance (V1) to the top edge of said upper knife; a second distance sensor (15) capable of measuring the vertical distance (V2) to the lower end of the lower knife; - calculation means (16) capable of calculating said overlap on the basis of said perpendicular distance (V1) and said perpendicular distance (V2); Equipped with The method comprises: - measuring a first vertical distance V1 between said first distance sensor (14) and said upper circular trimming knife (8); - measuring a second vertical distance V2 between said second distance sensor (15) and said lower circular trimming knife (11); - calculating an overlap L MEASURED based on the first and second perpendicular distances, the diameter of the upper circular trimming knife (D1) and the diameter of the lower circular trimming knife (D2), and the position of the first distance sensor relative to the position of the second distance sensor; A method for providing the above.

2. - the upper and lower circular trimming knives have a gap distance (D ＧＡＰ ), - at least one of said upper shaft (10) or lower shaft (13) is horizontally movable; The trimming device is a third distance sensor (17) capable of measuring a first horizontal distance (H1) to said upper knife; a fourth distance sensor (18) capable of measuring a second horizontal distance (H2) to said lower knife; Further comprising: - said calculation means are capable of calculating said gap distance based on said first horizontal distance (H1) and said second horizontal distance (H2); The method of claim 1.

3. The method of claim 1 or 2, wherein the first, second, third and fourth distance sensors are inductive sensors.

4. The method of any one of claims 1 to 3, wherein both the upper shaft and the lower shaft are vertically movable.

5. L ＭＩＮＩＭＵＭ From L ＭＡＸＩＭＵＭ and a method for determining an overlapping operating range up to -L ＭＥＡＳＵＲＥＤ L ＭＩＮＩＭＵＭ and L ＭＡＸＩＭＵＭ and comparing -L ＭＥＡＳＵＲＥＤ L ＭＩＮＩＭＵＭ If L is smaller than ＭＥＡＳＵＲＥＤ L ＭＩＮＩＭＵＭ vertically moving at least one of the movable shafts to set the distance at least equal to -L ＭＥＡＳＵＲＥＤ L ＭＡＸＩＭＵＭ If it is greater than ＭＥＡＳＵＲＥＤ Up to L ＭＡＸＩＭＵＭ vertically moving at least one of the movable shafts to set The method according to any one of claims 1 to 4, comprising:

6. - measuring a first horizontal distance H1 between said third distance sensor (17) and said upper knife (8); - measuring a second horizontal distance H2 between said fourth distance sensor (18) and said lower knife (11); -Gap distance G ＭＥＡＳＵＲＥＤ based on the first and second horizontal distances, a thickness (T1) of the upper and lower circular trimming knives (T2), and a position of the third distance sensor relative to a position of the fourth distance sensor; 10. The method of claim 2 or claim 5 which relies on claim 2, comprising:

7. G ＭＩＮＩＭＵＭ From G ＭＡＸＩＭＵＭ A gap operating range is defined up to, and the method comprises: -G ＭＥＡＳＵＲＥＤ G ＭＩＮＩＭＵＭ and G ＭＡＸＩＭＵＭ and comparing -G ＭＥＡＳＵＲＥＤ G ＭＩＮＩＭＵＭ If it is smaller than ＭＥＡＳＵＲＥＤ G ＭＩＮＩＭＵＭ horizontally moving at least one of the movable shafts to set the at least equal -G ＭＥＡＳＵＲＥＤ G ＭＡＸＩＭＵＭ If it is greater than ＭＥＡＳＵＲＥＤ Up to G ＭＡＸＩＭＵＭ horizontally moving at least one of the movable shafts to set The method of claim 6 comprising:

8. A method for assessing wear on the trimming device, comprising: - while the upper and lower circular trimming knives are stationary, overlap L is applied according to any one of claims 1 to 7 ＳＴＩＬＬ and measuring - according to any one of claims 1 to 7, the overlap L between the rotating upper and lower circular trimming knives ＲＯＴＡＴＩＮＧ and measuring - the two measured values ​​L ＳＴＩＬＬ and L ＲＯＴＡＴＩＮＧ and comparing -L ＳＴＩＬＬ and L ＲＯＴＡＴＩＮＧ The difference between ＤＡＮＧＥＲ issuing an alert if the A method for providing the above.

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