JP2003175449A - Grinding machine for steel strip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding machine for steel strip capable of reducing an edge drop of steel strip occurring during grinding, eliminating indentation defect, and preventing poor shapes and winding failure during cold rolling. <P>SOLUTION: This grinding machine for steel strip comprises a grinder 2 structured by arranging a contact roll 5 and an idler roll 6 in parallel and endlessly winding a grinding belt 4 around the two rolls and a belly roll device 3 where a belly roll 8 is liftably supported by a supporting member 10 having a lifting means 9. The surface of the belly roll 8 is a rubber lining 8-1 of 85 to 95 Hs in hardness and the surface of the facing contact roll 5 is a rubber lining 5-1 of 60 to 75 Hs in hardness. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding device for grinding a surface of a steel strip. [0002] A steel strip such as stainless steel is finished by hot rolling, annealing, pickling and cold rolling. Generally, the surface of the steel strip after pickling has many flaws, and after the flaws are removed by a grinding device, cold rolling is performed. The grinding device will be described with reference to FIG. [0003] The grinding device is located between a steel strip pay-off reel (not shown) and a take-up reel (not shown).
It comprises a grinding machine 2 for grinding the surface of the steel strip 1 and a billy roll device 3 for supporting the steel strip. In the grinding machine 2, a grinding belt 4 is endlessly wound between a contact roll 5 and an idler roll 6,
It is configured such that the contact roll 5 can be rotated by the driving device 7. The billy roll device 3 is configured such that a billy roll 8 is supported by a support member 10 having a lifting / lowering means 9 such as a hydraulic cylinder so as to be able to move up and down. Billy roll
8 applies a grinding pressure to the steel strip 1 by elevating the elevating means 9. The grinding pressure is determined by the amount of elevation of the elevation means. [0006] The steel strip 1 is passed between the billy roll 8 and the grinding belt 4, and the flaws on its surface are ground and removed. Conventionally, in order to increase the grinding efficiency, a nip width is secured by lining rubber 5-1 on the surface of the contact roll 5, and a metal roll is used for the opposing billy roll 8. When a steel strip is ground by a grinding device combining a rubber-lined contact roll and a metal billy roll, the following phenomenon may occur in the steel strip. (1) Edge drop occurs and causes cracks and breaks during cold rolling, resulting in deterioration of quality and productivity. (2) Indentation flaw of powder is generated on the surface and quality is reduced. (3) Width A thickness gradient occurs in the direction, resulting in poor shape and poor winding. There are several proposals as a method of preventing such a grinding failure of a steel strip. A continuous grinding line equipped with a tensioning device that combines a feed leveler and bridle rolls in front of the grinding device. As a billy roll of the grinding line, a crown formed roll or a crown billy roll in which the surface layer portion of the roll is made of an elastic material such as rubber, or a roll body is made of a hollow elastic material such as rubber, and the hollow portion is formed of air or the like. A roll that forms a crown by injecting gas is used (see Japanese Patent Application Laid-Open No. 8-25202). An ester urethane resin is used as the lining resin of the contact roll, and the rubber hardness is Hs80-90.
By using a contact roll with a serration angle of more than 55 ° and 70 ° or less, the grinding efficiency is high, the continuity is high, and the grinding of the metal band that allows normal grinding of the surface of the workpiece after grinding is performed. Apparatus (see JP-A-2-109675). An apparatus for grinding a metal strip wherein the rubber hardness at both ends of the contact roll is lower than the rubber hardness at the center (see Japanese Patent Application Laid-Open No. 6-155274). In the above-mentioned method of using a crown roll for a billy roll, the crown (cross-sectional shape in the width direction) of the steel strip differs for each steel strip. It is extremely difficult to change the crown of the steel strip, and even if the crown is variable like a hollow rubber roll, it is necessary to constantly monitor the grinding state in the width direction of the steel strip as in the conventional case. In addition, the structure of the billy roll becomes complicated, and the equipment becomes very expensive. In the method using an ester-based urethane resin for the contact roll, edge drops and indentation flaws may occur on the steel strip since the opposing billy roll is a metal roll. An object of the present invention is to provide a steel strip grinding apparatus which reduces edge drop of a steel strip generated during grinding, eliminates indentation flaws, and does not cause defective shape and poor winding in cold rolling. It is in. The inventor of the present invention has investigated the deformation state of the contact roll and billy roll during the grinding of the steel strip, reduced the edge drop generated during the grinding of the steel strip, and reduced the indentation flaw. It was confirmed that it is effective to apply a rubber lining to the billy roll and the contact roll and adjust the hardness thereof in order to eliminate the occurrence of the shape defect and the winding defect in the cold rolling. Was completed. The gist of the present invention resides in the following steel strip grinding apparatus shown in FIG. FIGS. 1A and 1B are conceptual views showing a steel strip grinding apparatus according to the present invention. FIG. 1A is a front view as viewed from the front in the direction in which the steel strip passes, and FIG. It is AA sectional drawing. A contact roll 5 and an idler roll 6 are provided in parallel, a grinding machine 2 constituted by a grinding belt 4 wound endlessly around the two rolls, and a billy roll 8 having a lifting means 9 A steel strip grinding device comprising a billy roll device 3 supported up and down by a support member 10, wherein the surface of the billy roll 8 has a hardness of Hs85 to Hs9.
5. A grinding device for a steel strip in which the rubber lining 8-1 is 5 and the surface of the opposing contact roll 5 is a rubber lining 5-1 having hardness Hs60 to Hs75. The hardness Hs of the rubber is a value measured in a lined state using an A-type and a D-type hardness meter manufactured by Kobunshi Keiki Co., Ltd. BEST MODE FOR CARRYING OUT THE INVENTION In order to investigate the cause of grinding failure of a steel strip, the deformation state of a contact roll and a billy roll during grinding was investigated. 1. When grinding by combining a rubber-lined contact roll and a metal billy roll without lining: A contact roll with a 17.5 mm Hs60 neoprene (rubber) lined on the surface of a steel sleeve with an outer diameter of 195 mm and an inner diameter of 136 mm Using a grinding device that combines a steel roll with a billy roll (diameter 240 mm), a stainless steel strip (SUS 304, thickness 4.5 mm, width 1035 mm) was subjected to a grinding pressure of 98 kN (10 tons) and statically observed. . Note that a belt containing alumina abrasive grains (# 60) was used as the grinding belt. FIG. 2 is a schematic diagram showing the deformation of the contact roll when a rubber-lined contact roll and a metal billy roll are pressed. FIG. 1 (a)
FIG. The contact roll 5 includes a rubber lining 5
Since −1 is applied, bending deformation occurs at the end of the steel strip 1 due to the grinding pressure, as shown in FIG. This bending deformation increases in the vicinity of the edge of the steel strip, and the plate thickness in the vicinity decreases, that is, so-called edge drop easily occurs.
This phenomenon appears remarkably when severe surface flaws (deep flaws) are removed, the grinding pressure at the end of the steel strip 1 increases, and the ductility decreases due to grinding burn. Generate. For this reason, the steel strip has ear cracks, which impairs the product quality. In addition, when the strip is severe, the steel strip may be broken, leading to a significant decrease in productivity. Since the billy roll 8 is a metal roll, grinding powder (abrasive grains and chips removed from the grinding belt, hereinafter referred to as "grinding powder") is placed between the steel strip 1 and the billy roll 8. They may be caught in and cause indentation flaws. When the rolling reduction at the time of cold rolling is small, the indentation flaws remain after rolling to impair product quality and reduce the yield. Further, since the cross-sectional profile in the width direction of the steel strip 1 before grinding differs depending on the steel strip, the operator visually observes the degree of grinding in the width direction of the steel strip 1 on the exit side of the grinding device, and The pressure (or reduction amount) of the right and left lifting means 9
Need to adjust. If the left and right pressure adjustments of the billy roll 8 are different, the left and right plate thicknesses of the steel strip 1 after grinding are different, and a gradient is formed in the plate width direction. This may cause defects such as defective shape and poor winding at the time of cold rolling in the next step. From these experiments, it was possible to elucidate the cause of the edge drop, the cause of the indentation flaw, and the cause of the thickness gradient in the width direction. Then, the case where rubber lining was applied to both the contact roll and the billy roll was examined. 2. When rubber lining is applied to both the contact roll and the billy roll: Except that the surface of the billy roll is lined with urethane (rubber) of hardness Hs95 by 15 mm,
The above 1. The test was performed under the same conditions as those shown in (1) and the deformation state of the roll was investigated. FIG. 3 is a schematic diagram showing the deformation of the rubber-lined contact roll and the rubber-lined billy roll when both rolls are pressed. This figure is an enlarged view of a portion B in FIG. If neoprene (rubber) 5-1 having a hardness of Hs60 is lined on the surface of the contact roll 5 and urethane (rubber) 8-1 having a hardness of Hs95 is lined on the surface of the billy roll 8, FIG. As shown, contact roll 5 and steel strip 1
2, the deformation of the contact portion is smaller than in the case of FIG. 2, the contact area is reduced, and the edge drop is reduced. The grinding powder caught on the contact surface between the steel strip and the billy roll at the time of grinding is pushed into the rubber lining of the billy roll, so that the occurrence of a pressing flaw in the steel strip can be prevented. Even when a difference occurs between the left and right reduction amounts of the billy roll, the difference can be reduced by the rubber lining, and problems such as a shape defect and a winding defect during cold rolling can be prevented. it can. EXAMPLE A grinding experiment was performed on a stainless steel strip (JIS SUS 304) using a grinding apparatus as shown in FIG. (Example 1) Stainless steel strip (JIS SUS 30
4, the plate thickness is 4.5 mm and the plate width is 1035 mm) using a roll having the specifications shown in Table 1 and a grinding machine having a grinding belt of # 60 alumina abrasive grains. The pressing force of the billy roll is 98 kN (10 tons). A grinding experiment was performed. [Table 1] The thickness of the steel strip before and after grinding was measured with a micrometer from the end face to 100 mm from the center in the width direction, and the results are shown in FIGS. 4 and 5. FIG. 4 is a diagram showing the thickness distribution when a metal billy roll is used. FIG. 5 is a diagram showing the thickness distribution when a billy roll lined with urethane rubber is used. From FIGS. 4 and 5, the difference in sheet thickness (edge drop amount) between the position of 25 mm and the position of 10 mm from the end surface of the steel strip end before and after grinding was compared. In the case of a metal billy roll, as shown in FIG. 4, the edge drop amount before grinding was 21 μm (4147 μm).
m-4126μm), edge drop after grinding is 38μm
(4126 μm-4088 μm), which is about 1.8 times larger after grinding. On the other hand, in the case of a billy roll lined with urethane rubber, as shown in FIG. 5, the edge drop amount before grinding is 21 μm (4140 μm-4119 μm),
The edge drop after grinding is 25μm (4128μm-4103μ
m), which is 1.2 times after grinding. That is,
It can be seen that when a billy roll lined with urethane rubber was used, the change in the amount of edge drop due to grinding was small. When the rubber-lined billy roll of the present invention is used, the change of the crown before and after the grinding is smaller than that of the metal billy roll. This is because the rubber lining improves the contact state with the steel strip. (Example 2) Stainless steel strip (JIS SUS 30
(4, plate thickness: 3.0mm, plate width: 1032mm) using the same grinding device as in Example 1 and equalizing the left and right reduction amounts of the billy roll and the work side (W / S) reduction amount on the drive side. A grinding experiment was carried out when opening 1 mm compared to the reduction of (D / S). The thickness before and after the grinding was measured, and the difference in the thickness after the grinding between the case where the right and left reduction amounts were equal and the case where the reduction amount was different was obtained. [Table 2] FIG. 6 is a diagram showing the change in the sheet thickness direction in the sheet width direction when the left and right reduction amounts of the billy roll are equal and different. This figure is a diagram comparing the difference in plate thickness after grinding in Table 2 between the case of using a metal billy roll and the case of using a billy roll lined with urethane rubber. As can be seen from FIG. 6, all of them tend to rise to the right, but the thickness in the width direction is larger when the rubber-lined billy roll is used than when the metal billy roll is used. The fluctuation of the difference is small. This is considered to be because the rubber lining can absorb the deviation of the reduction amount. (Example 3) The hardness of the rubber lining of the contact roll and the billy roll was variously changed as shown in Table 3, and the same as in Example 1 using a SUS 304 steel strip having a thickness of 3.0 mm and a width of 1035 mm. Was subjected to a grinding test. [Table 3] As evaluations, the presence or absence of grinding flaws on the billy roll by the grinding belt, the edge drop ratio of the steel strip (the ratio of the thickness difference between the 10 mm position and the 25 mm position from the end of the plate before and after the grinding), and the grinding dust to the steel strip The presence or absence of indentation flaws was investigated. Table 3 shows the results. As apparent from Table 3, the number 1 of the invention example
In the tests of ~ 4, the rubber hardness of the contact roll was 60
Since the hardness of the rubber of the billy roll was 85 to 95 in Hs, no grinding flaw of the billy roll by the grinding belt and a flaw of pushing into the steel strip were detected. The edge drop ratio of the steel strip was 1.24 or less, which was good. On the other hand, in the tests of Comparative Examples Nos. 5 to 8, the rubber hardness of the billy roll was as low as 60 to 70 in Hs.
Billy roll grinding flaws by the grinding belt were observed.
In the tests of Nos. 9 and 10, the rubber hardness of the contact roll was as high as 80 and 90 in Hs, so that the edge drop ratio of the steel strip was as large as 1.90 and 1.91. In the test of No. 11, since the steel billy roll was used, the edge drop ratio of the steel strip was as large as 1.80, and the indentation flaw in the steel strip was detected. According to the steel strip grinding apparatus of the present invention, the surface of the billy roll is lined with rubber having a hardness of Hs85 to Hs95,
Since the opposed contact rolls are lined with rubber having a hardness of Hs60 to Hs75, the edge drop of the steel strip is small, and no indentation flaw due to grinding powder is generated. Also, even if the rolling amount of the billy roll becomes uneven on the left and right, the rubber lining of the two rolls absorbs it, so the grinding amount is also uniform, and the poor shape and poor winding in cold rolling are reduced. Does not occur.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual diagram showing a steel strip grinding apparatus of the present invention;
(a) is a front view as viewed from the front in a direction in which the steel strip passes, and (b) is a cross-sectional view taken along the line AA in (a). FIG. 2 is a schematic diagram showing deformation of a contact roll when a rubber-lined contact roll and a metal billy roll are combined and pressed. FIG. 3 is a schematic diagram showing deformation of rubber-lined contact rolls and rubber-lined billy rolls when both rolls are pressed. FIG. 4 is a diagram showing a thickness distribution when a metal billy roll is used. FIG. 5 is a diagram showing a thickness distribution when a billy roll lined with urethane rubber is used. FIG. 6 is a diagram illustrating a change in a sheet thickness difference in a sheet width direction between when a right and left reduction amount of a billy roll is equal and different. [Explanation of reference numerals] Steel strip 2. Grinding machine 3. Billy roll device4. Grinding belt 5. Contact roll6. Idler roll 7. Drive device8. Billy roll 9. Elevating means 10. Support member

Claims (1)

Claims: 1. A grinding machine in which a contact roll and an idler roll are provided in parallel, a grinding belt is wound endlessly around the two rolls, and a support member in which a billy roll has elevating means. A grinding device for a steel strip comprising a billet roll device supported so as to be able to move up and down, wherein the surface of the billy roll is made of rubber lining having a hardness of Hs85 to Hs95, and the surface of the contact roll facing the hardness is Hs60
A steel strip grinding apparatus comprising a rubber lining of Hs75.