JPH0112629B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for preventing heavy polishing in steel strip polishing such as removing surface flaws from steel strips. Steel strips often have surface flaws due to causes during the steelmaking and hot rolling processes, and in order to commercialize steel strips, it is necessary to remove surface flaws, and a surface polisher is used as a device to remove surface flaws. used. In general, a surface polishing machine for steel strips passes a steel strip 1 fed from an uncoiler between breaker rolls 2 and 2' as shown in FIG.
2' is pushed up and guided by a billy roll 3 while being bent, and an endless abrasive belt 4 made of abrasive grains adhered to paper or cloth is pressed against the steel strip 1 by a contact roll 5. The polishing belt 4 is rotated to polish the steel strip 1 to remove surface flaws from the steel strip. In addition, in order to improve the grindability and life of the abrasive belt 4 and to absorb the generated heat, the abrasive belt 4 and the steel strip 1 are
Grinding oil 6 is sprayed by a spray nozzle device 7 onto the area in contact with the grinding oil 6. The surface flaws on the steel body 1 are flaws caused by bending of the edge of the plate during hot rolling, partial peeling of the surface due to non-metallic inclusions, and heave flaws caused by foreign matter entering during the hot rolling process. The flaw exists as an uneven portion 8, and the uneven portion 8 ranges from a size that is not easily noticeable to a size that is large enough to be easily monitored visually. Polishing is performed to eliminate surface flaws on the steel strip 1, but if the flaws have large irregularities 8, the amount of grinding by the abrasive belt 4 increases locally, and the amount of heat generated per unit time becomes too high. The drawback was that the oil could catch fire. Polishing of such large scratches is hereinafter referred to as heavy polishing. In order to eliminate the ignition of grinding oil during heavy grinding, it is desired to produce a grinding oil with a high flash point, but a grinding oil suitable for grindability and rust prevention for other machines has not yet been obtained. . Using grinding oil with a common flash point,
To prevent the above-mentioned ignition, it is necessary to avoid heavy abrasion. Table 1 shows examples of grinding oils commonly used for polishing steel strips.

[Table] In order to avoid heavy sanding, the unevenness of the steel strip surface due to surface flaws should be monitored by humans before sanding, and if there are flaws that are likely to cause heavy sanding, lower the billy roll 3 and remove the surface of the steel strip 1. There is a method of avoiding contact with the polishing belt 4 and leaving it unpolished. However, this method requires a supervisor at all times, resulting in poor work efficiency.Furthermore, the supervisor's ability to supervise varies, making it impossible to completely prevent heavy polishing. The object of the present invention is to eliminate the above-mentioned drawbacks, and to provide a method that has good workability and completely prevents heavy polishing even when using a grinding oil with an ordinary flash point. The details of the present invention will be explained with reference to embodiments shown in the figures. In FIG. 2, the steel strip 1 sent out from the uncoiler 9 is bent by breaker rolls 2, 2' and the billy roll 3, and the abrasive belt 4 is pressed against the steel strip 1 by the contact roll 5 disposed opposite to the billy roll 3. It will be done. The steel strip 1 that has been polished is transferred to a deflector roll 10
The direction is changed by the recoiler 11. In the case of a continuous surface polishing machine in which the line flow is unidirectional, a welding machine 12 is provided to connect two continuously fed steel strips, and the welding machine 12 is provided to connect the trailing end of the preceding steel strip and the leading end of the following steel strip. is welded, and before being wound up by the recoiler 11, it is divided again by the shear 13. Before being bent by the breaker roll 2 for polishing, the steel strip 1 is bent into a serpentine shape as shown in FIG. One or more touch rolls 16 are arranged facing the push-up roll 15 so as to be in contact with the bent steel strip, and the touch rolls 16 are formed to be able to move up and down. When the steel strip is passed between the push-up rolls 15 and the tatsuchi rolls 16, it is bent by the push-up rolls 15 and the press rolls 14, and in the case of scratches, inclusions and foreign objects are peeled off. Even if the surface has already peeled off before polishing, or if the surface flaw is difficult to see with the naked eye, the concave surface flaws will become clearly visible and expanded due to bending.
In addition, convex scratches stand out. Therefore, the local unevenness due to surface flaws is magnified. The partial irregularities caused by the surface flaws are detected by a surface flaw detection means, for example, the Tatsuchi Roll 16. The tatsuchi roll 16 uses one or more rolls with a width selected in advance according to the size of the flaw to be detected, and is placed at a position corresponding to a part where flaws are likely to occur, such as near both side edges of the steel plate, for example. . When the Tatsuchi Roll 16 is located in the flaw, it will rise in the case of a convex flaw, and will fall in the case of a concave flaw, or if a part of the Tatsuchi Roll 16 is located in the flaw part, one end of the Tatsuchi Roll will rise or fall. This Tatsuchi Roll 1
6, the location of the surface flaw and the size of the unevenness are detected. When the size of the unevenness is large enough to require heavy polishing, when the detection signal indicates that the flaw comes into contact with the polishing belt 4, the billy roll 3 is lowered to leave the corresponding uneven portion unpolished. Here, the push-up roll 15, presser roll 14, 1
It is best to make the positional relationship of 4' the same as the positional relationship of the sanding machine's billy roll 3 and breaker rolls 2 and 2', but if space is limited, the diameter of the push-up roll should be set equal to or smaller than the billy roll diameter. If the distance is maintained, there is no problem even if the distance between the presser rolls 14 and 14' is shortened. The billy roll 3 is connected to an elevating cylinder 17, and the billy roll 3 is moved by operating the elevating cylinder 17 in response to a signal obtained by processing a signal for detecting the movement of the touch roll 16 by a calculation unit 18.
is lowered. As a means for detecting surface flaws, a distance meter using ultrasonic waves or eddy currents may be used instead of the Tatsuchi Roll 16.

[Brief explanation of drawings]

Figure 1 is an explanatory perspective view of a conventional steel strip surface polisher.
FIG. 2 is a schematic diagram of a continuous surface sander according to the present invention. 1... Steel strip, 2, 2'... Breaker roll, 3... Billy roll, 4... Abrasive belt, 5... Contact roll, 14, 14'... Presser roll, 15... Push-up roll, 16... Tatsuchi roll, 17... Cylinder.

Claims (1)

[Scope of Claims] 1 In steel strip polishing in which the surface of the steel strip is polished by pressing an abrasive belt, the steel strip is bent by rolls within the line before polishing, and surface flaws on the surface of the bent steel strip are removed. The position and depth of the unevenness are detected by a surface flaw detection means, and when the unevenness detected by the unevenness detection signal from the surface flaw detection means reaches the polishing position, the abrasive belt and the steel strip are removed. A method for preventing heavy abrasion in steel strip polishing, characterized by moving at least one of the rollers that press against the abrasive belt to avoid contact between the steel strip and the abrasive belt. 2. As a surface flaw detection means, one or more tatsuchi rolls with a desired width are arranged in the width direction of the steel strip and touched to the steel plate, and the unevenness of surface flaws on the steel strip is detected by measuring the vertical movement of the tatsuchi rolls. A method for preventing heavy polishing in steel strip polishing according to claim 1. 3. Steel strip polishing according to claim 1, characterized in that the unevenness of surface flaws on the steel strip is detected using a distance meter that applies either ultrasonic waves or eddy currents as surface flaw detection means. How to prevent heavy abrasion in 4. The steel strip according to claim 1, characterized in that in order to avoid contact between the steel strip and the abrasive belt, a cylinder lowers a billy roll that pushes up the steel strip toward the abrasive belt and bends the steel strip. How to prevent heavy abrasion during polishing.