JPS5953352B2 - Descaling method for steel strips - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for descaling steel strips.

In order to remove the oxide scale layer that occurs on the surface of hot-rolled steel strips, methods are used to immerse the steel strip in an acid solution or spray the scale surface with an acid solution to dissolve and remove the scale through a chemical reaction. However, in order to increase production efficiency, the dissolution reaction must be carried out in a short time. The present invention provides a grinding plate that applies strong pressure to the surface of the steel strip, and slides the grinding plate against the steel surface to mechanically peel off the oxide scale layer and activate the oxidation boundary film, thereby causing a dissolution reaction. The aim is to shorten descaling time by accelerating descaling.

Conventional surface grinding of steel strips using an acid solution involves applying strong pressure to a flat grinding plate from both sides of the steel strip, keeping the grinding plates stationary, and increasing the relative speed due to the movement of the steel strip. A given method is being used.

However, it is known that the effect of promoting oxidation reaction is significantly reduced when the steel strip passes through the steel strip at a slow speed. This is because 1) the peeling effect is reduced, and 2) an oxidation reaction boundary layer is formed at the contact area between the acid solution and the scale, which slows down the reaction. In other words, as the steel strip 2 passes through the plate, the acid solution that contacts the plate surface forms a layer and moves together with the plate, so the speed of the acid liquid that contacts the plate surface becomes the same as the plate speed, and the relative speed of the two increases. This is because it becomes close to 0. In order to eliminate this phenomenon, the boundary layer may be destroyed by stirring the acid solution, and the new acid solution may be constantly brought into contact with the plate surface. The present invention was invented based on the above-mentioned principle, and will be described below with reference to embodiments.

In FIGS. 1 and 2, 1 is a tank made of corrosion-resistant material. A steel strip 2 runs vertically from the bottom of the tank 1, and is descaled while passing through the tank 1.

Reference numeral 3 designates an upper roll that supports the steel strip, 4 a support bearing for the roll 3, and 5 a grinding plate support frame that supports the grinding plate 12 made of a nylon brush or the like.

Another grinding plate 14 facing the grinding plate 12 is a steel strip 2.
The grinding plate 14 is supported by a grinding plate support frame 13. Reference numeral 6 denotes an eccentric shaft, and pins 6a and 6b are fixed to its front and rear surfaces at positions exactly 1800 degrees out of phase.

The eccentric shaft 6 is rotated at a constant speed by a worm 11 in the direction of arrow a. The worm 11 is driven by an electric motor 10. 7 is a continuous rod attached between the pin 5a of the grinding plate support frame 13 and the pin 6a fixed to the eccentric shaft, and 8 is also attached between the pin 6b of the eccentric shaft and the pin 5a of the support frame 5. It is a connecting rod.

Reference numeral 9 denotes a guide for the grinding plate support frames 5 and 13, which guides the vertical movement of the support frames.

That is, when the eccentric shaft 6 rotates in the direction a, the connecting rods 7,
The support frames 5 and 13 alternately move up and down via the
(When the support frame 5 faces in the Y direction, the support frame 1
3 in the Y'' direction, and when the support frame 5 is in the x direction, the support frame 13 is in the x'' direction). The grinding plates 12 and 14 are densely planted with a fibrous material (for example, nylon containing grinding abrasive grains or polypropylene fiber, etc.) having elasticity suitable for rubbing the surface of the steel strip so as not to impede the flow of the acid solution. This is what I did.

Note that the support frames 5 and 13 are fitted into the support frames 5 and 13 to facilitate replacement. 15 is an acid liquid nozzle, and the steel strip material 2
An acid solution flows down from both sides to dissolve oxidized scale.

16 is also an acid liquid spray nozzle, which is provided to forcibly feed the acid liquid to the center of the grinding plates 12 and 14 to further enhance the descaling effect.

The acid liquid spray nozzles 15 and 16 are connected to a return pipe 18 for the acid collected at the bottom of the tank 1 → acid storage tank 19 → pressure pump 20
→ Heat exchanger 21 → Supply via supply pipe 22 or flexible tube 17. The circulating acid solution is heated in the heat exchanger 21 and supplied to the spray nozzle. Reference numeral 24 denotes a lower roll supported by a bearing 25, and the strip sea bream 2 is supported by the roll 5 roll 24 and the lower roll 2 and runs vertically upward.

Although not shown, the rolling force of the support frames 5 and 13 on the steel strip 2 is as follows:; Even in the case of a horizontal type in which the steel strip material is immersed, the same descaling effect can be achieved if the swinging mechanism is installed outside the acidic atmosphere. With the above configuration, when the eccentric shaft 6 is rotated in the direction a by the electric motor 10, the connecting rod 8 causes the support frame 5 to swing up and down, and the connecting rod 7 causes the support frame 13 to swing up and down.

Then, the grinding plates 12 and 14 also move up and down to grind the surface of the steel strip. In this case, since the moving directions of the grinding plates 12 and 14 are opposite, their frictional forces cancel each other out, and no additional tension is applied to the steel strip 2. When the acid solution chemically reacts with the steel strip scale layer, even if the reaction rate slows down due to passivation in the oxidation reaction boundary layer, it is forcibly stirred by the grinding plate and the flow from the nozzles 15 and 16 is reduced. The acid solution reacts efficiently with scale.

In addition to descaling through a chemical reaction, the abrasive grains contained in the grinding plate also add mechanical peeling action, making extremely efficient descaling possible and significantly reducing the time required for descaling.

[Brief explanation of the drawing]

FIG. 1 shows an example of an apparatus for carrying out the present invention. FIG. 2 shows a sectional view taken along the line 11-11 in FIG.

Claims (1)

[Claims] 1. A pair of grinding plates is provided that presses both the front and back sides of the steel strip, and the pair of grinding plates are alternately slid in opposite directions at a speed equal to or higher than the threading speed of the steel strip. Features: Descaling method using acid solution for steel strip material.