JPH09155435A - Method and equipment for descaling steel by shot blasting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the mechanical and automatic descaling by adjusting the number of revolution of a steel shot means according to the traveling speed of a steel. SOLUTION: A speed sensor 7 to detect the traveling speed is fitted to a carriage roll 2 of a steel strip 1, and the detected value is inputted to a computing element 8 as the steel strip speed detection signal 9. In the computing element 8, the operation is achieved so that the relationship to make the kinetic energy of the shot particles constant is satisfied, and the operated value is outputted to a control power source 6 of a driving motor 5 as the command 10 on the number of revolution of the driving motor 5 of rotary blades 4. The number of revolution of the rotary blades 4 is measured by a number of revolution sensor 17 attached to the driving motor 5, and transmitted to the control power source 6 of the driving motor 5 as the number of revolution detected signal 11. The number of revolution detected signal 11 is compared with the number of revolution command 10 by the power source 6, and the rotary blades 4 are operated by the constantly new number of revolution command 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for descaling a steel material by shot blasting, and more particularly to a technique effective for descaling stainless steel.

[0002]

2. Description of the Related Art In general, continuous annealing and pickling (usually in equipment called a so-called AP line) is generally carried out for mass production of cold-rolled stainless steel sheet. This is because when cold rolling a hot rolled coil of SUS304, which is a typical austenite type, has a large work hardening, it is possible to perform austenite annealing and pickling in advance to facilitate subsequent cold rolling. is there. In addition, ferrite type SUS43
In No. 0, only pickling is performed on the AP line, and another batch furnace is used for annealing.

By the way, in the pickling of steel materials, in order to facilitate the pickling, it is general to remove the scale generated by the heat treatment in advance. However, in the case of stainless steel, it is extremely difficult to perform descaling by water injection performed on general steel, so it is necessary to employ more severe mechanical means. Therefore, a shot blasting method in which a steel ball having a grain size of 0.3 to 0.5 mm (also referred to as a steel shot, hereinafter, simply shot) is collided with the steel sheet surface at high speed to destroy and remove the scale is adopted.

This shot blasting device is generally shown in FIG.
The system shown in is used. That is, a rotating impeller is used as a projector, and the shot is circulated and supplied to the projector by a bucket elevator, and is shot on the upper and lower surfaces of a traveling steel strip. And
This slamming is based on the rough idea that descaling is currently required to be above a certain level,
The rotation speed of the projector (actually, the rotation speed of the electric motor used) is adjusted by the operator's visual judgment.

[0005]

However, in the projection method based on the human visual judgment that the above-mentioned descaling should be ensured at a certain level or more, an excessive or excessive shot impact may occur and The quality of the surface is deteriorated and the shot grains are rapidly deteriorated, and there are problems in terms of quality and economy.

In view of the above circumstances, the present invention provides a method and apparatus for descaling a steel material by shot blasting, which allows a shot to be hit on the surface of a steel material with technically appropriate judgment and without human intervention. Has an aim.

[0007]

In order to achieve the above-mentioned object, the inventor has focused on the relationship between the traveling speed of a steel material to be treated and the kinetic energy of shot grains, and finds out the scale amount of the treated material. The present invention has been completed as a method to be applied when is constantly constant. That is, in the present invention, a steel shot is struck by a projecting means rotating at high speed on the surface of a running steel material, and in removing the scale adhering to the surface, the rotation speed of the projecting means is adjusted according to the traveling speed of the steel material. Is a descaling method for steel products by shot blasting. In addition, the present invention, the above adjustment,
It is also a method for descaling a steel material by shot blasting, which is characterized in that it is performed based on the following formula.

V = k√S where v: shot speed of shot grains (m / sec) S: traveling speed of steel strip (m / sec) k: constant Furthermore, the present invention is a traveling means for steel material, Descaling of steel material by shot blasting, which comprises a plurality of blades for holding a steel shot, and a rotary blade for projecting the steel shot onto the surface of the running steel material, and a shot supply means for mounting the steel shot on the rotary blade. In the device, a speed sensor that detects the traveling speed of the steel material, and the detection value is received, and the rotational speed of the rotor blade that satisfies the relational expression between the kinetic energy of shot grains and the traveling speed of the steel material that is stored in advance is calculated. And a rotation speed command from the calculator,
A descaling apparatus for steel products by shot blasting, comprising: a power source for controlling the number of rotations of the rotary blade driving electric motor.

According to the present invention, the traveling speed of the steel material is detected, processed by the arithmetic unit, and then output as the rotation speed command of the electric motor for driving the rotor for shot projection. The rotation speed of the blades becomes proportional to the traveling speed of the steel material, the kinetic energy of the shot is maintained constant even if the traveling speed of the steel material changes, and stable descaling can always be performed automatically without human intervention. become.

In order to achieve the object of the present invention, the relationship between the kinetic energy of the shot grains and the traveling speed of the steel material is that the shot grain always strikes the steel surface with a constant kinetic energy even if the traveling speed of the steel strip changes. As shown in the following equations (1) to (3). Therefore, the present invention is to project the shot onto the steel surface so as to always satisfy the following expression (3).

If the traveling speed of the steel material is S (m / sec) and the kinetic energy of the shot grains is E (J), then E ÷ S = K (1) where K = const The kinetic energy E (J) possessed is the mass M (kg) of the shot grain, and the projection velocity of the shot grain is v
Assuming that (m / sec), E = 1 / 2Mv ² (2) Substituting equation (2) into equation (1) and rearranging, (1 / 2Mv ² ) ÷ S = K v ² = 2SK / M Here, if k = √2K / M is set, v = k√S ... (3) is finally obtained.

Therefore, if the shot speed v of the shot particles, that is, the rotational speed of the shot projection rotor is controlled so as to be proportional to the square root of the traveling speed S of the steel product based on the equation (3), the desorption from the steel product is performed. The scale is always performed with the same kinetic energy and is almost constant.

[0013]

1 is a schematic diagram showing the overall configuration of a descaling apparatus according to the present invention. Steel strip to be processed 1
Are traveling on the line by the transport rolls 2 as traveling means. The rotary wing 4, which is a shot projection means,
It is arranged between the transport rolls and is rotated by the driving electric motor 5. The shot grains 12 are supplied to the rotary blades 4 through a hopper 3 of a supply means, and by the rotation thereof, they are projected on the running steel strip 1 and descaling is performed. Conventionally, in the apparatus having such a configuration, the operator visually observes the degree of descaling of the steel strip 1 and appropriately adjusts the rotation speed of the rotary blade 4.

The present invention adds the following elements to the above device,
It is deployed so that it can be automatically driven mechanically. First, a speed sensor (specifically, a pulse generator) 7 for detecting the traveling speed is attached to the transport roll 2 of the steel strip 1, and the detected value is input to a calculator 8 as a steel strip speed detection signal 9. . Then, the signal 9 is calculated in the calculator 8 so as to satisfy the relationship shown in FIG. 2, that is, the relationship for keeping the kinetic energy of the shot grains 12 constant, and the electric motor for driving the rotor 4 is driven. 5 as a rotation speed command 10 for the driving electric motor 5
Is output to

On the other hand, the rotation speed of the rotary blade 4 is measured by a rotation speed sensor (specifically, a pulse generator) 17 attached to the driving motor 5 for driving the rotary blade 4, and the rotation speed of the driving motor 5 is measured. It is sent to the control power supply device 6 as a rotation speed detection signal 11. Then, the rotation speed detection signal 11 and the rotation speed command 10 are compared by the power supply device 6, and the rotary blade 4 is always driven by the new rotation speed command 10.

FIG. 3 is an example of the performance results of the steel material descaling device according to the present invention, and shows the relationship between the rotational speed of the driving motor 5 for the rotor blade 4 and the traveling speed of the steel material. FIG.
According to the above, when the traveling speed of the steel material (stainless steel plate, SUS304) is 25 (m / min) or less, the descaling property deteriorates. Therefore, the rotation speed of the electric motor 5 at that point is 750 rp.
We decided to set m as the lower limit.

In the above embodiment, the case of the square root function of the equation (3) has been described, but the present invention is not limited to this, and a simple proportional relation, for example, v = bS + c,
The effect of descaling was slightly reduced, but it was effective.

[0018]

As described above, according to the present invention, constant descaling can be performed mechanically and automatically regardless of the traveling speed of the steel material. As a result, there was a secondary effect of extending the life of shot grains and improving the power consumption rate.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a descaling device according to the present invention.

FIG. 2 is a diagram showing a processing function of an arithmetic unit used in the present invention.

FIG. 3 is a diagram showing a relationship between a traveling speed of a steel material and a rotation speed of a rotary blade driving electric motor when the present invention is applied.

FIG. 4 is a vertical cross-sectional view of a conventional steel material descaling device by shot blasting.

[Explanation of symbols]

 1 Steel Material (Steel Strip) 2 Conveyor Roll 3 Hopper 4 Rotor Blade 5 5 Drive Motor 6 5 Power Supply Device 7 Speed Sensor (Pulse Generator) 8 Calculator 9 Running Speed Detection Signal 10 5 Rotation Speed Command 11 5 Rotation speed detection signal 12 Shot (grain) 13 Screw conveyor 14 Bucket elevator 15 Exhaust port 16 Rotary separator 17 Rotation speed sensor

Claims (3)

[Claims] 1. When a steel shot is struck by a projecting means rotating at high speed on the surface of a running steel material to remove scale adhering to the surface, the number of revolutions of the projecting means is adjusted according to the running speed of the steel material. A characteristic method for descaling steel by shot blasting. 2. The method for descaling a steel material by shot blasting according to claim 1, wherein the adjustment is performed based on the following formula. v = k√S Here, v: shot particle projection speed (m / sec) S: traveling speed of steel strip (m / sec) k: constant 3. A steel material running means, a rotary blade for holding a steel shot by a plurality of blades, and projecting the steel shot onto the surface of the running steel material, and a shot supply means for mounting the steel shot on the rotary blade. In a descaling device for steel materials by shot blasting equipped with, a speed sensor for detecting the traveling speed of the steel material, and a relational expression between the kinetic energy of the shot and the traveling speed of the steel material, which is stored in advance, in response to the detected value. Shot blasting, comprising: a computing unit that computes the rotational speed of the rotor blade that satisfies the above condition; and a power supply that receives a rotational speed command from the computing unit and that controls the rotational speed of the rotor blade driving electric motor. Descaling equipment for steel products.