JPH05112833A - Treatment of surface layer on trimmed waste of surface treated steel sheet - Google Patents

Abstract

PURPOSE:To remove a surface layer containing a plating layer a trimmed waste in high efficiency by projecting grinding grains to the trimmed waste continuously cut from a surface treaded steel sheet. CONSTITUTION:In a surface treating manufacturing equipment line for galvanizing, etc., before the traveled surface treated sheet 1 is coiled in a coiling machine 2, the edge parts in sheet width direction are trimmed by a trimmer 3. The cutoff trimmed waste 4 comes into a chamber 5. Grit is injected toward the surface of the traveled trimmed waste 4 in the chamber 5 from blast nozzles 6. The trimmed waste 4 is ground to remote the surface layer of the plating waste, etc. The injected grit is carried to a grit recovering vessel 8 and separated into the grit as possible to reuse and the grit as impossible to reuse and dust. The surface treated trimmed waste 4 is coiled in a hoop coiling machine 11 and incorporated in a waste receiver 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for continuously removing trim scraps after trimming a steel sheet (including a steel strip; the same applies hereinafter) surface-treated by plating or the like.

[0002]

2. Description of the Related Art A rolled cold-rolled steel sheet is trimmed in order to form an edge portion of the sheet width into a predetermined sheet width. Trimmed scraps (hoop-shaped scraps of steel plates) that have been cut are put into a converter or the like as scraps and used as resources.
Recently, the demand for steel sheets surface-treated by plating or the like with improved corrosion resistance has increased, and the amount of plated trim waste has also increased accordingly.

However, if this is charged into a converter as it is, fumes of plated metal are generated, which significantly corrodes furnace wall bricks and at the same time deteriorates the working environment, and also causes casting defects during molten steel casting. There is. Therefore, the surface layer including the plating layer must be removed from the trim scraps in advance, and a low-cost and highly efficient removal technique is required.

Conventionally, as a method for treating Zn-plated steel scrap,
In Japanese Patent Laid-Open No. 57-85916, Z
A pretreatment method is disclosed in which the plated Zn is heated to a temperature near the boiling point of n to evaporate and remove the plated Zn. However, this method requires treatment in a closed container in a high temperature atmosphere in order to prevent scattering of evaporated Zn, which increases equipment and operating costs and makes it difficult to install it in a plated steel sheet production line. Further, Japanese Patent Laid-Open No. 63-96224 discloses that Zn-plated steel plate scrap is heated to 700 to 900 ° C. and shot-blasted while being kept at that temperature. This method also has a problem in common with the above-mentioned publication because it is heated to a temperature at which Zn is melted.

On the other hand, although dissolution treatment using a partial chemical solution has been studied, it is expected that this also causes new problems such as waste liquid treatment and increases the treatment cost.

[0006]

Under the present circumstances, there is no suitable method for removing the surface layer of trim scraps of the surface-treated steel sheet, and it is left in the scrap yard or the life of the converter is shortened. Reuse must be carried out while accepting, and the demand for this reuse realization technology is extremely large. In order to meet the above-mentioned demand, the present invention enables to continuously remove the surface layer from the trim scraps of the surface-treated steel sheet with high efficiency and low cost, and further enables the removal treatment in the surface-treated steel sheet manufacturing equipment line. The purpose of the present invention is to provide a method for effectively using this trim scrap that has been out of the range of use.

[0007]

In order to achieve the above object, the present invention has the following structure. That is, (1) the surface layer of surface-treated steel sheet trim scraps characterized in that grinding particles are projected onto the trim scraps continuously cut from the running surface-treated steel plate to remove the surface layer including the plating layer of the trim scraps. Treatment method, and (2) surface treated steel sheet production line,
A trimmer provided in front of the coil winder trims the traveling surface-treated steel sheet, projects abrasive particles on the continuously cut trim scraps, and removes the surface layer including the plating layer of the trim scraps. It is a characteristic surface treatment method for surface-treated steel sheet trim scraps.

The present invention will be described in detail below. Generally, the plated metal is soft, and when removing it from the steel plate surface with a tool such as a bite or milling cutter, the plated metal is welded to the cutting edge and the cutting ability decreases rapidly, so frequent tool replacement is required. Become. Grinding with a grinder causes significant clogging by the plated metal, and must be replaced frequently or special cleaning treatment such as online dressing must be performed.

According to the present invention, the trim particles, which are free from the above-mentioned replacement and clogging, and which can be continuously circulated (hereinafter referred to as a grid), are cut by a surface layer removing device provided in a surface-treated steel sheet manufacturing equipment line. Continuously project on scraps. FIG. 1 shows an apparatus for carrying out the method of the present invention, which is installed in a surface treatment (Zn plating) manufacturing facility line. That is, the running Zn-plated steel plate 1 is trimmed at the edge portion in the plate width direction by the trimmer 3 before being wound by the winder 2, and the separated hoop-shaped trim waste 4 enters the chamber 5 while running, Then, the surface is removed by plating with a grid and the plating layer and the like are removed. A pair of blast nozzles 6 or a plurality of blast nozzles 6 are installed in the chamber 5 so as to face each other so as to sandwich the trim scrap hoop 4, and a grid is placed from the nozzle 6 toward the surface of the trim scrap 4 running. To jet. The sprayed grid is collected together with the grinding dust in the lower chute of the chamber 5, and is transferred and collected from the draft pipe 7 to the grid recovery tank 8 using high pressure air or water as a transfer medium. In the grid collection tank 8, the reusable grid is separated from the non-reusable grid and dust, and the latter is sent to the dust collection device 9,
The former is supplied to the blast nozzle 6 through the circulation pipe 10 by using high pressure air or liquid as a medium.
Ejects together with the high pressure medium. If the amount of reusable grids is insufficient, new grids may be added as needed.

The trimmed waste 4 which has been surface-treated is the hoop winder 1.
1 is wound on a coil 12 of an appropriate size, and a scrap receiver 13
To store. Reference numeral 14 represents a cutter.

Since the grid jetted from the nozzle is considerably high speed, the tip of the nozzle is worn. Therefore, at least the tip of the nozzle is preferably made of wear-resistant material such as alumina, SiC, sialon.

The grid (particles) to be ground is preferably, but not limited to, SiC, alumina, glass beads or the like. In addition, the particle size greatly affects the equipment and operation. Fig. 2 shows the relationship between the grid grain size (mm), the grinding amount (mg / cm ² · sec, solid line) and the blast nozzle life (hr, dotted line). The amount of grinding increases, but the nozzle life decreases. Naturally, the longer the nozzle life, the better, but at least the periodic inspection cycle (720 hours)
Is necessary, and the grinding amount should be large in terms of equipment cost, while at least 1 mg / cm from the line operation side.
^It must be ² seconds or more. Therefore, it is preferable that the grid grain size is 20 μm or more and 2 mm or less.

Air or water is used as the grid carrier medium for the nozzle, and the jet from the nozzle is jetted by pressurized air. This air pressure has a great influence on the grinding amount and the equipment cost. FIG. 3 shows these relationships (solid line indicates grinding amount, dotted line indicates equipment cost, and one-dot chain line indicates average value of both). If the air pressure is increased, the grinding force increases and the grinding amount increases. The air pressure is preferably 15 kg / cm ² or less, and the grinding amount is at least 1 mg / cm ² because the amount of wear of the nozzle increases and the life of the nozzle increases and the cost of the device increases and the manufacturing cost of pressurized air increases.・ Air pressure of 0.5 kg / cm ² or more is recommended because it requires more than a ^second .

In the present invention, the plating metal on the surface of the steel sheet can be removed by projecting the abrasive particles as described above.
Further, in order to make the equipment compact or to further improve the work speed, cutting with a bite or grinding with a grinder or the like may be combined in addition to the grid injection processing. In these combined processes, most of the plated metal is removed by the projection of grinding particles, so the tool life is not reduced.

Examples of the present invention will be described below.

[0016]

EXAMPLE A test for continuously treating trim scraps continuously generated from a Zn-plated steel sheet by the apparatus shown in FIG. 1 was carried out in a surface-treated steel sheet manufacturing facility. The test conditions and grid injection conditions are as follows. The trim scraps removed from the surface layer were melted, and the fume generation state at this time [fume generation amount g (Zn) / kg (Fe) per 1 kg of iron) was examined. The results are shown in Table 1.

[Test conditions] Line speed 100 m / min Trim width 10 mm Plating thickness 6 μm [Grid injection conditions] Carrier air pressure 3 to 5 kg / cm ² Grid material SiC grid diameter 50 to 800 μm Nozzle distance 30 μm

[0018]

[Table 1]

As is clear from Table 1, the sample No. 1 in which the trim scraps were melted as they were without surface treatment was used. In the case of No. 13, about 50% of the deposited plating metal (Zn) is generated as fumes. Fume generation amount of 1 to 12 is extremely small, N
o. I was able to hold it down to 1/680 at the maximum.

[0020]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the surface layer can be continuously removed with higher efficiency and lower cost than the trim scraps of the surface-treated steel sheet, and the removal treatment can be performed in the surface-treated steel sheet manufacturing equipment line. It is possible to effectively use this trim waste, which is out of the range of reuse at present, as scrap to be charged into a converter or the like, and its industrial effect is extremely large.

[Brief description of drawings]

1 shows an example of an apparatus for carrying out the method of the invention.

FIG. 2 shows the relationship between the grid particle size (mm), the grinding amount (solid line), and the jet nozzle life (dotted line).

FIG. 3 shows the relationship between air pressure, grinding amount (solid line), and equipment cost (dotted line).

[Explanation of symbols]

 1: Zn-plated steel plate 2: Winder 3: Trimmer 4: Trim scraps 5: Chamber 6: Blast nozzle 7: Draft pipe 8: Grid recovery tank 9: Dust recovery device 10: Circulation pipe 11: Hoop winder 12: Coil 13: Waste receiver 14: Cutter

Claims (2)

[Claims] 1. A surface layer of surface-treated steel plate trim scraps, characterized in that grinding particles are projected onto trim scraps continuously cut from a running surface-treated steel plate to remove a surface layer including a plating layer of the trim scraps. Processing method. 2. In a surface-treated steel sheet production line, a trimmer provided in front of a coil winder trims a traveling surface-treated steel sheet and projects grinding particles onto continuously cut trim scraps to trim trim scraps. A surface treatment method for surface-treated steel sheet trim scraps, which comprises removing the surface layer including the plating layer.