JPH0550202A - Method for grinding billet - Google Patents

Abstract

PURPOSE:To reduce costs by smoothly grinding to remove defective parts such as scratches, damages, etc., on the surface or its neighbourhood of billets and thereby improving the yield of ornamental parts. CONSTITUTION:A prticulate polishing and cleaning material 6 such as garnet sand is evenly and dispersedly mixed in a high pressure water 9 which is supplied to the mixing chamber 10 of a nozzle head 4, and projected in a fine diameter jet 2 on the slab 3 of a billet at a super high speed so as to grind and remove the defective parts. Consequently, without smelting or thermal deterioration of the defective parts of the slab on the surface or in its neighbourhood, the yield is improved, the quality is raised, and the cost is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The disclosed technology belongs to the field of technology for removing scratches and flaws by grinding the surface of a slab in a continuous casting line.

[0002]

BACKGROUND OF THE INVENTION As is well known to those skilled in the art, a slab, a billet, or a steel piece subjected to roll casting that is cast in a continuous casting process may be accompanied by various flaw defects in the casting or rolling casting process. The flaw defect has a disadvantage in that the product yield and the product quality are deteriorated in subsequent subsequent processes.

Therefore, in order to cope with this, flaw defects are removed by a maintenance work at the stage of manufacturing billets such as slabs and billets, and the slabs and billets from which flaws have been removed are supplied to subsequent subsequent processes to improve product yield and yield. We try to prevent the deterioration of product quality.

[0004] As a means for such a steel piece maintenance operation, hot scarf welding and grinding with a grinder are generally used. The former hot scarf welding is disclosed in, for example, JP-A-52 As in the invention, it is necessary to provide a crater operation platform having a plurality of craters on a side surface on which two gate-shaped frame beams are arranged in parallel and a plurality of craters on a support beam on the upper surface so as to be vertically movable and laterally movable. Alternatively, as disclosed in Japanese Patent Laid-Open No. 52-81048, a method is disclosed in which a plurality of torches arranged in a row are used for fusion cutting to enable removal of wide defects without performing auxiliary welding. ..

Further, as the latter grinding using a grinder, for example, as in the invention of Japanese Patent Laid-Open No. 48-46993, a grinding wheel is used with a hydraulic cylinder or an air cylinder to improve the grindability, and the grinding of a billet or the like is performed. Alternatively, as in the invention of Japanese Patent Application Laid-Open No. 1-252729, when grinding a stainless cast piece or a stainless steel piece with a grinder, the grinder is maintained within a specific temperature range to avoid self-hardening of stainless steel. A method for effectively removing the defective portion has been devised.

[0006] Further, in addition to the means for removing flaws such as the above-mentioned hot scarf fusing and grinding with a grinder, a method mainly involving descaling at the stage of steel slab production is disclosed in, for example, JP-A-51-97894. Various inventions have been proposed, such as the invention of Japanese Patent Laid-Open Publication No. 2003-242242, in which a predetermined abrasive cleaning material is sprayed on the surface of a stainless steel plate from a nozzle to perform grinding and descaling together.

[0007]

However, the above-mentioned various steel piece maintenance means have various problems as described below.

First, Japanese Patent Laid-Open No. 52-5 related to scarf welding
As in the invention disclosed in Japanese Laid-Open Patent Application No. 644, a crater operation platform is provided in which two gantry frame beams are arranged in a balanced manner, and a crater operation platform support beam on a top surface has a plurality of craters and is vertically movably and laterally mounted. Aspects and methods such as the invention of Japanese Patent Application Laid-Open No. 52-81048, in which a plurality of torches arranged in a row are used for fusing to enable the fusing of wide defects without performing auxiliary fusing, The hot scarf work itself has high temperature and high dust, which not only causes the work environment to worsen significantly, but also makes it difficult to determine the flaw defects remaining on the surface of the welded steel piece after hot scarf treatment. There are difficulties.

Further, the hot scarf method cannot control the depth of fusing, resulting in uneven fusing. Therefore, a scar defect is left behind, or the amount of hot scarf is increased to prevent leftover defects. As a result, there is a drawback that the yield is lowered.

Further, even when automation is carried out to improve the working environment and work efficiency by using such a hot scarf system, it requires large-scale equipment as compared with other methods, which is disadvantageous in that the cost becomes high economically. ..

As disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 48-46993, as a grinding method using a grinder, a grinding wheel is improved in grindability by using a hydraulic cylinder or an air cylinder to grind a billet or the like. A method of performing and a method of caring for the grinder in a specific temperature range when grinding a stainless cast piece or a stainless steel piece with a grinder as in the invention as in the invention of JP-A-1-252729 is also the hot scarf method described above depending on the type of the steel piece. Similarly, the work is performed in a bad environment where high temperature and high dust are generated, and there is a disadvantage that it is difficult to determine the flaw defects remaining on the surface after grinding as described above, and the demerits such as extremely high flaw removal cost. Is accompanied by.

If the width of the grinder is increased, the amount of unnecessary shaving is increased, the driving force is increased, the running cost is increased, and the yield is poor. Therefore, if the width of the grinder is decreased, the efficiency is lowered, There is a disadvantage that many grinders are required, and the maintenance time becomes long, and in addition, as in the invention of the above-mentioned Japanese Patent Laid-Open No. 51-97894, the abrasive cleaning material is sprayed from the nozzle onto the surface of the stainless steel plate by a wet method. At present, the main methods for removing and repairing flaws on steel slabs, such as grinding and descaling, are mainly the latter descaling, and it is not technically sufficient to grind and remove flaws on steel slabs. , Which cannot be effectively adopted.

[0013]

OBJECT OF THE INVENTION The object of the invention of this application is to solve the problems of steel piece maintenance based on the above-mentioned prior art, and to improve the working environment and to improve the automation, steel pieces and cast pieces after grinding are important. Not only it is possible to easily identify the flaw defect remaining on the surface of, the defect defect portion can be selectively removed according to the state of the flaw defect, the cost of the product is reduced, the yield is improved, Further, the present invention aims to provide an excellent method for grinding a billet, which can surely assure the quality of products and benefit the field of application of processing technology in the steel industry.

[0014]

Means for Solving the Problems In order to solve the above-mentioned problems, the structure of the invention of the present application, which is based on the above-mentioned object and has the above-mentioned claims as its gist, is made up of garnet sand, silica sand, alumina, sand iron, cast iron grid, etc. The specified fine-grained abrasive cleaning material is mixed into high-pressure water at a specified pressure in a state of uniform dispersion to make it an ultra-high-speed water jet, and is continuously jetted from the nozzle as a jet with a small diameter of a prescribed small size to form a slab. By collisionally projecting on the surface of the rope, etc., defects and scratches harmful to the product existing near the surface of the rope are automatically ground and removed by a non-mechanical contact method. , Before or after grinding, or both, the surface of the rope and the vicinity of the surface are automatically skinned and sensed,
By adding a function to search for the presence or absence of defects and scratches, the position, etc., the technical measures have been taken to enable the grinding line to be fully automated and unmanned.

[0015]

BACKGROUND OF THE INVENTION Next, to explain the background of the invention of this application, FIGS. 1 to 3 are schematic views of a grinding principle of a casting slab by a high-pressure water jet mixed with an abrasive (abrasive water jet), In the principle mode shown in FIGS. 1 to 3, reference numeral 1 denotes a nozzle of a so-called abrasive water jet device, which is, for example, garnet in the form of fine particles uniformly dispersed in high pressure water of a predetermined pressure supplied to a mixing chamber (not shown). By mixing abrasives such as sand, silica sand, alumina, iron sand, cast iron grit, etc., to form a jet 2 with a small diameter of a predetermined small size and injecting it into the slab material 3 of the steel billet of the work material at an ultra high speed. Various modes of cutting (grinding) when the relative traverse speed (nozzle feed speed or feed speed of the slab material 3) of the nozzle 1 with respect to the slab material 3 is increased (slowed) are shown.

Thus, FIG. 1 shows a mode used for normal cutting in which the work material 3 is cut through the entire thickness t by grinding, and the slab material 3 can be cut well in the relative speed region. This is the case where a sufficiently low speed region is used, and the drag line 4 is formed over the plate thickness t of the slab material 3.

On the other hand, FIG. 2 shows a case where the nozzle 1 (and the subaru material 3) are moved relative to each other at a higher speed than in the case of FIG. 1 described above, and cutting is performed up to the bottom of the plate thickness t of the slab material 3. In other words, the cutting depth h ₂ is periodically changed at the cutting bottom by a difference of Δh ₁ in terms of cutting phenomenon.

FIG. 3 shows a case where the traverse is performed at a higher relative speed of the nozzle 1 (with the slab material 3) than in the case of FIG. 2, and the cutting depth h ₂ becomes shallow, but the bottom depth varies. Since Δh ₂ is small, the bottom surface of the cutting groove is smoothed, and so-called groove cutting grinding is possible.

Thus, the invention of this application applies the grinding principle and cutting speed range of the abrasive water jet to the surface grinding of the slab material 3 of the steel slab.

Further, in the invention of this application, the surface of the slab material 3 of the steel slab is formed by using the above-mentioned principle so that the abrasive grains of the abrasive material in the ultra-high speed jet jet in which the abrasive material is mixed with the high-pressure water are mixed. Even if it is microscopic, due to the erosion effect on the slab material 3, it is possible to receive a reliable grinding effect and remove the flaw defects and scratches in an ideal state where heat is not generated.

Depending on the manner of relative feed operation of the nozzle 1 portion forming the jet jet, the surface of the slab material 3 of the steel slab is made uniform, or only defects or scratches existing on the surface or in the vicinity thereof. Can be partially selectively smoothed through grinding.

Then, a flaw defect is formed on the surface of the slab material 3 of the steel slab or in the vicinity thereof by improving the system for detecting a defect or the like used before or after the above-mentioned grinding process, or both of them. It is possible to detect the presence / absence, position, and size.By inputting this information as feedback for grinding processing or by feeding it back, the process of removing defects and scratches on the flaw surface of the steel slab can be stabilized. ,
In addition, it is possible to surely guarantee, and further, it is possible to expose the full automation of the work process.

Since the ground surface of the steel slab after the grinding is not covered with oxide scale or the like, the defect detection check after the cutting can be relatively easily performed.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following is a description of an embodiment of the invention of this application with reference to the drawings starting from FIG.

The same parts as those in FIGS. 1 to 3 are designated by the same reference numerals. 4 and 5 show the manner of grinding the slab material 3 of the steel bill in one embodiment of the invention of the present application together with the structure of the nozzle head 4, in which the side feed type abrasive nozzle head 4 is shown. Hose 5
The abrasive cleaning material 6 such as garnet sand supplied by the above is sucked and supplied to the mixing chamber 10 by using the negative pressure generated by the Venturi effect of the super-high-speed water jet 9 generated by the water nozzle 8 connected to the high-pressure water pipe 7. Inside the abrasive nozzle 1 extending from the mixing chamber 10, the water jet 9 and the abrasive cleaning material 6 are mixed and accelerated, and a small diameter of a predetermined smaller size than the abrasive nozzle 1 is obtained. Is jetted onto a predetermined portion of the slab material 3, and the surface of the slab material 3 that moves relatively is ground by the above-described processing principle.

In this case, the axis of the abrasive nozzle 1 is held at an appropriate angle with respect to the slab material 3 according to the type of the slab material 3, and at a suitable speed and pitch so as to sufficiently cover surface defects and the like. Predetermined grinding or the like can be performed by moving the slab material 3 relative to the slab material 3 while swinging or rotating by feeding.

According to the experiment, the jet pressure of the jet 2 is 2000
If it is set to kg / cm ² , for example, the projection angle on the slab material 3 is
The angle is 10 to 170 °, and the relative speed between the slab material 3 and the abrasive nozzle 1 when the abrasive nozzle 1 swings and rotates is about 1 to 10 m / min. (However, it differs slightly under various conditions such as the polishing and cleaning material 6).

FIGS. 6 and 7 further explain in detail an example of a method of operating the above-mentioned abrasive nozzle 1. As shown in the drawings, the method of swinging the abrasive nozzle 1 is the cutting of the slab material 3. Various combinations of range, direction, and pitch feed can be adopted.

In the embodiment shown in FIG. 7, the defects 12, 12 are
At the boundary between the ground part 3'and the unprocessed part 3 '' for the ', 12''and12''' parts, appropriate rounding is performed to prevent an extreme difference in plate thickness (step). ing.

The abrasive nozzle 1 can be ground in the same manner as described above by rotating motion with a proper radius and pitch feeding instead of swinging.

Next, FIG. 8 is a block diagram showing the whole system including the inspection process. In this embodiment, a multi-joint robot is used as the driving device 13 of the abrasive nozzle 1. The search result obtained by the inspection stage 14 in the front stage of the grinding is used as position information (location, size, depth, etc.) for grinding the defects 12 and the like of the slab material 3 by the defect detection mechanism 15 such as a CCD camera. The data is input to the detection system 16, and the grinding (scarfing) stage 17 can automatically perform grinding in accordance with the input.

Further, if necessary, the inspection during the grinding and after the grinding is carried out by an optical means to detect the defects 15 ′, 1
It is also possible to use 5 ″ together with the defect detection system 16 and use the result as feedback during grinding or for regrinding.

Further, in the embodiment, the used abrasive material 6 is collected and supplied to the abrasive material supply device 19, pulverized into fine powder and separated and reused. It is adopted.

Reference numeral 20 is a high-pressure water generator, 21 is a nozzle drive controller, 22 is an overall grinding controller, and
Reference numerals 3 and 24 are waste polishing materials, and 25 is an inspection stage. 9 and 10 show aspects of the external view of the entire system of the embodiment shown in FIG. 7, in which the system grinds the surface of the slab material 3 or the like of the steel slab continuously with a tact time of 7 minutes on average. For this reason, this is a mode in which cooperative operation is performed by three articulated robots.

Although the above-described embodiments have been described with reference to a relatively typical mode, other various modifications and combinations can be adopted as the embodiments of the invention of this application. A direct injection method (a method of preliminarily mixing the abrasive and water with high pressure and injecting slurry in a high pressure state in a slurry state from the nozzle section) is used as the abrasive nozzle head, or various combinations of rotary and swing movements are used as the nozzle operation method. It is possible to adopt various modes such as the above.

[0036]

As described above, according to the invention of this application, non-contact and automatic grinding can be performed by jetting a high-pressure water jet mixed with a polishing and cleaning material onto a steel slab. It is possible to significantly improve the harsh working environment with noise and heat (unmanned, etc.) by using scarfing (melt cutting), which was previously used, and by using a means for removing defects and scratches by grinding stones, etc. Stable and reliable removal of harmful defects and scratches existing on or near the surface of steel slabs, and excellent removal at the required depth without any melting or thermal alteration of the material. The effect is played.

In addition, the need for removing defects and scratches on the surface of steel slabs has tended to increase more and more in recent years with the demand for higher performance of raw materials, and the invention of this application is a very beneficial manufacturing process. The excellent effect that the processing means can be provided is achieved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a cutting aspect of the cutting principle of the invention of this application by an abrasive water jet.

FIG. 2 is a schematic sectional view of the same partial depth cutting mode.

FIG. 3 is a schematic cross-sectional view of the same surface grinding.

FIG. 4 is a partial schematic cross-sectional view of surface grinding of a slab material with an abrasive nozzle.

FIG. 5 is a partial sectional front view of the same.

FIG. 6 is a schematic plan view of an array of defective portions of a slab material.

FIG. 7 is a vertical sectional view of the same.

FIG. 8 is an overall block diagram of a slab material grinding system aspect of the invention of this application.

FIG. 9 is a plan view of the entire system mechanism arrangement.

FIG. 10 is a front view of the same.

[Explanation of symbols]

 6 Abrasive material 3 Steel piece 2 Jet 12 Defect 9 High pressure water 4 Nozzle head

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Fujiya Nogami 1-1, Toibata-cho, Tobata-ku, Kitakyushu City Shin-Nippon Steel Co., Ltd. Machinery Engineering Department, Yawata Works Co., Ltd. (72) Kenji Minami Tobata-ku, Kitakyushu No. 1 Toibata-cho Machine Engineering Room, Equipment Department, Yawata Manufacturing Co., Ltd., Nippon Steel Co., Ltd. (72) Inventor, Tomoji Shimogasa 1-1, Tobata-cho, Tobata-ku, Kitakyushu City Machine Engineering Room, Equipment Department, Yawata Manufacturing Co., Ltd. 72) Inventor Hiroyuki Matsumura 3-1-1 Higashikawasakicho, Chuo-ku, Kobe City Kawasaki Heavy Industries Ltd. inside the Kobe factory (72) Inventor Kawa 3-1-1 Higashikawasakicho, Chuo-ku, Kobe City Kawasaki Heavy Industries, Ltd. Inside the Kobe factory (72) Inventor Kyoji Tsujita 3-1-1 Higashikawasakicho, Chuo-ku, Kobe City Kawasaki Heavy Industries, Ltd. Inside the Kobe factory (72) Invention Hidenori Tanaka 3-1-1 Higashikawasaki-cho, Chuo-ku, Kobe City Kawasaki Heavy Industries Ltd. Kobe factory

Claims (4)

[Claims] 1. A method of grinding a steel slab by projecting the blasting and cleaning material from a nozzle onto a steel slab during a continuous casting process in a line, wherein high-pressure water containing finely divided polishing and scavenging material mixed in a uniformly dispersed state is used. A small diameter jet is projected onto the surface of the steel slab, and at least the flaw portion on the surface and in the vicinity thereof is ground, and a grinding method is characterized. 2. The grinding method according to claim 1, wherein in the grinding by the jet during a continuous casting process in a line, a defect existing portion is finished to be substantially smooth. 3. The polishing and cleaning material is supplied at a high water pressure of 0.5 kg / min or more, and high pressure water is supplied at a pressure of 1000 kgf / cm ² or more and a flow rate of 21 / min or more. By premixing in the state or by mixing in the nozzle head after ejecting high pressure water to make high pressure water mixed with polishing and cleaning material, and the projection angle (collision angle) to the surface of the billet is 10 ° ~ 170
The grinding according to any one of claims 1 and 2, characterized in that the grinding is performed by projecting on the surface of the steel piece under the condition that the injection distance between the nozzle and the steel piece is within 200 mm. Method. 4. A method for grinding a steel slab by projecting a polishing agent from a nozzle onto the steel slab in a continuous casting process in a line,
The steel slab and defects near the surface of the slab are automatically detected, and high-pressure water mixed with finely divided abrasive is uniformly dispersed on the surface of the slab before and / or after the detection. A method for grinding, characterized in that a jet having a diameter is projected and the surface and at least a flaw portion in the vicinity thereof are ground.