JP4637786B2 - Quality control method for steel bars for reinforced concrete - Google Patents

Description

The present invention relates to a quality control method for steel bars for reinforced concrete used to reinforce various concrete structures.

  Steel bars for reinforced concrete (hereinafter referred to as steel bars) are used as a material to reinforce concrete in various structures such as the foundations of houses, high-rise buildings, and piers. In order to improve the adhesion of this steel bar to concrete, deformed steel bars with ribs and numerous nodes formed on the surface are the mainstream, but some have simple circular cross sections. All steel bars have an important role in maintaining the strength of the building, and details are defined in JIS G3112.

  Steel bars are produced by using a steel material made by melting raw materials in a furnace and processing it into a predetermined shape, but the products produced by the same melting operation are chemical components and mechanical properties. Is almost uniform. Therefore, samples are taken for each melting operation, chemical components and mechanical properties are measured, and all the measured values are recorded. Based on this record, a “steel inspection certificate” is created and the quality is ordered from the client. Has been reported. In addition to the measured values, this certificate contains the molten steel number (lot number) that is assigned for each melting operation. If the molten steel number can be grasped even after shipment, it can be verified against the steel inspection certificate. . In addition, although the format of the steel material inspection certificate is uniquely determined by each manufacturer, the items specified in JIS G3112 are always described.

  The finished steel bar is cut to a certain length, and then a predetermined number is bound with a wire or the like and shipped to the customer. It is prescribed in the above JIS that it is attached every bundle. Widely used as this identification mark is a metal plate called a metal tag, which describes the type symbol, molten steel number or inspection number, nominal diameter or name, manufacturer name or abbreviation thereof. Based on the molten steel number, it can be compared with a steel material inspection certificate, and quality and origin can be confirmed until just before construction. FIG. 4 shows a conventional steel bar quality control method. FIG. 4 (A) shows an example of a steel inspection certificate format, and FIG. 4 (B) shows a metal bar attached to a bound steel bar. State.

  After the steel bars are shipped and the binding is released, it is impossible to grasp the molten steel numbers individually if various molten steel numbers are mixed. However, the quality of the steel bar is guaranteed, and even if it is impossible to grasp the molten steel number in general buildings, there is little problem. However, facilities that require extreme safety, such as power plants, may use only certain steel bars, and it is possible to proceed with construction work while referring to the steel inspection certificate indicating the source. is there. In addition, when investigating a building after completion due to troubles, etc., it may be desired to refer to a steel material inspection certificate in order to investigate the quality at the time of manufacturing the steel bar. However, conventionally, there is no method other than examining the metal plate to refer to the steel material inspection certificate after it has been shipped, and once the binding has been broken, it has been difficult to grasp the molten steel number.

Steel bars play an important role in maintaining the strength of buildings, and it is necessary to eliminate as much as possible the factors that lead to strength reduction. In addition, it is necessary to consider that the lifetime of a building extends over several decades. In addition, the following patent documents are mentioned as a technique relevant to this invention.
Noto 3101640 Publication

The present invention has been developed based on such a situation, and an object of the present invention is to provide a quality control method for steel bars for reinforced concrete, in which the quality at the time of manufacture can be ascertained in a single unit and is excellent in reliability.

The invention described in claim 1 for solving the above-mentioned problems is a steel material inspection certificate in which chemical components and mechanical properties of the steel material are described for each melting operation, and each melting operation in the steel material inspection certificate. And an identification mark for specifying a molten steel number assigned to the steel bar, which is formed by protruding from a region partitioned by ribs and nodes continuously at a predetermined interval. A quality control method for steel bars for reinforced concrete, characterized in that the quality at the time of manufacture can be grasped in units of one by checking a sign against the steel material inspection certificate .

  The molten steel number is given each time the raw material is melted using a furnace, and is different for each melting operation even in the same furnace. In addition, the molten steel produced in a single melting operation is stirred in the molten state, so the physical property values are almost uniform.The sample is extracted and the chemical composition and mechanical properties are measured. Based on this, a steel inspection certificate is created. The identification mark corresponds to the molten steel number, which makes it possible to identify the lot and date of the melting operation, and to collate with the steel material inspection certificate. Here, the identification mark is a concept including all visually distinguishable displays such as characters such as numerals and alphabets, figures such as squares and triangles, and combinations thereof. As a result, if the steel bar is not embedded in the building, the molten steel number can be grasped at any time by visually reading the identification mark.

The display position of the identification mark is the peripheral surface of the bar, and the identification mark is continuously displayed in consideration that the bar is cut to a predetermined length for shipping and then cut again. In addition, the form of the steel material inspection certificate is not necessarily limited to paper, and may be electronic data premised on use with a computer.

  By configuring in this way, it is possible to read the identification mark for each steel bar when unpacking and carrying it to the site, or when it is assembled into a predetermined shape on site, and based on this, the steel material By examining the inspection certificate, it is possible to grasp the measurement results such as the chemical composition of the steel bar. In addition, about steel bar, both the product made from the electric furnace which melt | dissolved the scrap and the product made from the blast furnace which used the iron ore as a raw material exist, However, This invention is applicable in any case. However, in the case of Blast Furnace, the inspection number may become an identification mark instead of the molten steel number.

Further, the identification mark is formed so as to protrude from the area defined by the rib and the node protruding from the side peripheral surface . For this reason, there is little fear that reading will be impossible over time, or it will disappear in a harsh environment, and even if it is recovered from a building, it can be read with high probability. Moreover, since the cross-sectional area of the steel bar is slightly increased by forming by the bulging, there is no problem in strength. However, since stress concentration is likely to occur near the base of the identification mark, measures such as finishing the corners into curved surfaces are necessary. The present invention is limited to deformed steel bars in which ribs and nodes protrude from the side peripheral surface, and one or more characters are displayed for each area defined by the ribs and nodes. Will not be divided.

As in the first aspect of the invention, it is recovered from the building by a quality control method in which an identification mark (molten steel number) is displayed on each bar and the quality at the time of manufacture can be grasped in a single unit. and the quality at the time of manufacture of steel bars can easily grasp, verification can be quickly and efficiently carried out. In other words, in addition to the bar steel shipment stage to the construction stage, traceability can be established from when it is finally disposed, and it is excellent in various aspects such as improved reliability and separation during recycling.

In addition , by forming the identification mark so as to protrude from the surface of the steel bar, there is no possibility that it will not be visible over time like paint. Therefore, even if it encounters a harsh environment at the time of construction, it does not disappear, and even after it is recovered from the building, there is a high probability that it can be read. Moreover, since the cross-sectional area of the steel bar is not reduced as inscribed, the strength reliability is excellent. In addition, adhesion to concrete does not decrease.

  FIG. 1 shows an embodiment of the present invention. FIG. 1 (A) shows the appearance of a steel bar 1 and FIG. 1 (B) shows a steel material inspection certificate 11. In the steel bar 1 in this figure, two series of nodes 3 are arranged at equal intervals in the axial direction, and a rib 2 extending in the axial direction is formed at the boundary between both nodes 3. And the identification mark 4 which shows a molten steel number is formed in the area | region divided by the rib 2 and the node 3. FIG. The identification mark 4 here is a four-digit number, and it can be clearly understood that “3754” is displayed. Although the identification mark 4 is formed so as to protrude from the side surface of the steel bar 1, it does not protrude from the rib 2 or the node 3. Therefore, even if it encounters dirt adhesion or wear that may occur in general, reading does not become difficult. The specific character string of the identification mark 4 is uniquely determined by the manufacturer and is not uniform. However, the steel bar 1 also includes the manufacturer's abbreviation 5 and matches these two as clues. By searching the steel material inspection certificate 11 of the identification mark 4, the quality at the time of manufacture can be finally grasped.

  The steel material inspection certificate 11 is often created for each construction site as shown in the figure, and since a plurality of molten steel numbers are described, it is necessary to select only the relevant one from these. The steel material inspection certificate 11 shown in the figure does not faithfully reproduce the actual format. In addition, in the steel bar 1 in the figure, corners are emphasized in order to express the shape clearly, but in reality, the roots of the ribs 2 and the joints 3 are rounded to prevent stress concentration.

  FIG. 2 shows an example of a method for producing the steel bar 1 according to the present invention. Here, scrap 21 collected at various places is used as the raw material of the steel bar 1, and an amount of scrap 21 corresponding to the processing capacity of the furnace 22 is input as shown in FIG. Thereafter, as shown in FIG. 2B, the inside of the furnace 22 is heated to melt the scrap 21, and at the same time, refining is performed to adjust chemical components while removing impurities. When melting is finished, the furnace 22 is tilted as shown in FIG. 2 (C) and poured into the dedicated container 23, and then the molten steel is gradually cooled as shown in FIG. To produce.

  Furthermore, after the steel ingot 30 is heated again as shown in FIG. 2 (F), the sectional area is gradually narrowed down by a rolling mill 24 composed of a plurality of rolls as shown in FIG. 2 (G). It has a cross section close to that at the time of shipment. Then, finish rolling for adjusting to the final product shape as shown in FIG. In this process, the rib 2 and the node 3 are formed, and the identification mark 4 is rolled. However, since the steel bar 1 is too long and difficult to handle as it is, the quality inspection is performed at the same time by cutting to a specified length as shown in FIG. Finally, as shown in FIG. 2J, the identification mark 4 is bundled with the same steel bar 1 before shipment. A sample is extracted for each melting operation to measure chemical components, and the measurement result and the molten steel number for specifying the melting operation are written in the steel material inspection certificate 11.

  FIG. 3 is a perspective view showing details of finish rolling. Rolls 25 and 26 for forming the steel bar 1 and rolling the identification mark 4 are arranged one above the other, and the steel bar 1 passes between these rolls. Each roll 25, 26 has a total of five main grooves 27 for forming, but this does not form the five steel bars 1 at the same time. To go. Finally, when the five main grooves 27 are worn out and the work cannot be continued, the rolls 25 and 26 are exchanged. By providing the plurality of main grooves 27 in this manner, the number of times the rolls 25 and 26 are replaced can be reduced, and productivity is improved.

  In the main grooves 27 of both rolls 25 and 26, a groove 28 extending in the width direction is engraved to form the node 3, and an identification mark 4 (four-digit molten steel number) is provided on the upper roll 25. The character groove 29 for rolling is engraved. Since the character groove 29 has a concave shape, the steel bar 1 is rolled so that the character is raised. Different identification marks 4 are assigned to the five main grooves 27, and the steel bar 1 produced by the same melting operation continuously uses one of the five main grooves 27. And when switching to the steel bar 1 produced by a different melting operation, a different main groove 27 is used. Therefore, the rolls 25 and 26 as shown in FIG. Of course, at the stage of manufacturing the rolls 25 and 26, it is necessary to determine the assignment of the identification mark 4 based on the production plan. In the figure, a character groove 29 of “1234” is cut in the central main groove 27, and an identification mark “1234” is rolled on the steel bar 1 passing through the main groove 27. The diameter of the rolls 25 and 26 is about 50 cm at the maximum, and the identification mark 4 is rolled at intervals of about 1.5 m.

The embodiment example of this invention is shown, (A) is an external appearance of a steel bar, (B) is a steel material inspection certificate. The steel inspection certificate is a reference example and is different from the actual document. An example of the production method of the steel bar by this invention is shown, and work progresses in order of (A) to (J). It is a perspective view which shows the detail of finish rolling. The quality control method of the steel bar currently implemented is shown, (A) is a format example of a steel material inspection certificate, (B) is the state which attached the metal tag to the bound steel bar. The steel inspection certificate is a reference example and is different from the actual document.

1 Reinforced concrete bar (bar)
2 Rib 3 Section 4 Identification mark (molten steel number)
5 Manufacturer's abbreviation 11 Steel inspection certificate 21 Scrap 22 Furnace 23 Dedicated container 24 Rolling mill 25 Roll (upper)
26 rolls (lower side)
27 Main groove 28 Node groove 29 Character groove 30 Steel ingot

Claims (1)

Steel inspection certificate (11) that describes the chemical composition and mechanical properties of steel for each melting operation ,
The identification mark (4) for specifying the molten steel number given for each melting operation in the steel material inspection certificate (11) is continuously provided with a predetermined interval, and the rib (2) and the node (3). And a steel bar (1) formed so as to protrude from the region partitioned by
A quality control method for steel bars for reinforced concrete, wherein the identification mark (4) is checked against the steel material inspection certificate (11) to make it possible to grasp the quality at the time of manufacture.

Images