Oxygen-free galvanizing device for hot-rolled ribbed steel bars

Abstract

The utility model provides an oxygen-free galvanizing device for hot-rolled ribbed steel bars, which comprises a reduction sealing cover and a galvanizing sealing cover which are communicated through a transfer channel, a reduction mechanism arranged in the reduction sealing cover, and a galvanizing mechanism arranged in the galvanizing sealing cover, the reduction mechanism comprises a reduction cylinder which is horizontally arranged and internally provided with a rectangular channel in a transversely penetrating mode. The two ends of the reduction cylinder are connected with a head end nitrogen pipe and a tail end nitrogen pipe correspondingly. A plurality of mixed reducing gas inlets are formed in the middle of the reducing cylinder in parallel in the length direction; and the nitrogen pressure of the head-end nitrogen pipe and the tail-end nitrogen pipe is greater than the pressure of the mixed reducing gas. According to the device, the surface layer of the high-temperature ribbed steel bar is reduced through mixed reducing gas, then the high-temperature ribbed steel bar is conveyed to the galvanization mechanism for galvanization in the inert gas atmosphere, the reduction, conveying and galvanization processes are all carried out in an oxygen-free environment, oxidation of the surface of the steel bar is effectively avoided, and the influence of a steel bar oxidation layer on galvanization quality is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of ribbed steel bars, in particular to an oxygen-free galvanizing device for hot-rolled ribbed steel bars. Background Art

[0002] Hot-rolled ribbed steel bars, commonly known as threaded steel bars, have high strength, high toughness, and good seismic resistance. They are ideal products for high-rise buildings and are widely used in the field of building concrete. In order to increase the corrosion resistance of steel bars and improve the strength and life of reinforced concrete, hot-dip galvanizing is usually performed on the outside of hot-rolled ribbed steel bars. After hot-dip galvanizing, the surface of the steel bar is covered with a pure zinc layer in the form of complete physical protection. A Zn-Fe alloy layer is also formed between the pure zinc layer and the steel bar matrix, which isolates the steel bar matrix from the atmosphere, thereby protecting the steel bar matrix from corrosion.

[0003] Before galvanizing, the surface of the ribbed steel bar needs to be treated in advance to remove the oil film, oxide layer and other impurities on the surface before entering the zinc pot for galvanizing. However, since the ribbed steel bar is in a heated state during galvanizing, once the oxide layer is removed and the steel matrix is ​​exposed, the steel matrix is ​​still very easy to react with the air for oxidation, thereby affecting the subsequent galvanizing effect; moreover, during the galvanizing process, the high-temperature steel bar will inevitably undergo oxidation reaction to generate iron oxide scale, thereby affecting the bonding strength between the coating and the matrix. Therefore, how to avoid the influence of oxygen on the galvanizing of ribbed steel bars and improve the bonding strength between the coating and the matrix has become a key issue restricting the quality of galvanizing of ribbed steel bars. Utility Model Content

[0004] The utility model provides an oxygen-free galvanizing device for hot-rolled ribbed steel bars in order to overcome the disadvantages of the prior art.

[0005] The technical solution adopted by the utility model to solve its technical problems is:

[0006] An oxygen-free galvanizing device for hot-rolled ribbed steel bars comprises a reduction sealing cover and a galvanizing sealing cover connected by a transfer channel, a reduction mechanism arranged in the reduction sealing cover, and a galvanizing mechanism arranged in the galvanizing sealing cover; the front end of the reduction sealing cover is provided with an inlet for the ribbed steel bars to pass through, and the rear end of the galvanizing sealing cover is provided with an outlet for the ribbed steel bars to pass out;

[0007] The reduction mechanism comprises a reduction cylinder which is arranged horizontally and has a rectangular channel extending therethrough, the two ends of the reduction cylinder being respectively connected to a head nitrogen pipe and a tail nitrogen pipe, the head nitrogen pipe and the tail nitrogen pipe being connected to a compressed nitrogen pipeline after penetrating a reduction sealing cover; a plurality of mixed reduction gas inlets are arranged in parallel along the length direction in the middle of the reduction cylinder, the mixed reduction gas inlets being connected to a mixed reduction gas source outside the reduction cylinder; the pressure of nitrogen introduced into the head nitrogen pipe and the tail nitrogen pipe being greater than the pressure of mixed reduction gas introduced into the mixed reduction gas inlets.

[0008] A further improvement of the utility model is that the mixed reducing gas is a nitrogen mixed gas, wherein the hydrogen content is 5% to 8%.

[0009] A further improvement of the utility model is that a dewatering and descaling device is further arranged inside the reduction sealing cover; the dewatering and descaling device is arranged upstream of the reduction mechanism.

[0010] A further improvement of the utility model is that a channel is transversely opened inside the dewatering and descaling device to accommodate multiple ribbed steel bars arranged side by side, the front end of the channel corresponds to the inlet of the reduction sealing cover, and the rear end of the channel corresponds to the rectangular channel of the reduction cylinder; a purge air knife is arranged on the top and bottom of the dewatering and descaling device, and the purge air knife is connected to the high-pressure nitrogen pipe.

[0011] A further improvement of the utility model is that the angle between the blowing direction of the purge air knife and the horizontal direction is 45°.

[0012] A further improvement of the utility model is that the top of the reduction sealing cover and the top of the galvanized sealing cover are also connected through an escape pipe, and a discharge tower for high-altitude discharge of nitrogen is arranged at the tail end of the galvanized sealing cover.

[0013] The beneficial effects of the utility model are:

[0014] The utility model provides an oxygen-free galvanizing device for hot-rolled ribbed steel bars, which adopts a reduction sealing cover and a galvanizing sealing cover which are interconnected, reduces the surface layer of the high-temperature ribbed steel bars by mixed reducing gas, and then transports them to a galvanizing mechanism for galvanizing in an inert gas atmosphere. The reduction, transportation and galvanizing processes are all carried out in an oxygen-free environment, effectively avoiding oxidation of the steel bar surface and solving the problem of the influence of the steel bar oxide layer on the galvanizing quality.

[0015] In the utility model, the reduction cylinder is filled with nitrogen and mixed reduction gas, which becomes the first level of protection; the reduction sealing cover and the galvanizing sealing cover are filled with nitrogen, which becomes the second level of protection. The two-level protection set by positive pressure effectively isolates the outside air from the ribbed steel bars, ensuring that the high-temperature ribbed steel bars are reduced and galvanized in an inert and oxygen-free environment, thereby improving the surface composition of the steel bars during galvanizing, making the coating and the steel bar matrix more firmly and stably combined. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is the overall structure connection flow chart of the utility model;

[0017] In the figure: 1. reduction sealing cover, 1-1. dewatering and descaling device, 1-2. purge air knife, 1-3. reduction cylinder, 1-4. head end nitrogen pipe, 1-5. tail end nitrogen pipe, 1-6. mixed reduction gas branch pipe, 1-7. distribution cross pipe, 1-8. mixed reduction gas main pipe, 2. galvanized sealing cover, 2-1. discharge tower, 3. transfer channel, 4. escape pipe, 5. ribbed steel bars. DETAILED DESCRIPTION

[0018] The utility model will be further described below in conjunction with the accompanying drawings.

[0019] An oxygen-free galvanizing device for hot-rolled ribbed steel bars, such as Figure 1 As shown, it includes a reduction sealing cover 1 and a galvanizing sealing cover 2 which are interconnected, a reduction mechanism arranged in the reduction sealing cover 1, and a galvanizing mechanism arranged in the galvanizing sealing cover 2. The outlet of the reduction sealing cover 1 and the inlet of the galvanizing sealing cover 2 are connected through a transfer channel 3, and the transfer channel 3 is arranged horizontally. The ribbed steel bar 5 first enters the reduction sealing cover 1 for surface reduction, and then is horizontally pushed into the galvanizing sealing cover 2 through the transfer channel 3 for galvanizing.

[0020] The reduction sealing cover 1 and the galvanized sealing cover 2 are both welded with steel plates. The front end of the reduction sealing cover 1 is provided with an entrance for the ribbed steel bars 5 to pass through, and the rear end of the galvanized sealing cover 2 is provided with an exit for the ribbed steel bars 5 to pass through. The rest of the parts are sealed.

[0021] The reduction mechanism includes a reduction cylinder 1-3, which is a horizontal long cylinder with a rectangular channel in the middle; the two ends of the reduction cylinder 1-3 are respectively connected to the head end nitrogen pipe 1-4 and the tail end nitrogen pipe 1-5, and the head end nitrogen pipe 1-4 and the tail end nitrogen pipe 1-5 are connected to the compressed nitrogen pipeline after passing through the reduction sealing cover 1. A plurality of mixed reduction gas inlets are arranged in parallel along the length direction in the middle of the reduction cylinder 1-3, and the plurality of mixed reduction gas inlets are connected to the distribution cross pipe 1-7 through the mixed reduction gas branch pipe 1-6, and then connected to the mixed reduction gas source outside the reduction cylinder 1-3 through the mixed reduction gas main pipe 1-8. The pressure of nitrogen introduced into the head end nitrogen pipe 1-4 and the tail end nitrogen pipe 1-5 is greater than the pressure of the mixed reducing gas introduced into the middle part, so that the mixed reducing gas is sealed in the middle part of the reduction cylinder 1-3 and is not easy to leak out. When the ribbed steel bars 5 pass through the reduction cylinder 1-3, the hot steel bar surface contacts the reducing gas, the surface oxides undergo a reduction reaction, the surface oxides are removed, and the steel matrix is ​​exposed.

[0022] The mixed reducing gas is a nitrogen-hydrogen mixed gas, in which the hydrogen content is 5% to 8%. A high hydrogen content will increase the risk of explosion, and a low hydrogen content cannot ensure the full reduction of the steel bar surface. It has been determined through experiments that a hydrogen content of 5% to 8% is sufficient to reduce a small amount of thin iron oxide scale on the surface of the ribbed steel bar 5. If it is suitable for the reduction of thicker iron oxide scale, the hydrogen content can be appropriately increased according to the content of the iron oxide scale, and an auxiliary heater can be added upstream of the reduction cylinder 1-3 to appropriately increase the temperature of the ribbed steel bar 5 to ensure the reduction effect.

[0023] In order to ensure the full reduction of iron oxide scale on the steel bar surface, a dewatering and descaling device 1-1 is further provided inside the reduction sealing cover 1. The dewatering and descaling device 1-1 is provided upstream of the reduction mechanism. The ribbed steel bar 5 after surface cleaning enters the reduction sealing cover 1, is first further decontaminated and dried by the dewatering and descaling device 1-1, then enters the reduction mechanism to fully reduce the trace oxide generated on the steel bar surface, and finally is sent to the galvanizing mechanism for direct galvanizing.

[0024] The dewatering and descaling device 1-1 is a rectangular box-type structure, and a channel is transversely provided inside the dewatering and descaling device 1-1 to accommodate a plurality of ribbed steel bars 5 arranged side by side. A purge air knife 1-2 is provided at the top and bottom of the dewatering and descaling device 1-1. The purge air knife 1-2 is connected to the high-pressure nitrogen pipe, and the spraying direction of the purge air knife 1-2 is at an angle of 45° to the horizontal direction. The trace oxide scale and moisture on the surface of the ribbed steel bar 5 are removed by the inclined purge of the high-pressure nitrogen. The air flow channel inside the purge air knife 1-2 is gradually contracted to ensure the pressure and purge effect of the purge nitrogen.

[0025] The top of the reducing sealing cover 1 and the top of the galvanizing sealing cover 2 are also connected through an escape pipe 4. One end of the escape pipe 4 is arranged on the reducing sealing cover 1 between the mixed reducing gas main pipe 1-8 and the tail nitrogen pipe 1-5, and the other end is connected to the front end of the galvanizing sealing cover 2. The nitrogen introduced by the head end nitrogen pipe 1-4 and the tail end nitrogen pipe 1-5, and the mixed reducing gas enter the galvanizing sealing cover 2 through the transfer channel 3 and the escape pipe 4 respectively, so that the galvanizing sealing cover 2 maintains an oxygen-free inert environment, ensuring that the ribbed steel bars 5 are in an inert atmosphere before and during galvanizing, and no oxidation occurs on the surface. A discharge tower 2-1 is arranged at the tail end of the galvanizing sealing cover 2, and nitrogen and trace hydrogen are discharged to a high place through the discharge tower 2-1.

[0026] Generally speaking, the nitrogen pressure introduced into the head nitrogen pipe 1-4 and the tail nitrogen pipe 1-5 is 0.3 kg, the mixed reduction gas pressure introduced into the middle of the reduction cylinder 1-3 is 0.2 kg, and the nitrogen pressure introduced into the dewatering and descaling device 1-1 is 7 kg to 8 kg. The gas pressure can be adaptively adjusted in the actual production process.

[0027] Since the ribbed steel bars 5 after the hot rolling are arranged in parallel and transported forward synchronously, in order to restrain and smooth the ribbed steel bars 5 laterally and enable them to be transported smoothly and continuously to avoid steel piling, the inlet ends of the reduction cylinder 1-3 and the dewatering and descaling device 1-1 are connected to the trumpet mouth with a large front and a small rear, which is used to restrain and feed the multiple ribbed steel bars 5 into the box laterally and transport them continuously.

[0028] The working principle of the utility model is:

[0029] The reduction cylinder is the main reactor of the utility model. In the reduction cylinder, the pressure of the nitrogen introduced at the two ends is greater than the mixed reducing gas introduced in the middle. The mixed reducing gas is sealed in the middle of the reduction cylinder to prevent hydrogen from escaping and reduce the hydrogen content. When the ribbed steel bars pass through the reducing atmosphere in the middle of the reduction cylinder, the oxides react with the hydrogen to produce a reduction reaction.

[0030] As the gas in the reduction cylinder is continuously introduced, nitrogen (including trace amounts of hydrogen that does not participate in the reduction reaction) gradually fills the reduction sealing cover, enters the galvanizing sealing cover through the transfer channel and the escape pipe and fills it, so that the galvanizing process is also carried out in an inert gas atmosphere, effectively isolating the influence of oxygen on the ribbed steel bars.

[0031] In addition, the nitrogen pressure introduced into the dewatering and descaling device is as high as 7 to 8 kilograms, which blocks the inlet end of the reduction sealing cover to prevent air from entering the reduction sealing cover.

[0032] In summary, the reduction cylinder is filled with nitrogen and nitrogen-hydrogen mixed gas, which is the first level of protection; the reduction sealing cover and galvanized sealing cover are filled with nitrogen, which is the second level of protection. Compared with the outside world, the reduction sealing cover / galvanized sealing cover and reduction cylinder are all positive pressure, effectively isolating the air.

[0033] The embodiments described above are merely descriptions of preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. An oxygen-free galvanizing device for hot-rolled ribbed steel bars, characterized in that: The invention comprises a reduction sealing cover (1) and a galvanized sealing cover (2) which are connected via a transfer channel (3), a reduction mechanism arranged in the reduction sealing cover (1), and a galvanizing mechanism arranged in the galvanized sealing cover (2); the front end of the reduction sealing cover (1) is provided with an inlet for the ribbed steel bars (5) to pass through, and the rear end of the galvanized sealing cover (2) is provided with an outlet for the ribbed steel bars (5) to pass out; The reduction mechanism comprises a reduction cylinder (1-3) which is arranged horizontally and has a rectangular channel extending therethrough; the two ends of the reduction cylinder (1-3) are respectively connected to a head nitrogen pipe (1-4) and a tail nitrogen pipe (1-5); the head nitrogen pipe (1-4) and the tail nitrogen pipe (1-5) penetrate a reduction sealing cover (1) and are connected to a compressed nitrogen pipeline; a plurality of mixed reduction gas inlets are arranged in parallel in the middle of the reduction cylinder (1-3) along the length direction; the mixed reduction gas inlets are connected to a mixed reduction gas source outside the reduction cylinder (1-3); and the pressure of nitrogen introduced into the head nitrogen pipe (1-4) and the tail nitrogen pipe (1-5) is greater than the pressure of mixed reduction gas introduced into the mixed reduction gas inlets.

2. The oxygen-free galvanizing device for hot-rolled ribbed steel bars according to claim 1, characterized in that: The mixed reducing gas is a nitrogen mixed gas, wherein the hydrogen content is 5% to 8%.

3. The oxygen-free galvanizing device for hot-rolled ribbed steel bars according to claim 1, characterized in that: A dewatering and descaling device (1-1) is also provided inside the reduction sealing cover (1); the dewatering and descaling device (1-1) is provided upstream of the reduction mechanism.

4. The oxygen-free galvanizing device for hot-rolled ribbed steel bars according to claim 3, characterized in that: A channel capable of accommodating a plurality of parallel ribbed steel bars (5) is transversely provided inside the dewatering and descaling device (1-1), the front end of the channel corresponds to the entrance of the reduction sealing cover (1), and the rear end of the channel corresponds to the rectangular channel of the reduction cylinder (1-3); a purge air knife (1-2) is arranged at the top and the bottom of the dewatering and descaling device (1-1), and the purge air knife (1-2) is connected to a high-pressure nitrogen pipe.

5. The oxygen-free galvanizing device for hot-rolled ribbed steel bars according to claim 4, characterized in that: The included angle between the blowing direction of the purge air knife (1-2) and the horizontal direction is 45°.

6. The oxygen-free galvanizing device for hot-rolled ribbed steel bars according to claim 1, characterized in that: The top of the reduction sealing cover (1) and the top of the galvanized sealing cover (2) are also connected via an escape pipe (4), and a discharge tower (2-1) for high-altitude discharge of nitrogen is arranged at the tail end of the galvanized sealing cover (2).

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