High-efficiency centering coil heating system for high-speed cold-rolled steel bars

Abstract

The high-efficiency, centering coil heating system for high-speed cold-rolled rebar includes an induction coil with an insulating tube concentrically inserted through it. The induction coil and the insulating tube are located within an insulating housing. A wire entry and exit die are mounted on the front and rear panels of the housing, respectively. Each die has a stopper machined near the end of the insulating tube, with the stopper and the axis of the insulating tube aligned. Each die has a wire hole. The axis of the wire hole on the wire entry die deviates from the axis of the stopper, or the axis of the wire hole on the wire exit die deviates from the axis of the stopper, or both the axis of the wire hole on the wire entry die and the axis of the wire hole on the wire exit die deviate from the axis of the stopper. The axes of the wire holes on the wire entry die and the wire hole on the wire exit die are parallel to the axis of the stopper. This system significantly improves equipment efficiency.

Description

Technical Field

[0001] The invention relates to cold-rolled steel bar production equipment, in particular to coil induction heating equipment used in cold-rolled steel bar production, and belongs to the technical field of cold-rolled wire rod production equipment. Background Art

[0002] Due to its superior performance, cold-rolled ribbed steel bars can reduce the overall amount of steel used in construction and have been widely used. During the production and rolling process of cold-rolled steel bars, the steel bars undergo multiple cold-rolling reductions (generally at least two rolling passes). After one rib is pressed, work hardening continues to form as the degree of deformation increases, and its plasticity and toughness indicators decrease. After reaching a certain level, it must undergo annealing heat treatment to improve its toughness and ductility, balance its mechanical properties, and meet the requirements of corresponding national standards. At present, mainstream cold-rolled steel bar production lines mainly use induction heating technology to anneal steel bars. Induction heating uses the principle of electromagnetic induction. A high-frequency current passes through an induction coil to generate a high-frequency magnetic field inside the coil. Eddy currents are generated on the surface of the steel bars in the coil, and heat is generated by the resistance of the steel bars, causing the surface of the steel bars to be heated. The induction coil on existing production lines is made of a hollow copper tube spiral, cooled by a coolant. To prevent contact between the rebar and the induction coil, which could cause a short circuit and damage, an insulating tube is added between the rebar and the coil. To minimize wear on the insulation tube, the ends of the insulation tube are supported in holes slightly larger than the tube's outer diameter. The tube's ends are restrained to prevent movement. However, since the insulation tube is typically made of wear-resistant material, it is quite brittle during use. When the rebar vibrates significantly, especially after the flying shear is activated, the shearing resistance combined with the kinetic energy of the rebar's movement creates a large amplitude, which can easily cause the insulation tube to crack. If the insulation tube cracks, replacement is very troublesome. The rebar must be sheared and removed before the induction coil can be removed. This leads to high equipment maintenance costs. Furthermore, the cold-rolled rebar induction heating coil is made of multiple turns of hollow copper tube spiral. When a high-frequency current i passes through the coil, a high-frequency magnetic field is generated within the coil. According to Faraday's law of electromagnetic induction, eddy currents are generated on the surface of the rebar within the coil, causing heating. Analysis of the magnetic flux distribution within the induction coil shows that the magnetic flux φ is greatest at the centerline. This ensures that the induced current generated on the rebar surface is maximized when the rebar is centered on the coil, resulting in higher heating efficiency and greater energy savings. Currently, there is a significant difference in diameter between the insulating tube and the rebar. Although the induction heating equipment has transmission wheels (rollers) at a certain height to support the rebar at a certain height, the uneven conveying force on the production line and the length of the induction heating equipment itself can cause the rebar to deviate significantly from the center during the heating process, resulting in significant energy waste. Summary of the Invention

[0003] The purpose of the present invention is to overcome the problems of easy damage and low energy utilization efficiency in the current cold-rolled steel bar induction heating process, and to provide a high-speed cold-rolled steel bar high-efficiency centering coil heating system.

[0004] In order to achieve the purpose of the present invention, the following technical solutions are adopted: a high-speed cold-rolled steel bar high-efficiency centering coil heating system, including an induction coil, an insulating tube is concentrically inserted in the induction coil, the induction coil and the insulating tube are located in an insulating box, and an inlet mold and an outlet mold are respectively installed on the front end plate and the rear end plate of the insulating box, the inlet mold and the outlet mold are respectively processed with stoppers that match the insulating tube near the end of the insulating tube, the two ends of the insulating tube are matched at the stoppers, the axis of the stoppers and the axis of the insulating tube are located on the same straight line, and wire holes that communicate with the stoppers are respectively opened on the inlet mold and the outlet mold, the axis of the wire hole on the inlet mold deviates from the axis of the stoppers, or the axis of the wire hole on the outlet mold deviates from the axis of the stoppers, or the axis of the wire hole on the inlet mold and the axis of the wire hole on the outlet mold both deviate from the axis of the stoppers, and the axis of the wire hole on the inlet mold and the axis of the wire hole on the outlet mold are both parallel to the axis of the stoppers.

[0005] Furthermore, the axis of the wire hole on the inlet mold and the axis of the wire hole on the outlet mold are both deviated from the axis of the stop, the axis of the wire hole on the inlet mold and the axis of the wire hole on the outlet mold deviate in opposite directions, and the deviation amount is equal.

[0006] Furthermore, the axis of the wire hole on the inlet mold deviates upward from the axis of the stopper, and the axis of the wire hole on the outlet mold deviates downward from the axis of the stopper.

[0007] Furthermore, the diameter of the wire hole is 1.3-1.6 times the diameter of the corresponding steel bar.

[0008] Furthermore, the value of the upward deviation of the axis of the wire hole on the wire feed mold from the stop is 0.1-0.3 times the diameter of the corresponding steel bar through the wire hole.

[0009] Furthermore, the outer end of the box of the inlet mold and the inner end of the box of the outlet mold are both bell mouths, the small end of the bell mouth of the inlet mold is connected to the wire hole of the inlet mold, the large end of the bell mouth of the outlet mold is located at the stop, and the small end is connected to the wire hole of the outlet mold, and the axis of the bell mouth is located on the same straight line as the stop or on the same straight line as the wire hole on the corresponding mold.

[0010] Furthermore, the inlet mold and the outlet mold have a gap in the entire length that is radially connected to the wire hole.

[0011] Furthermore, the taper of the bell mouth is 40° to 60°.

[0012] Furthermore, the insulating tube is a mica tube or a corundum tube.

[0013] The positive and beneficial technical effects of the present invention are as follows: the system uses a housing, an inlet mold, and an outlet mold in combination to ensure that during the production process, the vibration of the steel bars caused by changes in tension or shearing is shielded outside the housing, greatly reducing damage to the insulating tube and wear of the induction coil. The inlet and outlet molds are made of wear-resistant alloy materials to ensure the long-term use of the molds. The reasonable design of the bell mouth, stop, and wire hole on the inlet and outlet molds ensures that the steel bars always run close to the center line of the induction coil, greatly improving the efficiency of the equipment and achieving significant energy-saving effects. The eccentricity between the two wire holes and the coil axis can further optimize the above effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is an overall schematic diagram of the present invention.

[0015] Figure 2 It is a schematic diagram of the wire feeding mold.

[0016] Figure 3 It is a schematic diagram of the wire outlet mold.

[0017] Figure 4 It is a three-dimensional schematic diagram of the wire feeding mold.

[0018] Figure 5 It is a cross-sectional diagram of the steel bar travel being guided by the wire hole. DETAILED DESCRIPTION

[0019] In order to more fully explain the implementation of the present invention, implementation examples of the present invention are provided. These implementation examples are merely elaborations of the present invention and do not limit the scope of the present invention.

[0020] The invention is further explained in detail in conjunction with the accompanying drawings, in which the following marks are: 1: induction coil; 2: insulating tube; 3: insulating box; 4: axis of insulating tube; 5: inlet mold; 6: wire hole of inlet mold; 7: bell mouth of inlet mold; 8: axis of wire hole on inlet mold; 9: outlet mold; 10: wire hole of outlet mold; 11: bell mouth of outlet mold; 12: axis of wire hole on outlet mold; 13: stopper on inlet mold; 14: stopper on outlet mold; 15: steel bar; 16: wire hole of the same size concentric with the steel bar; 17: gap; 18: front end plate; 19: rear end plate.

[0021] As shown in the accompanying drawings, the high-efficiency, centering coil heating system for high-speed, cold-rolled steel bars comprises an induction coil 1, with an insulating tube 2 concentrically extending through it. The induction coil and insulating tube are located within an insulating housing 3. An inlet die 5 and an outlet die 9 are mounted on the front and rear panels 18 and 19 of the insulating housing, respectively. These inlet and outlet dies have a radial gap 17 extending along their entire length, communicating with the conductor holes. This gap prevents eddy currents from forming on the surfaces of the inlet and outlet dies, potentially heating them and thus blocking the eddy current path.

[0022] The inlet mold and the outlet mold are respectively processed with stoppers that match the insulating tube near the end of the insulating tube. The two stoppers in the figure are stoppers 13 on the inlet mold and stoppers 14 on the outlet mold. The two ends of the insulating tube are matched at the stoppers, and the axis of the stoppers and the insulating tube are located on the same straight line. 4 in the figure shows 4: the axis of the insulating tube. Wire holes that communicate with the stoppers are respectively opened on the inlet mold and the outlet mold. The diameter of the wire holes is 1.3-1.6 times the diameter of the corresponding steel bar. The two wire holes in the figure are respectively the inlet mold wire hole 6 and the outlet mold wire hole 10. The wire hole axis 8 on the inlet mold deviates from the axis of the stopper, or the wire hole axis 12 on the outlet mold deviates from the axis of the stopper, or the wire hole axis 8 on the inlet mold and the wire hole axis 12 on the outlet mold both deviate from the axis of the stopper. The wire hole axis on the inlet mold and the wire hole axis on the outlet mold are both parallel to the axis of the stopper. More specifically, the axis of the wire hole on the wire inlet mold and the axis of the wire hole on the wire outlet mold both deviate from the axis of the stopper. The deviation directions of the axis of the wire hole on the wire inlet mold and the axis of the wire hole on the wire outlet mold are opposite, and the deviation amounts are equal. The axis of the wire hole on the wire inlet mold deviates upward from the axis of the stopper, and the axis of the wire hole on the wire outlet mold deviates downward from the axis of the stopper. The value of the upward deviation of the axis of the wire hole on the wire inlet mold from the stopper is 0.1-0.3 times the diameter of the corresponding steel bar through which the wire hole passes. Figure 1 、 Figure 2 、 Figure 3 、 Figure 5 shown.

[0023] The outer end of the box of the inlet mold and the inner end of the box of the outlet mold are both bell mouths. The small end of the bell mouth 7 of the inlet mold is connected to the wire hole 6 of the inlet mold. The large end of the bell mouth 11 of the outlet mold is located at the stopper, and the small end is connected to the wire hole 10 of the outlet mold. The axis of the bell mouth is located on the same straight line as the stopper or on the same straight line as the wire hole on the corresponding mold. The taper of the bell mouth is 40° to 60°. The taper of the bell mouth refers to the angle formed after the bell mouth is opened, that is, Figure 1 、 Figure 2 、 Figure 3 The angle between the upper and lower sides of the middle bell mouth.

[0024] The following table shows the corresponding hole sizes on the mold for common cold-rolled steel bar diameter specifications:

[0025]

[0026] The diameter of the stopper is 0.3 mm larger than the outer diameter of the insulating tube. The mold material can be 5CrMnMo mold steel.

[0027] In this system, the two wire holes are set up and down off the axis of the stopper, which can produce a better effect than the case where the three are concentric. Figure 4 The technical effect of the invention is further optimized (in the case of a wire hole 16 of the same size concentric with the steel bar) as described below: When designing the wire hole in the mold, both the guiding and limiting function and the smooth passage of the steel bar must be considered. When the wire hole is small, its guiding and limiting function is good, but it is easy to cause material blockage. Especially in high-speed cold rolling, when the wire hole is large, its guiding and limiting function is reduced, but the material can pass smoothly. Because the wire hole wears to a certain size and becomes ineffective, when the hole diameter increases, the life of the mold is shortened, replacement becomes more frequent, and the cost of consumables is high. Therefore, the wire hole can only be made as small as possible while ensuring smooth passage of the material. If it is reduced to a certain size, it will cause material to pass smoothly.

[0028] In this system, the diameters of the two wire holes are as small as possible to ensure smooth passage of materials. The interface diagram after eccentric setting is as follows: Figure 5 As shown, from Figure 5 It can be seen that after the eccentric setting, the steel bar is actually in the "eye"-shaped hole formed by the overlapping part of the front and rear guide holes. The upper and lower spaces of this "eye"-shaped hole are significantly smaller than those of the wire hole. This is actually equivalent to using a smaller "eye"-shaped hole for guidance and limitation. This limitation can make the axis of the steel bar closer to the axis of the insulating tube during the heating process, achieving better energy-saving effects. At the same time, it can also better prevent vibration waves from affecting the insulating tube and spiral coil. At the same time, because the wire hole itself can meet the requirements of smooth material flow, the diameter of the wire hole is reduced while ensuring smooth material flow. In addition, this arrangement can also extend the service life of the mold, because the offset of the two wire holes actually makes the wire hole diameter smaller. From the above description, we know that the smaller the wire hole diameter, the larger the amount that can be ground, and the longer the service life. Taking 6mm steel bars as an example, the wire hole is 9mm; if it is worn to 12mm, it must be scrapped. The wear on each side is 1.5mm. The wire hole is offset to 0.25 times the steel bar diameter, that is, 1.5mm, which is equivalent to doubling the wear on one side of the wire hole. In actual application, the service life of the mold is extended by about 1.8 times in this case. Because of the factor of increased wear on one side, the present invention can also effectively extend the service life of the mold.

[0029] After describing the embodiments of the present invention in detail, people familiar with the technology can clearly understand that various changes and modifications can be made without departing from the scope and spirit of the above-mentioned patent application. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are within the scope of the technical solution of the present invention, and the present invention is not limited to the embodiments of the examples given in the specification.

Claims

1. A high-efficiency centering coil heating system for high-speed cold-rolled steel bars, comprising an induction coil with an insulating tube concentrically passing through the induction coil, characterized in that: The induction coil and insulating tube are located in an insulating box, and an inlet mold and an outlet mold are respectively installed on the front end plate and the rear end plate of the insulating box. The inlet mold and the outlet mold are respectively processed with stoppers that match the insulating tube near the end of the insulating tube, and the two ends of the insulating tube are matched at the stoppers. The axis of the stoppers and the insulating tube are located on the same straight line. Wire holes that communicate with the stoppers are respectively opened on the inlet mold and the outlet mold. The axis of the wire hole on the inlet mold deviates from the axis of the stoppers, or the axis of the wire hole on the outlet mold deviates from the axis of the stoppers, or the axis of the wire hole on the inlet mold and the axis of the wire hole on the outlet mold both deviate from the axis of the stoppers, and the axis of the wire hole on the inlet mold and the axis of the wire hole on the outlet mold are both parallel to the axis of the stoppers.

2. The high-speed cold-rolled steel bar high-efficiency centering coil heating system according to claim 1, characterized in that: The axes of the wire holes on the inlet mold and the outlet mold deviate from the axis of the stopper. The deviation directions of the axes of the wire holes on the inlet mold and the outlet mold are opposite, and the deviation amounts are equal.

3. The high-efficiency centering coil heating system for high-speed cold-rolled steel bars according to claim 2, characterized in that: The axis of the wire hole on the wire inlet mold deviates upward from the axis of the stopper, and the axis of the wire hole on the wire outlet mold deviates downward from the axis of the stopper.

4. The high-efficiency centering coil heating system for high-speed cold-rolled steel bars according to claim 1 is characterized in that: The diameter of the wire hole is 1.3-1.6 times the diameter of the corresponding steel bar.

5. The high-efficiency centering coil heating system for high-speed cold-rolled steel bars according to claim 3 is characterized in that: The value of the upward deviation of the axis of the wire hole on the wire feeding mold from the stop is 0.1-0.3 times the diameter of the corresponding steel bar passing through the wire hole.

6. The high-efficiency centering coil heating system for high-speed cold-rolled steel bars according to claim 1 is characterized in that: The outer end of the box of the inlet mold and the inner end of the box of the outlet mold are both bell mouths. The small end of the bell mouth of the inlet mold is connected to the wire hole of the inlet mold. The large end of the bell mouth of the outlet mold is located at the stop, and the small end is connected to the wire hole of the outlet mold. The axis of the bell mouth is located on the same straight line as the stop or on the same straight line as the wire hole on the corresponding mold.

7. The high-efficiency centering coil heating system for high-speed cold-rolled steel bars according to claim 1 is characterized in that: The entire length of the wire inlet mold and the wire outlet mold is provided with a gap which is communicated with the wire hole in the radial direction.

8. The high-efficiency centering coil heating system for high-speed cold-rolled steel bars according to claim 6, characterized in that: The taper of the bell mouth is 40° to 60°.

9. The high-speed cold-rolled steel bar high-efficiency centering coil heating system according to claim 1, characterized in that: The insulating tube is a mica tube or a corundum tube.

Images