JP2015093277A - Mold for continuous casting and continuous casting method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for continuous casting which is provided with a vibration device, can enhance filling properties of a mold flux film between the mold and a solidification shell while reducing friction between the mold and the solidification shell, and further has high durability.SOLUTION: A mold for continuous casting is provided with a vibration device. The vibration device comprises: a plurality of suspension members comprising plate springs for suspending the mold so as to enable vibration displacement thereof in a vertical direction and a horizontal direction; a vertical drive device for vibrating the mold in the vertical direction; and a horizontal drive device for vibrating the mold in the horizontal direction. Concerning stiffness of the plurality of suspension members, stiffness thereof with respect to the vibration displacement in the horizontal direction is greater than stiffness thereof with respect to the vibration displacement in the vertical direction. It is preferable that the suspension members comprise vertical plate springs extending out in the vertical direction and having upper and lower ends joined to the mold and horizontal plate springs extending out in the horizontal direction and having one ends joined to the vertical plate springs.

Description

  The present invention relates to a continuous casting mold with a vibration device to promote lubrication between the mold and the solidified shell of the slab. The present invention also relates to a continuous casting method using the continuous casting mold.

  In continuous casting of steel, it is important to ensure a lubricity between the mold and the solidified shell by allowing mold flux to flow smoothly between the mold and the solidified shell. As a method for enhancing the lubricating action between the mold and the solidified shell, there is a method of imparting vibration to the mold. For example, in Patent Document 1, by applying ultrasonic vibration to a mold and periodically changing the vibration frequency within a certain range, the frictional resistance between the mold and the solidified shell is reduced uniformly, and the mold flux A method for making the flow of the water uniform is disclosed.

  In Patent Document 2, the vertical vibration waveform of the mold is changed to a waveform deviated from a sine wave, the positive strip time is lengthened, and the amount of mold flux flowing into the mold and the solidified shell is increased. Is disclosed. The positive strip time means the length of a period in which the speed of the mold in the drawing direction of the slab is faster than the drawing speed of the slab during one vibration period of the mold.

Japanese Patent Publication No.59-6735 Japanese Examined Patent Publication No. 4-79744

  However, although the method described in Patent Document 1 can achieve a certain effect of improving the lubrication action, since the ultrasonic vibration is easily attenuated, the complexity of having to install a large number of ultrasonic vibrators and the ultrasonic vibration Corrosion of the copper plate that constitutes the casting mold becomes a problem. For this reason, the method described in the document has never been put to practical use.

  Moreover, although the method of patent document 2 can obtain the improvement effect of a fixed lubrication effect | action, the effect was limited. Further, this method has little effect of improving the filling property of the mold flux film between the mold and the solidified shell, and the solidified shell cannot be stably cooled.

  The present invention has been made in view of these problems, and it is possible to reduce the frictional resistance between the mold and the solidified shell and improve the filling property of the mold flux film between the mold and the solidified shell. It is an object of the present invention to provide a continuous casting mold having higher durability. Another object of the present invention is to provide a method for continuously casting a slab using the continuous casting mold.

  In order to solve the above problems, the present inventors first examined a mold that can vibrate the mold in the horizontal direction in addition to the vibration in the vertical direction.

  In order to realize horizontal and vertical vibrations using a conventional lever-type mold vibration device, there are the following problems. The lever-type mold vibration device is a device in which a lever suspends a mold and constitutes a link, and vibration generated by a drive device is transmitted to the mold as vertical vibration through the link. In order to apply horizontal vibration to the mold with this vibration device, the shape of the bearing of the rotary shaft is an oblong shape that is long in the horizontal direction so that the rotary shaft of the lever that suspends the mold can be displaced in the horizontal direction. It is difficult to design such as having a shape such as the above or a circle having a diameter larger than that of the rotation axis. In addition, when the bearing is made oval or larger than the shaft, the rotating shaft has a backlash with respect to the bearing, and an impact is generated between the rotating shaft and the bearing when the mold is vibrated. The durability of the bearing is reduced.

  The present inventors proceeded with investigations based on these problems, and by utilizing the elastic expansion and contraction of the leaf springs by suspending the mold on the support using suspension members composed of a plurality of leaf springs. Amplitude can be obtained, and it is suitable for vibration addition, and since there is no backlash part, it is high even if vertical and horizontal vibrations are applied to the mold using a driving device. It was found to have durability.

  And the present inventors examined the vibration method of a casting_mold | template using this casting_mold | template. The vertical vibration has a pumping action that promotes the flow of molten mold flux between the mold and the solidified shell. As a result of the study, the rigidity of the suspension member shall be greater for the horizontal vibration displacement than for the vertical vibration displacement, and a fine horizontal vibration should be added to the vertical vibration. In addition to the pumping action, it was found that the action of reducing the frictional resistance between the mold and the solidified shell and the action of increasing the filling property of the mold flux film between the mold and the solidified shell can be obtained.

  This invention is made | formed based on such knowledge, The summary exists in the casting mold for continuous casting provided with the following vibration apparatus.

  A continuous casting mold provided with a vibration device, wherein the vibration device includes a plurality of suspension members made up of leaf springs for suspending the mold in a vertical and horizontal direction, and the mold in the vertical direction. It consists of a vertical drive device that vibrates and a horizontal drive device that vibrates the mold in the horizontal direction, and the rigidity of the suspension member is greater with respect to the horizontal vibration displacement than with respect to the vertical vibration displacement. A casting mold for continuous casting characterized by the above.

  In the continuous casting mold according to the present invention, the suspension member extends along the vertical direction, the upper and lower ends extend along the horizontal direction, and one end extends along the horizontal direction. It is good also as what consists of a horizontal leaf | plate spring joined to. The suspension member may be composed of a pair of inclined leaf springs having an inclination with respect to the horizontal direction and having one end joined to the mold. Furthermore, you may provide the tension | pulling apparatus which adjusts the tension | tensile_strength provided to the said suspension member.

  The vertical drive device may be a hydraulic cylinder, and the horizontal drive device may be a vibrator that rotates an eccentric weight.

  The gist of the present invention resides in the following continuous casting method.

In the continuous casting method using the continuous casting mold of the present invention, the vertical vibration of the mold is 2 to 15 mm, the frequency is 10 to 500 cpm, and the following formula (1) The vertical driving device and the vertical driving device are set so that the negative strip speed ratio N satisfies the condition of 0 to 100%, and the horizontal vibration of the mold satisfies an amplitude of 1 to 1000 μm and a frequency of 10 to 10000 Hz. A continuous casting method, wherein the horizontal driving device is controlled.
N = (Vm−Vc) / Vc × 100 (1)
Here, N is the actual negative strip speed rate (%), Vm is the average value of the descending speed during the descending period in one vibration period of the vertical vibration of the mold, Vc is the casting speed of the slab, and Vm and Vc. The vertical direction is positive.

  In the continuous casting method of the present invention, it is preferable to control the horizontal driving device or the tensioning device so that the time average value of the amplitude of the horizontal vibration of the mold satisfies 5 to 150 μm.

  According to the continuous casting mold of the present invention, it is possible to give the mold a vibration obtained by adding a fine horizontal vibration to the vertical vibration, reducing the frictional resistance between the mold and the solidified shell, The filling property of the mold flux film between the mold and the solidified shell can be enhanced. Therefore, it is possible to cool the solidified shell stably. In addition, the continuous casting mold of the present invention has high durability because it does not have backlash.

  According to the continuous casting method of the present invention, since this continuous casting mold is used, a slab can be stably produced over a long period of time.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows 1 aspect of the casting mold for continuous casting of this invention, The figure (a) is a top view, The figure (b) is A direction sectional drawing of the figure (a). It is a block diagram which shows another aspect of the casting mold for continuous casting of this invention, The figure (a) is a top view, The figure (b) is B direction sectional drawing of the figure (a). It is a block diagram which shows another aspect of the casting mold for continuous casting of this invention, The figure (a) is a top view, The figure (b) is C direction sectional drawing of the figure (a). It is a block diagram which shows the aspect of the casting_mold | template for continuous casting of a comparative example, the figure (a) is a top view, The figure (b) is D direction sectional drawing of the figure (a).

1. 1. Configuration of Continuous Casting Mold of the Present Invention FIG. 1 is a configuration diagram showing one embodiment of the continuous casting mold of the present invention, FIG. 1 (a) is a plan view, and FIG. It is A direction sectional drawing of a). A mold 1 shown in FIG. 1 is an assembly mold including a pair of long side copper plates 11, a pair of short side copper plates 12, and a cooling box 13 surrounding these copper plates. Cooling water for cooling the long side copper plate 11 and the short side copper plate 12 flows through the cooling box 13. In the vicinity of the side surface of the mold 1, a distance meter 2 for measuring the vibration displacement from the stationary state of the mold 1 is disposed. The distance meter 2 may be a vortex type or a laser type as long as it is a non-contact type.

  The mold 1 is suspended between two support walls 4 arranged in parallel by a suspension member 3 composed of a plurality of leaf springs. The support wall 4 is provided so as to stand upright on the upper surface of the support base 5, and a vertical driving device 6 that vibrates the mold 1 in the vertical direction is disposed so as to contact the upper surface of the support base 5 and the lower surface of the cooling box 13. The FIG. 1 shows an example in which a hydraulic stepping cylinder is arranged as the vertical drive device 6. Further, a horizontal driving device 7 that vibrates the mold 1 in the horizontal direction is disposed on a side surface of the cooling box 13 connected to the suspension member 3. The figure shows an example in which a vibrator is arranged as the horizontal driving device 7. As the vibrator, for example, a type in which an eccentric weight is rotated by a motor can be used. A roller apron 8 for guiding the cast slab is disposed below the mold 1.

  A total of four suspension members 3 are arranged on the side surface of the cooling box 13 that faces the support wall 4. Each suspension member 3 includes a vertical leaf spring 31 that is a leaf spring extending along the vertical direction and a horizontal leaf spring 32 that is a leaf spring extending along the horizontal direction. As shown in FIG. 1B, the upper and lower ends of the vertical leaf spring 31 are joined to a recess provided on the side surface of the cooling box 13. One end of the horizontal plate spring 32 in the longitudinal direction is joined to the support wall 4, and the other end is firmly joined to the center of the vertical plate spring 31 in the longitudinal direction by bolts and nuts or welding. The horizontal plate spring 32 is mainly responsible for the vertical vibration displacement, and the vertical leaf spring 31 is mainly responsible for the horizontal vibration displacement.

  The horizontal leaf spring 32 bends due to the weight of the mold 1 when the mold 1 is suspended. Therefore, the horizontal leaf spring 32 is not strictly horizontal even when the vibration device is not driven, and allows a slight inclination. .

  The rigidity of the suspension member 3 is set to be greater with respect to the horizontal vibration displacement than with respect to the vertical vibration displacement. Such rigidity of the suspension member 3 can be realized by making the rigidity of the vertical leaf spring 31 larger than that of the horizontal leaf spring 32. For example, when the vertical leaf spring 31 and the horizontal leaf spring 32 are made of the same material, the thickness of the vertical leaf spring 31 is made larger than the thickness of the horizontal leaf spring 32, or the length of the vertical leaf spring 31 is set to the horizontal leaf spring 32. It can be realized by making it longer than the length of.

  When the mold 1 is vibrated by the vertical drive device 6 and the horizontal drive device 7 by increasing the rigidity of the suspension member 3 with respect to the horizontal vibration displacement, rather than the rigidity with respect to the vertical vibration displacement. The horizontal vibration has a smaller amplitude and a higher frequency than the vertical vibration. As a result, it is possible to reduce the frictional resistance between the mold and the solidified shell during continuous casting and to increase the filling property of the mold flux film between the mold and the solidified shell.

  In FIG. 1, the suspension members 3 are arranged at the four corners of the mold 1. However, as long as the mold 1 can be stably suspended, the number and position of the suspension members 3 are not limited thereto.

  The suspension member may be any member that can suspend the casting mold so as to be able to vibrate and displace in the vertical direction and the horizontal direction, and is not limited to the one composed of the vertical leaf spring and the horizontal leaf spring shown in FIG.

  2A and 2B are configuration diagrams showing another embodiment of the continuous casting mold of the present invention, in which FIG. 2A is a plan view, and FIG. 2B is a cross-sectional view in the B direction of FIG. . The mold shown in the figure has the same configuration as the mold shown in FIG. 1 except that the shape of the suspension member is different, and substantially the same parts are denoted by the same reference numerals.

  In the mold 1 shown in FIG. 2, each suspension member 3 includes a pair of upper and lower inclined leaf springs 33 having an inclination with respect to the horizontal direction. Each of the two inclined leaf springs 33 has one end in the longitudinal direction joined to the vicinity of the center in the vertical direction of the side surface of the cooling box 13, and the other end joined to the support wall 4.

  Generally, a suspension member for suspending a mold mainly takes a vibration displacement in a vertical direction when arranged horizontally like the horizontal leaf spring shown in FIG. Further, when arranged vertically like the vertical leaf spring shown in FIG. 1, it mainly takes charge of the horizontal vibration displacement. On the other hand, when the suspension member is arranged to be inclined from the horizontal direction, the suspension member has a characteristic of handling the horizontal vibration displacement in addition to the vertical vibration displacement. The proportion of the horizontal vibration displacement that is handled increases as the inclination increases. For this reason, as shown in FIG. 2, by arranging the inclined plate spring 33 so that the horizontal length thereof is longer than the vertical length, that is, the inclination of the inclined plate spring 33 from the horizontal direction is 45 °. By arrange | positioning so that it may become the following, the rigidity with respect to the horizontal vibration displacement of the suspension member 3 can be made larger than the rigidity with respect to a perpendicular direction. The inclination of the inclined leaf spring 33 from the horizontal direction is preferably in the range of 3 to 30 °.

  The suspension member 3 shown in FIG. 2 utilizes the characteristics of the inclined leaf spring, and an unexpected vibration mode is likely to occur compared to the suspension member composed of the horizontal leaf spring and the vertical leaf spring shown in FIG. While designing is difficult, there is an advantage that the structure is simple and can be manufactured at low cost.

  On the other hand, since the suspension member shown in FIG. 1 separately handles the vertical vibration displacement and the horizontal vibration displacement by a horizontal leaf spring and a vertical leaf spring having different installation directions, respectively, the suspension member shown in FIG. There is an advantage that the degree of freedom of design is high.

  Here, strictly speaking, the horizontal leaf spring of the suspension member also has elasticity in the horizontal direction and expands and contracts in the horizontal direction, so that itself can be displaced in the horizontal direction. Therefore, if a horizontal driving device having a large driving force is used, the vertical leaf spring is eliminated from the suspension member shown in FIG. 1, and the horizontal vibration displacement is possible only with the horizontal leaf spring. However, as in the case of the suspension member shown in FIG. 1, when the vertical vibration displacement and the horizontal vibration displacement are divided into horizontal leaf springs and vertical leaf springs having different installation directions, only the horizontal leaf springs are used for suspension. Compared with, design is possible.

  FIG. 3 is a block diagram showing another embodiment of the continuous casting mold of the present invention, where FIG. 3 (a) is a plan view and FIG. 3 (b) is a cross-sectional view in the direction C of FIG. 3 (a). . The mold shown in the figure has the same configuration as the mold shown in FIG. 1 except that the suspension member includes a tension device, and substantially the same parts are denoted by the same reference numerals.

  The mold and the suspension member that suspends the mold integrally have a natural frequency, and this natural frequency can be changed depending on the cross-sectional shape and length of the plate spring of the suspension member. The natural frequency is desirably small when a vibration having a large amplitude and a small frequency is added, and is desirably large when a vibration having a small amplitude and a large frequency is added. However, as shown in FIG. 1 and FIG. 2, when the leaf spring is joined to another member, the natural frequency is uniquely determined and cannot be adjusted.

  Therefore, as shown in FIG. 3, a tension device 34 is provided between one end of the vertical leaf spring 31 and the cooling box 13 of the mold 1 to apply a tension force to the vertical leaf spring 31 and adjust the tension force. Provide. By adjusting the tensile force applied to the vertical leaf spring 31 using the tension device 34, the natural frequency of the mold and the suspension member can be adjusted to an appropriate value according to the casting conditions and the vibration conditions of the mold. It is. As the tension device 34, for example, a hydraulic cylinder can be used.

  Although FIG. 3 shows an example in which the tension device 34 is provided only on the vertical leaf spring 31, the tension device 34 may be provided on both the vertical leaf spring 31 and the horizontal leaf spring 32, or only one of them. It may be provided. When provided on the horizontal plate spring 32, it may be provided on the support wall 4 side or on the cooling box 13 side.

  In addition, the inclined plate spring 33 shown in FIG. Also in this case, the tension device 34 may be provided on the support wall 4 side or may be provided on the cooling box 13 side.

  In the continuous casting mold of the present invention, it is preferable to use a hydraulic cylinder as the vertical driving device and a vibrator that rotates the eccentric weight as the horizontal driving device.

  The vertical drive device has a pump function of pushing the melted mold flux between the mold and the solidified shell by the interaction between the vertical vibration of the mold and the movement of the solidified shell in the casting direction. Therefore, it is necessary to be able to control vibration conditions such as frequency and amplitude according to the casting speed, and it is preferable to use a hydraulic cylinder.

  In addition, the horizontal drive device applies fine vibration having a higher frequency than vibration in the vertical direction to the mold to reduce the frictional resistance between the mold and the solidified shell, and between the mold and the solidified shell. It aims at improving the filling property of the mold flux film in. In order to achieve these objectives, it is not necessary to strictly control the amplitude of the horizontal vibration, and no problem arises even if the vibration frequency is constant regardless of the casting conditions. For this reason, a vibrator that rotates the eccentric weight is used as the horizontal driving device, and vibration is performed at the natural frequency of the casting mold and the suspension member, so that an inexpensive and reasonable design is possible. Even if the vibration of the vibrator generates a vibration that is superimposed on the vertical vibration by the hydraulic cylinder as a result, no problem occurs.

2. The continuous casting method of the slab of the present invention The continuous casting method of the slab of the present invention uses the above-described continuous casting mold of the present invention, and the vibration in the vertical direction of the mold is 2 to 15 mm and the frequency is 10. A vertical drive device that satisfies the conditions of ˜500 cpm and the actual negative strip speed rate of 0 to 100%, and the horizontal vibration of the mold satisfies the amplitude of 1 to 1000 μm and the frequency of 10 to 10,000 Hz. And a method of controlling the horizontal drive.

The actual negative strip speed rate is a value indicating how much the average value of the speed during the period in which the mold that vibrates up and down is lower than the casting speed of the slab, and is calculated by the following equation (1). be able to.
N = (Vm−Vc) / Vc × 100 (1)
Here, N is the actual negative strip speed rate (%), Vm is the average value of the descending speed during the descending period in one vibration period of the vertical vibration of the mold, Vc is the casting speed of the slab, and Vm and Vc. The vertical direction is positive.

  In the conventional continuous casting method in which the mold is vibrated only in the vertical direction, the vibration in the vertical direction of the mold is normally 2 to 15 mm, the frequency is 10 to 500 cpm, and the actual negative strip speed ratio is 0 to 100. The vertical drive device was controlled according to the casting speed so as to satisfy the condition of%.

  On the other hand, in the continuous casting method of a slab according to the present invention, horizontal vibration is added in addition to the conventional vertical vibration conditions. This horizontal vibration has an amplitude of 1-1000 μm and a frequency of 10-10000 Hz. As long as the amplitude and frequency in the horizontal direction are within the specified range, they may be changed according to casting conditions such as casting speed, or may be kept constant at all times.

  According to the continuous casting method of the present invention, it is possible to reduce the frictional resistance between the mold and the solidified shell and to increase the filling property of the mold flux film between the mold and the solidified shell. It is possible to promote lubrication with the shell and to cool the solidified shell stably. In addition, the continuous casting method of the present invention uses the continuous casting mold of the present invention having high durability by using a suspension member made of a leaf spring, so that a slab can be manufactured stably over a long period of time. Can do.

  When the amplitude of the vibration in the horizontal direction is smaller than 1 μm, an effect such as enhancing the filling property of the mold flux film cannot be obtained. On the other hand, if the amplitude of the vibration in the horizontal direction is larger than 1000 μm, the slab is excessively strained, causing a crack at the solidification interface, and an internal crack remains in the manufactured slab. Therefore, the amplitude of the horizontal vibration is set to 1 to 1000 μm.

  On the other hand, when the frequency of horizontal vibration is less than 10 Hz, the effect of improving the filling property of the mold flux film cannot be obtained. On the other hand, in order to set the frequency of the horizontal vibration to a value higher than 10000 Hz, the rigidity of the leaf spring constituting the suspension member must be excessively increased. Even if the rigidity is increased, an excessive driving force is required for the horizontal driving device in order to obtain an amplitude in the range of 1 to 1000 μm, which is not practical for industrial use. Therefore, the frequency of the horizontal vibration is 10 to 10,000 Hz. When a vibrator that rotates an eccentric weight is used as the horizontal drive device, the frequency of horizontal vibration can be changed according to casting conditions.

  Furthermore, it is preferable to control the horizontal driving device or the tension device so that the time average value of the amplitude of the vibration in the horizontal direction of the mold satisfies 5 to 150 μm. Thereby, the filling property of the mold flux film between a casting_mold | template and a solidification shell can be improved more.

  Here, the “time average value of the amplitude of the horizontal vibration of the mold” is a value obtained by calculating an average value of all strokes (amplitudes) of the horizontal vibration of the mold over an arbitrary operation time of 10 cycles or more of vibration. Say.

  In the continuous casting mold of the present invention, since the mold is suspended by a suspension member made of a leaf spring, it is difficult to keep the amplitude constant when the mold is vibrated. For example, when the target value of the horizontal amplitude of the mold is set to 100 μm, the actual value may vary between 50 and 150 μm. In such a case, the time average value of the amplitude for 1 minute immediately before the control time point is used as the reference value for controlling the amplitude, and the output of the horizontal drive device (the inertial force of the vibrator) so that this reference value approaches the target value. ) May be controlled.

1. Invention Example 1
A specific example (invention example 1) of the continuous casting mold of the embodiment shown in FIG. 1 will be described. In the mold of Example 1 of the present invention, the suspension member 3 composed of the horizontal leaf springs 32 and the vertical leaf springs 31 is arranged in a total of four sets, one set at each of the four corners of the cooling box 13 of the mold 1. Further, two stepping cylinders are arranged as the vertical driving device 6, and two vibrators are arranged as the horizontal driving device 7. In the vicinity of the side surface of the mold 1, a vortex type distance meter 2 is arranged.

  In this mold, a vibration in the vertical direction is mainly generated by the vibration applied by the vertical driving device 6 and the elastic expansion and contraction of the horizontal leaf spring 32, and the vibration applied by the horizontal driving device 7 and the elastic force of the vertical leaf spring 31 are generated. The horizontal deflection mainly causes horizontal vibration.

  The horizontal leaf spring 32 constituting the suspension member 3 was made of steel having a width of 180 mm, a thickness of 30 mm, and a length of 800 mm, and the vertical leaf spring 31 was made of steel having a width of 180 mm, a thickness of 70 mm, and a length of 500 mm. One end of the horizontal leaf spring 32 is firmly joined to the center of the vertical leaf spring 31 in the vertical direction by welding. Since the vertical leaf spring 31 is thicker and shorter than the horizontal leaf spring 32, the vertical leaf spring 31 has higher rigidity than the horizontal leaf spring 32, and the rigidity of the suspension member 3 is higher in the horizontal direction than in the vertical direction against vibration displacement. The rigidity against vibration displacement was larger.

  The weight of the mold 1 was 10 t, and the natural frequency in the horizontal direction between the vertical leaf spring 31 and the mold 1 was 200 Hz.

  The vibrator as the horizontal driving device 7 is a type in which an eccentric weight is rotated by a motor, the degree of eccentricity of the weight can be changed steplessly, and the inertial force can be adjusted. The maximum frequency of the vibrator was 300 Hz, and it was possible to generate an inertial force of a maximum of 100 kN with two.

  When continuous casting is performed using the mold of Example 1 of the present invention, the horizontal vibration of the mold is measured using a distance meter while operating the vibrator at 200 Hz which is the natural frequency of horizontal vibration during operation. The amplitude is measured, and the inertial force generated by the vibrator is adjusted so that the time average value of the amplitude in the horizontal direction is in the range of 5 to 20 μm. If the time average value of the horizontal amplitude exceeds 20 μm even after adjusting the inertial force, the horizontal frequency is adjusted by shifting the operating frequency of the vibrator horizontal drive device 7 from 200 Hz.

2. Invention Example 2
A specific example (invention example 2) of the continuous casting mold of the embodiment shown in FIG. 2 will be described. In the mold of Example 2 of the present invention, a suspension member 3 composed of two upper and lower inclined leaf springs 33 arranged so that the normal line of the surface is inclined from the vertical direction is set in one set at four corners of the cooling box 13 of the mold 1. A total of 4 sets were arranged. Further, two stepping cylinders are arranged as the vertical driving device 6, and two vibrators are arranged as the horizontal driving device 7. In the vicinity of the side surface of the mold 1, a vortex type distance meter 2 is arranged.

  In this mold, vertical and horizontal vibrations are generated by the vibrations applied by the vertical driving device 6 and the horizontal driving device 7 and the elastic expansion and contraction and bending of the inclined leaf springs 33 arranged at an angle.

  The inclined leaf spring 33 constituting the suspension member 3 is made of steel having a width of 150 mm, a thickness of 50 mm, and a length of 1020 mm, and is inclined so that the horizontal length is 1000 mm and the vertical length is 200 mm. That is, the inclined leaf spring 33 is disposed so as to be inclined 11.3 ° from the horizontal direction. Since the horizontal length of the inclined leaf spring is longer than the vertical length and the inclination of the inclined leaf spring from the horizontal direction is 45 ° or less, the rigidity of the suspension member 3 is higher than the rigidity against the vibration displacement in the vertical direction. However, the rigidity against the vibration displacement in the horizontal direction was larger.

  The weight of the mold 1 was 8 t, and the natural frequency in the horizontal direction between the inclined leaf spring 33 and the mold 1 was 170 Hz.

  The vibrator as the horizontal driving device 7 is a type in which an eccentric weight is rotated by a motor, the degree of eccentricity of the weight can be changed steplessly, and the inertial force can be adjusted. The maximum frequency of the vibrator was 200 Hz, and it was possible to generate an inertial force of up to 80 kN with two.

  When continuous casting is performed using the mold of Example 2 of the present invention, during operation, the vibrator is operated at 170 Hz, which is the natural frequency of horizontal vibration, and the horizontal vibration of the mold is measured using a distance meter. The amplitude is measured, and the inertial force generated by the vibrator is adjusted so that the time average value of the amplitude in the horizontal direction is in the range of 20 to 150 μm. If the time average value of the horizontal amplitude exceeds 150 μm even after adjusting the inertial force, the horizontal frequency is adjusted by shifting the operating frequency of the vibrator from 170 Hz.

3. Invention Example 3
A specific example (Example 3 of the present invention) of the continuous casting mold of the embodiment shown in FIG. 3 will be described. In the mold of Example 3 of the present invention, the suspension member 3 composed of the horizontal leaf springs 32 and the vertical leaf springs 31 is arranged in a total of four sets, one set at each of the four corners of the cooling box 13 of the mold 1. Further, two stepping cylinders are arranged as the vertical driving device 6, and two vibrators are arranged as the horizontal driving device 7. A laser type distance meter 2 was disposed in the vicinity of the side surface of the mold 1.

  In this mold, a vibration in the vertical direction is mainly generated by the vibration applied by the vertical driving device 6 and the elastic expansion and contraction of the horizontal leaf spring 32, and the vibration applied by the horizontal driving device 7 and the elastic force of the vertical leaf spring 31 are generated. The horizontal deflection mainly causes horizontal vibration.

  The horizontal leaf spring 32 constituting the suspension member 3 was made of steel having a width of 110 mm, a thickness of 30 mm, and a length of 900 mm, and the vertical leaf spring 31 was made of steel having a width of 110 mm, a thickness of 50 mm, and a length of 400 mm. One end of the horizontal leaf spring 32 is firmly joined to the center of the vertical leaf spring 31 in the vertical direction by welding. Since the vertical leaf spring 31 is thicker and shorter than the horizontal leaf spring 32, the vertical leaf spring 31 has higher rigidity than the horizontal leaf spring 32. The rigidity of the suspension member 3 is higher than the vibration against the vertical vibration displacement in the horizontal direction. The rigidity against was larger.

  Between one end of the vertical leaf spring 31 and the cooling box 13 of the mold 1, a hydraulic cylinder is provided as a tension device 34 that applies a tensile force to the vertical leaf spring 31. The maximum tensile force that can be applied by the hydraulic cylinder was 800 kN.

  The weight of the mold 1 is 12 t, and the natural frequency in the horizontal direction between the vertical leaf spring 31 and the mold 1 is 120 Hz when the displacement of the hydraulic cylinder is fixed and no tensile force is applied to the vertical leaf spring 31. . The maximum horizontal natural frequency obtained by adjusting the tensile force applied by the hydraulic cylinder was 200 Hz.

  The vibrator as the horizontal driving device 7 is a type in which an eccentric weight is rotated by a motor, the degree of eccentricity of the weight can be changed steplessly, and the inertial force can be adjusted. The maximum frequency of the vibrator was 200 Hz, and it was possible to generate an inertial force of up to 50 kN with two.

  When performing continuous casting using the mold of Example 3 of the present invention, the horizontal direction of the mold using a distance meter while operating the vibrator at 120 to 150 Hz, which is within the range of the natural frequency in the horizontal direction, during operation. , And the inertial force generated by the vibrator is adjusted so that the time average value of the horizontal amplitude is in the range of 10 to 50 μm. Even if the inertial force is adjusted, if the time average value of the amplitude in the horizontal direction exceeds 50 μm, the tension applied to the vertical leaf spring is increased, and the natural frequency in the horizontal direction is shifted from the operating frequency of the vibrator, Adjust the horizontal amplitude.

4). Comparative example

  4A and 4B are configuration diagrams showing an aspect of a continuous casting mold of a comparative example, where FIG. 4A is a plan view, and FIG. 4B is a cross-sectional view in the direction D of FIG. The mold shown in the figure is substantially the same as the mold shown in FIG. 1 except that the form of the suspension member is different, the distance meter is not provided, and the horizontal drive device is not provided. The same parts are denoted by the same reference numerals.

  In the mold of the comparative example, a total of four sets of eight suspension members 3 each consisting of only two horizontal plate springs 35 arranged horizontally are arranged at the four corners of the cooling box 13 of the mold 1 in total. Further, two stepping cylinders are arranged as the vertical drive device 6.

  In this mold, the vibration in the vertical direction is generated by the vibration applied by the vertical drive device 6 and the elastic expansion and contraction and bending of the horizontal leaf spring 35. There is almost no horizontal vibration. The horizontal leaf spring 35 constituting the suspension member 3 was made of steel having a width of 150 mm, a thickness of 30 mm, and a length of 800 mm.

5. Continuous Casting Test In order to confirm the effect of the continuous casting method of the present invention, a test for continuously casting a slab using the mold of Example 1 of the present invention and the mold of a comparative example was performed, and the results were evaluated.

5-1. Test Method The cast of the slab was subjected to a continuous casting test by placing the mold of Example 1 of the present invention and the mold of the comparative example on a vertical bending type continuous casting machine. The size of the cross section of the inner wall surface of the mold composed of the long side copper plate and the short side copper plate was 250 mm in thickness and 1300 mm in width. The effective length of the mold was 800 mm. The long side copper plate of the mold was 30 mm thick.

  The molten steel used contained, in mass%, C: 0.04%, Si: 0.01%, Mn: 0.35%, acid-soluble Al: 0.03%, with the balance being Fe and impurities. Low carbon aluminum killed steel was cast at a drawing speed of 1.5 m / min.

Mold flux used, the proportion of CaO and SiO ₂ as the main component in the chemical composition (CaO / SiO ₂₎ is 1.20, Al ₂ O ₃ as the other properties modifying component, MgO, Na ₂ O and F It was made of the brand containing. This mold flux, once melted, has a viscosity at 1300 ° C. of 0.3 Pa · s, and when melted, it is crystallized at 1150 ° C. when cooled at a cooling rate of 1 ° C./min. There was something.

  In continuous casting using the mold of Example 1 of the present invention, the mold is vibrated in the vertical direction using the stepping cylinder under the following conditions, and the vibration frequency of each vibrator is set to the natural frequency in the horizontal direction between the vertical leaf spring and the mold. The inertial force generated by the two vibrators was changed in a total of 10 to 100 kN, and the time average value of the horizontal amplitude of the mold was controlled so as to approach the target value of 50 μm. As a result, the actual value of the time average value of the amplitude in the horizontal direction was in the range of 20 to 100 μm. Here, the horizontal amplitude of the mold was measured using an eddy current distance meter, and feedback control was performed using this measured value.

  In continuous casting using the mold of the comparative example, the mold was vibrated in the vertical direction using the stepping cylinder under the following conditions, and was not vibrated in the horizontal direction.

In continuous casting using the molds of Example 1 of the present invention and the comparative example, the vertical vibration of the mold is 3 to 8 mm in amplitude, 50 to 300 cpm, and an actual negative strip represented by the following formula (1) The vertical drive device was controlled so as to satisfy the condition that the speed ratio N was 5 to 80%.
N = (Vm−Vc) / Vc × 100 (1)
Here, N is the actual negative strip speed rate (%), Vm is the average value of the descending speed during the descending period in one vibration period of the vertical vibration of the mold, Vc is the casting speed of the slab, and Vm and Vc. The vertical direction is positive.

5-2. Test results (1) Friction resistance The driving force generated by the stepping cylinder was measured during casting and during idling. A frictional resistance value generated between the inner wall surface of the mold and the cast slab was calculated from the difference between these driving forces. As a result, in the casting using the mold of Example 1 of the present invention, the frictional resistance value was 25% smaller on average than the casting using the casting mold of the comparative example. This is the effect of reducing the frictional resistance in the mold due to the application of vibration in the horizontal direction.

(2) Variation of mold temperature A thermocouple is installed at a position 10 mm away from the inner wall of the long side copper plate of the mold and half the width of the mold and 1/2 the effective length. did. Using this thermocouple, the temperature of the mold and its variation were measured.

  The standard deviation of the temperature variation of the mold was 2.8 ° C. in the casting using the mold of Example 1 of the present invention, and 4.5 ° C. in the comparative example. That is, when the mold of Example 1 of the present invention is used, the standard deviation of the temperature variation of the mold can be reduced to half that when the mold of the comparative example is used.

  When the temperature fluctuation of the mold becomes large, the cast slab surface is warped and separated from the inner wall of the mold when casting a steel grade with a large solidification shrinkage of the slab, or between the mold and the solidified shell of the slab. It is known that the mold flux film existing between them may be excessively crystallized, resulting in non-uniform voids between the mold flux film and the inner wall surface of the mold.

  The low carbon aluminum killed steel used in this test is a steel type with small solidification shrinkage. Therefore, the reason why the temperature fluctuation of the mold was small in the casting using the mold of Example 1 of the present invention was that the gap between the mold flux film and the inner wall surface of the mold was kept small, that is, the mold flux film It is considered that the filling property is high.

  According to the continuous casting mold of the present invention, it is possible to give the mold a vibration obtained by adding a fine horizontal vibration to the vertical vibration, reducing the frictional resistance between the mold and the solidified shell, The filling property of the mold flux film between the mold and the solidified shell can be enhanced. Therefore, it is possible to suppress the seizure between the mold and the solidified shell and to cool the solidified shell stably. Further, the continuous casting mold of the present invention uses a leaf spring suitable for adding vibration as a suspension member, and has high durability because it does not have backlash.

  According to the continuous casting method of the present invention, since this continuous casting mold is used, a slab can be manufactured stably over a long period of time.

1: mold, 11: long side copper plate, 12: short side copper plate, 13: cooling box, 2: distance meter,
3: Suspension member, 31: Vertical leaf spring, 32: Horizontal leaf spring, 33: Inclined leaf spring,
34: tension device, 35: horizontal leaf spring, 4: support wall, 5: support base,
6: Vertical drive device, 7: Horizontal drive device, 8: Roller apron

Claims (8)

A continuous casting mold provided with a vibration device,
The vibration device includes:
A plurality of suspension members composed of leaf springs for suspending the mold so that vibration displacement in the vertical and horizontal directions is possible;
A vertical drive device for vibrating the mold in the vertical direction;
It consists of a horizontal drive device that vibrates the mold in the horizontal direction,
The continuous casting mold according to claim 1, wherein the rigidity of the suspension member is greater with respect to horizontal vibration displacement than with respect to vertical vibration displacement.   The suspension member extends along a vertical direction, and has a vertical leaf spring whose upper and lower ends are joined to the mold, and a horizontal leaf spring that extends along a horizontal direction and one end is joined to the vertical leaf spring. The continuous casting mold according to claim 1, wherein   2. The continuous casting mold according to claim 1, wherein the suspension member is inclined with respect to a horizontal direction and includes a pair of inclined leaf springs with one end joined to the mold.   The continuous casting mold according to any one of claims 1 to 3, further comprising a tension device that adjusts a tensile force applied to the suspension member.   The continuous casting mold according to any one of claims 1 to 4, wherein the vertical driving device is a hydraulic cylinder, and the horizontal driving device is a vibrator for rotating an eccentric weight. A continuous casting method using the continuous casting mold according to any one of claims 1 to 5,
The vertical vibration of the mold satisfies the conditions that the amplitude is 2 to 15 mm, the frequency is 10 to 500 cpm, and the actual negative strip speed ratio N expressed by the following formula (1) is 0 to 100%. ,
As for the horizontal vibration of the mold, the amplitude is 1-1000 μm and the frequency is 10-10000 Hz.
A continuous casting method comprising controlling the vertical driving device and the horizontal driving device.
N = (Vm−Vc) / Vc × 100 (1)
Here, N is the actual negative strip speed rate (%), Vm is the average value of the descending speed during the descending period in one vibration period of the vertical vibration of the mold, Vc is the casting speed of the slab, and Vm and Vc. The vertical direction is positive.   The continuous casting method according to claim 6, wherein the horizontal driving device is controlled so that a time average value of a vibration amplitude in a horizontal direction of the mold satisfies 5 to 150 μm. A continuous casting method using the continuous casting mold according to claim 4,
The continuous casting method according to claim 6, wherein the horizontal driving device or the tensioning device is controlled so that a time average value of amplitudes of vibrations in the horizontal direction of the mold satisfies 5 to 150 μm.

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