WO1994006583A1

WO1994006583A1 - Method of casting continuous slab

Info

Publication number: WO1994006583A1
Application number: PCT/JP1992/001205
Authority: WO
Inventors: Seiji Itoyama; Hirokazu Tozawa; Shuji Takeuchi; Kenichi Sorimachi
Original assignee: Kawasaki Steel Corporation
Priority date: 1992-09-22
Filing date: 1992-09-22
Publication date: 1994-03-31
Also published as: CA2098572C; CA2098572A1

Abstract

When a slab is drawn while a mold formed of a long wall and a short one is vertically vibrated in the process of vertical type continuous casting, said long side wall is moved away from the slab with a hydraulic cylinder (4) actuated in a time zone in which large frictional force acts upon the slab. On the contrary, in a time zone in which large frictional force does not act on the slab, the long side wall having been kept away from the slab is brought closer thereto. In this way, by moving the long side wall away from or closer to the slab repeatedly, a depth of oscillation mark is reduced so that a slab with less segregation at the valley of oscillation mark may be obtained.

Description

Construction method of the connecting piece

Technical field

The present invention relates to a continuous metal structure, particularly a vertical continuous structure.

The present invention relates to a method of manufacturing a continuous field piece that can reduce the depth of a simulation mark and obtain a piece with less segregation of a mark valley.

Background art

Conventionally, with the aim of eliminating the need for maintenance work on the connecting piece surface, especially when manufacturing stainless steel (SUS304), the right side of the oscillation mark valley on the surface of the piece was corrected. Vertical 錶 -type vibration methods have been proposed to reduce or prevent segregation. For example, in Japanese Unexamined Patent Application Publication No. 2-290656, Japanese Patent Application Laid-Open No. 2-290656 describes a continuous cycling type in which a structure space is formed by two pairs of rectangular surfaces, during a negative strip time period in a longitudinal vibration, or in a time zone. There is a technology that relatively isolates a pair of 铸 -shaped walls only during the mold descending time zone.

It has been recognized that this method is considerably more effective than the case where only a simple longitudinal vibration is applied. However, according to the 'experimental results', it was found that the effect was small when the frequency of the cycline was small. Further, in the above method, the consumption of the mold paddle is reduced, and the problem of breakout due to restraint occurs. Therefore, there is a concern that it may cause a problem of hindering the stable structure. there were.

In the past, regarding the mechanism and cause of the bias in the oscillating mark valley, negative pressure was generated in the liquid lubricating film between the 錶 and the solidified shell by the 鐯 type longitudinal vibration. It has been said that the negative pressure causes the unsolidified, concentrated molten steel between the dendrites on the surface of the solidified shell to leach onto the shell surface.

However, as a result of the present inventors' investigation of the segregated portion of the piece, the segregation was found to impede continuous growth of the solidified shell due to fracture of the seal due to tensile force acting on the seal and buckling due to compressive force. However, it was found that the cause was that the concentrated solution flowed out of the shell surface from the shell fracture portion or the buckling portion. Therefore, preventing the shell from breaking or buckling in the early stage of solidification, that is, simultaneously reducing the tensile force and the compressive force acting on the shell, is an effective means for preventing segregation.

The present invention significantly reduces segregation at the oscillation mark valleys on the surface of a piece, as well as high cycle conditions, even in a low cycle with a small life frequency f, and has a stable structure. It is an object of the present invention to provide a method for extracting a connecting piece that enables the drawing. Disclosure of the invention

SUMMARY OF THE INVENTION The present invention relates to a positive strip and a negative strip while vibrating in a vertical direction a mold for a vertical continuous structure having two pairs of cylindrical walls forming a structure. At least one pair of 錶 -shaped walls is moved away from the solidified shell at one time in each time period within the time zone, and the 铸 -shaped walls are moved away from the solidified shell during other time periods. That repeats during continuous production This is the construction method.

Further, in the present invention, a positive strip having no negative strip time zone while vibrating in a vertical direction a vertical continuous manufacturing die formed by forming a manufacturing space by two pairs of die walls. At least one pair of 上昇 -shaped walls is moved away from the solidified shell at one time in each of the 上昇 -shaped rising and falling zones, and the other 鐯 -shaped rising and falling time zones In the meantime, a series of operations for bringing the 鐯 -shaped wall away from the solidification shell into close proximity can be repeated during continuous production. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a graph showing a temporal change of a vertical vibration velocity and a horizontal displacement of a rectangular wall according to an embodiment of the present invention.

FIG. 2 is a graph showing the time-dependent changes in the vertical vibration velocity of the 铸 type and the horizontal displacement of the 铸 type wall according to another embodiment of the present invention. FIG. 3 is a schematic perspective view showing a 铸 -shaped horizontal moving device used for carrying out the present invention.

FIG. 4 is a schematic diagram showing an oscillation mark and a segregation layer.

FIG. 5 is a graph showing a conventional type I vibration waveform and a type III retraction and forward timing.

FIG. 6 is a schematic diagram between the 錶 -shaped wall and the solidified sur. BEST MODE FOR CARRYING OUT THE INVENTION

As shown in Fig. 1, when the 铸 reaches the top point, the 縦 vertical speed In degrees V _m 0 and Do Ri, velocity V _m when铸型begins to descend Ri gradually Do rather fast speed V m when錶型reaches the lowest point is 0. When the m type starts to rise again, the speed V m increases. The longitudinal vibration of type 鐯 is the pulling speed of piece 鐯. In relation to this, the time during which the vertical speed v _m of the vertical type is faster than the pull-out speed V _c of the piece is referred to as the negative strip time T _n .

As shown in Fig. 1, (1) The time when the relative speed is large at the positive stripping time T p during which the tensile force acts on the solidified shell during the vertical vibration of the vertical type, from t _t to t ₂ At least one pair of 壁 -shaped walls are retracted horizontally at a time so as to move relatively away from the solidification shroud. Open as the position of. Negate I ugly Application Benefits Tsu if no flop time _T n (Τ π = 0) is rather low at one time from the time the relative speed is greater t ₄ to t ₅ in铸型rising period Remind as in Figure 2 X is retreated (separated) so that a pair of 壁 -shaped walls are relatively far apart. Open as the position of.

By doing so, the distance X from the distance X s between the longevity wall 9 and the solidified shell 12 as shown in FIG. The mold powder 10 on the molten steel 11 flows sufficiently between the mold wall 9 and the solidification shell 12 to reduce the frictional force between the rust mold wall 9 and the solidification shell. . Y indicates the direction of pulling out one piece.

In Figure 1, followed, at one time up to the big time of the relative velocity of the Negate I Buss Application Benefits Tsu Bed time to the action of the compressive force T _[pi t 3 or et t ₄ to Shiweru, relatively铸型wall Move the X-shaped wall away from the solidification shroud. Open as the position of. In addition, when there is no Negate I ugly door Clip time Remind as in FIG. 2 _(Τ π = 0) is,铸 During the time when the relative velocity is large during the mold descent period from time t2 to t3, the 壁 -shaped wall is moved relatively horizontally from the solidified shell, and the 铸 -shaped wall is set to X. Open as the position of. In the absence of the negative strip, the relative velocity between the mold and the solidified shell is always upward, so it is considered that no compressive force acts on the shell. However, the solidified shell at the meniscus in the mold III grows continuously, and its position is constant, so it works even when the compression force is T _n = 0.

Their to from time t 2 or al t 3 to and time t ₄ in the time zone or first view other than the above to t 5, also the time t in FIG. 2, from t ₂ to and the time "t ₃ from t 4 Until then, the cylindrical wall is advanced to approach the solidified shell and the 錶 -shaped wall is closed at the position of XS, that is, the distance X between the 铸 -shaped and solidified shell is between X. and Xs. When such a type II horizontal vibration that changes the distance between the type II wall surface and the solidified shell is applied, the frictional force acting on the initial type solidified shell in the type II mask portion is Considering the frictional force between the mold and the solidified shell, the shear force of the mold powder between the mold and the solidified shell can be calculated by the following equation.

F = A-u (d V / d X) (1)

However, A: Contact area between 錶 type and solidification sur

u: Viscosity of the mold paddle flowing between the 壁面 -shaped wall and the solidified shell

V: Relative velocity between the 铸 type wall and the solidification shell

X: Distance between 鐯 type and solidification sur As can be seen from the above equation (1), the friction force F acting on the solidified shell decreases when the distance X between the 鐯 type and the solidified shell is increased. That is, according to the present invention, the tensile force and the compressive force acting on the shell of the meniscus portion in the early stage of solidification can be greatly reduced, and as a result, the continuity of the solidified shell is maintained, so that the oscillation mark depth is shallow. In other words, the probability that a prayer is formed in the Mark Valley is smaller than in the conventional technology.

The effects described above are not largely affected by the waveform of vertical vibration waveform ゃ锛, which causes the wall of the mold to move forward and backward (close and open) in the horizontal direction (hereinafter referred to as horizontal vibration). The longitudinal vibration shown in Fig. 1 is a sinusoidal wave, and the horizontal vibration is a trapezoidal wave. The amplitude of the horizontal vibration is desirably within 1 mm in order to prevent the risk of the molten metal to enter the gap between the rectangular corners and to cause a restraint break.

Hereinafter, a description will be given based on examples of the present invention.

Example 1 1

As a horizontal vibration device, generally, in a continuous slab machine, as shown in Fig. 3, a short side 2 of a rectangular shape is fixed to a long side 1 of a rectangular shape through a panel 3 for a short side clamp. The method of doing it is taken. In the present invention, the opening and closing of the short-side clamp hydraulic cylinder 4 is provided in the hydraulic circuit. Therefore, in the present invention, the opening and closing of the short-side clamp hydraulic cylinder 4 is also provided in the hydraulic circuit. By moving through the upper and lower solenoid valves 5 and 6, the 铸 -shaped movement is performed. 7 indicates a hydraulic motor, and 8 indicates a hydraulic tank. If a gap is left between the long side of the mold and the short side of the mold during fabrication, molten steel will enter the gap and cause trouble. easy. Therefore, the retraction amount of type。 shall be within lmm.

The depth d of the oscillation mark 13 on the surface of the piece when the piece of stainless steel (SUS 304) is continuously manufactured by applying the horizontal vibration device of the rectangular wall shown in Fig. 3 above (see Fig. 4) ) And the segregation layer depth d ₂ at the oscillation mark part, the segregation thickness (d ₂ -d 1) of the oscillation part is obtained, and the segregation layer thickness (d ₂ -d!) And the oscillation mark to investigate the depth d _2. For comparison, only the case of the conventional longitudinal vibration (sign wave) and the case of the vibration wave shown in FIGS. 5 (a) and (b) shown in Japanese Patent Application Laid-Open No. 2-290656 are disclosed. A survey was also conducted. Fig. 5 (a) shows the case where the vibration of type III moves the type wall backward during the negative strip period, and Fig. 5 (b) shows the type when the type III descends. This is the case where is retracted. The manufacturing conditions of the present invention are as follows: (1) One-piece pulling speed V c = 1.2 / min, (2) Longitudinal frequency: f = 150 times Z, amplitude (S) = 5.3 mm, longitudinal vibration waveform = sin, horizontal vibration Amplitude = 0.3 mrn, horizontal vibration pattern is trapezoidal wave (see Fig. 1), 铸 type wall opening / closing timing is angle conversion (zero degree when V _{m in} Fig. 1 is exactly maximum) in), to 130 degrees to 105 degrees (from the first during time t ₂ ~ t ₃ in Figure) and 240 degrees to 275 degrees (time t ₄ ~ t ₅ between) in FIG. 1 closed (X s position), Otherwise, it is open (X. position). The speed of movement from open to closed or from closed to open was SOmmZsec. The mold pad used was a lubricant with a viscosity of 1.1 poise at 1300 ° C and a solidification temperature of 900 ° C.

Example 1 2

As an example when T _N = 0 with no negative strip time ティ As shown in Fig. 2, the horizontal opening / closing timing is set to 110 to 160 degrees (between times t and t2 in Fig. ₂ ) and 250 to 290 degrees, assuming that the amplitude of the mold longitudinal vibration is S = 2. Omm. and a (second diagram between times t ₃ ~ t ₄₎ is closed, open in others. Other conditions were the same as in Example 1.

Table 1 Vertical segregation of type III

No. Vibration method Vibration conditions Oscillation Remarks Horizontal vibration conditions Thickness Occurrence rate

Amplitude Frequency u 2 U 1 Mark depth

imm) (cpm) (mm) (%) d 2 (mm)

5.3 1 5 0 No horizontal vibration n Q fi 7 f 0.4 2 T _N > 0

1 Conventional method

2 3 0 0 Horizontal vibrator 0.1 0 2 5 0.1 5 T- ¹ -M 1¾> ο v

2 Conventional method 5.3 1 5 0 Negative phase opening 0.2 0 4 3 0.37 TN> 0

3 Conventional method 2 1 5 0 Open when descending type 铸 0.1 8 3 4 0.3 2 T _N = 0

4 Present invention 5.3 1 5 0 Conditions of the present invention 0 0 0.2 1 T _N > 0

(As shown in Fig. 1)

5 Present invention 2 1 5 0 Conditions of the present invention 0 0 0.1 5 T _N = 0

(As shown in Fig. 2)

Table 1 shows the results of the above slab comparison between Examples 1 and 2 and the conventional method. Table 1 shows that, according to the present invention, as compared with the conventional method, the incidence of occurrence of the prayer in the oscillation valley due to the thickness is significantly reduced and almost completely eliminated. I understand. Industrial applicability

In order to minimize the compressive and tensile forces acting on the initial solidification shell, the wall of the mold is opened and closed horizontally with respect to the solidification elbow in accordance with the timing of the longitudinal vibration of the mold (forward and backward). By providing a cycling vibration method, the segregation of the oscillation mark valleys on the surface of the piece can be significantly reduced at a lower vibration frequency than in the past. as a result,

(1) Under high-cycle vibration conditions where dangerous restraint breaks occur, there is no need to build, reducing productivity problems.

(2) In the case of stainless steel SUS 304 slab, the amount of segregation on the surface of the slab is reduced by a grinder before rolling, as before. Since it is possible to send pieces to the next process, an improvement in yield can be expected.

Claims

The scope of the claims

1. Positive stripping time and negative stripping time while vertically oscillating a mold for vertical continuous construction with two pairs of mold walls forming a rust space. At least one pair of i-shaped walls is moved away from the solidified shell at one time during each time zone in the zone, and a series of operations is performed to move the 铸 -shaped wall away from the solidified shell to the solidified shell in other time zones. A method for producing a cycling piece, which is repeated during production.

2. While oscillating in the vertical direction, a vertical continuous construction mold formed by two pairs of rectangular walls forming a cylindrical space, cycling only under the conditions of the positive stripping time. In each of the rise and fall time periods of the mold, at least one pair of mold walls was moved away from the solidification shell and the other in the rise and fall time zones A method for producing a continuous life piece, wherein a series of operations for bringing a wall surface close to a solidified shell are repeated during continuous production.