JPS59147713A - Taking-up method of thin strip - Google Patents

Abstract

PURPOSE:To generate a difference between rolling tension and taking-up tension and prevent deformation of a coil by providing tension bridle rolls between the last stand and a tension reel. CONSTITUTION:Tension bridle rolls 7 are installed between the last stand 3a and a deflector roll 4, and a strip 1 rolled to a plate thickness of <=0.3mm. through the last stand 3a of a cold tandem mill is taken up by controlling to generate a difference between the exit tension of the last stand 3a and the taking-up tension. By this way, a coil of good-looking shape can be obtained in the field of a thin strip and coil taking up work of high rollability and good product yield can be effected.

Description

[Detailed Description of the Invention] The present invention relates to a method for winding thin IJ strips, in particular, a method for winding thin strips after cold rolling a hot rolled steel strip in a tandem mill without causing breakage or poor winding shape. An advantageous method for winding into a coil is proposed.

FIG. 1 is a route map of the tension reel installed on the exit side of the tandem mill, and the hot rolled steel strip guided through the pickling process is placed at the final stand 81Lvil- of the tandem mill 8 shown in the figure.
It is then cold-rolled and wound onto a tension reel 5 via a deflector roll 4 to form a coil 2 as shown in the drawings. In such a winding line, the exit tension of the final stand 3a of the tandem mill directly serves as the coil winding tension. That is, in the conventional device, the tension between the final stand 8a and the tension reel 6 was basically for rolling and at the same time for coil winding.

In this way, in conventional winding technology, the rolling tension and the winding tension are commonly used. It is normal to set the above-mentioned tension to a somewhat high value, and this tendency is particularly noticeable in thin strips with small plate thicknesses. This is because, for example, if such tension is small, slipping or chattering occurs between the work roll 6 of the tandem mill and the strip 1, which adversely affects the quality of the product.

Note that the above-mentioned slip means that the neutral point (described later) deviates from the arc of contact between the work roll 6 and the strip 1, leading to breakage of the strip 1.

Chattering is when the neutral point vibrates violently in the direction of exit within the contact arc, which can cause the thickness of the strip 1 to fluctuate or even break.

What about the coil winding and rolling properties? If given priority, coil 2 is wound with a higher tension than necessary, so
When the tension reel 5 is removed, a deformed coil is generated in which the inner winding portion of the coil is buckled, as shown in FIG. 2 (a). This phenomenon is noticeable in thin materials with small plate thickness, and does not adversely affect the quality of the product.

The quality of the above-mentioned coil winding shape, etc. will be qualitatively described in further detail in FIG. 8. In the figure, the vertical axis is the tension, and the horizontal axis is the strip thickness. In the figure, the upper left region (A) partitioned by the boundary line ab is the buckling deformation region of the coil. In addition, if the winding tension is too low, the entire coil becomes an oval shape as shown in Fig. 2 (b), but the region that shows this winding shape is at the bottom left corner separated by the boundary aOd in the figure. This portion can be identified as the elliptical deformation region (B). Therefore, in the case of an IJ tube having a plate thickness of t0 or more, it can be wound without causing coil deformation if it is wound with tension σ□. On the other hand, when considered from the point of view of rollability, the area surrounded by the boundary line ef and the boundary #gh <c)
was the optimal range. This is because slipping and chattering occur in the area below the boundary line gh, and breakage of the strip N occurs in the area above the boundary line 6f.

From the above, for strips with a plate thickness of t2 or more, it is possible to set σ8 as a tension that does not completely impede rolling properties or cause coil deformation, but when the plate thickness is in the range of t□ to 1s. If priority is given to rollability for the strip inside the coil, coil deformation (buckling) will occur.

Conventionally, in order to prevent this coil buckling deformation, a cylinder made of steel or the like is fully inserted into the inner diameter of the coil, for example, a plate 7
A method was adopted in which a steel strip of 1 t was wound with a tension σ8 indicated by point R in the figure.As another method, focusing on the fact that buckling occurs at the inner winding part of the coil, By consciously rolling the tip of the corresponding strip to make it thicker, for example, a copper strip with a thickness t1 has a thickness t, which is represented by the point 4s at the tip, and is wound with a tension σ. .

However, with the former method, the manufacturing cost of the cylinder, workability,
The latter method is unfavorable in terms of safety, etc.
There was a drawback that the yield of the product was significantly poor.

In addition, the limit plate thickness t shown in Fig. 8 is empirically determined to be 0.80 m.
m neighborhood Te,? ) ツ7', :.

The object of the present invention is to solve the problem of the above-mentioned prior art with a plate thickness of 0.
It is an object of the present invention to provide a winding method that can advantageously solve the problem even for thin strips of 80 mm or less. A specific configuration for achieving the above object of the present invention will be described below.

FIG. 4 is a diagram showing the distribution of tension on the exit side of the final stand of a cold tandem mill with a plate thickness of Q, 9rn, and about m, and the horizontal axis shows the number of rolled coils. It can be seen from the figure that the actual rolling tension is in the range of 5 to 10 kg/mm2.
The central value is 7.0 to 7.5 ni/rn, rn". When the rolling tension is 5 kq/mm or less, the frequency of occurrence of slip chattering increases rapidly, and when the rolling tension is 10 kg /mm or more, it was confirmed that buckling deformation of the coil occurs frequently even though rollability is given priority.However, if coil deformation is ignored, one rolling tension of around 16 kg/mm'' is enough to cause IJ tube rupture. Limit values were observed in many experiments.

Therefore, from the perspective of giving priority to rollability, the optimum value of the rolling tension, that is, the final stand exit tension is 5 to 16.
It was found to be in the range of kg/m and mA.

The fifth □□□ schematically shows what has been stated above. However, such a phenomenon is true for thin strips with a plate thickness of Q, 3Q mm or less, where a certain degree of tolerance is allowed for some troubles that may occur during operation.

Next, the point where the strip threading speed, that is, the rolling speed, and the circumferential speed of the work roll of the rolling mill match is generally called the neutral point, and the position of this neutral point is the tension between the final stand exit side and the tension between the strip and the work roll. We investigated how it is affected by the friction coefficient.

In determining the position of the neutral point, it was determined as the ratio of the contact angle φ and the neutral angle φ as shown in FIG.

In addition, here, Hllll's rolling load formula and Hltahoo
An OK roll flat type was used.

p = −17 days t, os+1.79 pI74F1.
02 r ) R' = R (1+OoP/7h) Also, the second point of B1an6 & For6 was used as the neutral point.

Here, P: Rolling load E: Young's modulus: Average deformation resistance on the exit side φ: Neutral angle R: Roll diameter Hn,
Hl: Dimensionless quantity R': Flat roll diameter t: Tension h: Plate thickness k: Deformation resistance Δh=hi-ha φ: Contact angle μ: Friction coefficient
Subscript: 1, 0: Entry side and: Reduction rate
Indicates the extension side・m: Poisson's ratio Subscript...
n: indicates neutral point The calculation results using the above formulas are shown in FIG.

As a result, the smaller the tension on the exit side of the final stand, the more φn/
The ratio of φ becomes smaller. Furthermore, it can be seen that for the same plate thickness, the smaller the tension, the greater the influence of the friction coefficient μ on φn/φ. That is, it can be seen that the smaller the tension, the more severe the change in the neutral point when the friction coefficient changes due to disturbances such as uneven rolling oil adhesion. This confirms the tendency described in FIG. 5 that the smaller the tension on the exit side of the final stand, the more likely chattering and slipping will occur.

Fig. 8 shows the relationship between the winding tension and the plate thickness when the IJ tube is wound at a constant tension. From this figure, it can be seen that the optimum winding tension of the coil is in the range of 4 to 7 ky/mm, and that around 5 kg/rnm is particularly suitable.

Now, in Fig. 8, we conducted a qualitative study on the influence of the winding tension on the coil shape, and in this regard, the tendency can also be read from Fig. 8. From the above explanation, it is clear that the present invention When considering the winding method for thin materials, especially strips with a thickness of 0.80 yycm or less, the optimum range of the final stand exit tension is 5 to 16 kg/mm, which is the optimum range of the coil winding tension. is found to be 4 to 71 cy/mm. Therefore, in order to satisfy both the rollability and the coil winding shape for thin IJ tubes, a tension control device that can control the above tension range is required between the final stand of the cold tandem mill and the tension reel. For example, it is necessary to use a tension pry roll or a complete linear motor.

FIG. 9 shows an example in which a tension ply roll 7 is disposed between a final stand 8 and a deflector roll 4 as a specific example of a tension control device. This tension pry roll 7 makes it possible to control the final stand exit tension and the winding tension to be different tensions.

In this example, the winding angle of the strip 1 around the tension prydle roll 7 is 2π, so if P friction coefficients between the strip and the tension prydle roll 1 o and os are given, the following equation is obtained. That is, by using the above-mentioned tension control device, it becomes possible to control the winding tension within the range of /1.65 to 1 times the final stand exit tension. The following table shows the results of experiments conducted on this device.

Table Example of winding a 77L strip with a thickness of Q, 19Qyyi without an inner diameter cylinder As shown above, a tension ply roll is placed between the final stand and the tension reel to create a difference between the rolling tension and the winding tension. To independently control
It is very effective in preventing coil deformation. Further, instead of the tension pry roll, a tension control device ring including a set of linear motors may be used.

Furthermore, if the tension control method described above is adopted between the final stand and the tension reel, when batch cold rolling is performed in units of coils, the thickness of the innermost strip of the coil will be the same as that of the product. Because it becomes thicker than the thickness,
Coil buckling deformation is less likely to occur and the effect is not that great.

However, if a welding machine is installed on the entry side of a cold tandem mill and the ends of the strip are welded and rolled in a fully continuous manner, The method of the present invention is extremely effective.

In addition, when winding into a strip coil, reducing the winding tension from the inner coil to the outer coil (Chee Birch/John) improves the coil winding appearance (coil deformation, telescope, etc.) Although this is known from experience, it is possible to implement the present invention without affecting the L-rolling conditions.

As explained above, according to the present invention, it is possible to obtain a coil with a neat winding shape in the field of thin strips, and to perform a coil winding operation with good rolling workability and product yield.

[Brief explanation of drawings]

Fig. 1 is a route diagram showing an example of the equipment layout of a conventional tandem mill tension reel, Fig. 2 is a front view of a deformed coil caused by poor coil winding tension, and Fig. 8 is a diagram showing the winding tension and A graph showing the coil deformation limit determined by the thickness of the tube and the range of optimal final stand exit tension. Figure 4 shows the final stand exit tension range when a strip with a thickness of around 0°2 mm is cold rolled The tension distribution diagram, Figure 5, is
A graph showing the influence 411i of final stand exit side tension on rollability, Figure 6 is an explanatory diagram showing the contact angle and neutral angle, and Figure 7 is a final stand exit side tension, neutral angle, and contact angle. Is it a shadow of the friction coefficient that does not match the ratio? Figure 8 is a graph showing the influence of the relationship between winding tension and plate thickness on coil deformation. Figure 9 is a graph showing the influence of the relationship between winding tension and plate thickness on coil deformation. Figure 9 is a graph showing the influence of the relationship between winding tension and plate thickness on coil deformation. FIG. 2 is a route diagram of the outlet side arrangement of the cold rolling equipment of the present invention. 1...Strip, z...Coil, 8...
・Tandem mill, 8a... Tandem mill final stand, 4... Deflector roll, 5... Tension reel, 6... Work roll, 7... Tension pry roll. 1st drawing 3rd drawing Stritz 0 non-faith thickness 4th drawing Qiu Zhao coil teaching

Claims (1)

[Claims] 1 Q after passing through the cold tandem mill final stand,
IJ tube rolled to a thickness of 3 nm or less,
A method for winding a thin strip, characterized in that a tension control device is interposed between the final stand and the tension reel to apply different tensions to the final exit tension and the winding tension. East After passing the cold tandem mill final stand, Q.
The strip rolled to a thickness of 13 mg> or less is controlled to a final stand exit tension of 5 to 16 mm using a tension control device installed between the final stand and the tension reel.
The tension is within the range of kf/l m, and the winding tension is 4 to 7.
kg/l? L? A method for winding an IJ tube according to claim 1, characterized in that the winding is performed by controlling the tension within a range of W.