JPH06170407A - Method for reducing amount of contraction of internal diameter of winding coil - Google Patents

Abstract

(57) [Summary] [Purpose] In reverse rolling in which leader materials are attached to both ends of a steel strip coil and rolled, the leader material does not slip even if the coil inner diameter contracts during winding, reducing the amount of inner diameter shrinkage. However, it can be easily inserted into the payoff reel in the next process. [Structure] A leader material 3 having a surface friction coefficient μ satisfying the following expression is used as the leader material by increasing the friction coefficient between layers by performing shot processing and groove processing on the leader material attached to both ends of the steel strip coil. Where σ: unit tension (kg / mm ² ), σ _r : coil inner diameter tightening stress (k
g / mm ² ), σ _t : Coil tangential stress (kg / mm
² ), r _i : inner radius of coil (m), r _s : outer radius of leader material (m), r _o : outer radius of coil (m), t: strip plate thickness (mm). μ ≧ (r _S σ _t −r _o σ) t / 2π _{r i} σ _r

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reducing the shrinkage of the winding coil inner diameter, and more particularly to a method for selecting the characteristics of a leader material to be welded to both ends of a steel strip to be reverse rolled.

[0002]

2. Description of the Related Art FIG. 1 shows a development view of a steel strip coil with a leader material. Leader materials 3 are attached to both ends of the base material 2 (steel strip) of the coil. As shown in FIG. 4, this coil 1 is
When rolling with the Rivas rolling mill 7, a leader material is used for the waste winding of the tension reel 5 in order to improve the yield.

Generally, as the material of the leader material, relatively inexpensive general steel is used, and the surface texture is not emphasized.

[0004]

Generally, when a stainless steel or a special steel is rolled by a reverse rolling mill 7 as shown in FIG. 4,
A leader material having a length corresponding to the waste winding of the tension reel 5 is welded to the tip and tail ends of the coil base material (steel strip),
The stakes are improved. A relatively inexpensive general steel is used for this leader material. In addition, reverse rolling is generally performed with high tension, and therefore the coil tightening force σ _r of the coil inner diameter generated during winding is also large. It is known that the change amount δ of the coil inner diameter at the end of the winding of the reverse rolling is reduced by the elasto-plastic deformation shown by the following expression (A).

[0005]

[Equation 2]

Where σ: unit tension (kg / mm ² ) r _i : inner radius of coil (m) r _o : outer radius of coil (m) E: Young's modulus of coil (kg / mm ² ) r: coil balance Radius (mm) (the coil radius at the moment when the reel expansion force becomes σ _r or more with respect to the increasing σ _r during coil winding) However, the measured shrinkage δ ′ is The value is about double. This is because the above formula (A) does not take into consideration the occurrence of interlayer slip during shrinkage. Marking 8 is performed after the leader material 3 is actually wound around the reel 5 as shown in FIG.
As a result of observing the state of No. 3, it was found that there was a deviation and a slip occurred, as shown in FIG. It is considered that when slippage occurs, the tightening force propagates when the inner diameter contracts, resulting in an added state. Excessive contraction due to this slip causes a change in the coil inner diameter, causing a problem that the coil cannot be inserted in the next process line and the user's payoff reel. Becomes

An object of the present invention is to solve such a problem.

[0008]

In order to solve the above-mentioned problems, the present invention increases the friction coefficient of the leader material and prevents slippage even if the leader material is wound and contracted. That is, according to the present invention, in reverse rolling in which a leader material is attached to both ends of a steel strip coil and rolled, a leader material having a surface friction coefficient μ satisfying the following formula is used as the leader material. This is a method for reducing the amount of inner diameter shrinkage.

[0009]

[Equation 3]

Where σ: unit tension (kg / mm ² ) σ _r : coil inner diameter tightening stress (kg / mm ² ) σ _t : coil tangential stress (kg / mm ² ) r _i : coil inner radius (m ) R _o : outer radius of coil (m) r _s : outer radius of leader material (m) t: strip plate thickness (mm).

[0011]

According to the present invention, the leader material attached to both ends of the steel strip coil is shot or grooved to increase the coefficient of friction between the plates, so that the tightening force generated during winding is increased. Even if the inner diameter of the coil contracts, the slip between the strip layers is prevented, so that the contraction amount δ (theoretical value) of the total inner radius can be set to a value according to the formula (A). Further, as a method of selecting the friction coefficient, the interlayer slip generation condition expression at the coil inner diameter r ₀ during coil winding is expressed by t · r _o σ + 2πr _i μσ _r ≦ tr _s σ _t and no interlayer slip is generated. In order to

[0012]

[Equation 4]

Where σ: unit tension (kg / mm ² ) σ _r : coil inner diameter tightening stress (kg / mm ² ) σ _t : coil tangential stress (kg / mm ² ) r _i : coil inner radius (m ) R _o : outer radius of coil (m) r _s : outer radius of leader material (m) t: it is necessary to subject the leader material to shot processing so as to satisfy the strip thickness (mm). By these, the shrinkage amount of the inner diameter can be suppressed according to the theoretical value, and by preventing the slip, the deviation flaw of the inner diameter can be reduced.

[0014]

[Example] Rolled coil material SUS304, width 1000 m
Reverse rolling was performed to a rolled material of 2 mm having a thickness of 4 mm. A test was conducted using SS41, a material having a width of 950 mm, a thickness of 4 mm and a surface roughness Ra = 1 μm as a leader material. The conditions are shown below. Coil inner radius r _i = φ660 / 2 Balancing radius r = φ720 / 2 Coil outer radius r _o = φ1500 / 2 Plate thickness t = 2 mm Leader material outer radius φ685 / 2 Unit tension σ = 30 kg / mm ² Cylinder expansion force P = 3.6 kg / mm ^{2 The} balance radius r is the coil radius at the moment when the reel expanding force becomes σ _r or more with respect to the increased σ _r during coil winding.

Conventionally, the coil diameter before winding was φ660, but after winding, it becomes φ653, and the shrinkage amount of the inner diameter δ ′ = 7.
mm. At this time, when the friction coefficient of the leader material was investigated, it was μ = 0.15 with rolling oil, and it was considered that there was a high possibility of slippage. Therefore, as a result of performing a test as shown in FIG. There was a deviation of a = 2 to 3 mm.

In the embodiment, Ra = 3 μ as shown in FIG.
The inter-layer friction coefficient μ was increased by using the shot processed leader material 3 of m and the leader material 4 having the groove depth h = 0.5 mm and the groove pitch p = 100 mm as shown in FIG. On the calculation,

[0017]

[Equation 5]

Therefore, μ ≧ 0.213 is a necessary condition,
The surface is processed to satisfy this. When wound with this coil, the coil diameter before winding φ660 became a winding diameter φ657.6, which was drastically reduced to δ = 2.4 mm. Similarly, a slip test as shown in FIG. 3 was performed, but the amount of deviation of the marking 8 was almost 0, and no slip occurred.

Therefore, the shrinkage amount δ of the latter is a value as the theoretical value, and only the elasto-plastic component due to the tightening force. Figure 5
Shows the graph of the above results. The inner diameter of the coil after the final winding was improved from φ653 to φ657.6 so that the coil could be easily inserted into the pay-off reel in the next step, and there was no displacement flaw even if it occurred near the inner diameter of the coil.

The processing of the surface of the leader material used in this method may be any processing as long as the above expression (B) is satisfied, and is not limited to shot processing or groove processing.

[0021]

Industrial Applicability According to the present invention, the leader material attached to both ends of the steel strip coil is subjected to shot processing, groove processing, etc. to increase the coefficient of friction between layers, so that the leader material can be manufactured even if the inner diameter of the coil shrinks during winding. Since it is prevented from slipping, the contraction amount of the inner diameter can be reduced, and the coil can be easily inserted into the payoff reel in the next step.

Further, since the inter-layer slip is prevented, there is also an effect that the slippage defect of the coil can be reduced.

[Brief description of drawings]

FIG. 1 is a development view of a coil with a shot processing leader material.

FIG. 2 is a development view and a partially enlarged view of a coil with a grooved leader material.

FIG. 3 is an explanatory diagram of a leader material inter-layer slip experiment.

FIG. 4 is a schematic diagram of a reverse rolling mill that requires a coil with a leader material.

FIG. 5 is a graph showing the effect of the present invention.

[Explanation of symbols]

1 coil 2 mother board 3,4 leader material 5 tension reel 6 deflector roll 7 reverse rolling machine 8 marking

Claims (1)

[Claims] 1. A winding coil, wherein a leader material having a surface friction coefficient μ satisfying the following expression is used as the leader material in reverse rolling in which a leader material is attached to the front and tail ends of a steel strip and rolled. How to reduce the amount of inner diameter shrinkage. [Equation 1] Where: σ: unit tension (kg / mm ² ) σ _r : coil inner diameter winding tightening stress (kg / mm ² ) σ _t : coil tangential stress (kg / mm ² ) r _i : coil inner radius (m) r _o : coil outer radius (m) r _s: reader material outside radius (m) t: strip thickness (mm)