KR20160141536A

KR20160141536A - Repair method according to the sheet rolling mill roller bearing assembly for a football injury

Info

Publication number: KR20160141536A
Application number: KR1020150077355A
Authority: KR
Inventors: 주용태; 김종욱
Original assignee: 주식회사 정진이엔티
Priority date: 2015-06-01
Filing date: 2015-06-01
Publication date: 2016-12-09

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a repair method for damage to a bearing assembly shaft portion of a steel plate rolling roller for a steelworks, and more particularly to a method for repairing wear of an assembly shaft portion formed on both sides of a rolling roller, And more particularly, to a new type repairing method for repairing a new type of rolling mill for steel rolling mill due to damage to a bearing assembly shaft, in which productivity can be improved through rapid maintenance, and the rolling operation can be stably and continuously performed.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of repairing a roller assembly for a rolling mill,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a repair method for damage to a bearing assembly shaft portion of a steel plate rolling roller for a steelworks, and more particularly to a method for repairing wear of an assembly shaft portion formed on both sides of a rolling roller, And to a maintenance method for repairing a new type of rolling mill for steel rolling mill in which a bearing assembly shaft is damaged in order to improve productivity through rapid maintenance and to maintain stable continuity of the rolling operation.

In general, steel rolling takes the billet or imported stainless steel billet manufactured in the casting factory to remove defects in the billet inspection loss process, and then feeds the steel plate process through heating, rolling, cooling and correction (inspection and testing) It is production work.

In this steel sheet rolling, a guide roller is provided in front of the inlet side rolling roller of the hot rolling of the steel sheet so as to guide the material to prevent troubles by accurately blowing the material into the roll shape, and then, through the rolling rollers, To produce steel plates.

However, in the process of passing the steel sheet through the rolling roller, the steel plate and the rolling roller collide with each other to cause damage to the assembly shaft portions on both sides of the rolling roller. If the impact damage continues as described above, the rolling of the rolling roller, A problem arises.

Further, there is a problem that the abrasion of the assembly shaft frequently occurs in the rolling process which is a continuous operation, and it is difficult to maintain the continuous rolling process by repairing the rolling roller at any time.

In a conventional technique for performing maintenance and repair in accordance with the degree of damage of the rolling roller, the notch processing device of the rolling roller is disclosed in Japanese Patent Application Laid-Open No. 10-2009-0069011 (published Jun. 29, 2009)

And a cutting tool portion provided with a bite provided on the rotary shaft, wherein a cutting tool portion provided on the tool bar of the lathe, a rotary shaft provided with power from the rotary drive portion, and a cutting tool portion provided on the rotary shaft, And a plurality of notches extending along the axial direction are formed.

However, the maintenance and repair of the assembly shaft portion can not be achieved quickly even through the configuration of the maintenance of the rolling roller as described above.

Therefore, there is a need to provide a repair method of a new type of damaged assembly shaft that can maintain the continuity of the rolling process by rapidly performing maintenance due to abrasion of the bearing assembly shaft portions of several steel rolling rollers used in steelworks have.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to shorten the time required for maintenance by rapidly repairing the wear parts of the bearing assembly shaft portions on both sides of the rolling roller in accordance with continuous rolling A new steel sheet rolling mill capable of maintaining a stable maintenance state by providing a structure capable of maintaining continuous steel sheet rolling process without fail and at the same time providing a structure for preventing fall-off of a reinforcing ring inserted to compensate for abrasion at an assembling shaft portion And to provide a maintenance method in which the roller is damaged by the bearing assembly shaft.

In order to achieve this object,

According to an aspect of the present invention,

An outer diameter machining step of removing the eccentricity and machining the surface of the abrasive assembly shaft by removing the abrasive rolling roller having the abrasion occurred on the assembly shaft of the rolling mill installed in the rolling mill of the steel mill,

A diameter of the assembled shaft portion 10 is measured to compensate for the thickness before the abrasion of the assembling shaft portion 10, and a reinforcing ring 20 having a diameter for compensation with a thickness before abrasion is prepared. A reinforcing ring preparing step of processing the diameter of the reinforcing ring to increase;

A reinforcing ring inserting step of inserting a heated reinforcing ring 20 into the machined assembling shaft portion 10 to adhere the inner surface of the reinforcing ring 20 to the outer surface of the assembling shaft portion 10 and bonding them together;

The cooling ring is cooled at room temperature in a state where the heated reinforcing ring 20 is joined to the assembling shaft portion 10 and the reinforcing ring is contracted and the diameter is reduced so as to be firmly bonded to the outer surface of the assembling shaft portion 10 step;

And an inspection and finishing step of finishing the outer circumferential surface of the reinforcing ring in a state where the reinforcing ring 20 is joined to the assembling shaft portion 10 in a heat shrinking manner to complete the repair and installing the reinforcing ring in the rolling process.

The thickness of the reinforcing ring (20) is formed to be equal to or larger than the outer diameter of the assembled shaft portion (10).

A hole 31 is formed in a boundary portion between the assembling shaft portion 10 and the reinforcing ring 20 and the fixing pin 30 is inserted after the adhesive is put into the hole so that the reinforcing ring 20 is separated from the assembling shaft portion 10, So that it can be prevented from turning.

The inner surface of the hole 31 is formed by tapping, an adhesive is injected, and a bolt having a fixing pin function is fastened.

As described above, the repairing method according to the present invention for repairing the bearing assembly shaft part of the steel rolling roller for steelworks can quickly repair the damaged part of the assembly shaft of the steel rolling roller, thereby maintaining the continuity of the stable steel rolling process have.

In addition, it is possible to prevent separation of the reinforcing ring from the assembling shaft portion by inserting a plurality of fixing pins into the connecting portion between the reinforcing ring assembled to the assembling shaft portion and the assembling shaft portion, thereby maintaining the maintenance state stably.

1 is a side view showing a bearing assembly shaft portion of a steel plate rolling roller for a steelworks according to the present invention.
2 is a side view showing a state in which a bearing assembly shaft portion is damaged according to the use of a steel sheet rolling roller for a steelworks according to the present invention.
FIG. 3 is a side view of a steel sheet rolling mill according to the present invention, in which a reinforcing ring and a fixing pin are shrunk for repairing a bearing assembly shaft portion
4 is a perspective view showing a state in which a fixing pin is inserted in a state in which a reinforcing ring is shrunk for repairing a bearing assembly shaft portion of a rolling mill for a steel mill according to the present invention,
5 is a block diagram for explaining a repairing method according to a bearing assembly shaft portion damage of a steel plate rolling roller for a steelworks according to the present invention

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

FIG. 1 is a side view showing a bearing assembly shaft portion of a steel plate rolling roller according to the present invention, FIG. 2 is a side view showing a state where a bearing assembly shaft portion is damaged according to the use of a steel plate rolling roller for a steelworks according to the present invention, FIG. 4 is a side view of the steel plate rolling roller according to the present invention, in which the reinforcing ring and the fixing pin are shaved for repairing the bearing assembly shaft portion of the rolling roller, FIG. 6 is a perspective view showing a state where the fixing pin is inserted in a state where the reinforcing ring is shrunk for repair due to damage; FIG.

As shown in the drawings, a repair method according to the present invention for repairing a bearing assembly shaft portion of a steel plate rolling roller according to the present invention includes a method of mounting a reinforcing ring 20 on a surface of a damaged assembly shaft portion 10 formed on both sides of a rolling roller 100 So as to repair the assembling shaft portion with the diameter before being damaged by the thickness of the reinforcing ring 20. [

That is, as shown in the figure, for example, the assembly shaft portion 10 having an initial diameter of 899.8 mm and a length of 670 mm is worn by collision with the steel sheet due to use of the rolling roller, eccentricity is generated on one side, The reinforcing ring 20 for compensation of the worn thickness is inserted into the outer surface of the assembled shaft portion 10 while the outer diameter of the assembling shaft portion 10 is machined to eliminate the eccentricity.

At this time, the inner diameter of the inserted reinforcing ring 20 is equal to or larger than the diameter of the assembled shaft portion 10, and is coupled to the assembling shaft portion 10 through a heat shrink method.

The shrink fitting method is a technique of joining metals by using thermal expansion and contraction of a metal as a known technique. It is advantageous in that there is no welding defect due to mechanical joining not depending on welding and the process is simple. It is widely used for parts.

That is, the inner diameter of the reinforcing ring 20 must be joined to the outer diameter of the assembled shaft portion 10 so that the inner diameter of the reinforcing ring 20 is smaller than or equal to the diameter of the assembling shaft portion 10, The inner diameter of the reinforcing ring 20 becomes narrower due to thermal expansion, so that the inner diameter of the reinforcing ring 20 becomes narrower after being deformed to be inserted into the assembly shaft 10 and then cooled at room temperature. At this time, A strong bonding force is generated between the outer diameter of the assembling shaft portion 10 and the inner diameter of the reinforcing ring 20 and is firmly bonded to the outer surface of the assembling shaft portion 10.

The abrasion of the assembled shaft portion 10 can be restored to its original state by the heat shrinking joint of the reinforcement ring 20 as described above.

3 to 4, when the reinforcing ring 20 is joined to the surface of the assembling shaft 10, a plurality of fixing pins 30 are inserted into the connecting portion in an auxiliary manner, Even if the joint portion between the shaft portion 10 and the reinforcing ring 20 is separated, it is possible to prevent the reinforcing ring 20 from being loosened or loosened.

That is, in the state where the reinforcing ring 20 is joined to the surface of the assembling shaft portion 10 in a heat shrinking manner, the hole 31 is drilled in the boundary portion between the assembling shaft portion 10 and the reinforcing ring 20, So that the reinforcing ring 20 is prevented from being dislodged or loosened.

Particularly, the inner surface of the hole 31 is tapped to form a female thread, an adhesive is applied to the inside, and a bolt is inserted for the fixing pin to prevent the fixing pin from coming off.

The repair method according to the bearing assembly shaft damage of the steel plate rolling roller formed through the above process will be described step by step.

Assembly shaft Outer diameter machining step

Among the rolling rollers installed in the rolling mill of the steel mill, the rolling rollers where abrasion occurred on the assembling shaft portions are removed from the rolling line and the worn assembling shafts are machined to remove the eccentricity and smooth the surface.

Reinforcing ring Ready

In order to compensate the thickness of the assembling shaft portion 10 before it is worn, the diameter of the assembled shaft portion 10 is measured, and a reinforcing ring 20 having a thickness for compensation with a thickness before worn is prepared.

At this time, the inner diameter of the reinforcing ring 20 is formed to be equal to or larger than the outer diameter of the assembled shaft portion 10 processed.

Further, the reinforcing ring 20 is heated to a high temperature so that the diameter is increased by thermal expansion.

Reinforcing ring insertion

The heated reinforcing ring 20 is inserted into the machined assembly shaft portion 10 so that the inner surface of the reinforcing ring 20 is brought into close contact with the outer surface of the assembling shaft portion 10 to be joined to each other.

Room temperature cooling

The heated reinforcing ring 20 is joined to the assembling shaft portion 10 and is cooled at room temperature so that the reinforcing ring is contracted and is tightly bonded to the outer surface of the assembling shaft portion 10 through a deformation process in which the diameter is reduced .

Insert Fixed Pin

The hole 31 having the female screw hole is drilled in the boundary portion between the assembly shaft 10 and the reinforcing ring 20 and the bolt as the fixing pin is tightened after the adhesive is put into the fixing shaft 30 so that the fixing pin 30 is held firmly, Thereby preventing the ring 20 from falling out or being loose.

Inspection and Completion

As described above, the outer peripheral surface of the reinforcing ring is smoothly processed in the state that the reinforcing ring 20 is joined to the assembling shaft portion 10 in a heat shrinking manner, and the repair is completed and installed in the rolling process.

The structure strength of the steel plate rolling roller that has been repaired through the above-described heat-shrinking method is analyzed as follows.

■. Of steel rolling rollers Structural strength analysis

1. Analysis of PB Roll operation condition

-. The rolling force is transmitted to the barrel part of the PB roll through the slip sliding bearing

2. Force regulating method for strength analysis of thrust bearing assembly part

One). Examination of structural strength of PB roll material based on dynamic load rating of thrust bearing specification

- When selecting the first bearing, it is selected including the safety factor. Bearing is damaged first when abnormal load is applied.

2). Thrust Bearing Specifications

Bearing No. Supplier Rated Load Rating - Radial Rated Load Rating -Thrust NP479560 TIMKEN 7340 kN 2170 kN

3. Structural Strength Analysis Boundary Conditions

One). A: Because PB roll and chock assy are left-right type, 1/2 million analysis: Symmetry plane X direction Fixed

2). B: Slope bearing contact: Compressed Only Support (compression direction only, purple)

3). C: Load Load, Bearing Load - 7340kN, Approx 750ton (Red)

4). Load load position: Outermost edge 300mm (Bearing width, see figure)

5). Thrust Bearing Assembly Dimension Details

existing Heat Shrink

■. The reinforcement ring part due to heat shrinkage is expected to be 30-50mm, and the interpretation thickness is interpreted as the worst case 50mm.

6). Mechanical Properties of PB Roll Material (Refer to PB Roll Tensile Test Results)

Name of material Yield strength Rated Load Rating -Thrust High Carbon-Chromium Steel 59 kgf / mm < 2 > (602 MPa) 109 kgf / mm < 2 > (1112 MPa)

4. Results of structural strength analysis - Comparison of load distribution

One). Thrust bearing part diameter - θ899.8 (existing)

_

2) .Thrust Bearing part diameter - θ800 (when shrinking)

■. Comparison of material yield stress and structural analysis results

Case Maximum stress location Maximum stress Maximum stress / yield stress (%) Diameter 899.8 (Original) R120 part 67.7 11.2% Diameter 800 (when shrinking) Ring fitting R40 91.7 15.2%

5. Conclusion

Structural strength test results for the case where the thrust bearing assembly was remodeled by ring seams

-. The maximum stress is 91.7 MPa stress distributed in the R40 part of the heat sinking end, which increases the yield strength of the PB roll material to 15.2%, which is increased by about 4%.

■. Reinforcing ring Heat Shrink Hoop's Stress and Fatigue Strength Analysis

1. Internal pressure and hoop's stress

One). Internal pressure according to fastening amount

2). Hoop's Stress due to internal pressure

3). Hoop's Stress according to the amount of fastening: Considering the thickness of the reinforcing ring 30 ~ 50t (The fastening amount is calculated for 0.4 ~ 0.8 per face)

4) Heat-shrink reinforcement ring Application material: SCM440H

Name of material Yield strength The tensile strength Surface hardness SCM440H 834 MPa 980.7 MPa Hs: 45-50

5). Hoop's Stress and Applied Stiffening Ring Material and Stress Level Comparison Criteria

⇒ Considering the safety factor of 3 against the yield strength of SCM440H,

⇒Hoop's stress is designed not to exceed 278MPa

6). Determination of fastening amount: t30 / t50 It is judged to be safe when tightness is set to 0.6 or less per side

2. Fatigue Life Review

1) Material S-N diagram for fatigue life review (fatigue diagram): PB Roll No S-N curve of chemical composition.

Material C Si Mn Cr Mo Ni DFPBR 0.70 to 1.00 Max. 0.5 Max. 1.6 1.0 to 1.8 0.3 to 0.6 Max.0.5.

2) The maximum stress (PB Roll tensile strength: 1112 MPa)

Case Maximum stress location Maximum stress Maximum stress / tensile stress (%) Diameter 899.8 (standard) R120 part 67.7 6.1% Diameter 800 (when shrinking) Strengthening of reinforcing ring R40 91.7 8.2%

⇒ It is 8.2% of tensile stress, which is less than half of the tensile stress.

※ S-N diagram of S25C (fatigue diagram)

⇒ Repetitive stress amplitude of PB roll: 0 ~ 91.7MPa.

3. Conclusion

Application of Heat Shrinkage It is considered safe that the reinforcing ring material SCM440H has a safety margin of less than 0.6mm per side.

It is judged that the diameter reduction by heat shrinkage does not affect the fatigue life.

The present invention has been described with reference to the embodiments shown in the attached drawings, but it will be understood that various modifications and other embodiments are possible for those skilled in the art.

10: assembly shaft portion 20: reinforcing ring
31: hole 30: fixing pin

Claims

An outer diameter machining step of removing the eccentricity and machining the surface of the abrasive assembly shaft by removing the abrasive rolling roller having the abrasion occurred on the assembly shaft of the rolling mill installed in the rolling mill of the steel mill,
A diameter of the assembled shaft portion 10 is measured to compensate for the thickness before the abrasion of the assembling shaft portion 10, and a reinforcing ring 20 having a diameter for compensation with a thickness before abrasion is prepared. A reinforcing ring preparing step of processing the diameter of the reinforcing ring to increase;
A reinforcing ring inserting step of inserting a heated reinforcing ring 20 into the machined assembling shaft portion 10 to adhere the inner surface of the reinforcing ring 20 to the outer surface of the assembling shaft portion 10 and bonding them together;
The cooling ring is cooled at room temperature in a state where the heated reinforcing ring 20 is joined to the assembling shaft portion 10 and the reinforcing ring is contracted and the diameter is reduced so as to be firmly bonded to the outer surface of the assembling shaft portion 10 step;
And an inspection and finishing step of finishing the repairing of the outer peripheral surface of the reinforcing ring in a state where the reinforcing ring (20) is joined to the assembling shaft portion (10) by a heat shrinking method, Repair method for damage to bearing assembly shaft of rolling roller for steel plate.

The method according to claim 1,
Wherein a thickness of the reinforcing ring (20) is equal to or larger than an outer diameter of the assembled shaft portion (10).

The method according to claim 1,
A hole 31 is formed in a boundary portion between the assembling shaft portion 10 and the reinforcing ring 20 and the fixing pin 30 is inserted after the adhesive is put into the hole so that the reinforcing ring 20 is separated from the assembling shaft portion 10, Wherein the bearing assembly shaft portion of the steel rolling roller for steelworks is damaged.

The method of claim 3,
Wherein the inner surface of the hole (31) is tapped, an adhesive is put into the hole, and a bolt having a fixing pin function is fastened to the steel plate rolling roller.