JPH0976161A - Manufacturing method of double structured grinding wheel for on-line roll grinding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a double structured grinding wheel for on-line roll grinding without causing a defect and a crack to a corner part of a tapered head end surface outer margin. SOLUTION: A preload (compression) is applied to a grinding wheel 14 on the outer peripheral side toward the center of a grinding wheel 12 on the inner peripheral side by contraction due to hardening of a resin binder as the grinding wheel 14 on the outer peripheral side is integrally fastened on the outer periphery of the grinding wheel 12 on the inner peripheral side by hardening of the resin binder, and the strength of the grinding stone 14 on the outer peripheral side is improved and a damage of a defect, a crack, etc., of the outer margin is favourably prevented as the preload is directed in a direction opposite to the frictional direction with a work roll 40 during on-line roll grinding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grindstone for grinding an outer peripheral surface of a work roll for rolling on-line, and particularly,
The present invention relates to a method for manufacturing a double-structured grindstone for online roll grinding with less damage such as chipping.

[0002]

2. Description of the Related Art For example, a work roll of a rolling machine for rolling a material to be rolled such as a steel plate or a steel ingot is roughened at a contact portion with the material to be rolled or corresponds to a side end portion of the material to be rolled. The part is locally worn off. Further, similar uneven wear or the like also occurs in other rolls such as a backup roll that backs up the work roll. For this reason, it is necessary to re-grind the outer peripheral surface of those rolling rolls, but as one means therefor, a grindstone having a cylindrical shape is used, and its tapered tip surface is pressed against the outer peripheral surface of the rolling roll. Then, by rotating the grindstone along with the rotation of the roll, or by forcibly rotating the grindstone separately from the rolling roll by a drive motor or the like, between the tapered tip surface and the outer peripheral surface of the rolling roll. It has been proposed to generate sliding friction and perform grinding while the rolling roll is still installed in the stand of the rolling mill, that is, online. For example, JP-A-61-140312
JP, JP-A-61-154706, JP-A-62.
That is the grinding method or apparatus described in Japanese Patent Publication No. 127109. In this way, the operating rate of the rolling mill is improved as compared with the case where the rolling rolls are individually removed and ground.

[0003]

By the way, as a grindstone used for grinding a rolling roll as described above, generally, a vitrified grindstone capable of obtaining an excellent grinding action is preferably used. When attempting to grind a rolling roll, vibration of the rolling roll accompanying rolling, or collision with unevenness such as steps or protrusions generated on the outer peripheral surface of the rolling roll due to uneven wear, etc. There is a problem that defects or cracks occur at the corners of the outer peripheral edge. This is because when the stress due to the sliding friction between the tapered tip surface and the outer peripheral surface of the rolling roll is concentrated on the corners of the outer peripheral edge of the tapered tip surface,
It is considered that the strength of the vitrified grindstone, which generally has a high elastic modulus and is weak against impact, is insufficient at the corners of the outer peripheral edge of the tapered tip surface.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a double-structured grindstone for online roll grinding which does not cause defects or cracks at the corners of the outer peripheral edge of the tapered tip surface. It is to provide a manufacturing method of.

[0005]

The gist of the method of the present invention for achieving the above-mentioned object is that it has a cylindrical shape and its tapered tip surface is on the outer peripheral surface of the work roll for rolling. The outer circumferential surface of the rolling work roll is made online by causing sliding friction between the rolling work roll and the outer circumferential surface of the rolling work roll in a state of being pressed with being offset from the rotational axis of the rolling work roll. A method for producing a double-structured grindstone for online roll grinding for grinding by means of: (a) a vitrified grindstone in which abrasive grains are bonded by an inorganic binder, which has a cylindrical shape.
A step of preparing a grindstone, (b) a pouring step of pouring a fluid grindstone raw material containing abrasive grains and a resin binder into an annular space between the first grindstone and a die surrounding the outer periphery thereof, (c) By curing the resin binder contained in the flowable grindstone raw material poured in the pouring process, a resinoid grindstone in which abrasive grains are bound by the resin binder and at the same time as hardening of the dendritic fat binder And a resin binder curing step of forming a second grindstone integrally fixed to the outer peripheral side of the first grindstone.

[0006]

As described above, the second grindstone is integrally fixed to the outer periphery of the first grindstone by the hardening of the resin binder, so that the second grindstone is not covered by the shrinkage due to the hardening of the resin binder. 1 While a preload is applied toward the center of the grindstone and its preload is in the opposite direction to the direction of friction with the work roll for rolling during online roll grinding, the strength of the second grindstone is increased, Damage such as chipping or cracking of the outer peripheral edge is preferably prevented.

Further, since the second grindstone is fixed to the outer peripheral side of the first grindstone at the same time when the resin binder is hardened, as compared with the case where the second grindstone is fixed to the outer peripheral side of the first grindstone using an adhesive. As a result of the mutual engagement of the abrasive grains at the boundary surface, a high fixing strength of the second grindstone can be obtained, so that peeling of the second grindstone due to friction with the work roll for rolling is preferably prevented.

Moreover, since the first grindstone is a vitrified grindstone and the second grindstone is a resinoid grindstone, a structure in which a resinoid grindstone excellent in impact resistance is provided on the outer peripheral side of the first grindstone excellent in grindability Therefore, grinding efficiency and durability can be obtained at the same time.

Here, the first grindstone has an elastic modulus of 2000 to 70 in order to obtain practically sufficient grinding performance.
A vitrified whetstone having an abrasive grain in the range of 00 kgf / mm ² , for example, feldspar, porcelain stone, refractory clay, etc., in which abrasive grains are bound together with an inorganic binder is preferably used.

The second grindstone has a modulus of elasticity at least lower than that of the first grindstone and is 100 to 1000 kgf / mm.
The occurrence of damage such as chipping is more effective by using resininoid grindstone with a binder within the range of ² , such as epoxy resin, polyvinyl alcohol resin, phenol resin, etc. And excellent impact resistance can be obtained. In particular, the second grindstone includes glass short fibers, carbon short fibers,
By uniformly mixing the reinforcing material such as Al ₂ O ₃ fiber, the impact resistance is further improved and the deformation due to thermal expansion is suppressed.

When the second grindstone is fixed to the outer peripheral side of the first grindstone, if the volume of the second grindstone occupies 5 to 50%, practically satisfactory grinding performance and impact resistance can be obtained. If it is less than 5%, the impact resistance tends to be inadequate, while if it exceeds 50%, a decrease in grinding performance becomes a problem. The above grinding performance and impact resistance are substantially greatly affected by the wall thickness of the grindstone in the radial direction, and the volume ratio is determined in consideration of the size of the grindstone.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a longitudinal sectional view of a double-structured grindstone (hereinafter, simply referred to as grindstone) 10 for online roll grinding which is an embodiment of the present invention. This grindstone 10 is for grinding a roll of a hot rolling mill online, and has a cylindrical inner peripheral side grindstone 12 and an outer periphery integrally fixed to the outer peripheral side of the inner peripheral side grindstone 12. And a side grindstone 14. The inner peripheral side grindstone 12 is composed of a vitrified grindstone in which an inorganic substance such as feldspar, porcelain stone, and refractory clay is used as a binder, and its elastic modulus is Al ₂ O ₃ , SiC,
Depending on the mixing ratio of the abrasive such as CBN and the above-mentioned binder,
Within the range of 2000-7000 kgf / mm ² , preferably 50
It is set to be about 00 kgf / mm ² , and for example G
C320K8V, PA220L8V (JIS standard), C
B170M100VN1 (outlet 100) or the like is preferably used. Further, the tip end surface 18 of the inner peripheral side grindstone 12 is a tapered surface which inclines toward the rear end side at an angle θ from a plane perpendicular to the axial center toward the outer peripheral side. The inner grindstone 12 corresponds to the first grindstone.

On the other hand, the outer peripheral grindstone 14 is composed of a resinoid grindstone in which an epoxy resin is used as a binder, and its elastic modulus is Al ₂ O ₃ , SiC, CBN.
100 to 1 depending on the mixing ratio of the abrasive grains and the binder such as
Within the range of 000 kgf / mm ² , it is preferably set to be about 600 kgf / mm ² , for example, GC220J8B.
Y, WA220J8BY (JIS standard), CBNC22
0J100BY (outlet 100) or the like is preferably adopted. Further, the tip end surface 22 of the outer peripheral side grindstone 14 is continuously inclined from the tip end surface 18, and the outer peripheral side corner is chamfered into an R shape having a radius of curvature of about 5 mm. The outer peripheral side grindstone 14 corresponds to a second grindstone which has a different binding agent and a low elastic modulus from the inner peripheral side grindstone 12 formed of a vitrified grindstone. It should be noted that impact-resistant reinforcing materials such as short glass fibers, short carbon fibers, and Al ₂ O ₃ fibers are uniformly mixed into the outer circumferential grindstone 14 as needed to enhance the strength against impact and to prevent deformation due to thermal expansion. Is being prevented.

Here, exemplifying the dimensions of each part of the grindstone 10 of the present embodiment, the diameter dimensions d ₁ , d ₂ and d ₃ are 240 mm, 220 mm and 120 mm, respectively. The wall thickness is 10 mm, and the ratio of the volume of the outer peripheral side grindstone 14 to the total volume of the inner peripheral side grindstone 12 and the outer peripheral side grindstone 14 is about 21%. The angle θ is about 0.
From 5 ° to 1 °, the length L in the axial direction is about 48 mm. It should be noted that these dimensions are appropriately determined in consideration of various grinding conditions such as the diameter of the roll to be ground and the attitude of the grindstone 10 at the time of grinding.

The inner grindstone 12 and the outer grindstone 14 are fixed to one surface of a disk-shaped backing plate 23 having a circular hole in the center. The backing plate 23 is made by hardening abrasive grains of Al ₂ O ₃ , SiC, CBN or the like with a phenol resin, and a nut 28 is embedded on the other surface. Then, the bolt 30 is fastened to the nut 28 through the mounting flange 33 fixed to the tip of the shaft 32, whereby the grindstone 10 is mounted on the shaft 32 rotatably supported by the bearing device (not shown), and the roll of the rolling mill is rolled. Used for grinding.

Next, an example of a method of manufacturing the grindstone 10 of this embodiment will be described with reference to FIGS.

FIG. 2 is a perspective view showing the inner peripheral side grindstone 12 alone. When manufacturing this inner circumference side grinding wheel 12,
First, the above-mentioned Al ₂ O ₃ , SiC, CBN, etc. abrasive grains and a binder such as feldspar, porcelain stone, refractory clay, etc. are mixed at a predetermined ratio, stirred, and then press-formed into a cylindrical shape and Baking at about 1400 ° C. After that, the tip end surface 18 and the like are finished so as to have the above-described dimensions, and the outer peripheral surface and the lower surface are roughened if necessary. This step corresponds to the step of preparing the inner peripheral side grindstone 12 which is a cylindrical vitrified grindstone in which abrasive grains are bonded by an inorganic binder.

The inner circumference prepared as described above
The side grindstone 12 is a backing as shown in FIG.
It is fixed to one surface of the plate 23 with an adhesive. the above
Epoxy resin adhesive is preferably used as the adhesive.
You. In this step, the base end surface of the inner peripheral side grindstone 12 is a disc-shaped burr.
Bucking that is fixed concentrically with one surface of the locking plate 23
It corresponds to the grab plate fixing process. Above backing
Rate 23 is Al₂O _Three, Filler such as SiC and
In order to obtain the required mechanical strength with the nole resin,
After mixing at a specified ratio, stir and mix
Insert the nut 28 to be embedded in the
After forming without a press, bake at about 200 ℃, then finish
In addition to processing, one surface is roughened if necessary.
Is manufactured in advance.

Subsequently, as shown in FIG. 4, a mold 34 having a cylindrical shape having substantially the same size as the outer shape of the backing plate 23 is fitted to the outer peripheral portion of the backing plate 23, and the Al ₂ Abrasive grains such as O ₃ , SiC, and CBN, epoxy resin that is a resin binder, and impact resistant reinforcing materials such as glass short fibers, carbon short fibers, and Al ₂ O ₃ fibers are mixed at a predetermined ratio. The fluid grindstone raw material that has been agitated is poured into the annular space between the mold 34 and the inner peripheral side grindstone 12. This process is for the inner grinding wheel 1
It corresponds to a pouring step of pouring a fluid grindstone raw material containing abrasive grains and a resin binder into an annular space between 2 and a mold 34 surrounding the outer periphery thereof.

By leaving the epoxy resin in that state at room temperature, the epoxy resin is hardened and the abrasive grains are bonded to produce the outer peripheral grindstone 14, and at the same time, the outer peripheral grindstone 14 is moved to the inner peripheral side. Grinding stone 12 and backing plate 2
3 is fixed. This step corresponds to a resin binder hardening step of hardening the resin binder contained in the fluid grindstone raw material poured in the above-mentioned pouring step, and the outer peripheral side grindstone 14 (where the abrasive grains are bound by the resin binder ( When the resinoid grinding wheel is formed, the outer peripheral side grinding wheel 14 is integrally and firmly fixed to the outer peripheral side of the inner peripheral side grinding wheel 12 due to the general property of the resin that when the resin binder is cured, the resin binder shrinks at the same time. It is fixed.

Finally, take out from the mold 34,
By finishing the tip surface 22 of the outer peripheral side grinding wheel 14 and the like, the inner peripheral side grinding wheel 12, the outer peripheral side grinding wheel 14, and the backing plate 23 are integrally fixed to each other to obtain the grindstone 10.

On the other hand, the grindstone 10 has the shaft 32.
And is used in the usage mode shown in the conceptual diagrams of FIGS. 5 to 7, for example. In these figures, 40
Is a work roll which is disposed substantially horizontally on a hot rolling mill (not shown) and is driven to rotate around a rotation axis l.
0 indicates that the rotation axis m is s with respect to the rotation axis l.
Is offset downwardly by a certain angle, and the angle α is substantially the same as the angle θ with respect to the plane n perpendicular to the rotation axis l.
It is arranged in a posture that only tilts. The grindstone 10 is rotatably supported around a rotation axis m via a shaft 32, and is pressed by a pressing means (not shown) to the tip surfaces 18, 2
2 is pressed against the outer peripheral surface of the work roll 40 during hot rolling, so that the work roll 40 is rotated in the counterclockwise direction indicated by the arrow in FIG. It is reciprocated (oscillated) in the axial direction of 40, that is, in the left-right direction in FIGS. At this time, the grindstone 10 is, for example, 400 to 10
Although it is rotated at a peripheral speed of 00 m / min, since the moving direction and moving speed of each part of the tip surfaces 18 and 22 of the grindstone 10 are different from the moving direction and moving speed of the outer peripheral surface of the work roll 40, the contact between them occurs. Sliding friction occurs in the portion, and the outer peripheral surface of the work roll 40 is ground. In the actual roll grinding, a plurality of such grindstones 10 are usually arranged at regular intervals in the axial direction of the work roll 40. Further, FIGS. 5, 6, and 7 are a front view, a right side view, and a plan view, respectively.

When the grindstone 10 is pressed against the outer peripheral surface of the work roll 40 during hot rolling in this way to perform grinding, the grindstone is vibrated by the work roll 40 or collides with irregularities formed on the surface thereof. A comparatively large impact is applied to 10. Further, in the above-described use mode, the sliding friction causes a tensile stress to act on the outer peripheral side portion of the tip surfaces 18, 22 of the grindstone 10 and a compressive stress to act on the inner peripheral side portion thereof. For this reason, when the grindstone 10 is composed of only a vitrified grindstone that has excellent heat resistance and grinding performance, but has a high elastic modulus and low impact resistance, chipping and cutting at the outer peripheral edge portion where tensile stress is applied There is a problem that cracks and the like are likely to occur.

On the other hand, the grindstone 10 of the present embodiment has an inner grindstone 12 made of a vitrified grindstone capable of obtaining excellent cutting performance and an outer grindstone made of a resinoid grindstone having a low elastic modulus and high impact resistance. Since it has a double structure integrally provided with 14, the impact resistance of the outer peripheral side portion to which the tensile stress is applied is significantly improved, and the occurrence of chipping or cracking in the outer peripheral side portion. In addition to being satisfactorily prevented, the inner peripheral side grinding wheel 12 ensures excellent grinding performance.

In particular, the outer peripheral grindstone 14 is composed of a resinoid grindstone having an epoxy resin as a binder, and has a very low elastic modulus of about 600 kgf / mm ² and a radius of the outer peripheral grindstone 14. Since the wall thickness in the direction is 10 mm, the occurrence of chipping, cracking, etc. can be effectively prevented. In addition, the thickness of the inner peripheral side grindstone 12 in the radial direction is 5
Since it is 0 mm, it is possible to obtain sufficient grinding performance for practical use while improving the impact resistance performance in the outer peripheral side portion as described above.

Further, since impact-resistant reinforcing materials such as glass short fibers, carbon short fibers, and Al ₂ O ₃ fibers are uniformly mixed in the outer peripheral grindstone 14, the outer peripheral grindstone 14 is thermally expanded. Deformation is well prevented,
Impact resistance is further improved.

Further, since the outer peripheral grindstone 14 is integrally fixed to the outer peripheral surface of the inner peripheral grindstone 12 by the curing of the epoxy resin binder, the outer peripheral grindstone 14 is attached to the outer peripheral grindstone 14 due to the property of the epoxy resin contracted by the curing. The applied load (compression) is applied toward the center of the inner peripheral side grindstone 12, and the preload thereof is in the opposite direction to the friction direction with the work roll 40 during the online roll grinding. Therefore, damage such as chipping or cracking of the outer peripheral edge is suitably prevented.

Since the outer peripheral grindstone 14 is fixed to the outer peripheral surface of the inner peripheral grindstone 12 simultaneously with the curing of the epoxy resin binder, it is fixed to the outer peripheral surface of the inner peripheral grindstone 12 using an adhesive. As compared with the case where the outer peripheral side grindstone 14 is engaged with each other at the boundary surface, a higher fixing strength of the outer peripheral side grindstone 14 can be obtained.
Peeling off of No. 4 is suitably prevented.

Although one embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be implemented in other modes.

For example, although the backing plate 23 is fixedly mounted in the above-mentioned embodiment, the nut 28 is directly embedded in the grindstone 12 on the inner peripheral side, so that the backing plate 2 is provided.
3 may be omitted. It is also possible to use a disk-shaped backing plate having no hole in the center or a backing plate made of another material.

In the above embodiment, the grindstone 10 is offset with respect to the rotation axis l of the work roll 40, and is pressed against the outer peripheral surface of the work roll 40 in a posture inclined with respect to the plane n. Although the usage mode in which grinding is performed so as to be rotated along with the rotation of 40 has been described, the attitude of the grindstone 10 is changed, and the grindstone 10 is forcibly rotated by connecting a drive motor, a brake device, or the like. The grindstone 10 of the present embodiment can be used in various modes such as giving power. In that case, the shape, size, etc. of each part will be changed according to the usage mode.

Further, the outer peripheral grindstone 14 of the above embodiment has a
Lath short fiber, carbon short fiber, Al ₂O_ThreeFiber etc.
The impact-resistant reinforcement material of
Not necessarily required, and other than epoxy resin
Shrink-curable resin binders such as phenolic resins, poly
Resinoid grindstone using vinyl alcohol resin, etc.
Can also be used.

In the above embodiment, the case where the work roll 40 of the hot rolling mill is grinded online has been described. However, the grindstone 10 can be used for online grinding of another roll such as a backup roll that backs up the work roll 40. The present invention can be similarly applied to a grindstone for grinding a rolling roll of a hot rolling mill or a cold rolling mill.

Although not illustrated one by one, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a dual structure grindstone for online roll grinding according to an embodiment of the present invention.

FIG. 2 is a perspective view showing an inner peripheral side grindstone alone for explaining an example of a method for manufacturing the double-structured grindstone of FIG. 1, which is a vitrified grindstone in which abrasive grains are bonded by an inorganic binder. It corresponds to the step of preparing the first grindstone having a cylindrical shape.

FIG. 3 is a vertical cross-sectional view showing a state in which an inner peripheral side grindstone is fixedly mounted on a backing plate for explaining an example of a method for manufacturing the double-structured grindstone of FIG. 1, corresponding to a backing plate fixing step. There is.

FIG. 4 is a vertical cross-sectional view showing a state in which a mixture of an outer peripheral side grinding stone is poured between an inner peripheral side grinding stone and a mold for explaining an example of a method for manufacturing the double-structured grindstone of FIG. It corresponds to a pouring step of pouring a fluid grindstone raw material containing abrasive grains and a resin binder into an annular space between an inner circumference side grindstone and a die surrounding the outer circumference.

FIG. 5 is a front view conceptually explaining an example of a usage mode of the double-structured grindstone of FIG. 1.

FIG. 6 is a right side view conceptually explaining an example of a usage mode of the double-structured grindstone of FIG. 1.

FIG. 7 is a plan view conceptually explaining an example of a usage mode of the double-structured grindstone of FIG. 1.

[Explanation of symbols]

 10: Double structure grindstone 12: Inner circumference grindstone (1st grindstone) 14: Outer circumference grindstone (2nd grindstone) 18, 22: Tip surface 40: Work roll (work roll for rolling)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koichi Sabun Koichi Saki, Akui-cho, Akita Prefecture, Itayama, Itayama Character, Nishi-kaido, No. 22 at No. 22 (72) Inventor, Kanji Hayashi, 4-chome, Kannon-Shinmachi, Nishi-ku, Hiroshima-shi, Hiroshima No. 22 Mitsubishi Heavy Industries, Ltd. Hiroshima Works (72) Inventor Takayuki Goto 1-8-8, Koura, Kanazawa-ku, Yokohama, Kanagawa Prefecture Mitsubishi Heavy Industries, Ltd. Basic Technology Research Laboratory (72) Inventor Hisao Matsushima Nishi-ku, Hiroshima-shi, Hiroshima 4-6-22 Kannon Shinmachi Mitsubishi Heavy Industries Ltd. Hiroshima Works

Claims (1)

[Claims] 1. A cylindrical shape, the tapered tip end surface of which is pressed against the outer peripheral surface of the rolling work roll by being offset from the rotation axis of the rolling work roll. Sliding friction is generated between the outer peripheral surface of the rolling work roll, a method for manufacturing an online roll grinding double-structured grindstone for grinding the outer peripheral surface of the rolling work roll online. A step of preparing a first grindstone having a cylindrical shape, which is a vitrified grindstone in which abrasive grains are bonded by an inorganic binder, and an abrasive grain and a resin in an annular space between the first grindstone and a die surrounding the outer periphery thereof. A pouring step of pouring a fluid grindstone raw material containing a binder, and a resin binder contained in the fluid grindstone raw material poured in the pouring step are cured, whereby the resin binder is used for grinding. And a resinoid hardening step of forming a second grindstone integrally bonded to the outer peripheral side of the first grindstone at the same time when the resinoid grindstone in which particles are bonded is hardened. Method for producing double-structured grindstone for online roll grinding.