JP2966336B2 - Manufacturing method of double structure grinding wheel for online roll grinding - Google Patents

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, in particular,
The present invention relates to a method for producing a double-structured grinding wheel 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 mill for rolling a material to be rolled, such as a steel plate or an ingot, has a rough surface at a contact portion with the material to be rolled or a roll corresponding to a side end of the material to be rolled. The part is locally worn out. Further, similar uneven wear and the like also occurs in other rolls such as a backup roll for backing up the work roll. For this reason, it is necessary to re-grind the outer peripheral surface of these rolling rolls, but as one means, using a grinding wheel having a cylindrical shape, the tapered tip surface is pressed against the outer peripheral surface of the rolling roll. Then, by rotating the grindstone with the rotation of the roll or forcibly rotating the grindstone separately from the rolling roll by a drive motor or the like, the distance between the tapered tip surface and the outer peripheral surface of the rolling roll is increased. It has been proposed to generate sliding friction and grind the rolling rolls as they are incorporated in the stand of the rolling mill, ie, online. For example, Japanese Unexamined Patent Publication No.
JP, JP-A-61-154706, JP-A-61-154706
This is the grinding method or apparatus described in JP-A-127109. By doing so, the operation rate of the rolling mill is improved as compared with the case where the rolling rolls are removed one by one and grinding is performed.

[0003]

As a grindstone used for grinding the above-mentioned rolling roll, a vitrified grindstone which generally provides an excellent grinding action is preferably used. However, such a vitrified grindstone can be used on-line by using such a vitrified grindstone. When trying to grind the rolling roll, the rolling of the grinding wheel due to vibration of the rolling roll due to rolling, or collision with unevenness such as a step or a projection on the outer peripheral surface of the rolling roll due to uneven wear, etc. There has been a problem that chipping or cracking occurs at the corners of the outer peripheral edge. This is because when stress due to sliding friction between the tapered tip surface and the outer peripheral surface of the rolling roll is concentrated on the corner of the outer peripheral edge of the tapered tip surface,
Generally, it is considered that the strength of the vitrified grindstone having a high elastic modulus and being vulnerable to impact is insufficient at the corner 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 dual-structure grinding wheel for online roll grinding in which chipping or cracking does not occur at 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 object is to form a cylindrical shape and to have a tapered tip end surface on an outer peripheral surface of a work roll for rolling. The outer peripheral surface of the rolling work roll is brought online by generating sliding friction with the outer peripheral surface of the rolling work roll in a state where the outer peripheral surface of the rolling work roll is pressed while being offset from the rotation axis of the rolling work roll. (A) a vitrified whetstone having abrasive grains bonded by an inorganic binder and having a cylindrical shape;
A step of preparing a grindstone; (b) a step of pouring a flowable grindstone material containing abrasive grains and a resin binder into an annular space between the first grindstone and a mold surrounding the outer periphery thereof; (c) by curing the resin binder contained in the poured flowability grindstone material in its pouring step, a resinoid grindstone abrasive grains bound by the resin binder that tree
And a resin binder curing step of forming a second grindstone integrally fixed to the outer peripheral side of the first grindstone at the same time as the curing of the grease binder.

[0006]

According to this configuration, the second grinding wheel is integrally fixed to the outer periphery of the first grinding wheel by the hardening of the resin binder. A load (compression) is applied toward the center of the first grindstone, and the preload is opposite to the direction of friction with the work roll for rolling during online roll grinding, so that the strength of the second grindstone is increased, Damage such as chipping or cracking of the outer peripheral edge is suitably prevented.

Further, since the second grinding wheel is fixed to the outer peripheral side of the first grinding stone at the same time as the curing of the resin binder, it is compared with a case where the second grinding stone is fixed to the outer peripheral side of the first grinding stone using an adhesive. As a result, a high bonding strength of the second grindstone is obtained by the mutual engagement of the abrasive grains at the boundary surface, so that peeling of the second grindstone due to friction with the work roll for rolling is suitably prevented.

In addition, 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 grinding stone has an elastic modulus of 2000 to 70 in order to obtain practically sufficient grinding performance.
A vitrified whetstone in which abrasive grains are bound using an inorganic binder such as feldspar, pottery stone, refractory clay or the like within a range of 00 kgf / mm ² is preferably used.

The second grindstone has an elastic modulus lower than at least the first grindstone, and is 100 to 1000 kgf / mm.
^{By using} a resinoid whetstone with a binder within the range of ² , for example, epoxy resin, polyvinyl alcohol resin, phenolic resin, etc., which has the general property of shrinking when cured, the occurrence of damage such as chipping is more effective Prevention and excellent impact resistance can be obtained. In particular, such a second grindstone has a short glass fiber, a short carbon fiber,
If a reinforcing material such as Al ₂ O ₃ fiber is uniformly mixed, impact resistance is further improved and deformation due to thermal expansion is suppressed.

When the second grinding stone is fixed to the outer peripheral side of the first grinding stone so that its volume occupies 5 to 50%, grinding performance and impact resistance which are practically satisfactory can be obtained. When it is less than 5%, the impact resistance tends to be insufficient. On the other hand, when it exceeds 50%, a decrease in grinding performance becomes a problem. The above-mentioned grinding performance and impact resistance are substantially affected by the thickness of the grinding wheel in the radial direction, and the ratio of the volume is determined in consideration of the size of the grinding wheel.

[0012]

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 dual-structure grinding wheel (hereinafter simply referred to as a grinding wheel) 10 for online roll grinding according to one embodiment of the present invention. This grindstone 10 is for grinding a roll of a hot rolling mill online, and has an inner peripheral grindstone 12 having a cylindrical shape and an outer periphery integrally fixed to the outer peripheral side of the inner peripheral grindstone 12. And a side grindstone 14. The inner peripheral side grindstone 12 is made of a vitrified grindstone using an inorganic material such as feldspar, pottery stone, or refractory clay as a binder, and has an elastic modulus of Al ₂ O ₃ , SiC,
Depending on the mixing ratio between the abrasive such as CBN and the binder, etc.,
Preferably within the range of 2000-7000 kgf / mm ² ,
It is set to be about 00 kgf / mm ^2.
C320K8V, PA220L8V (JIS standard), C
B170M100VN1 (outlet 100) or the like is preferably used. Further, the distal end surface 18 of the inner peripheral side grinding stone 12 is a tapered surface that is inclined toward the rear end side at an angle θ from a plane perpendicular to the axial center toward the outer peripheral side. Note that the inner peripheral side grinding wheel 12 corresponds to a first grinding wheel.

On the other hand, the outer peripheral side grindstone 14 is formed of a resinoid grindstone using epoxy resin as a binder, and its elastic modulus is Al ₂ O ₃ , SiC, CBN.
100 to 1 depending on the mixing ratio between the abrasive grains and the binder.
It is set to be preferably about 600 kgf / mm ² within a range of 000 kgf / mm ² , for example, GC220J8B
Y, WA220J8BY (JIS standard), CBNC22
0J100BY (outlet 100) or the like is suitably employed. The tip surface 22 of the outer peripheral grinding wheel 14 is continuously inclined from the tip surface 18, and the outer peripheral corner is chamfered into an R shape having a radius of curvature of about 5 mm. The outer peripheral grindstone 14 is different from the inner peripheral grindstone 12 made of a vitrified grindstone and corresponds to a second grindstone having a different elasticity and a low elastic modulus. In addition, an impact-resistant reinforcing material such as a glass short fiber, a carbon short fiber, or an Al ₂ O ₃ fiber is uniformly mixed into the outer peripheral side grindstone 14 as necessary, so that the impact resistance is increased, and deformation due to thermal expansion is performed. Is prevented.

Here, when exemplifying the dimensions of the respective parts of the grindstone 10 of the present embodiment, the diameters d ₁ , d ₂ , d ₃ are 240 mm, 220 mm, 120 mm, respectively, and The wall thickness is 10 mm, and the ratio of the volume of the outer peripheral grindstone 14 to the total volume of the inner peripheral grindstone 12 and the outer peripheral grindstone 14 is about 21%. In addition, the angle θ is about 0.
5 mm to 1 mm, the length L in the axial direction is about 48 mm. Note 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 during grinding.

The inner and outer grinding wheels 12 and 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 formed by hardening abrasive grains such as Al ₂ O ₃ , SiC, and CBN with a phenol resin, and has a nut 28 embedded on the other surface. Then, the bolt 30 is fastened to the nut 28 through a mounting flange 33 fixed to the tip of the shaft 32, so that the grindstone 10 is mounted on the shaft 32 rotatably supported by a bearing device (not shown). Used for grinding.

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

FIG. 2 is a perspective view showing the inner grinding wheel 12 alone. When manufacturing the inner peripheral grinding wheel 12,
First, abrasive grains such as Al ₂ O ₃ , SiC, and CBN and a binder such as feldspar, porcelain stone, and refractory clay are blended at a predetermined ratio, stirred, pressed into a cylindrical shape, and pressed. It is fired at about 1400 ° C. Thereafter, the front 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 subjected to roughening as necessary. This step corresponds to a step of preparing the inner peripheral side grinding stone 12 which is a cylindrical vitrified grinding stone to which abrasive grains are bound by an inorganic binder.

The inner periphery prepared as described above
As shown in FIG.
One surface of the plate 23 is fixed by an adhesive. the above
Epoxy resin adhesive is preferably used as the adhesive.
You. In this step, the base end face of the inner grinding wheel 12 is disc-shaped.
Backing fixed concentrically with one surface of the locking plate 23
It supports the plate fixing process. The above backing bag
Rate 23 is Al_TwoO _ThreeAnd filler such as SiC
With the phenolic resin to obtain the required mechanical strength.
After mixing at the specified ratio, stir and mix on the lower surface, that is, the other surface.
Insert the nut 28 to be embedded in the
After baking at less than 200 ° C, finish
Process and roughen one surface as necessary.
Is manufactured in advance.

Subsequently, as shown in FIG. 4, a cylindrical mold 34 having substantially the same dimensions 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, CBN, etc., an epoxy resin as a resin binder, and an impact-resistant reinforcing material such as short glass fiber, short carbon fiber, and Al ₂ O ₃ fiber are blended at a predetermined ratio. The fluid grindstone raw material thus stirred is poured into an annular space between the mold 34 and the inner peripheral grindstone 12. In this step, the inner peripheral grinding wheel 1
This corresponds to a pouring step of pouring a fluid grindstone raw material containing abrasive grains and a resin binder into an annular space between the mold 2 and a mold 34 surrounding the outer periphery thereof.

The epoxy resin is cured by leaving it at room temperature in this state, and the abrasive grains are combined to produce the outer peripheral grindstone 14. At the same time, the outer peripheral grindstone 14 is Whetstone 12 and backing plate 2
3 is fixed. This step corresponds to a resin binder curing step of curing the resin binder contained in the fluid grindstone raw material poured in the pouring step, and the outer peripheral grindstone 14 (to which the abrasive grains are bound by the resin binder). When the resin binder is hardened at the same time as the resin binder is hardened, the resin is shrunk at the same time as the resin binder is hardened, so that the outer grindstone 14 is integrally and firmly attached to the outer circumference of the inner grindstone 12. It is fixed.

Then, finally, take it out of the mold 34,
By performing finishing on the tip end surface 22 of the outer peripheral side grinding stone 14 and the like, the grinding stone 10 in which the inner peripheral side grinding stone 12, the outer peripheral side grinding stone 14, and the backing plate 23 are integrally fixed to each other is obtained.

On the other hand, the grinding wheel 10 is mounted on the shaft 32
, And is used, for example, in the usage modes shown in the conceptual diagrams of FIGS. In these figures, 40
Reference numeral denotes 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 means that the rotation axis m is the dimension s with respect to the rotation axis l.
At the same time as the angle θ with respect to a 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 the tip surfaces 18, 2 are pressed by pressing means (not shown).
When the work roll 2 is pressed against the outer peripheral surface of the work roll 40 during hot rolling, the work roll 40 is rotated in the counterclockwise direction indicated by an arrow in FIG. It is reciprocated (oscillated) in the axial direction of 40, that is, in the horizontal 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, the moving direction and the moving speed of each part of the tip surfaces 18 and 22 of the grindstone 10 are different from the moving direction and the moving speed of the outer peripheral surface of the work roll 40. Sliding friction occurs in the portion, and the outer peripheral surface of the work roll 40 is ground. In actual roll grinding, a plurality of such grindstones 10 are arranged at regular intervals in the axial direction of the work roll 40. FIGS. 5, 6, and 7 are a front view, a right side view, and a plan view, respectively.

When grinding is performed by pressing the grindstone 10 against the outer peripheral surface of the work roll 40 during hot rolling as described above, the grindstone is vibrated by the work roll 40 or collides with irregularities formed on the surface thereof. 10, a relatively large impact is applied. Further, in the above usage mode, the sliding friction causes a tensile stress to act on the outer peripheral portion of the tip surfaces 18 and 22 of the grindstone 10 and a compressive stress to act on the inner peripheral portion. For this reason, when the above-mentioned grindstone 10 is composed of only a vitrified grindstone having high modulus of elasticity and low impact resistance, although excellent heat resistance and grinding performance can be obtained, chipping or cracking occurs at the outer peripheral edge where a tensile stress is applied. There was a problem that cracks and the like easily occurred.

On the other hand, the grindstone 10 of the present embodiment has an inner grindstone 12 made of a vitrified grindstone which provides excellent cutting performance, and an outer grindstone made of a resinoid grindstone having a low elastic modulus and high impact resistance. 14, the impact resistance of the outer peripheral portion to which the tensile stress is applied is greatly improved, and the occurrence of chipping and cracking in the outer peripheral portion is reduced. In addition to being prevented well, excellent grinding performance is ensured by the inner peripheral grinding wheel 12.

In particular, the outer peripheral side grinding wheel 14 is formed of a resinoid grinding stone using an epoxy resin as a binder, and its elastic modulus is extremely low at about 600 kgf / mm ^2. Since the thickness in the direction is 10 mm, the occurrence of the chipping, cracking and the like is effectively prevented. The radial thickness of the inner peripheral grinding wheel 12 is 5
Since it is 0 mm, it is possible to obtain a sufficiently satisfactory grinding performance for practical use while improving the impact resistance performance on the outer peripheral side portion as described above.

Further, since the impact resistance reinforcing material such as short glass fiber, short carbon fiber, Al ₂ O ₃ fiber or the like is 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 hardened by the property of the epoxy resin contracted by the curing. The applied load (compression) is applied toward the center of the inner peripheral grinding wheel 12 and the preload thereof is opposite to the direction of friction with the work roll 40 during online roll grinding. The damage of the outer peripheral edge, such as chipping or cracking, is suitably prevented.

Since the outer peripheral grinding wheel 14 is fixed to the outer peripheral surface of the inner peripheral grinding wheel 12 simultaneously with the curing of the epoxy resin binder, it is fixed to the outer peripheral surface of the inner peripheral grinding wheel 12 using an adhesive. As compared with the case where the abrasive grains are engaged with each other at the boundary surface, a higher bonding strength of the outer peripheral grinding wheel 14 is obtained, so that the outer peripheral grinding wheel 1 due to friction with the work roll 40 is obtained.
4 is suitably prevented from peeling off.

While the embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be embodied in other forms.

For example, in the above embodiment, the backing plate 23 is fixed, but the nut 28 is directly buried in the grindstone 12 on the inner peripheral side, for example.
3 may be omitted. It should be noted that a disc-shaped backing plate having no hole in the center or a backing plate of another material can be used.

In the above embodiment, the grindstone 10 is offset with respect to the rotation axis l of the work roll 40 and pressed against the outer peripheral surface of the work roll 40 in a posture inclined with respect to the plane n. The use mode in which the grinding is performed so that the grinding wheel 10 is caused to rotate along with the rotation of the grinding wheel 40 has been described. However, the posture of the grinding wheel 10 is changed, and the grinding wheel 10 is connected to a drive motor or a brake device to forcibly rotate the grinding wheel 10. The grindstone 10 of the present embodiment can be used in various modes, for example, for giving power. In such a case, the shape, size, and the like of each part are changed according to the usage mode.

The outer peripheral grindstone 14 of the above embodiment is
Lath short fiber, carbon short fiber, Al _TwoO_ThreeFiber etc.
Impact strengthening material is mixed in.
It is not always necessary, and other than epoxy resin
Shrink-curing resin binders such as phenolic resins, poly
Resinoid whetstone 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 ground online has been described. However, the grinding wheel 10 is used for online grinding of another rolling roll such as a backup roll for backing up the work roll 40. Of course, 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 specifically exemplified, the present invention can be embodied in various modified and improved forms based on the knowledge of those skilled in the art.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a dual-structure grinding wheel for online roll grinding according to one embodiment of the present invention.

FIG. 2 is a perspective view showing an inner peripheral grinding wheel as a single unit for explaining an example of a method of manufacturing the dual structure grinding wheel of FIG. 1, and is a vitrified grinding wheel in which abrasive grains are bonded by an inorganic binder. This corresponds to a step of preparing a first grindstone having a cylindrical shape.

FIG. 3 is a longitudinal sectional view showing a state in which an inner peripheral grinding wheel is fixed to a backing plate for explaining an example of a method of manufacturing the dual structure grinding wheel of FIG. 1, and corresponds to a backing plate fixing step. I have.

FIG. 4 is a longitudinal sectional view showing a state in which a mixture of an outer peripheral grinding wheel is poured between an inner peripheral grinding wheel and a mold in order to explain an example of a method of manufacturing the dual structure grinding wheel of FIG. 1; This corresponds to a pouring step of pouring a flowable grindstone material containing abrasive grains and a resin binder into an annular space between the inner peripheral grindstone and a mold surrounding the outer periphery.

FIG. 5 is a front view conceptually illustrating an example of a use mode of the dual-structure grindstone of FIG.

FIG. 6 is a right side view conceptually illustrating an example of a usage mode of the dual-structure grindstone of FIG.

FIG. 7 is a plan view conceptually illustrating an example of a usage mode of the dual-structure grindstone of FIG.

[Explanation of symbols]

 10: Double structure whetstone 12: Inner circumference whetstone (first whetstone) 14: Outer circumference whetstone (second whetstone) 18, 22: Tip surface 40: Work roll (work roll for rolling)

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kanji Hayashi 4-6-22 Kanon Shinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Mitsubishi Heavy Industries, Ltd. Hiroshima Works (72) Inventor Takayuki Goto 1-chome, Yukiura Kanazawa-ku, Yokohama 8-1 Mitsubishi Heavy Industries, Ltd. Basic Technology Research Laboratory (72) Inventor Hisao Matsushima 6-22, Kannonshinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Works (56) References JP-A-60-1985 9661 (JP, A) JP-A-62-127109 (JP, A) JP-A-62-88579 (JP, A) JP-A-63-100949 (JP, A) Japanese Utility Model Laid-open No. 62-25156 (JP, U) Japanese Utility Model Application No. 55-138067 (JP, U) Japanese Utility Model Application No. 52-157089 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B24D 7/14

Claims (1)

(57) [Claims] In a state in which a cylindrical shape is formed and a tapered tip surface thereof is pressed against an outer peripheral surface of a rolling work roll while being offset from a rotation axis of the rolling work roll, A method for producing a double-structured grinding wheel for online roll grinding for online grinding of the outer peripheral surface of the rolling work roll, wherein the sliding friction is generated between the outer peripheral surface of the rolling work roll and the outer peripheral surface of the rolling work roll, A step of preparing a first grindstone which is a vitrified grindstone having abrasive grains bonded by an inorganic binder and having a cylindrical shape; and an abrasive space and a resin in an annular space between the first grindstone and a mold surrounding the outer periphery thereof. A pouring step of pouring a flowable grindstone raw material containing a binder, and by hardening a resin binder contained in the flowable grindstone raw material poured in the pouring step, grinding is performed with the resin binder. A resin binder hardening step of forming a second grindstone which is a resinoid grindstone having grains bonded thereto and which is integrally fixed to the outer peripheral side of the first grindstone simultaneously with curing of the resin binder. Method for producing a dual-structure grinding wheel for online roll grinding.