JPH04279206A - Method for grinding small diameter roll for rolling mill - Google Patents

Abstract

PURPOSE:To improve the surface roughness of roll and to raise the efficiency of finish grinding by using a grinding wheel for rough grinding a small diameter roll and, using a abrasive film layer formed by spraying abrasive grains on the surface for finish grinding, grinding without changing contact pressure with the small diameter roll. CONSTITUTION:The grinding wheel 1 is used for rough grinding that is executed for removing flaws and sizing the small diameter roll 4 and, for finish grinding that is done for adjusting the roughness of roll 4 surface, a lapping film 14 which the layer of abrasive grains is formed on the film is formed into endless- shape and constantly fed with a roller 9 for revolving. And contact pressure of a contact roller 10 which is brought into contact with the small diameter roll 4 through the film can be kept constant by controlling a hydraulic cylinder. Thus, it is easy to grind the roll by accurately controlling the constant feeding without changing contact pressure and great care.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method for polishing small diameter rolls for rolling mills, which uses a polishing film at a constant contact pressure for final polishing.

0002

[Prior Art] Small diameter rolls for rolling mills generally have a diameter of 20 mm.
The diameter is 0 mm or less, and the material used is die steel, semi-high speed steel, high speed steel, etc. In addition, the hardness of these rolls is Shore hardness, and the die steel is Hs75~
85, semi-high speed steel Hs80-90, high speed steel
It is very hard, such as Hs85-95,
In addition, the roll surface roughness is center line average roughness Ra0.03~0
．． A fairly fine finish of about 2 μm is required.

[0003] In general, a method for polishing small diameter rolls for rolling mills is as shown in FIG.
Polishing was carried out using a rotating grindstone 1 having a diameter of 80 mm and made of Al2O3 and SiC, and an apparatus configured as shown in FIG. That is, in the method using this device, the grinding wheel 1 is moved by the motor 3 through the V-belt 2 to a 500 to 1000 γ
The grinding wheel 1 is rotated at a high speed of 100 μm and brought into contact with a small-diameter roll 4 for a rolling mill (hereinafter simply referred to as a roll) that rotates at a low speed of 10 to 100 γpm to polish the surface of the roll. The entire surface of the roll 4 is polished by moving it in the axial direction of the supported roll 4. Here, the above-mentioned movement of the grinding wheel 1 is carried out about 3 to 5 times, and the movement in the former stage is for the purpose of removing defects and determining dimensions (diameter adjustment of the roll), and the movement in the latter stage is for the purpose of adjusting the surface roughness.

In addition, when polishing small diameter rolls, roll deflection becomes a problem, so the roll deflection adjusting device 8 is
Three of them are installed on the opposite side of the grindstone 1 for polishing and constant adjustment. As shown in FIG. 7, this adjustment is performed by moving the adjustment device 8 laterally to compensate for the decrease in the contact pressure with the roll 4 due to the decrease in the diameter of the grindstone.

[0005]

[Problems to be Solved by the Invention] However, the above conventional methods have the following problems. During polishing, the roll is ground, and the abrasive grains of the whetstone fall off and the diameter of the whetstone becomes smaller, so the contact situation between the roll and the whetstone changes constantly. In order to adjust the changing contact situation,
The roll deflection adjustment device and grinding wheel rotation status (rotation speed - motor load current, grinding wheel movement speed) were manually adjusted. As a result, there were individual differences in work time and finished surface roughness of the rolls. Particularly in the final polishing of small-diameter rolls, the rolls are deflected, and the surface roughness is small, resulting in relatively large individual differences.

[0006] Also, with a rotary whetstone, polishing is possible only when the abrasive grains whose surfaces have been worn fall off and new abrasive grain surfaces appear on the surface, so the polishing finish changes depending on the amount of exposed new abrasive grain surfaces. It's coming. That is, if there are many new abrasive grain surfaces, the roll surface roughness will increase, and if there are few, the roughness will decrease. With rotary whetstones, this adjustment is left to humans, so there are large individual differences. Particularly in final polishing with small roughness, there are large individual differences, so it was necessary to develop a new polishing method.

The present invention has been made in view of these conventional problems, and includes a method in which the polishing film is polished at a constant advance without changing the contact pressure with the roll during final polishing. The purpose is to solve the above issues.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention uses a rotary grindstone for rough polishing to remove defects and measure dimensions when polishing small diameter rolls for rolling mills, and adjusts the surface roughness. The final polishing is a polishing method for small-diameter rolls for rolling mills in which a thin layer of abrasive film is sprayed onto the surface and polished at a constant feed without changing the contact pressure with the small-diameter roll. be.

[0009]

[Operation] The present invention adjusts the roughness of the roll surface by performing rough polishing using a conventional method using a rotary grindstone, which has not caused problems in the rough polishing process for removing defects and determining dimensions of small diameter rolls. In final polishing, a polishing film (lapping film) with an abrasive layer formed by spraying a thin layer onto the film is formed into, for example, an endless shape, and this is stretched between a rotating roller and a contact roller as shown in Figure 2. Then, the rotating roller is rotated at a constant speed by a motor to feed the wrapping film at a constant rate. Further, the contact pressure of the contact roller that contacts the small diameter roll via the film can be kept constant by controlling a fluid pressure cylinder that presses the contact roller in the contact direction. Therefore, it is easy to accurately control and polish by performing constant feeding without changing the contact pressure without relying on human hands. As described above, it is possible to eliminate the influence of increased individual differences in finished surface roughness and roll deflection, and it is possible to perform polishing with excellent quality and efficiency.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below with reference to the drawings. FIG. 1 is a schematic diagram of an embodiment of a polishing apparatus used in the polishing method of the present invention. Note that the same parts as in the conventional example are given the same reference numerals, and redundant explanation will be omitted.

In the figure, frame A is a rough polishing section equipped with a rotary grindstone 1 as in the conventional example, and frame B is a finish polishing section equipped with a lapping film 14 according to the present invention. It is disposed on a frame C so as to be movable in a direction perpendicular to the axis of a certain small diameter roll 4, and the frame C is disposed so as to be reciprocatable in parallel to the roll axis.

In the final polishing section provided in the frame B, a wrapping film 14 is stretched between the film rotating roller 9 and the contact roller 10, as shown in FIG.
The rotating roller 9 is rotated by the motor 3 to feed the film 14 at a constant rate (5 to 100 mm/min in this embodiment). In addition, the contact roller portion is connected to the wrapping film 1 by a fluid pressure cylinder 11 as shown in FIG.
4 can be pressed against the small diameter roll 4 with a constant pressure (1 to 50 kg/cm). The wrapping film 14 is
As shown in FIG. 4, abrasive grains 12 (SiO2
, SiC) is sprayed to a thickness of several 10 to several 100 μm to form an endless tape. The preferred size of the abrasive grains is, for example, No. 220 to No. 1000.

With the polishing apparatus having the above configuration, the small diameter roll 4
To perform polishing, first frame B, which is the final polishing part,
is moved back from the roll 4, only the frame A, which is the rough polishing part, is brought close to the roll 4, and the rotary grindstone 1 is brought into rolling contact with the roll 4, and the frame C is reciprocated from side to side to remove defects as in the conventional example. , and perform dimension polishing. Next, when the rough polishing is completed, the frame A is moved back from the roll 4, and the frame B is moved so that the wrapping film 14 is in rolling contact with the small diameter roll 4. At this time, the contact pressure of the wrapping film 14 against the roll 4 is maintained so as not to change during polishing by controlling the fluid pressure cylinder 11 by appropriate known means, thereby eliminating the possibility of individual differences caused by manual labor as in the past. Therefore, the surface roughness of the roll 4 can be finished uniformly. In addition, wrapping film 1
4 is pressed against the roll 4 by a contact roller 10 lined with an elastic material such as rubber, so that the influence of deflection of the roll can be eliminated.

Next, as a small diameter roll for a rolling mill, a diameter of 1
An example in which polishing was performed on a material with a diameter of 20 mm, a barrel length of 1700 mm, and a material made of semi-high-speed steel (hardness Hs 89) is shown. The rotating grindstone used had a roughness of No. 220, a width of 80 mm, and an outer diameter of 810 mm, and the wrapping film had a roughness of No. 1000 and a width of 80 mm.

[0015]

[Table 1]

[0016] Before polishing, the roughness of the roll is Ra≒0.3 μm.
The target roughness after polishing is Ra≒0.1μm.The conventional method uses only a rotary grindstone, whereas in the method of the present invention, rough polishing for removing defects and dimensioning is performed using a rotary grindstone, and final polishing is performed using a lapping film. Ta. Table 1 shows the polishing conditions at this time.

Table 1 shows rough polishing using a rotary grindstone under the same conditions, followed by final polishing, which is a comparison between the conventional method and the method of the present invention. In the conventional method, because the polishing conditions change every moment, roll deflection adjustment had to be used. In this case, the deflection adjustment was performed by a skilled person, and there was no repolishing.

The result is that in the conventional method, Ra = 1.13 μm.
(average of N=22), σ=0.25 μm, and in this method, Ra=1.08 μm (average of N=18), σ=0.
07 μm, clearly indicating that the method according to the present invention had less variation and was able to improve the quality. Note that if cost is ignored, film polishing from rough polishing to final polishing is possible. For example, if films with different finishes are placed side by side and the films are changed between rough polishing and final polishing, complete labor savings are possible.

[0019]

[Effects of the Invention] As explained above, by polishing according to the method of the present invention, the variation in roll surface roughness is reduced. (In the experimental example, for the target Ra=0.1 μm, σ=0.25 μm in the conventional method and σ=0.07 μm in the method of the present invention). Additionally, roll deflection adjustment during final polishing is no longer necessary. Furthermore, while the conventional method required redoing the final polishing by about 3%, this method did not require it at all.

[0020] As a result of the above, the roll surface roughness quality can be improved;
Efficiency has been improved by saving labor in adjusting roll deflection and reducing rework of final polishing.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a polishing apparatus for performing polishing according to the present invention.

FIG. 2 is a perspective view of a final polishing section according to the present invention.

FIG. 3 is a side view of means for keeping the contact pressure of the polishing film constant.

FIG. 4 is an enlarged cross-sectional view of the polishing film.

FIG. 5 is a perspective view of a rotating grindstone.

FIG. 6 is a schematic diagram of a conventional polishing apparatus.

FIG. 7 is a sectional view showing the operation of a roll deflecting device in a conventional example.

[Explanation of symbols]

1 Rotating whetstone 4 Small diameter roll for rolling mill 14 Polishing film

Claims (1)

[Claims] Claim 1: When polishing small-diameter rolls for rolling mills, a rotary grindstone is used for rough polishing to remove defects and size, and for final polishing to adjust the surface roughness, a thin layer is sprayed onto the surface by spraying abrasive grains. A method for polishing a small-diameter roll for a rolling mill, comprising polishing the resulting polishing film at a constant feed without changing the contact pressure with the small-diameter roll.