JPS6012147A - Roller mill - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized in that a raw material fed onto a grinding table rotating around a vertical axis is sandwiched between a rotatable grinding roller that is pressed toward the top surface of the grinding table and the grinding table. Regarding the improvement of roller mills for crushing, in particular, reduction of vibration,
This relates to a roller mill that aims to improve grinding efficiency.

Conventionally, drum mills such as ball mills have been used to crush cement clinker, blast furnace slag, etc., but such drum mills have low efficiency, increase running costs, and are extremely uneconomical.

From this point of view, efforts have been made in recent years to use the above-mentioned relatively efficient roller mills for pulverizing blast furnace slag and the like using cement clinker nozzles.

However, in the case of a roller mill, unlike drum mills, the raw material is not crushed by colliding and grinding the raw material with crushing media such as balls, but instead of being crushed between the crushing table supported on the machine base and the crushing roller. Since the raw material is actively crushed by the squeezing force of both rollers, the vibration generated in the crushing rollers is often transmitted to the machine base, so the vibration is larger than that of a drum mill. This is an obstacle in using it for crushing clinker and blast furnace slag.

Furthermore, although it is known that roller mills have better grinding efficiency than drum mills, the efficiency of current roller mills is not necessarily satisfactory, and it is thought that there is considerable room for improvement.

The causes of vibrations in roller mills as mentioned above, especially those caused by the vibrations of the crushing rollers, can be roughly divided into those caused by the hardness of the raw material or its changes, and those caused by the slippage of the crushed raw materials in the radial direction of the crushing rollers. There is so-called self-excited vibration, and the present invention aims to reduce the latter self-excited vibration and improve grinding efficiency.

First, the cause of the self-excited vibration will be explained with reference to FIGS. 1 to 4.

FIG. 1 is a side sectional view showing the structure of a conventional general roller mill. In the figure, 1 is a crushing table, which is actively rotated around a vertical shaft 2 by a drive source such as a motor (not shown). Ru.

An annular groove 3 centered on the vertical axis 2 is formed on the upper surface of the crushing table 1, and the annular groove 3 has an arcuate cross-sectional shape concave downward as shown in the figure.

Further, on the upper part of the crushing table 1, its outer peripheral surface 4.51.
is attached in a state where it is pressed in the direction of the annular groove 3 through a gap 6 between the annular groove 3 and the annular groove 3.

That is, crushing rollers 5a, 51. For example, a roller shaft 9 inserted into the crushing chamber 8 from the main casing 7. ．． The roller shafts 9a and 9b are rotatably supported at 9 degrees, and the roller shafts 9a and 9b are connected to the main body casing 7.
Horizontal axis provided outside10. ．． 10t.

An arm 11a is swingably attached to the vertical inner surface of the arm 11a.
, llb, and the tip of the bolt 13 screwed into the stopper arm 12 comes into contact with the arm 11° (1 lb), thereby increasing the width of the gap 6 between the crushing rollers 5a, 5b and the annular groove 3. A minimum limit is set.

Further, each tip of the arm 1la111b of the above-mentioned set is connected to the rod 15a, 15I via the tensioning device 14.

are connected by.

Therefore, the raw material supplied to the center of the upper surface of the crushing table 1 is moved toward the outer circumference, that is, into the annular groove 3 by the conical upper surface shape of the crushing table 1 and the centrifugal force caused by the rotation of the crushing table 1, and is moved toward the outer circumference, that is, into the annular groove 3, , and the crushing table 1, and are crushed under pressure.

However, one of the crushing rollers, for example 5. If the layer thickness of the raw material bitten by the rod 15a1 is too thick, the crushing roller 5 rotates in the direction of escaping upward against the rotation biasing force of the tensioning device 14, so that the rotational force is applied to the tensioning of the rod 15a1. The information is transmitted via the device 14 and the rod 15I to the arm 11 to which the other crushing roller 5 is attached, and the crushing roller 5 is pressed in the direction of the annular groove 3 to crush the raw material according to changes in the layer thickness. The pressing force of the rollers 5a and 5b is automatically adjusted.

The raw material thus crushed by the crushing rollers 5a and sb is moved to the outer periphery of the crushing table 1 by the centrifugal force of the crushing table 1, and is moved by the upward air flow flowing out from the upward nozzle 16 surrounding the outer periphery of the crushing table 1. The particle size is sorted by a sorting device (not shown) installed at the top of the grinding chamber 8, and only fine powder with a certain precision or less is taken out of the grinding chamber 8, and coarse powder that does not reach a certain precision is sent to the grinding table again. It is returned to the upper surface of the container and is crushed.

By the way, in the conventional roller mill, the crushing rollers 5, L,
Conventionally, the radii of curvature r and R when cut along a plane passing through the outer circumferential surface 4 of the grinding table 1 and the roller shaft 9a or 9 of the annular groove 3 of the grinding table 1 are conventionally R>r. - In the example shown in FIG. 2(a), R''RIs?-rl, R1=rI+a.

d, = d0, the thickness d of the crushing roller in the radial direction of the gap 6 between both curved surfaces
is constant (d+), and in the example shown in (b) of the same figure, R=RISr=r2, R1>r2 +d6RI>r2
+ti2. d2 > d.

The thickness d of the gap 6 between both curved surfaces is set so that the thickness d2 on the front end side or the rear end side is always larger than the thickness do on the central part.

Therefore, in the conventional roller mill, as shown in FIG.
and the annular groove 3. Therefore, during the pinching, a pressing force Fl acts on the raw material G in a direction perpendicular to the roller shaft 9 supporting the crushing roller 5, and this pressing force F
A shearing force F2 in a direction perpendicular to , acts, and the raw material pulverized by the shearing force F2 tends to flow out from the gap 6 in the direction of the axis of the roller shaft 9 (that is, forward or backward).

In a roller mill, the layer thickness of the raw material G, that is, the thickness of the gap 6, changes rapidly due to the forward or backward outflow of the raw material.
The crushing roller 5 vibrates as the crushing roller 5 raises the rotating plate. Such self-excited vibrations occur each time a new raw material is bitten and pulverized.
The greater the tendency of the raw material powder to flow in the axial direction, the more likely this will occur, and in extreme cases, it will become impossible to operate.

In the case of a roller mill, as shown in FIG. 3 when the crushing roller 5 is viewed from the front, the raw material is crushed not at a point 16 directly below the roller where compression has been completed, but at a biting point at the rear of the crushing table l in the direction of movement. 17 (a point 1 distance behind the center of the roller), and as shown in FIG. peripheral speed F,
, the circumferential speed F of the outer circumferential surface of the crushing roller 5 in the rotational direction.

is deviated by an angle α, and a shearing force in the direction F5 acts on the raw material directly below the biting point 17 corresponding to this deviation angle α, and this shearing force F5 also prevents the flow of the raw material powder. It is thought that this causes an increase in self-excited vibration.

As described above, the cause of the self-excited vibration of the grinding roller 5 is due to the flow of raw material powder in the direction of the roller shaft 9 in the gap 6, but as shown in FIGS. 1 and 2, in the conventional roller mill, The thickness of the gap 6 may be constant in the direction of the roller shaft 9 (Fig. 2 (a)), or it may be thicker at the front or rear end than at the center (Fig. 2 (b)). In any case, since it is open to the front and rear, the shape is not designed to block the flow of raw material generated in the gap 6, and the structure is likely to cause self-excited vibration. be.

Furthermore, in the conventional roller mill, as described above, the structure is such that the pulverized raw material does not easily flow out (escape) from the gap 6 between the pulverizing roller 5 and the pulverizing table 1, so the pressing force F of the pulverizing roller 5, The raw material escapes before it can effectively act on the raw material powder, and sufficient compression and crushing is not performed, which is one of the reasons for reducing the crushing efficiency of the roller mill.

In view of the above points, the present invention aims to reduce self-excited vibration and improve grinding efficiency by preventing the flow of raw material in the axial direction of the roller in the gap between the grinding roller and the annular groove of the grinding table. The gist of this is that in a roller mill that crushes the raw material supplied onto a crushing table by pinching it between the crushing table and a crushing roller that is pressed toward the top surface of the crushing table, While forming an annular groove with an arcuate cross section that dips downward,
The present invention provides a roller mill in which the outer circumferential surface of the crushing roller facing the annular groove is formed into a drum shape or a flat right cylindrical shape recessed in an arc shape in the direction of the roller shaft supporting the crushing roller. .

Next, embodiments embodying the present invention will be described with reference to the accompanying drawings starting with FIG. 5 to provide an understanding of the present invention.

Here, FIGS. 5 and 6 are side sectional views of a crushing roller and a crushing table portion of a roller mill according to an embodiment of the present invention. Note that the same reference numerals are used for elements common to those shown in FIGS. 1 and 2.

What is shown in FIG. 5 is the outer circumferential surface 2 of the crushing roller 25 that is pressed toward the annular groove 3 bored on the top surface of the crushing table 1.
．． 4 is a roller mill formed in a right cylindrical shape (straight), and the cross-sectional shape of the annular groove 3 cut by the vertical plane including the roller shaft 9 is in the shape of a circular arc concave downward; Since the cross-sectional shape taken along the same vertical plane of the outer circumferential surface 24 of the crushing roller 25 is linear, the thickness of the gap 26 created at the opposing portion of the annular groove 3 and the outer circumferential surface 24 of the crushing roller 25 is smaller than that of the crushing roller. The thickness at the center of 25 when viewed in the width direction (roller axis direction).

is the largest, and narrows toward the front or rear when viewed in the axial direction of the roller shaft 9.

Therefore, in the case of this embodiment, the raw material that is pinched and crushed in the vicinity of the central part (the part where the thickness of the gap 26 is reduced) when viewed in the width direction of the crushing roller 24 is transferred to the axis of the roller shaft 9 as described above. It tries to flow (escape) toward the core, but the population of the gap 26 is 26. , and the outlet 26I, the thicknesses Da% and D are the thicknesses near the central portions thereof, as described above. Because it is narrower, the entrance 26. A blockage occurs at the outlet 26 and prevents further flow outward from there.

Therefore, the density of the raw material in the gap 26 only increases when the raw material is bitten and pulverized, and the raw material inside the gap 26 is not heated at the inlet 26° or the outlet 26.
Since the crushing roller 25 cannot escape from I and cannot approach any further in the direction of the annular groove 3, the self-excited vibration of the crushing roller 25 is reduced.

In the embodiment described above, the crushing roller 25 is formed into a right cylindrical shape, and the annular groove 3 facing the crushing roller 25 is formed into an arc shape concave downward, thereby reducing the thickness at the center of the gap 26 between the two. Thicknesses Da, D, at the inlet and outlet parts,
In this way, the gap 26 is narrowed at the entrance portion 26. Although the flow of the raw material could be blocked by forming a block between the gaps 26 and 26, the thickness of the gap 26 is responsible for blocking the flow of the raw material. Ratio between and Da or Gori: D
o / Da ori. The larger /DI, - is, the greater the occlusion is and the more effective it is.

In the example shown in FIG. 6, there is shown a crushing roller 25' that has a further enhanced obstructing property. The inlet portion 26. and outlet section 261. Thicknesses Da and Db at
and the thickness Do at the center. / Da ori.

/D is further increased compared to the example shown in FIG. 5, and the flow of the pulverized raw material in the axial direction of the roller is more reliably prevented near the center of the 25° width of the pulverizing roller. be done. However, the cross-sectional shape of the annular groove 3 and the outer circumferential surface 24 of the crushing roller 25 need not be a perfect circular arc shape as shown in the above embodiment, but may be a part of an ellipse or any other suitable curvature. It is sufficient as long as it has the following.

Table 1 below shows the vibration generation range in experiments in which the rotational speed of the sorting device was varied. There are some comparisons when driving,
The numbers on the upper left side of the table are the Blaine values (
ail/g), and the number on the upper right side is the amount of crushing (kg/h).
, the middle number indicates the grinding efficiency.
l (aa/K11b), and the lower row indicates the stability of operation. "Stable" indicates that only enough vibration is generated to maintain normal operation, and "vibration range" indicates that the operation is stable due to vibration. Indicates inability. The data for Ritzinger's fish in this table does not include the auxiliary power for sorting, equipment, or fans, and the data is not corrected by subtracting the power during no-load operation.

The Blaine value is a value for pulverization of raw materials not mixed with a pulverization aid.

As shown in Table 1, when the rotation speed of the sorting device is increased (that is, when the particle size of the product is made finer and the coefficient of friction between raw materials is lowered), vibration increases in both cases. It is recognized that when the right cylindrical crushing roller according to the present invention is used, stable operation is possible even if the sorting device is raised to 50 rpm, but with the conventional drum-shaped crushing roller, the rotation speed is 500 rpm.
pm, it became inoperable due to vibrations, indicating that the present invention is highly effective in suppressing vibrations.

When manufacturing cement raw materials, the Blaine value is at least 320.
It is necessary to ensure 0, but the rotation speed of the sorting device is 40O
When compared under the rpm condition, the conventional crushing table is close to the limit, but the present invention has a sufficient margin.

For example, Figure 7 shows the Blaine value (representing particle size in cm/g) for the throughput using a conventional roller mill (white circles represent experimental values) and a roller mill according to the present invention (black circles).
The relationship was determined through experiments, and as is clear from the figure, when the same amount of raw material is processed per unit time, the grinding efficiency of the roller mill according to the invention using the present invention is dramatically improved. It is understood that there are

In addition, the Blaine value of the product must generally exceed 3200, but in order to obtain this value with conventional roller mills, it is necessary to suppress the throughput to about 123 kg/h or less, but with the roller mill according to the present invention, , 190Kg/
The throughput of about 100 yen was secured, which confirms the improvement in pulverizing efficiency.

Furthermore, in the same graph, the micro-vibration region is the region where slight vibrations occur that do not interfere with operation at all, and the vibration region is the region where it is thought that if more vibration occurs, it will impede long-term operation. , is a part that generates vibrations larger than the micro-vibration range.In the roller mill according to the present invention, when the throughput is 110 kg/h or more, weak vibrations occur when the Blaine value exceeds 4250, and the particle size and vibration of the product are Furthermore, under similar conditions regarding the Richinger depth, the device of the present invention is superior to the conventional device, preventing the raw material from escaping and effectively applying the pressing force Fl of the crushing roller to the raw material. It was confirmed that the pulverization efficiency was improved.

The common mechanical conditions in the experiments described above are as follows.

Grinding table rotation speed 1100 rp Grinding roller pressure 1.9 tons/roller air volume 1
ON n? /min Effective diameter of the grinding table 320IllI+1 As described above, the present invention grinds the raw material supplied onto the grinding table by pinching it between the grinding table and the grinding roller pressed toward the top surface of the grinding table. In this roller mill, an annular groove having an arcuate cross section that is depressed downward is formed on the upper surface of the grinding table, and the outer circumferential surface of the grinding roller facing the annular groove is formed in a circular direction in the direction of the roller shaft supporting the grinding roller. Since this is a roller mill characterized by a flat right cylindrical shape with an arch-shaped concave drum-shaped The escape (flow) of
The vibration of the crushing roller is suppressed and the crushing efficiency is improved.

[Brief explanation of drawings]

Figure 1 is a side sectional view of a conventional roller mill, Figure 2 (a),
(b) is a side sectional view showing the relationship between the shapes of the crushing roller and the crushing table of the same roller mill, FIG. 3 is a front view of the crushing roller to explain the crushing state, and FIG. The plan view, FIGS. 5 and 6 are side sectional views showing the relationship between the grinding roller and the grinding table of a roller mill according to an embodiment of the present invention, and FIG. 7 is a graph showing the effects of the present invention. (Explanation of symbols) 1... Grinding table 3... Annular groove 9... Roller shaft 24... Outer peripheral surface 25... Grinding roller 26... Gap 26,... Inlet section 26s, ... Exit part Figure 5 Figure 6 Procedure Ne City Official Book (spontaneous) September 21, 1982 2 Name of the invention Roller Mill 3 Relationship with the person making the amendment Patent applicant address 651 Chuo, Kobe City 1-3-18 Wakihama-cho, Ward Name (119) Co., Ltd.? Shinto Seitaokasho representative Fuyuhiko Maki 4, agent 530 6, "Detailed description of the invention column" of the specification to be amended 7, Contents of the amendment 1, Line 6 of page 2 of the specification Delete "nozzle 10" from the . 4. Correct r500rpmJ to r600rpmJ in the 5th to 6th lines and 7th line of the same page 15. 5. On the 6th line of the same page, replace r400rpmJ with “
Correct to 500 rpm J. 6. On the 6th line of the same page, change the word rcm/g J to [
Correct to cd/gJ. 7. On the 2nd and 3rd lines of page 16, the phrase ``It is understood that the present invention...'' was replaced with ``The amount of processing at the same brane value can also be significantly increased." 8. rKg/h on the 6th and 8th lines of the same page, respectively.
" is corrected to rkg/hJ. 9. On the 9th line of the same page, it says, "Improvement in pulverization efficiency is confirmed." [Also, improvement in pulverization efficiency is confirmed.] ” is corrected. 10. On the 15th and 16th lines of the same page, "Reduce processing amount by 1"
When the speed is 10Kg/h or more, the Blaine value is 425.
The statement "When the Blaine value exceeds 4200 aJ/g at a throughput of 110 kg/h" has been corrected. 11. Delete lines 4 to 9 of page 17.

Claims (1)

[Claims] The raw material supplied onto the grinding table is connected to the grinding table,
In a roller mill that performs crushing by pinching between a crushing roller that is pressed toward the top surface of a crushing table, an annular groove with an arcuate cross section that concave downwards is formed on the top surface of the crushing table, and an annular groove that faces the annular groove is formed on the top surface of the crushing table. A roller mill characterized in that the outer circumferential surface of the crushing roller is shaped like a drum or a flat right cylinder that is concave in an arc shape in the direction of the roller shaft that supports the crushing roller.