JPS6012145A - 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 whose purpose is to improve crushing 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 uneconomical for non-electronic devices.

From this point of view, efforts have been made in recent years to use the above-mentioned relatively efficient roller mills for grinding cement tarinka hydraulic cylinder blast furnace slag, etc.However, in the case of roller mills, unlike drum mills, grinding media such as balls are used. The raw material is not crushed by collision with the ring material and grinding,
Since the material caught between the crushing table and the crushing roller, which are supported by the machine base, is actively crushed by the squeezing force between the two, vibrations generated in the crushing rollers, etc. are often transferred to the machine base. The fact that roller mills produce larger vibrations compared to drum mills is an obstacle to using roller mills for grinding cement 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 automatic vibration, and the present invention aims to reduce the latter automatic 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, a pair of crushing rollers 5a and 5I, whose outer peripheral surfaces 4 face the annular groove 3, are pressed in the direction of the annular groove 3 through a gap 6 between them and the annular groove 3. It is attached in a biased state.

That is, the crushing roller 5. ．． 5b are roller shafts 9a and 9I inserted into the crushing chamber 8 from the main casing 7.

The roller shafts 9a, 9b are rotatably supported by horizontal shafts 10. , Arms ita and tib are swingably attached to the vertical inner surface of 10b.
The tip of the bolt 13 screwed onto the stopper arm 12 contacts the arm 11° (111,), thereby increasing the width of the gap 6 between the crushing roller 58.5 and the annular groove 3. A minimum limit is set.

Further, the tips of the arms lla and llb of the set of arms are connected to rods 15a and 15I via a tensioning device 14.

are connected by.

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

However, if the layer of raw material bitten by one of the crushing rollers, for example 5a, is too thick, the crushing roller 5a will rotate in the direction of escaping upward against the rotation biasing force of the tensioning device 14. The rotational force is transmitted via the rod 15a, the tension device 14, and the rod 15I to the arm 11 to which the other crushing roller 5I is attached, which pushes the crushing roller 5b in the direction of the annular groove 3 and crushes the raw material. The pressing force of the crushing rollers 5a, 5b is automatically adjusted according to changes in layer thickness.

In this way, the crushing roller 5. ．． 5. The pulverized raw material is moved to the outer periphery of the pulverizing table 1 by the centrifugal force of the pulverizing table 1, and is blown up by the upward airflow flowing out from the upward nozzle 16 surrounding the outer periphery of the pulverizing table 1, and is pulverized. A sorting device (not shown) provided at the top of the chamber 8 sorts out the particle size, 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 returned to the top surface of the grinding table 1. Returned and crushed.

By the way, in the conventional roller mill, Fig. 2 (a) and (b)
As shown in FIG. Conventionally, the radii of curvature r and R when the annular groove 3 is cut along a plane passing through the roller shaft 9a or 9t are R><.

In the example shown in Figure 2(a) R'=RI%'r=r'1.

R1=r, +d, d1=d.

The thickness d in the radial direction of the crushing roller in the gap 6 between both convex surfaces is
is constant (dl), and in the example shown in Figure (b), R; R1, r = r2 + R+ 〉r2 + d6 %
RI>r2+a2. In this case, d7 > d6, the thickness d of the gap 6 between the two convex surfaces of ζ is set so that the thickness d2 on 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 F1 is applied to the raw material G in a direction perpendicular to the roller shaft 9 that supports the crushing roller 5, and this pressing force F
, a shearing force F2 is applied in a direction perpendicular to the shearing force F2, 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. Since the centrifugal force due to the rotation of the grinding table 1 is acting, outflow occurs exclusively in the radial direction outward of the grinding table 1.

In the roller mill, the outward flow of the raw material causes a sudden change in the layer thickness of the raw material G, that is, the thickness of the gap 6, which increases the rotational speed, causing the crushing roller 5 to vibrate. 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, the more likely it will occur, and in extreme cases, it will become impossible to operate.

In addition, in the case of a roller mill, as shown in FIG. 3 when the crushing roller 5 is viewed from the front, the crushing of the raw material is not carried out at a point 16 directly below the roller where compression has been completed, but at a point 16 at the rear of the crushing table 1 in the direction of movement. This is done at the biting point 17 (a point l behind the center of the roller), and as shown in FIG. 4, which is a plan view of the crushing roller 5, the biting point 1
The peripheral speed F in the rotational direction of the outer circumferential surface of the crushing roller 5 deviates from the peripheral speed F3 in the rotational direction (tangential direction) of the crushing table 1 in 7 by an angle α, and corresponds to this deviation angle α. Therefore, a shearing force in the F5 direction (outward direction) acts on the raw material directly below the biting point 17, and this shearing force F5 also causes the raw material powder to flow, which is thought to increase automatic vibration. It will be done.

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 is constant in the direction of the roller shaft 9 (Fig. 2 (a)), or is thicker at the outer end than at the center (Fig. 2 (b)). - In any case, since it is open to the outside, the shape is not designed to prevent the flow of raw material generated in the gap 6, and the structure is likely to cause self-excited vibration. .

Furthermore, according to the present inventor's experiment, which actually measured and confirmed the rotational speed of the crushing roller 5 and the rotational speed of the crushing table 1, the crushing roller 5 is rotated from the cross-sectional center line Y of the annular shape 83 as shown in FIG. Also, the actual crushing is performed in the area Z on the outside in the radial direction of the crushing table 1, and the area ZI' on the inside in the radial direction of the crushing table l hardly contributes to the crushing activity. It became clear that

Furthermore, the conventional roller mill has a structure in which the grinding material easily flows out (escapes) from the gap 6 between the grinding roller 5 and the grinding table 1 as described above, so that the pressing force F of the grinding roller 5 is reduced. .

The raw material escapes before it can effectively act on the raw material powder,
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 blocking the flow of raw material toward the outside of the grinding table in the gap between the grinding roller and the annular groove of the grinding table. The gist of this is that raw materials supplied onto a grinding table are transferred between the grinding table and a grinding roller rotatably supported on a roller shaft and pressed toward the top surface of the grinding table. The present invention provides a roller mill in which the grinding roller is crushed by pressing between the grinding rollers, and the grinding roller is formed with a tapered surface whose cross-sectional area decreases toward the tip of the roller shaft on the outer 5 circumferential surface of the grinding roller. By making this shape, the shape of the gap between the outer circumferential surface of the grinding roller and the annular groove of the grinding table becomes wedge-shaped as viewed in the radial direction of the grinding table, and the gap becomes narrower toward the outside of the grinding table. It is designed to restrict the flow in this direction.

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.

FIG. 5 is a side sectional view of a roller mill according to one embodiment of the present invention, and FIG. 6 is a schematic side sectional view of a roller mill according to another embodiment.

Note that the same reference numerals are used for elements common to those shown in FIGS. 1 and 2.

In FIG. 5, reference numeral 9 denotes the roller shaft, which is fixed to an arm 11 that is rotatable around a support shaft 10 attached to the main body 20. At the tip of the roller shaft 9, a crushing roller 2
5 is rotatably attached.

The tip of the outer peripheral surface 24 of the crushing roller 25 has a cross-sectional area of the roller shaft 9 when cut along a plane perpendicular to the roller shaft 9.
Tapered surface 24. which decreases towards the tip. is formed,
This tapered surface 24. The gap 26 sandwiched between the annular groove 3 and the annular groove 3 has a shape that becomes narrower toward the outside when viewed in the radial direction of the crushing taper l.

Therefore, the entrance portion 26 of the gap 26. The thickness DI of the outlet portion 26 is smaller than the thickness Da of the outlet portion 26.

Next, the operation of the grinding process performed by the grinding roller having the above-mentioned shape will be explained with reference to the example shown in FIG.

As described above, the powder moves in the radial direction due to the centrifugal force caused by the rotation of the grinding table 1, and flows into the annular groove 3.

The raw material that has flowed in there is caught in the gap 26 between the grinding roller 25 and the grinding roller 25 pressed onto the annular groove 3.

On the other hand, as shown in FIG. 5, the gap 26 between the annular groove 3 having a two-section arc shape and the tapered surface 24a of the crushing roller 25 is formed into a wedge shape whose cross-sectional area decreases toward the outside, as described above. ing.

Therefore, the raw material that is about to flow outward is at the outlet portion 26.
This causes a blockage at the outlet portion 26 and prevents the flow of the raw material in an outward direction, and only the material that has been sufficiently pulverized is allowed to pass through the outlet due to the clamping pressure at the outlet portion 26 which substantially contributes to the pulverizing action as described above. The material is discharged through the portion 26 to the outer circumference of the grinding table 1, so that the thickness of the gap 26 is kept constant and automatic vibration is reduced.

Furthermore, as the outward flow of the raw material is blocked as described above, the inconvenience of unpulverized raw material flowing outward from the crushing table 1 is eliminated, and only the sufficiently crushed raw material flows out in the direction of the nozzle 16. Therefore, the grinding efficiency increases dramatically.・ □For example, Figure 7 shows a conventional roller mill (white circles represent actual/experimental values) and a roller mill according to the present invention (black circles).
The relationship between the Blaine value (representing particle size and the unit is cm/g), which is applied to the throughput, was experimentally determined using It can be seen that when raw materials are processed, products with much finer particle sizes can be obtained using the present invention, and the milling efficiency of the roller mill according to the present invention is dramatically improved.

In addition, the Blaine value of the product must generally exceed 3200, but in order to obtain this value with a conventional roller mill, the throughput must be kept below about 123 kg/h. At roller mill, 170
A throughput of Kg/hF was ensured, confirming the improvement in pulverization efficiency.

Furthermore, in the same graph, the "slight vibration region" refers to the region where slight vibrations occur that do not interfere with operation at all, and the "weak vibration region" refers to the region where vibrations greater than this are likely to 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 115Kg/h or more, weak vibrations occur when the Blaine value exceeds 4300, and the particle size and vibration of the product are The relationship between them is clearly understood.

In the above explanation, the present invention has been explained with respect to a roller mill in which a crushing roller is pressed into an annular groove on a crushing table. However, the present invention is as shown in FIG.
Of course, it can also be applied to a roller mill in which the pulverizing roller 25' has a flat pulverizing surface. The roller shaft 9 has a tapered surface 24a' whose cross-sectional area further decreases rapidly toward the distal end.

As described above, the present invention crushes raw materials supplied onto a crushing table by pinching them between the crushing table and a crushing roller rotatably supported on a roller shaft and pressed toward the top surface of the crushing table. This roller mill is characterized by forming a tapered surface on the outer circumferential surface of the grinding roller, the cross-sectional area of which decreases toward the tip of the roller shaft. This prevents the crushed raw material from escaping (flowing) in the radially outward direction of the crushing table, suppressing the vibration of the crushing roller, and improving the crushing efficiency.

[Brief explanation of the drawing]

Figure 1 is a side sectional view of a conventional roller mill, Figure 2 (a),
(b) is a side sectional view showing the shape relationship between the crushing roller and the crushing table of the same roller mill, FIG. 3 is a front view of the crushing roller for explaining the crushing state, and 4th and 1 are the same crushing rollers. 5 is a side sectional view of a roller mill according to one embodiment of the present invention, FIG. 6 is a schematic side sectional view of a roller mill according to another embodiment, and FIG. 7 is a graph showing the effects of the present invention. It is. (Explanation of symbols) 1... Grinding table 3... Annular groove 9... Roller shaft 24... Outer peripheral surface 25... Grinding roller 26... Gap 26 □... Inlet part of gap 26 24,. 24. '...Tapered surface 26T...Exit portion Da...Thickness D of the entrance portion of the gap 26...Thickness of the exit portion of the gap 26. Applicant Kobe Steel Corporation Onoda Cement Co., Ltd. Agent Patent Attorney Takeo Honjo Figure 5□, 942°. procedure? City-1, Letter E (spontaneous) 2. Name of the invention Roller Mill 3. Relationship with the amended case Patent applicant address 1-3-18 Wakihama-cho, Chuo-ku, Kobe 651 Name (119) Co., Ltd.? The statement "Shindo Seitaoka Factory Representative Fuyuhiko Maki 4, Agent 〒530" is corrected to "The crushing roller 5 causes rotational speed." 2. In the 13th line of the same page, the 3rd line of the page, correct the phrase ``raw materials only'' to ``raw materials.'' 3. On the 8th line of the same page, replace ram'/gJ with "c
+Il/g”. 4. On the 12th to 13th lines of the same page, "It is understood that the roller mill according to the present invention..."
Correct the statement to "The amount of processing can be increased with the same brane value." 5. On page 14, line 5 of the same page, “processing amount is 115Kg/
"If the processing amount is 115 kg/h or more" is changed to "When processing amount is 115 kg/h or more.
Correct to ``de''. 6. Change rKg/h j to "kg/h" on the 16th line of the 13th page and the 18th line of the 13th page, respectively.
Correct to. procedure? Fushosho (spontaneous) 7... l, Incident indication 1982 Patent Application No. 120845 2
, Name of the invention Roller Mill 3, Relationship with the person making the amendment Patent applicant address 1-3-18 Wakihama-cho, Chuo-ku, Kobe 651 Name (119) Co., Ltd.? Shinto Seikaganakosho representative Fuyuhiko Maki 4, agent Column 〒530'', ``Brief explanation of drawings'' and ``Drawings'' Method 6 It is correct contents■, Claims column is as follows. Correct it as follows. [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 rotatably supported on a roller shaft and pressed toward the top surface of the crushing table, the outer circumferential surface of the crushing roller A roller mill characterized in that a tapered surface is formed in which the cross-sectional area when cut along a plane perpendicular to the roller shaft decreases toward the tip of the roller shaft.''■, Amended specification in the Detailed Description of the Invention column Make the following corrections. (1) In the 17th line of the 14th page, insert the following sentence after "It is done." When the present invention is applied to a roller mill with a flat upper surface of a grinding table as shown in FIGS. 8(a) to 8(d),
) can be considered. In the roller mill according to the modification shown in FIGS. 8(a) to 8(d), crushing rollers 258 to 25. A tapered surface whose cross-sectional area when cut along a plane perpendicular to the roller shaft decreases toward the tip of the roller shaft is commonly formed on the outer peripheral surface of the rollers a. Figures (a) to (C) show the crushing rollers 25=~25c with an annular groove formed in the center of their outer circumferential surface;
If the entire outer peripheral surface corresponds to one truncated cone, the same figure (b
) is the same figure (
C) is the same figure (b) and the same university) When the crushing roller 25c is placed between the top surface of the stepped crushing table 1a, the annular groove in the same figure (d) is omitted from the same figure (C). Each case is shown below. ” ■ Correction to the brief description of the drawing column (1) In the 18th line of page 15 of the specification, the phrase “Graph.” was replaced with “Graph. It is a schematic side view showing a modified example.'' is corrected. IV. Correction of drawings. Figure 8 will be supplemented as shown in the attached sheet. 8. List of attached documents (1) Drawings (Fig. 8) 1 copy Fig. 8 (a) (b) (c) (d)

Claims (1)

[Claims] The raw material supplied onto the grinding table is connected to the grinding table,
A roller that is rotatably supported on a roller shaft and pressed toward the top of the grinding table to grind the powder.In a mill, there is a taber on the outer circumferential surface of the grinding roller whose cross-sectional area decreases toward the tip of the roller shaft. A roller mill characterized by forming a surface.