PARABOLIC VIBRATION-PULSE MILL

Abstract

A parabolic vibration-pulse mill for grinding material, which comprises a case with an outer cone and an inner cone arranged inside on a spherical support, with driving vibrator mounted on a shaft of said inner cone through a bearing, the cones being fitted with mantles having working surfaces forming a grinding chamber between them, wherein, in a lower section of the grinding chamber, working surface of each mantle being formed by parabola of generatrix with its concavity, in longitudinal cross-section, facing a mill longitudinal axis; and wherein, in a upper section of the grinding chamber, working surface of each mantle being formed by parabola of generatrix with its convexity, in longitudinal cross-section, facing a mill longitudinal axis, and wherein conjugation of said parabolas is smooth.

Moreover, the mill, wherein parabolas can be defined by the formula h=k.Math.r.sup.2/R, wherein h is the distance along an axis of the parabola, between a vertex of the parabola and circle formed by a cross section of the parabola, r is the radius of said circle, R is the radius of an sphere defined by the inner cone.

The mill with vertical distribution of material in the grinding chamber, providing a grinding ratio up to 30, with little wear of grinding mantles and low energy consumption.

Claims

1. Parabolic vibration-pulse mill, comprising: a case with an outer cone and an inner cone arranged inside on a spherical support, with driving vibrator mounted on a shaft of said inner cone through a bearing, the cones being fitted with mantles having working surfaces forming a grinding chamber between them, wherein, in a lower section of the grinding chamber, working surface of each mantle being formed by parabola of generatrix with its concavity, in longitudinal cross-section, facing a mill longitudinal axis; and wherein, in a upper section of the grinding chamber, working surface of each mantle being formed by parabola of generatrix with its convexity, in longitudinal cross-section, facing a mill longitudinal axis, and wherein conjugation of said parabolas is smooth.

2. The mill of claim 1, wherein parabolas are defined by the formula h=k.Math.r.sup.2/R, wherein h is the distance along an axis of the parabola, between a vertex of the parabola and circle formed by a cross section of the parabola, r is the radius of said circle, R is the radius of an sphere defined by the inner cone, wherein coefficient k=3.6 for a parabola of generatrix in the upper section of the inner mantle, k=6.4 for a parabola of generatrix in the upper section of the outer mantle, and k=1.4 for parabolas of generatrices in the lower section of the inner mantle and in the lower section of the outer mantle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention is illustrated by way of example in the following drawings wherein:

[0023] FIG. 1 shows a longitudinal cross-section of the mill of the invention;

[0024] FIG. 2 is a longitudinal amplified cross-sectional view the grinding chamber according to the invention;

[0025] FIG. 3 is a longitudinal amplified semi-cross-sectional view the grinding chamber according to the invention, illustrating the disintegration process of the material under grinding, and

[0026] FIG. 4 shows the settlement scheme for creation of an initial profile of the inner mantle for the lower section of the grinding chamber.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Now referring in detail to the invention, the same comprises a vibration pulse mill, preferably for grinding of building mixes, wherein the mill comprises foundation 1 with resilient shock absorbers 2 supporting case 3 with outer cone 4 accommodating spherical support 5 and inner cone 6 with shaft 7 on which cylindrical bearing 8 is installed holding vibrator 9, namely unbalanced weigh. Cones 4 and 6 are fitted with mantles 10 and 11, respectively, which are wear-resistance shells. Said vibrator 9 is connected to motor 12 by means of cylindrical bearing 8, compensating shaft 13 and V-belt drive 14. The volume between working surfaces of mantles 10 and 11 is grinding chamber 21. Above the grinding chamber 21 feeding hopper 22 is arranged. Lower portions of mantles 10 and 11 are shaped by parabolic generatrices 16 and 17 with their concavities facing the mill longitudinal axis H, forming discharge zone 15. Upper portions of mantles 10 and 11 are shaped by parabolic generatrices 18 and 19 with their convexities facing the mill longitudinal axis H, forming charging zone 20. The ends of said parabolas of each mantle are smoothly conjugated.

[0028] According to the invention, the parabolas of generatrices forming the mantles 10, 11 can be described by the following formula, see FIG. 2:

h=k.Math.r.sup.2/R,(1)

where

[0029] hdistance along an axis of the parabola, between a vertex of the parabola and circle formed by a cross section of the parabola;

[0030] kcoefficient;

[0031] rradius of said circle, which is the cross section of the parabola;

[0032] Rradius of an sphere defined by the inner cone.

[0033] By inserting coefficient k in formula (1), the formula is as follows: [0034] for inner mantle 11:

h=3.6.Math.r.sup.2/Rupper parabola,

h=1.4.Math.r.sup.2/Rlower parabola; [0035] for outer mantle 10:

h=6.4.Math.r.sup.2/Rupper parabola,

h=1.4.Math.r.sup.2/Rlower parabola.

[0036] In other words, coefficient k=3.6 is for a parabola of generatrix in the upper section of the inner mantle, k=6.4 is for a parabola of generatrix in the upper section of the outer mantle, and k=1.4 is for a parabola of generatrix in the lower section of the inner mantle and in the lower section of the outer mantle.

[0037] Such a design of the grinding chamber 21 is the result, as it will be explained below, of mathematical analysis of vibration movement and disintegration of a layer of material in the grinding chamber during operation, and also of its technological check.

[0038] In particular, the profile of the working surface of the inner cone is constructed taking into account frequency of oscillations of inner cone with average amplitude of points of its mantle, average fineness of particles, tilt angle of the estimated generating line and the capture angle, which should not exceed 18, in each cross-section of the layer, at that the two last parameters form a basis for creation of a reciprocal profile of the working surface of outer mantle.

[0039] The settlement scheme for creation of initial profile of the inner mantle for the lower section of the grinding chamber on the side of maximum closeness of the inner cone to the outer cone is represented in FIG. 4.

[0040] A rectangular system of coordinates XOY is employed in the settlement scheme in FIG. 4, with the origin on the lower edge of the outer mantle of the fragment of the grinding chamber on the circle with radius r.sub.0 turned so that the axis OX is inclined on angle as to the horizontal line.

[0041] The geometry of an initial profile of the inner mantle for the lower fragment of the grinding chamber is set by the following equation:

[00001]$\begin{array}{cc}={\left[\left(1-i^{1-n^{*}}\right).Math.\frac{.Math.b.Math.\left(1-b.Math..Math.\cos .Math..Math.\right)}{.Math.c\left(1-c.Math..Math.\cos .Math..Math.\right)}+i^{1-n^{*}}\right]}^{\frac{1}{n^{*}-1}},& \left(2\right)\end{array}$

where

[0042] =y/y*relative transverse coordinate of a point of the generatrix of the inner mantle;

[0043] ytransverse coordinate of a point of the generatrix of the inner mantle;

[0044] y*value of the coordinate y in the reception section of the fragment of the grinding chamber;

[0045] i=y*/y.sub.0ratio of the coordinates y in the reception and discharge sections of the fragment of the grinding chamber;

[0046] y.sub.0value of the coordinate y in the discharge section of the fragment of the grinding chamber;

[0047] b=x/2r.sub.0relative longitudinal coordinate of a point of the generatrix of the inner mantle;

[0048] r.sub.0radius of the lower edge of the fragment of the grinding chamber;

[0049] c=l/2r.sub.0ratio of the estimated length of the generatrix to diameter of the lower edge of the fragment of the grinding chamber;

[0050] n*an exponent in Gaudin-Andreyev's equation for the granulometric distribution of material in the fragment of the grinding chamber:

q=(d/d.sub.max).sup.n*,(3)

where

[0051] qthe relative content of the class passing through a sieve with size opening d;

[0052] d.sub.maxthe smallest size of a sieve opening through which 100% of material passing.

[0053] The operational principle of the mill of the invention is described below. From motor 12 via V-belt drive 14 and compensating shaft 13, torque is transmitted to vibrator 9, which is an unbalanced weigh, which rotates through cylindrical bearing 8 on shaft 7 and creates centrifugal force inducing inner cone 6 to make circular oscillations about center C of spherical support 5 of inner cone 6.

[0054] In FIG. 1, the direction the material is fed to the feeding hopper 22 of the mill is indicated by arrow 23, and the direction of discharging of ground product is indicated by arrow 24.

[0055] Material is fed by gravity from the feeding hopper 22 to the grinding chamber 21 and it is crushed inside its own layer piece by piece through compression by the approaching movement of mantles 10 and 11 of cones 4 and 6. When material comes into the charging zone 20 of the chamber 21 between parabolic generatrices 18 and 19, it undergoes not only compression but also shear both in radial as well as in tangential directions since the tangent lines T in the midpoint of the top parabolic generatrices 18 and 19 do not cross sphere center C, which leads to shearing strains in the material layer and assures the effect of grinding big lumps, thus increasing here the grinding ratio. Certain slowdown of inner cone 6 due to said shearing strain also results in forward slip of vibrator 9 relative the plane 25, depicted in FIG. 3 and in FIG. 4, which can be created as result of longitudinal cross-section of chamber 21 at the moment of maximal approaching of mantles 10, 11. When resistance is reset, the vibrator 9 approaches to said plane, and crushing force grows at the same time. Such force pulses occur approximately 60 times per revolution of the inner cone, resulting in intermittent layer strains and further increasing the disintegrating effect. Therefore, with the rotation speed of said vibrator 1000 revolutions per minute, which corresponds to the number of oscillations of said inner cone, there will be 60 thousand pulses acting on the layer or 1000 pulses per second.

[0056] When material falls in intermediate zone from the upper charging zone 20 to the lower discharge zone 15 of the grinding chamber 21, it is slowed down, providing loosening of the layer in the lower zone 15, where lower parabolic generatrices 16 and 17 face by their convexities to the opposite side now.

[0057] Due to that the amplitude of said inner cone increases along with the crushing force. Therefore, also in the discharge zone 15 the grinding ratio remains high with low wear of the mantles.

[0058] Such active vibration pulse grinding effect of the layer, with the novel grinding chamber, allows obtaining more than 50% of finished grain size cement upon clinker crushing, which is close in performance to the ball mill yield. With that, however, energy consumption will be reduced by 10 times, while the wear of the grinding bodies will be 50 times lower.

[0059] The applicants carried out comparative technological tests of the inventive vibration pulse mill at their factory with the traditional mantles, corresponding to machines above mentioned as analogs and prototype, as well as with new developed parabolic mantles in accordance with the present application.

[0060] Experimental tests of the claimed vibration pulse mill with 700 mm diameter of bottom of the inner cone with crushing of quartzites with Bond index Wi=20 with 40 t/h capacity showed exit in product of 35% of class less than 100 microns at reduction ratio 26. And with crushing of clinker the product was obtained with containing 49% of the same class at reduction ratio 35.

[0061] Therefore, the distinctive features of this invention assure achievement of the said objective.

INDUSTRIAL APPLICABILITY

[0062] This invention can be most widely used for production of construction materials such as cement.