RU2044565C1 - Impact-centrifugal mill - Google Patents

Abstract

FIELD: chemical and food industries. SUBSTANCE: mill has grinding chamber 3, grinding disk 7 with working members-pins 9, breaking member 14 with the riffled surface, reflector 17 and frustum 15 with props 16. The mill is equipped with the accelerator of the rotation of the material flow made in the form of blades fastened on the lower side of grinding disk 7. In this case hole 11 being in communication with atmosphere is made in the bottom part of chamber 3. Props 16 of frustum 15 have the neutral steamlined configuration and are made in the shape of vertical ribs. The air flow is twisted under the action of the rotating grinding disk and of the accelerator of rotation of blades 10, it rises into the grinding zone, captures the material. passes between housing 4 of grinding chamber 3 and frustum 15, turns under the action of reflector 17 and is drawn through branch pipe 18 together with small particles. The large particles are thrown away by the centrifugal force to the inner surface of frustum 15 and return to the grinding zone. EFFECT: ensured product of the narrow granulometric composition and of high fineness of grinding at the smaller materials consumption, simpler design and manufacture. 2 cl, 2 dwg

Description

 The invention relates to devices for fine grinding of solid, including heat-sensitive materials, for example, compositions based on epoxy, polyester or acrylic resins in the manufacture of powder paints, and can be used in chemical, food and other industries.

 For fine grinding of materials of medium hardness (up to 4 units on the Mohs scale), pin impact mills, dismembrators and disintegrators are widely used [1] Particles of material passing through the rows of beats of a rotating grinding disk are subjected to impacts and are crushed as they move to the edge of the grinding disk.

 The advantage of mills is a relatively simple design, however, a high grinding fineness, determined by the speed of rotation of the disks, their diameter, number and location of beats, is unattainable due to the lack of a clear classification of particles by size during the grinding process.

 Known pin mills [2] having a cylindrical grinding chamber, in the lower part of which a rotating grinding disk with pins is installed, and in the upper part a classifier. In mills of this type, material from the grinding zone is directed by a stream of air to a classifier, which releases a finely divided part of the material from the mill, returning large particles to grinding.

 The disadvantage of such mills is the intersection of material flows to the classifier and vice versa, affecting the clarity of particle separation.

 To eliminate this drawback, a truncated cone [3] is installed in the grinding chamber located between the grinding disk and the classifier. The truncated cone supports have a special profile to reduce the speed of the swirling powder air flow.

 The installation of a classifier on the top cover of the grinding chamber of the mill complicates its maintenance, especially when grinding heat-sensitive materials, as well as if frequent cleaning of the grinding chamber is necessary.

 The closest to the claimed technical essence and the achieved result is an impact centrifugal mill [4] containing a grinding chamber, a grinding disk with working elements, a breaker element, a reflector, a truncated cone with supports and a classifier mounted coaxially to the grinding disk and equipped with an autonomous drive located below . The truncated cone supports have a special profile and act as a means to reduce the speed of the swirling powder air stream. Coarse particles, when they hit the classifier plates, are separated from the powder-air flow and are again directed to the grinding zone under the action of gravity.

 The disadvantages of the mill are the large consumption of materials, the complexity of the design of the bearing assembly and the manufacture of truncated cone supports having a special profile.

 The aim of the invention is to reduce material consumption, simplifying the design and manufacture of the mill.

 The goal is achieved in that a centrifugal impact mill containing a grinding chamber, a grinding disk with working elements, a breaker element, a reflector and a truncated cone with supports is equipped with an accelerator of rotation of the material flow, and the supports of the truncated cone have a neutral streamlined configuration. The accelerator of rotation of the material flow is made in the form of blades mounted on the lower side of the grinding disk, while in the bottom of the chamber an adjustable hole is made, communicated with the atmosphere. The supports of the truncated cone are made in the form of vertical ribs.

 In a mill made in this way, the air flow with the material to be crushed entering the grinding disk zone is twisted under the influence of a rotating disk and blade rotation accelerator, passes between the grinding chamber body and the truncated cone, turns and leaves the grinding chamber. Large particles under the action of centrifugal forces fall on the inner surface of the truncated cone and descend into the grinding zone. The supports of the truncated cone allow the flow to maintain the flow speed necessary to separate large particles. As a result, there is no need for a classifier with an autonomous drive.

 In Fig.1 shows a centrifugal impact mill; figure 2 section aa in figure 1.

 A shell 2 is mounted on the frame 1, on which the grinding chamber 3 is located, comprising a vertical cylindrical body 4, a cover 5 and a bottom 6. At the bottom of the grinding chamber 3, a grinding disk 7 is mounted, mounted in a bearing assembly 8 mounted on the frame 1. To the upper to the side of the disk 7, the working elements of the pins 9 are attached, and to its lower side an accelerator of rotation of the material flow, made in the form of blades 10. An opening 11 is made in the bottom of the chamber 3. A pipe 12 is attached to the shell 2, connected to the atmosphere and provided with a shutter Onkoy 13. The grinding disk 7 is connected to the drive by a V-belt drive. On the housing 4 in the grinding zone is fixed a baffle plate made in the form of a ring 14 with a corrugated surface. Above the grinding disk 7 is placed a truncated cone 15 connected to the housing 4 by supports 16 having a neutral streamlined configuration made in the form of vertical ribs, the height of which is 0.2-0.8 of the height of the truncated cone.

 On the cover 5 is mounted a reflector of the flow of material and air 17 and a pipe 18 of the output of crushed material connected to a cyclone and a bag filter (not shown).

 The loading pipe 19 is attached to the housing 4 in the grinding zone and is connected to the hopper 20, in the lower part of which an ejector 21 is installed.

 Impact-centrifugal mill operates as follows.

 Ejector 21 crushed material is fed from the hopper 20 through the pipe 19 to the grinding chamber 3, which is subjected to impacts on the pins 9 of the rotating grinding disk 7 and the baffle plate ring 14 with a corrugated surface. The blades 10 accelerate the rotation of the air flow, which rises into the grinding zone, captures particles of material, passes between the housing 4 and the truncated cone 15, turns under the influence of the reflector 17 and is pulled through the pipe 18 into the cyclone and bag filter by the fan of the latter. Small particles of powder fall into a cyclone, in which they are separated from the air stream and discharged. Large particles moving in a spiral at high speed are discarded by centrifugal force on the inner surface of the truncated cone 15, descend along it and again fall into the grinding zone. The grinding fineness is regulated by the flap 13 of the pipe 12.

 The proposed mill provides a powdery product with a narrow particle size distribution and a high grinding fineness with less material consumption, simplification of design and manufacture.

Claims (3)

 1. SHOCK-CENTRIFUGAL MILL, containing a grinding chamber, a grinding disk with working elements, a breaker element, a reflector and a truncated cone with supports, characterized in that it is equipped with an accelerator of rotation of the material flow, and the supports of the truncated cone have a neutral streamlined configuration.  2. The mill according to claim 1, characterized in that the accelerator of rotation of the material flow is made in the form of blades mounted on the lower side of the grinding disk, while in the bottom of the chamber there is a hole in communication with the atmosphere using a pipe using a pipe with an adjustable damper.  3. The mill according to claim 1, characterized in that the supports of the truncated cone are made in the form of vertical ribs.

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