DE202004013332U1 - Mixing tools for two and three-dimensional mixing of bulk material in pan mixers and shaft mixers has angle and free zone adjoining accumulation zone fulfilling condition of grain diameter multiplied by grain shape factor - Google Patents

Abstract

The mixing tools for two and three-dimensional mixing in pan mixers and shaft mixers (C) consist of a base component of constructional steel and are completely or partially lined with hard metal plates. With a constant or variable accumulation zone (Y) in the region of the hard metal plates a jamming grain length (A) of up to 8 mm is formed in the gap between the tool and mixer wall (B) and adjoining this region is a free zone (D) and a free angle of no less than 15 degrees to it which fulfils the condition of grain diameter multiplied by the grain shape factor.

Description

The The invention relates to mixing tools with carbide stocking for on and Double shaft mixer for 2- and 3-dimensional mixing of bulk solids, where the wear exposed surfaces the mixing troughs partially or completely with wear protection ceramics are occupied, with a wear pair with approximately the same hardening arises.

Such mixers are z. B. used for mixing concrete. It aggregates, cement, water and additives are intimately mixed. The aggregates in the form of sand, gravel, granules or chippings have a different wear effect on the stationary or moving parts in the mixer. One distinguishes the gap wear V sp, 1 and the surface wear V f, 1 , which is independent of the wear pair. In order to ensure the functioning of the wear pairing between the ceramic surface protection of the mixing trough and the mixing tool, a number of geometrical and terminal relationships must be taken into account. These are in 1 and are explained below.

The Clamping force P in the gap K can not exceed the crushing force of the Reach aggregate. This should be as small as possible there with magnifying Gap K and thus increasing Clamping diameter dk the clamping forces and wear disproportionately climb.

On the gap boundary surfaces K 1, 2 arise according to actio = reactio the same forces. The size of the forces also depends on which geological rock type is used as aggregate. The plow angle alpha can according to 1 - 4 also stowage angle can be up to 90 °. The plow or stowage angle alpha shapes the local stowage effect, which has an influence on the frequency of occurrence of grits. Thus, the jamming cement grain is influenced by the jamming cementmilk for "swimming away".

The clearance angle beta after 1 . 2 and 3 a free zone D 'must be upstream and / or downstream. The installation angle gamma 1 is usually 10 ° to 45 ° with significant tolerance deviations. The clamping grain length A has a great influence on the functioning of the wear pairing between wear lining and mixing tool. Basically, the clamping grain length is only as long as necessary. It must be ensured that the clamping grain leaves the clamping area A as quickly as possible. This presupposes that the clamping grain does not come to a standstill in the clamping area and moves through it as fast as possible. The smaller the hardness difference in the wear pairing, the smaller must the nip length be, ie with the same hardness, the nip length would theoretically have to be 0 and is therefore limited to a practical minimum. For large hardness differences, the clamping grain length must therefore be greater, but practically not exceed about 20 mm, otherwise the tendency for clamping grain standstill in the clamping zone is greater. The form factor F of the aggregates has a considerable influence on the geometry and installation design.

So the free dimension D, which results from the free angle gamma must be at least dk × F. ( 2 . 3 . 4 )

at Round grain and cubic broken splinters from impact mills or for downstream cubicles (vertical impact mills), F = 1.5 must be used become. In the case of split grain form approx. F = 2.0. For split use as Additive plays the storage zone Y on the mixing tool one to be considered Role, especially on the frequency X for the Gap load P in K.

With the geometry of the mixing tool are significant scope for optimal design and customization available. In summary It can be said that in practice only rock type, clamping force and Are given grain shape. The remaining Sizes like Jam angle and jam area, clamping length, clamping time, clearance angle, Clamp grain gap width, frequency the nip load and thus the gap and surface wear influenced and are configurable. The clamping force is conditionally designed, because the mixing tool is adjustable to a small gap. So far have been for ceramic wear linings usually mixing tools made of polymers used because of the low clamping forces. In extreme applications, they do not meet the requirements was standing.

In view of these circumstances, the invention has for its object to provide for polymeric mixing tools with low actio = reactio clamping forces replacement, which also meets extreme requirements for ceramic wear protection. This problem is solved by the fact that from the group of variable variables the most favorable geometrical conditions for the special employment of Hartme tallmischwerkzeugen be determined in mating with ceramic wear protection. The effects of wear low-level use with wear control should be compensated by eliminating the low-profile behavior by optimizing the geometric conditions. The object is achieved by the geometric conditions in accordance with 1 specifically adapted to wear protection pairing. That is, the ratio A / K is about 1; A, K <= 8 mm is desirable. For round grain or split use, the congestion zone is of importance. For chippings use solutions with large or small constant storage zone Y according to 2a ) and b ) for use. For round grain solutions come with variable storage zone according to 3 and 4 for use.

It demonstrate:

1 shows and explains goal-determining terms and designations, angles to be observed geometric sizes

2a . b shows examples of constructive design for mixing tools in side and bottom with large and small constant storage zone in section, variant a ) and b )

3a . b shows examples of structural design for mixing tools in side use and bottom insert with variable storage zone in section

4 shows a mixing tool for average use in the section with variable storage zone

In 1 As a rule, alpha denotes the plow angle, which is generally between 90 ° and 135 °. This angle must never be <90 °, because this results in an entrapping in the nip K Stauzone that promotes wear. Tools to be used include the clearance angle beta, which must be A> = 0 as a function of the clamping grain length. In the 0 range, it can be located in polymeric materials, wherein the clamping grain length A can be limited to a maximum of 20 mm. For carbide blending tools beta should be between 5 ° and 45 °. The clearance angle beta determines the subsequent free zone D.

With gamma is the installation angle of the mixing tools. In the Usually this is between 45 ° and 80 °. He determines the circulation speed and the power resistance in the mixing drum. The clamping grain length A determines the clamping time T in the gap K and the frequency of the nip load X. In existing in practice mixing tools are mainly in polymeric materials clamping lengths up to 50 mm available and clamping grain dk may be out of the clamping position not free, resulting in maximum wear and destruction of the Wear protection pairing to lead can. This creates the demand for the smallest possible practicable clamping lengths A.

The clamping grain gap width K determines the clamping force P resulting from actio = reactio. With a linear gap enlargement, the clamping force P increases disproportionately. So there is the desire to keep the gap width K as small as possible, but this is possible only as a function of the angularity of the machine axis. The pinch diameter dk is the grain diameter determined for aggregates from the sieve mesh. It is the basis in connection with the form factor F, for the determination of the free zones dk × F. The form factor F is for spherical aggregate 1 , with dice 1 . 3 with cuboid approx. 2, with fragment 2 to 3 ,

By Determination of dk × F can which are determined by the clearance angle forming free zones.

On the clamping time T and frequency The nip load X has the form factor on the

Wear reinforcing Influence. To counteract this, congestion zones of varying intensity are formed. While the surface wear VF on the solution the problem is irrelevant, is the gap wear Vsp in Split K is the measure of success the solution the task.

In 2 , Variant a ), z. B. side mixing tools shown in section with a large constant storage zone. This is made by hard metal plates 1 about 40 mm long and alpha = 90 ° to the mixer side wall 2 educated. The clamping grain length A should preferably be 5 mm and clamping gap K between 1 and 5 mm. Between the carbide tips 1 and 4 is a return 3 preferably up to 8 mm available.

For dk × F, this yields, for example - at round grain 32 dia., Approx. 1.5 × 32 = 48 mm - with grit 22 dia., Approx. 2.5 × 22 = 55 mm

In 2 , Variant b ), the small constant storage zone is shown. It is made by a tungsten carbide plate 5 about 10 mm long and alpha = 90 ° to the mixer wall B formed. With the carbide tips 6 is adjoined slightly by a variable storage area.

In 3 are mixing tools z. B. for side use with variable storage zone Y in the examples variant a ) and b ). The plow and stowage angle alpha is> 90 ° and can usefully vary up to 135 °, since beta is often 45 ° for side scrapers. For K and A is the same as for 2 , The tungsten carbide plate 7 is in variant a ) under alpha = 135 ° and in variant b ) an angle between 90 ° and 135 ° is provided. The variants a ) and b ) differ by the free zone design beta. In variant a ) is the length of the carbide tip 8th 0 mm to approx. 10 mm.

In variant a ) and b ) exist for the hard metal plate 8th and 9 two requirements, the clearance angle beta should be> = 15 ° and the requirement dk × F must be met.

4 shows z. B. a mixing tool for center use in three-dimensional mixing in section and in side view A. The main body 11 of the mixing tool is with tungsten carbide flakes 12 occupied and on the support arm 10 attached. The tungsten carbide plate 4 forms the clearance angle beta and the free zone D.

A

Terminal grain length

B

mixer wall or ground

C

mixing tool

D

free zone

dk

Terminal grain diameter

F

form factor

K

Terminal grain gap and areas

P

clamping force off actio = reactio

T

clamping time

X

frequency the nip load

V, sp

gap wear

V, f

flank wear

Z

direction of rotation of the mixing tool

Y

stagnation zone

α

plow angle and jam angle

β

clearance angle

γ

installation angle

1

Hard metal plates in the huge reservoir area

2

arrangement of the mixing tool in the side insert

3

return on the formation of free zone D

4

Tungsten Carbide Tiles for variable free zone

5

Hard metal plates in the small storage area of constant storage zone

6

Hard metal plates in the supplemental region constant storage zone

7

Hard metal plates in the variable reservoir area

8th

Hard metal plates for Formation of a constant free zone D

9

Hard metal plates for Forming a changeable Free zone D

10

holder for mixing tool / mixer arm

11

Basic body in mixing tool

12

Hard metal plate in the wear surface

Claims (5)

Mixing tools for 2- and 3-dimensional mixing in disc and shaft mixers consisting of a base body ( 11 ) consist of mild steel and are completely or partially covered with carbide flakes, characterized in that at constant or variable congestion zone in the field of hard metal plates in the gap to the mixer wall (B) form a clamping grain length (A) to about 8 mm and it is a Free angle beta with> = 15 ° and a free zone D joins, which multiplies the condition diameter of the grain with the Grain form factor fulfilled. Mixing tools according to claim 1, characterized that on the the storage area (Y) facing away from the mixing tool (C) Directly disposed carbide platelets a return to about 8 mm to form a constant or expanding Free zone (D) has. Mixing tools according to claim 1, characterized that for Split with form factor (F) of> = 2, the flight and traffic jam angle (alpha) is preferably 90 °. Mixing tools according to claim 1, characterized that from the clearance angle (beta) in the clearance between Mixer wall or floor and the mixer arm a free zone (D) determined from the multiplication grain diameter (dk) and form factor (F) results. Mixing tools according to claim 1, characterized that the clamping grain length (A) is preferably the same size like the clamping grain gap width (K), however, both sizes are in the range up to 10 mm.