阅读说明：本技术 一种涡流空气分级机弯扭叶片分级叶轮 (Bent blade classifying impeller of vortex air classifier ) 是由 杨旭亮 于 2019-11-06 设计创作，主要内容包括：本发明公开了一种涡流空气分级机弯扭叶片分级叶轮,由上轮盘、下轮盘以及中间的弯扭叶片构成。若干个弯扭叶片绕着分级叶轮几何中轴线进行环形等距排列,该弯扭叶片表现为径向弯曲和轴向扭曲的联合造型,其中径向弯曲为变曲率平滑弯曲,弯曲角度范围为5°～90°,扭曲角度为5°～60°。该弯扭叶片的截面轮廓包括叶片前缘、叶片后缘、叶盆和叶背,其中叶片前缘和叶片后缘由圆弧构成,叶盆和叶背由变曲率平滑曲线构成。本发明的分级叶轮气动性能优异,有效地减小了叶片间流道内旋涡运动的尺寸和强度,从而削弱了通道旋涡对粉体颗粒分离运动行为的扰动作用,提高了涡流空气分级机对超细粉体的分级精度,降低了分级下限和能量损失。(The invention discloses a bent blade grading impeller of a vortex air classifier, which consists of an upper wheel disc, a lower wheel disc and bent blades in the middle. The plurality of twisted blades are annularly and equidistantly arranged around the geometric central axis of the graded impeller, and the twisted blades are in a combined shape of radial bending and axial twisting, wherein the radial bending is variable-curvature smooth bending, the bending angle range is 5-90 degrees, and the twisting angle range is 5-60 degrees. The cross section profile of the twisted blade comprises a blade front edge, a blade rear edge, a blade basin and a blade back, wherein the blade front edge and the blade rear edge are formed by circular arcs, and the blade basin and the blade back are formed by variable-curvature smooth curves. The classification impeller provided by the invention has excellent pneumatic performance, and effectively reduces the size and strength of vortex motion in a flow channel between blades, thereby weakening the disturbance effect of channel vortex on the separation motion behavior of powder particles, improving the classification precision of a vortex air classifier on ultrafine powder, and reducing the lower classification limit and energy loss.)

1. The utility model provides a vortex air classifier benevolence blade classifying impeller, includes wheel dish (1), lower wheel dish (3) and vertical fixation in last wheel dish (1) and benevolence blade (2) between lower wheel dish (3), its characterized in that: a plurality of bending blades (2) are annularly and equidistantly arranged around the geometric central axis of the grading impeller to form an airflow channel,

the bending-twisting blade (2) is in a combined shape of radial bending and axial twisting, wherein the radial bending is non-equal curvature smooth bending, the bending angle range is 5-90 degrees, and the twisting angle range is 5-60 degrees;

the cross section of the twisted blade (2) is formed by sequentially connecting a blade front edge (4), a blade back (5), a blade rear edge (7) and a blade basin (6) end to end, wherein the blade front edge (4) and the blade rear edge (7) are both formed by circular arcs, and the blade back (5) and the blade basin (6) are both formed by curvature-variable smooth curves;

the installation angle gamma of the cranked blade (2) ranges from 30 degrees to 90 degrees.

2. The twisted blade classifying impeller of a vortex air classifier as claimed in claim 1, wherein: the grading impeller is cage-shaped, the upper wheel disc (1) is a closed disc, and the lower wheel disc (3) is a hollow disc.

3. A twisted blade classifying impeller according to claim 1 or 2, wherein: the middle of the lower wheel disc (3) is provided with a threaded hole.

Technical Field

The invention relates to a grading impeller for a vortex air classifier, which is particularly suitable for fine grading of superfine powder and belongs to the field of powder preparation.

Background

The eddy air classifier has a classifying impeller rotating at high speed to form a centrifugal force flow field of forced eddy, the centrifugal acceleration of particles in the flow field is hundreds times or even thousands times of the gravity acceleration, the particles are classified according to the particle size under the action of the centrifugal force and the fluid drag force generated by the rotating impeller, and the eddy air classifier is widely applied in industrial production and is a main technical way for classifying superfine powder. The size and the strength of a vortex between blade channels are directly determined by the geometric characteristics of blades of a grading impeller of the vortex air classifier, so that the stress characteristics and the motion trail of powder particles are influenced, and the grading precision and the lower limit of the grading particle size of the superfine powder are finally determined.

The classification impeller of the existing air classifier adopts straight blades or circular arc-shaped blades, for example, the Chinese patent application CN105195418A discloses a vortex air classifier blade rotating cage which adopts circular arc-shaped blades; chinese patent application CN104703717A discloses a rotary classifier, which adopts bent straight plate type rotating blades; the Chinese patent application CN106031901A discloses a cage-type rotor vortex superfine powder concentrator, wherein the cage-type rotors all adopt strip-shaped plate-shaped straight blades; chinese patent application CN 102225396a discloses a vortex air classification system, which adopts straight blades or circular arc blades. The existing research shows that the classification impeller adopting the straight blades or the circular arc blades has strong vortex motion in the flow passages among the blades, generates strong disturbance on the stress characteristics and the motion trail of powder particles, deteriorates the classification precision and has large gas energy loss; moreover, the smaller the size of the classifying cut particle, the more significant the above-mentioned disturbance has a deteriorating effect on the classifying accuracy, and the lower limit of the classification of the vortex air classifier is severely restricted.

Disclosure of Invention

The invention aims to provide a twisted blade classifying impeller of a vortex air classifier, which improves the classifying precision of superfine powder and reduces the lower classifying limit and the energy loss of the vortex air classifier.

In order to achieve the purpose, the invention adopts the technical scheme that: a bending blade classifying impeller of a vortex air classifier comprises an upper wheel disc, a lower wheel disc and bending blades vertically fixed between the upper wheel disc and the lower wheel disc, wherein a plurality of bending blades are annularly and equidistantly arranged around a geometric central axis of the classifying impeller to form an air flow channel;

the bending-twisting blade is in a combined shape of radial bending and axial twisting, wherein the radial bending is non-equal curvature smooth bending, the bending angle range is 5-90 degrees, and the twisting angle range is 5-60 degrees;

the cross section of the twisted blade is formed by sequentially connecting a blade front edge, a blade back, a blade rear edge and a blade basin end to end, wherein the blade front edge and the blade rear edge are both formed by circular arcs, and the blade back and the blade basin are both formed by variable-curvature smooth curves;

the installation angle gamma (the included angle of the front edge of the blade relative to the rear edge of the blade) of the crankle blade ranges from 30 degrees to 90 degrees.

Preferably, the grading impeller is cage-shaped, the upper wheel disc is a closed disc, and the lower wheel disc is a hollow disc.

Preferably, a threaded hole is formed in the middle of the disc body of the lower wheel disc.

When the device works, the twisted blade grading impeller rotates at a high speed, a centrifugal force field of forced vortex is formed in the peripheral annular grading space, powder particles are subjected to the comprehensive action of centrifugal force and gas drag force in the annular grading space, and finer powder particles enter the passage between the blades along with air flow due to smaller centrifugal force. The twisted blade can obviously reduce the size and strength of the horseshoe vortex at the front edge of the blade, limit the development of a boundary layer at the rear edge of the blade, weaken the disturbance of the vortex of the channel between the blades on the separation motion behavior of powder particles, greatly reduce the probability that thicker powder particles are sucked into the channel between the blades by the vortex at the front edge of the blade and thinner powder particles are returned out of the grading impeller by the vortex of the channel, and obviously improve the grading precision.

Compared with the prior art, the invention has the following beneficial effects:

the bent blade grading impeller of the vortex air classifier provided by the invention adopts a blade structure in a combined modeling of radial bending and axial twisting, and a channel formed by the bent blades has better pneumatic performance, so that the size and the strength of vortex motion in a flow channel between the blades are effectively reduced, the disturbance effect of the vortex of the channel on the separation motion behavior of powder particles is weakened, the grading precision of the vortex air classifier on ultrafine powder is improved, the lower grading limit and the energy loss are reduced, and an effective technical approach is provided for the efficient grading of the ultrafine powder.

Drawings

FIG. 1 is a schematic three-dimensional structure of a twisted blade classifying impeller according to the present invention;

FIG. 2 is a schematic cross-sectional profile of a cambered vane;

FIG. 3 is a schematic view of the stagger angle γ of a cambered vane;

in the figure, 1 is an upper wheel disc, 2 is a cranked blade, 3 is a lower wheel disc, 4 is a blade front edge, 5 is a blade back, 6 is a blade basin, and 7 is a blade rear edge.

Detailed Description

The present invention will be further described with reference to the accompanying drawings.

As shown in fig. 1, the vortex air classification curved twisted blade classification impeller comprises an upper wheel disc 1, a lower wheel disc 3 and curved twisted blades 2 vertically fixed between the upper wheel disc and the lower wheel disc; a plurality of bending blades 2 are arranged in an annular and equidistant mode around the geometric central axis of the grading impeller, and adjacent blades form an airflow channel; the upper wheel disc 1 is a disc, and the upper part is sealed; the lower wheel disc 3 is a disc with a hollow middle part and is used for discharging air and fine powder sucked into the impeller, a threaded hole is formed in the middle of the lower wheel disc 3 and is in threaded connection with a driving shaft of the variable frequency motor, and the axial fixation is realized by adopting a locking nut. The bending-twisting blade 2 is in a combined shape of radial bending and axial twisting, wherein the radial bending is non-equal curvature smooth bending, the bending angle range is 5-90 degrees, and the twisting angle range is 5-60 degrees.

As shown in fig. 2, the cross section of the twisted blade 2 is formed by sequentially connecting a blade front edge 4, a blade back 5, a blade rear edge 7 and a blade basin 6 end to end, wherein the blade front edge 4 and the blade rear edge 7 are both formed by circular arcs, and the blade back 5 and the blade basin 6 are both formed by a variable curvature smooth curve, which may be generated by a curve function or by spline curve fitting.

As shown in fig. 3, the installation angle γ (the included angle between the blade leading edge 4 and the blade trailing edge 7) of the twisted blade 2 ranges from 30 ° to 90 °.

In the grading process, the bending blade grading impeller rotates at a high speed under the driving of the variable frequency motor, and the rotating speed of the impeller can be regulated in a stepless manner through the variable frequency speed regulator. The grading impeller rotating at high speed generates a centrifugal force field of forced vortex to drive circumferential air and powder particles to generate centrifugal motion, meanwhile, the negative pressure environment inside the grading impeller applies centripetal gas drag force to the powder particles, thicker particles perform outward rotary motion due to the higher centrifugal force, and thinner particles enter the channels among the blades along with the airflow due to the higher gas drag force. The curvature of the cross section profile of the twisted blade is monotonously changed, smooth and free of sudden change, has good pneumatic performance, can remarkably reduce the size and strength of a horseshoe vortex at the front edge of the blade, limits the development of a boundary layer at the rear edge of the blade, weakens the disturbance of a channel vortex on the motion behavior of powder particles, greatly reduces the probability that thicker powder particles are sucked into a channel between the blades by the vortex at the front edge of the blade and finer powder particles are returned out of a grading impeller by the channel vortex, and remarkably improves the grading precision; meanwhile, compared with straight blades and arc-shaped blades, the swirl motion in the passage of the bent and twisted blade grading impeller is weaker, and the energy loss of secondary flow is smaller.

According to the implementation process, the bent and twisted blade classifying impeller of the vortex air classifier provided by the invention has better pneumatic performance and smaller energy loss, and the blades with variable curvature, radial bending and axial twisting combined shapes effectively reduce the size and the strength of the vortex motion in the flow channel between the blades, so that the disturbance of the vortex motion on the separation motion of powder particles is weakened, the classifying precision of the vortex air classifier on ultrafine powder is improved, and the lower limit of the classification of the ultrafine powder can be further improved.

The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.