CN113477512A

CN113477512A - Vibrating screen

Info

Publication number: CN113477512A
Application number: CN202110868249.4A
Authority: CN
Inventors: 段晨龙; 赵跃民; 江海深; 黄龙; 温鹏飞; 袁嘉乐; 潘淼; 卢佳旺
Original assignee: China University of Mining and Technology CUMT
Current assignee: China University of Mining and Technology CUMT
Priority date: 2021-07-30
Filing date: 2021-07-30
Publication date: 2021-10-08
Anticipated expiration: 2041-07-30
Also published as: CN113477512B

Abstract

The invention discloses a vibrating screen, which comprises: at least two unit screens, each unit screen comprising: the screen box is provided with a screen surface formed by extending along a first direction and a second direction, and two ends of the screen surface in the first direction are provided with a feeding end and a discharging end which are opposite; the screen surface is an inclined surface, and the height of the feeding end is higher than that of the discharging end; at least one excitation motor mounted on the sieve box along a second direction; the device comprises at least two unit sieves, wherein the at least two unit sieves are arranged along a first direction, and in the two adjacent unit sieves, the discharge end of one unit sieve is connected with the feed end of the other unit sieve, so that the screen surfaces of the at least two unit sieves are on the same plane; the vibration intensity of each unit screen is different, and the vibration intensity is reduced along with the reduction of the height along the first direction and by taking the height as a reference; wherein the first direction and the second direction are perpendicular to each other.

Description

Vibrating screen

Technical Field

The invention relates to the field of material screening equipment, in particular to a vibrating screen.

Background

The screening technology is widely applied to the fields of coal, metallurgy, petroleum, chemical industry, building materials, environmental protection and the like, is a key link in the production process of most enterprises, and plays roles in grading, dewatering, desliming and medium removal. When the traditional vibrating screen with equal vibration strength of units is adopted for deep screening of materials, the vibration strength of a feeding end and a discharging end is equal, the materials at the feeding end are easy to accumulate, the thickness of a material layer is increased, loosening and layering are slowed down, the screening efficiency is reduced, and the screening effect is deteriorated; the thickness of the material layer at the discharge end is rapidly reduced due to high vibration strength, the material moves too fast, the retention time on the screen surface is short, the screen cannot be penetrated in time, the unit area handling capacity is small, the screen surface utilization rate is low, the screening effect is poor, and the large-scale quality improvement and efficiency improvement of the coal in China are severely restricted.

Disclosure of Invention

In view of the above-mentioned problems and needs, the present invention provides a vibrating screen that achieves the above-mentioned objectives and provides other technical effects by adopting the following technical features.

The invention provides a vibrating screen, comprising:

at least two unit screens, each unit screen comprising:

the screen box is provided with a screen surface formed by extending along a first direction and a second direction, and two ends of the screen surface in the first direction are provided with a feeding end and a discharging end which are opposite; the screen surface is an inclined surface, and the height of the feeding end is higher than that of the discharging end;

at least one excitation motor mounted on the sieve box along a second direction;

the device comprises at least two unit sieves, wherein the at least two unit sieves are arranged along a first direction, and in the two adjacent unit sieves, the discharge end of one unit sieve is connected with the feed end of the other unit sieve, so that the screen surfaces of the at least two unit sieves are on the same plane;

the vibration intensity of each unit screen is different, and the vibration intensity is reduced along with the reduction of the height along the first direction and by taking the height as a reference;

wherein the first direction and the second direction are perpendicular to each other.

In this technical scheme, with the material input to the shale shaker on, adjust the vibration intensity (excitation motor's amplitude and frequency) of each unit sieve, make along first direction and use the height as the benchmark, along with the reduction vibration intensity reduction of height, the material moves along the screen cloth face, wherein, the vibration intensity of the unit sieve of material input is high, material moving speed accelerates, be favorable to the quick loose and layering of the material of the unit sieve of pan feeding, strengthen the effect of passing through the sieve, the vibration intensity of the unit sieve of material output is low, reduce fine particle material moving speed, the extension passes through the sieve time, improve screening efficiency, realize the uniform thickness screening. This shale shaker passes through the echelon change of vibration intensity, realizes high-efficient degree of depth screening, and the screen cloth face high-usage, the unit area handling capacity is big, and screening effect is good, simple structure moreover, and is stable high-efficient, convenient to use.

In addition, the vibrating screen according to the present invention may further have the following technical features:

in one example of the present invention, the sieve box includes:

two side plates extending along a first direction and oppositely arranged in a second direction;

the excitation beam is arranged along the second direction and connected with the two side plates;

the vibration excitation motor is fixedly connected to the vibration excitation beam, and the screen surface is connected between the two side plates.

In one example of the present invention, the excitation beam is adjustably movable in a first direction relative to the side plate.

In one example of the present invention, in both the excitation beam and the side plate, a waist hole is arranged in the first direction along one of them, and a fastener is coupled to the other of them, and the relative position between the excitation beam and the side plate is adjusted by the fastener.

In one example of the present invention, the sieve box further comprises:

and the two reinforcing beams are respectively arranged at the feeding end and the discharging end of the screen box, and the two ends of each reinforcing beam are respectively and fixedly connected with the two adjacent side plates.

In one example of the present invention, each of the unit screens further comprises: at least two supporting beam components are arranged on the supporting beam,

each corbel assembly is provided with at least two corbels, and each corbel is correspondingly connected to two sides of the reinforcing beam;

wherein, every corbel subassembly is highly different in the direction of height, and reduces to the discharge end direction by the pan feeding end along first direction.

In one example of the present invention, the method further comprises: the vibration-damping piece is arranged on the base,

the vibration damper is installed between the support beam and the reinforcing beam and configured to cause the support beam and the reinforcing beam to move relatively in a height direction by being deformed.

In one example of the invention, the damping member is a compression spring,

the reinforcing beam is fixedly provided with a mounting clamping sleeve, and the mounting clamping sleeve is provided with a first bulge extending towards the direction of the supporting beam;

a second bulge which is opposite to the first bulge and extends towards the reinforcing beam is formed on the supporting beam;

and two ends of the compression spring are sleeved on the first bulge and the second bulge respectively.

In one example of the present invention, the method further comprises: a flexible plate member is provided on the outer surface of the flexible plate member,

the device is arranged between two adjacent unit sieves, one side end of the device is connected with the discharge end of one unit sieve, and the other side end of the device is connected with the feed end of the other unit sieve.

In one example of the present invention, the method further comprises: a base seat is arranged on the base seat,

the base includes:

at least two crossbars extending along the third direction and arranged oppositely in the second direction;

at least one longitudinal bar extending along the second direction and coupling two adjacent transverse bars in a third direction;

wherein each said unit screen is adjustably movable in a first direction relative to said cross bar;

wherein the third direction is perpendicular to the second direction.

The following description of the preferred embodiments for carrying out the present invention will be made in detail with reference to the accompanying drawings so that the features and advantages of the present invention can be easily understood.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments of the present invention will be briefly described below. Wherein the drawings are only for purposes of illustrating some embodiments of the invention and are not to be construed as limiting the invention to all embodiments thereof.

FIG. 1 is a perspective view of one orientation of a shaker screen according to an embodiment of the present disclosure;

FIG. 2 is a perspective view of another orientation of a shaker screen according to an embodiment of the present disclosure;

fig. 3 is a perspective view of a shaker screen according to an embodiment of the present invention in yet another orientation.

List of reference numerals:

a vibrating screen 1000;

a unit screen 100;

a sieve box 110;

a screen surface 111;

a feeding end 1111;

a discharge end 1112;

side panels 112;

a waist hole 1121;

an excitation beam 113;

a fastener 1131;

a reinforcing beam 114;

installing a ferrule 1141;

a first bump 1142;

an excitation motor 120;

a corbel assembly 130;

a support beam 131;

a second protrusion 1311;

a damping member 140;

a flexible board member 200;

a base 300;

a cross bar 310;

a chute 311;

a longitudinal bar 320;

a first direction F;

a second direction S;

a third direction T;

and a height direction H.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of specific embodiments of the present invention. Like reference symbols in the various drawings indicate like elements. It should be noted that the described embodiments are only some embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention.

Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The use of "first," "second," and similar terms in the description and claims of the present application do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. Also, the use of the terms "a" or "an" and the like do not necessarily denote a limitation of quantity. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.

The present invention provides a vibrating screen 1000, as shown in fig. 1 to 3, including:

at least two unit screens 100, each unit screen 100 comprising:

a screen box 110 having a screen surface 111 extending along a first direction F and a second direction S, and having a feeding end 1111 and a discharging end 1112 opposite to each other at both ends of the screen surface 111 in the first direction F; wherein the screen surface 111 is an inclined surface and the height of the feeding end 1111 is higher than that of the discharging end 1112; that is, the material can be transported from the feeding end 1111 to the discharging end 1112 by its own weight, and is screened by the screen surface 111.

At least one vibration motor 120 mounted on the sieve box 110 along a second direction S; in other words, a plurality of excitation motors 120 may be provided at intervals along the first direction F.

Wherein at least two unit screens 100 are arranged along a first direction F, and in two adjacent unit screens 100, the discharge end 1112 of one unit screen 100 is coupled with the feed end 1111 of the other unit screen 100, so that the screen surfaces 111 of at least two unit screens 100 are on the same plane; in other words, the screen surfaces 111 of at least two unit screens 100 are on the same plane, so that the material can pass through each unit screen 100 in sequence, and the vibration intensity of each unit screen 100 can be adjusted respectively; at least two unit sieves 100 form the vibrating sieve 1000, so that the feeding end 1111 and the discharging end 1112 of the head-to-tail unit sieves 100 are respectively the feeding end 1111 and the discharging end 1112 of the vibrating sieve 1000, that is, the material is input by the unit sieve 100 with higher vibration intensity and output by the unit sieve 100 with lower vibration intensity;

wherein the vibration intensity of each unit screen 100 is different, and the vibration intensity is reduced along the first direction F and with the height as a reference; that is, when two or more excitation motors 120 are disposed on the same unit screen 100, the amplitude and frequency of each excitation motor 120 are equal, i.e., the vibration intensities of the same unit screen 100 are the same;

the fed unit sieve 100 has high vibration strength, the material movement speed is accelerated, the rapid loosening and layering of the fed unit sieve 100 are facilitated, the sieve penetration effect is enhanced, the vibration strength of the discharged unit sieve 100 is low, the movement speed of fine particle materials is reduced, the sieve penetration time is prolonged, and the sieving efficiency is improved;

it can be understood that the variation of the vibration intensity (amplitude and frequency) of the multi-unit sieve 100, the amplitude is adjusted by the mass and included angle of the eccentric block of the excitation motor 120, the frequency is adjusted by the multifunctional frequency converter, and the magnitude of the amplitude and the excitation frequency is adjusted, so that the vibration intensity of the multi-unit sieve 100 is changed in steps, and the equal-thickness sieving of the material group is realized;

wherein the first direction F and the second direction S are perpendicular to each other.

Specifically, the material is input to the vibrating screen 1000, and the vibration intensity (amplitude and frequency of the excitation motor 120) of each unit screen 100 is adjusted, so that the vibration intensity is reduced along with the reduction of the height as a reference along the first direction F, and the material moves along the screen surface 111, wherein the vibration intensity of the unit screen 100 for inputting the material is high, the material moving speed is accelerated, the material of the unit screen 100 for feeding is rapidly loosened and layered, the screen penetrating effect is strengthened, the vibration intensity of the unit screen 100 for outputting the material is low, the moving speed of fine particle materials is reduced, the screen penetrating time is prolonged, the screening efficiency is improved, and the uniform-thickness screening is realized. This shale shaker 1000 realizes high-efficient degree of depth screening through the echelon change of vibration intensity, and screen cloth face 111 high-usage, the unit area handling capacity is big, sieves effectually, simple structure moreover, and is stable high-efficient, convenient to use.

In one example of the present invention, the sieve box 110 includes:

two side plates 112 extending along the first direction F and oppositely disposed in the second direction S;

an excitation beam 113 arranged along the second direction S and coupling the two side plates 112;

the excitation motor 120 is fixedly coupled to the excitation beam 113, and the screen surface 111 is coupled between the two side plates 112;

that is, the two side plates 112 are connected by the vibration beam 113, so that the screen box 110 forms a whole, the vibration beam 113 is provided with the vibration motor 120, the vibration motor 120 drives the screen box 110 to vibrate, and the screen surface 111 is connected between the two side plates 112, for example, the screen can be fixed by welding or connecting a fastening piece; for example, the screen surface 111 is located at the lower end of the excitation beam 113, and the screen surface 111 located at the lower end is driven by the excitation motor 120 to vibrate, thereby screening the screen surface 111.

In one example of the present invention, the excitation beam 113 is adjustably movable in a first direction F with respect to the side plate 112; by adjusting the position of the excitation motor 120 on the unit screen 100, the power of the excitation motor 120 is reasonably distributed (especially, two or more excitation motors 120 are used to match the unit screen 100 with the best vibration intensity, and then the equal-thickness screening of the screen surface 111 is realized.

The position of the vibration beam 113 can be adjusted according to the accumulation condition of the materials on the screen surface 111, and the position arrangement of the mechanical vibration motor of the unit screen 100 is preferably adjusted.

In one example of the present invention, in both the excitation beam 113 and the side plate 112, a waist hole 1121 is disposed in the first direction F along one of them, a fastener 1131 is coupled to the other one of them, and the relative position between the excitation beam 113 and the side plate 112 is adjusted by the fastener 1131;

preferably, the fastening members 1131 or the waist holes 1121 are both symmetrically arranged in the second direction S;

the method comprises the following steps: waist holes 1121 are arranged at corresponding positions of the two side plates 112 along the first direction F, fasteners 1131 are respectively connected to two ends of the excitation beam 113 in the second direction S, the fasteners 1131 are matched with the waist holes 1121, and the relative movement and fixation of the excitation beam 113 and the side plates 112 are realized by adjusting the tightness of the fasteners 1131.

The second is as follows: waist holes 1121 are respectively arranged on both sides of the excitation beam 113 in the second direction S along the first direction F, correspondingly, fasteners 1131 are arranged at positions of the two side plates 112 corresponding to the waist holes 1121, the fasteners 1131 are matched with the waist holes 1121, and the relative movement and fixation of the excitation beam 113 and the side plates 112 are realized by adjusting the tightness of the fasteners 1131.

It can be understood that the waist hole 1121 is an oblong structure, and specifically, the waist hole 1121 of the oblong structure is a graph formed by selecting two points on a circle on the same straight line or selecting two end arcs on the circle symmetrical about the circle, and stretching the circle along the straight line or the arcs. The waist holes 1121 may allow the fasteners 1131 on the vibration beam 113 to move in the first direction F along the waist holes 1121, so that the position of at least one vibration motor 120 on the unit screen 100 is adjustable, and the power of the vibration motors 120 (especially two or more vibration motors 120) is reasonably distributed, so that the unit screen 100 is matched with the optimal vibration strength, and the equal-thickness screening of the screen surface 111 is realized.

In one example of the present invention, the sieve box 110 further includes:

at least two reinforcing beams 114 respectively arranged at the feeding end 1111 and the discharging end 1112 of the screen box 110, wherein both ends of each reinforcing beam 114 are respectively fixedly connected with the two adjacent side plates 112;

specifically, the stiffening beam 114 is a tubular structure, and flanges are respectively fixedly connected (e.g., welded) to two ends of the stiffening beam 114, and the flanges are respectively fastened to the two side plates 112 by bolts, so that the overall structural strength of the screen box 110 can be improved by providing the stiffening beam 114.

In one example of the present invention, each of the unit screens 100 further includes: at least two of the corbel assemblies 130,

each corbel assembly 130 has at least two corbels 131, and each corbel 131 is correspondingly coupled to two sides of the reinforcing beam 114;

wherein, the heights of each beam assembly 130 in the height direction H are different, and decrease from the feeding end 1111 to the discharging end 1112 along the first direction F;

taking an example that one unit screen 100 corresponds to two reinforcing beams 114, the height of the corbels 131 correspondingly connected to two sides of the same reinforcing beam 114 in the height direction H is constant, and the height of the corbels 131 gradually decreases from the feeding end 1111 to the discharging end 1112; in short, the inclination of the screen plane 111 is obtained by being supported by the corbel assembly 130;

in order to facilitate the connection between the beam support assembly 130 and the excitation beams 113, each excitation beam 113 penetrates through and protrudes from the corresponding side plate 112 in the second direction S.

Preferably, the height of the corbel assembly 130 is adjustable, such as a hydraulic cylinder, an air cylinder, etc., so that the inclination angle of the unit screen 100 can be flexibly adjusted.

In one example of the present invention, the method further comprises: the vibration damping member 140 is provided at the rear side thereof,

the vibration damper 140 is installed between the support beam 131 and the reinforcing beam 114, and configured to deform so that the support beam 131 and the reinforcing beam 114 move relatively in the height direction H; wherein the height direction H is mutually perpendicular to the second direction S and the third direction T.

The vibration strength of the vibration sieve 1000 can be reduced by disposing the vibration damping member 140, the vibration sieve 1000 can be protected, and the generation of noise can be reduced. The damping member 140 is, for example, a spring member, a spring sheet member, a rubber member, or the like.

In one example of the present invention, the damping member 140 is a compression spring,

a mounting sleeve 1141 is fixed on the reinforcing beam 114, and a first protrusion 1142 extending towards the direction of the support beam 131 is arranged on the mounting sleeve 1141;

a second protrusion 1311 opposite to the first protrusion 1142 and extending toward the reinforcing beam 114 is formed on the support beam 131;

two ends of the compression spring are respectively sleeved on the first protrusion 1142 and the second protrusion 1311;

the mounting sleeve 1141 is fastened and coupled to two sides of the reinforcing beam 114 by bolts, and the compression spring can be fixed by respectively sleeving two sides of the compression spring on the first protrusion 1142 of the mounting sleeve 1141 and the second protrusion 1311 of the support beam 131, so that the compression spring is prevented from slipping in the damping process, and the reliability is higher.

In one example of the present invention, the method further comprises: the flexible plate member 200 is provided with a flexible plate member,

the sieve is arranged between two adjacent unit sieves 100, one side end of the sieve is connected with the discharge end 1112 of one unit sieve 100, and the other side end of the sieve is connected with the feed end 1111 of the other unit sieve 100;

because the amplitude and the frequency of the excitation motor 120 on each unit sieve 100 are different, in the working process of the vibrating sieve 1000, the amplitude and the frequency between the unit sieves 100 are also different, so that the two adjacent unit sieves 100 have changed displacement, and the relative displacement change between the two adjacent unit sieves 100 can be met by connecting the flexible plate members 200, the occurrence of breakage is avoided, and the continuity of materials and the uniformity and the stability of material flow in the sieving process are ensured. For example, the flexible board 200 may be a polyurethane member, and the polyurethane member has wear resistance, so that the flexible board 200 is prevented from being worn due to strong friction between the material and the flexible board 200.

In one example of the present invention, the method further comprises: the base (300) is provided with a base,

the base 300 includes:

at least two crossbars 310 extending along the third direction T and arranged oppositely in the second direction S;

at least one longitudinal bar 320 extending along the second direction S and coupling two adjacent cross bars 310 in the third direction T;

wherein each of the unit screens 100 is adjustably movable in a first direction F with respect to the cross bar 310;

the third direction T is perpendicular to the second direction S and the height direction H;

specifically, a sliding groove 311 is extended on each cross bar 310 in the third direction T, and the branch beam 131 is coupled with the sliding groove 311 by coupling a fastening coupling at a lower end, thereby achieving the position adjustment of the unit screen 100 on the base 300;

in order to adjust the inclination angle of the screen surfaces 111 of two adjacent unit screens 100 to be on the same plane, plus the error in the actual installation process, the positions of two adjacent unit screens 100 need to be adjusted to meet the condition of the same plane.

The exemplary embodiment of the vibrating screen 1000 proposed by the present invention has been described in detail with reference to the preferred embodiments, however, it will be understood by those skilled in the art that many variations and modifications may be made to the specific embodiments described above, and many combinations of the various technical features and structures proposed by the present invention may be made without departing from the concept of the present invention, without departing from the scope of the present invention, which is defined by the appended claims.

Claims

1. A shaker screen, comprising:

at least two unit screens (100), each unit screen (100) comprising:

a screen box (110) having a screen surface (111) extending in a first direction (F) and a second direction (S), the screen surface (111) having opposite feed (1111) and discharge (1112) ends in the first direction (F); wherein the screen surface (111) is an inclined surface and the height of the feed end (1111) is higher than the height of the discharge end (1112);

at least one excitation motor (120) mounted on the sieve box (110) along a second direction (S);

wherein at least two unit screens (100) are arranged along a first direction (F), and in two adjacent unit screens (100), the discharge end (1112) of one unit screen (100) is connected with the feed end (1111) of the other unit screen (100) so that the screen surfaces (111) of the at least two unit screens (100) are on the same plane;

wherein the vibration intensity of each unit screen (100) is different, and the vibration intensity is reduced along the first direction (F) and with the height as a reference;

wherein the first direction (F) and the second direction (S) are perpendicular to each other.

2. The vibratory screen of claim 1,

the sieve box (110) includes:

two side plates (112) extending along a first direction (F) and arranged opposite in a second direction (S);

an excitation beam (113) arranged along the second direction (S) and coupling the two side plates (112);

the excitation motor (120) is fixedly connected to the excitation beam (113), and the screen surface (111) is connected between the two side plates (112).

3. The vibratory screen of claim 2,

the excitation beam (113) is adjustably movable in a first direction (F) relative to the side plate (112).

4. The vibratory screen of claim 3,

in both the excitation beam (113) and the side plate (112), a waist hole (1121) is disposed in a first direction (F) along one of them, a fastener (1131) is coupled to the other one of them, and the relative position between the excitation beam (113) and the side plate (112) is adjusted by the fastener (1131).

5. The vibratory screen of claim 2,

the sieve box (110) further comprises:

at least two reinforcing beams (114) are respectively arranged at the feeding end (1111) and the discharging end (1112) of the screen box (110), wherein two ends of each reinforcing beam (114) are respectively and fixedly connected with two adjacent side plates (112).

6. The vibratory screen of claim 5,

each of the unit screens (100) further comprises: at least two corbel assemblies (130),

each corbel assembly (130) is provided with at least two corbels (131), and each corbel (131) is correspondingly connected to two sides of the reinforcing beam (114);

wherein the height of each corbel assembly (130) in the height direction (H) is different and decreases from the feeding end (1111) to the discharging end (1112) along the first direction (F).

7. The vibratory screen of claim 6,

further comprising: a vibration damping member (140),

the vibration damper (140) is installed between the corbel (131) and the reinforcing beam (114) and configured to cause the corbel (131) and the reinforcing beam (114) to move relatively in the height direction (H) by being deformed.

8. The vibratory screen of claim 7,

the vibration damping member (140) is a compression spring,

an installation cutting sleeve (1141) is fixed on the reinforcing beam (114), and a first bulge (1142) extending towards the direction of the supporting beam (131) is arranged on the installation cutting sleeve (1141);

a second bulge (1311) which is opposite to the first bulge (1142) and extends towards the direction of the reinforcing beam (114) is formed on the support beam (131);

two ends of the compression spring are sleeved on the first protrusion (1142) and the second protrusion (1311) respectively.

9. The vibratory screen of claim 1,

further comprising: a flexible plate member (200),

the sieve is arranged between two adjacent unit sieves (100), one side end of the sieve is connected with the discharge end (1112) of one unit sieve (100), and the other side end of the sieve is connected with the feed end (1111) of the other unit sieve (100).

10. The vibratory screen of claim 1,

further comprising: a base (300) for supporting the device,

the base (300) comprises:

at least two crossbars (310) extending along a third direction (T) and arranged opposite in the second direction (S);

at least one longitudinal bar (320) extending along the second direction (S) and coupling two adjacent transverse bars (310) in a third direction (T);

wherein each said unit screen (100) is adjustably movable in a first direction (F) relative to said cross bar (310);

wherein the third direction (T) and the second direction (S) are perpendicular to each other.