CN110314848B

CN110314848B - Crop seed screening device

Info

Publication number: CN110314848B
Application number: CN201910556333.5A
Authority: CN
Inventors: 燕辉; 徐竹; 李心平; 耿令新; 林国森; 胡淑杰
Original assignee: Henan University of Science and Technology
Current assignee: Henan University of Science and Technology
Priority date: 2019-06-25
Filing date: 2019-06-25
Publication date: 2021-05-25
Anticipated expiration: 2039-06-25
Also published as: CN110314848A

Abstract

The invention relates to a crop seed screening device, which comprises an outer cylinder, wherein a screening box and a downward convex conical screening part are arranged in the outer cylinder; the upper top plate of the sieve box is an upwards-convex conical sieve plate, the conical sieve plate is provided with upper sieve holes, the upper sieve holes are communicated with the inner cavity of the sieve box, and the lower bottom plate of the sieve box is connected with a sieve box flow guide pipeline communicated with the inner cavity of the sieve box; an upper blanking channel for seeds falling from the conical screening plate to fall downwards onto the conical screening piece is arranged between the screening box and the outer cylinder; the conical screening piece is provided with a lower screening hole, the edge of the conical screening piece is abutted against the inner wall of the outer cylinder, and the bottom of the conical screening piece is provided with a discharge hole. The seeds entering the outer cylinder body are firstly screened through the screen box arranged on the upper part, and the seeds falling from the screen box are screened secondarily through the upper blanking channel and then fall on the conical screening part on the lower part, so that the problem that the seeds with different particle sizes cannot be screened completely through primary screening is solved.

Description

Crop seed screening device

Technical Field

The invention relates to a crop seed screening device.

Background

After the seeds of some crops are collected, the seeds need to be processed and treated to be put into the market, and in the process of processing and treating the seeds, the seeds are usually screened, namely, full seeds and non-full seeds are screened to obtain seeds with good quality. In the prior art, most seeds are screened manually or by using a sieve, so that the method is time-consuming and labor-consuming and is not suitable for large-scale screening.

The utility model discloses a chinese utility model patent that the bulletin number of authorizing is CN208275763U discloses a seed sieving mechanism, and this seed sieving mechanism is when screening the seed, and every grade of screening only gets into corresponding play workbin promptly through a filter, if the unloading point is nearer apart from going out the workbin, then leads to the seed to come too late screening and just get into out the workbin easily, makes the seed granule size that gets into out the workbin inconsistent, still needs to carry out the secondary screening, and the efficiency of seed screening is lower.

Disclosure of Invention

The invention aims to provide a crop seed screening device, which aims to solve the technical problem that when a seed screening device in the prior art is used for screening seeds, each stage of screening only passes through a primary filter plate and then enters a corresponding discharging box, so that the seeds are easy to enter the discharging box after being screened, and secondary screening is needed.

In order to realize the purpose, the technical scheme of the crop seed screening device is as follows:

the crop seed screening device comprises an outer cylinder body with a feed inlet, wherein a screening box and a downward convex conical screening part are arranged in the outer cylinder body; the screening box and the conical screening piece are arranged along the up-down direction; the upper top plate of the sieve box is an upwards-convex conical sieve plate, the conical sieve plate is provided with upper sieve holes, the upper sieve holes are communicated with the inner cavity of the sieve box, and the lower bottom plate of the sieve box is connected with a sieve box flow guide pipeline communicated with the inner cavity of the sieve box; an upper blanking channel for seeds falling from the conical screening plate to fall downwards onto the conical screening piece is arranged between the screening box and the outer cylinder; the conical screening piece is provided with a lower screening hole, the edge of the conical screening piece is abutted against the inner wall of the outer cylinder, and the bottom of the conical screening piece is provided with a discharge hole.

The beneficial effects are that: the seeds entering the outer cylinder body are firstly screened for the first time through the screen box arranged at the upper part, and the seeds falling from the screen box fall on the conical screening piece at the lower part through the upper blanking channel for secondary screening, so that the problem that the seeds with different particle sizes cannot be completely screened through the primary screening is avoided; meanwhile, the conical screening plate and the conical screening piece are beneficial to downward rolling of seeds by means of gravity, and screening efficiency is improved.

The screen box rotates around the central axis of outer barrel and assembles at the urceolus internally, crops seed sieving mechanism is including being used for driving screen box pivoted actuating mechanism. The sieve case rotates when the screening, has improved the efficiency of screening.

The lower bottom plate of the sieve box is a conical guide plate protruding downwards, and a guide pipeline of the sieve box is connected to the center of the conical guide plate. Through putting the central point that will sieve case water conservancy diversion pipe connection at the toper guide plate, the seed of being convenient for sieve incasement flows in sieve case water conservancy diversion pipeline, avoids the seed to stop at the sieve incasement, also can reduce the size of discharge gate simultaneously, and the corresponding size that can increase toper screening spare to make toper screening spare can carry out abundant screening to the seed.

The internal below of discharge gate of urceolus sets firmly the screening spare draft tube that is used for accepting the seed of landing from the toper screening spare, sieve case water conservancy diversion pipeline interval passes the discharge gate of toper screening spare extends into in the screening spare draft tube to enclose into the guide passageway that leads to the seed that flows from the discharge gate with screening spare draft tube, be equipped with the whereabouts material passageway that supplies to pass through from the seed of screening hole screening down between screening spare draft tube and the outer barrel. Through setting up screening spare draft tube, be convenient for collect the seed of landing from toper screening spare.

The sieve box flow guide pipeline is provided with a valve for cutting off the sieve box flow guide pipeline, a first collecting tank for collecting seeds falling through the falling material guide channel is arranged below the outer cylinder, and a second collecting tank for collecting seeds falling through the material guide channel is arranged below the screening part flow guide cylinder in the first collecting tank. Through setting up the valve, make sieve case water conservancy diversion pipeline and screening spare draft tube can share the second collecting vat. When the seed collecting device is used, the second collecting tank collects seeds falling through the material guide channel, and after the seeds are completely collected, the second collecting tank is removed; then open the valve, make the seed in the sieve case water conservancy diversion pipeline fall into first collecting vat and collect, it is comparatively convenient to collect, has reduced the use of a collecting vat.

The outer barrel body is further provided with an impurity screening structure above the screen box, and the impurity screening structure is provided with seed screening holes. So as to block impurities such as straws and the like remained in the seeds in the impurity screening structure and ensure the purity of the seeds.

Impurity screening structure and sieve case fixed mounting, impurity screening structure and sieve case wind the central axis of outer barrel rotates the assembly and is in it is internal that the urceolus, crops seed sieving mechanism is including being used for driving impurity screening structure and sieve case pivoted actuating mechanism. Impurity screening structure and sieve case all rotate when the screening, have further improved the efficiency of screening.

Impurity screening structure includes the screening bucket and sets firmly the carousel on the screening bucket, and impurity screening structure rotates through the carousel around the central axis of outer barrel and assembles in the urceolus, is equipped with on the bottom of screening bucket and/or the circumference lateral wall seed screening hole, the upper end opening of screening bucket constitutes the feed inlet. More seeds can be poured into to the screening bucket once, has improved the efficiency of screening.

The conical screening piece is a conical screening net which can be assembled in the outer cylinder body in a sliding mode in the up-down direction, and a vibrator is arranged on the conical screening net. Through being the toper screening net with the design of toper screening piece to increase the vibrator, make the less seed of granule can be quick drop down on the toper screening net, under the same condition of screening net size, improved the efficiency of screening, reduced the less seed of granule simultaneously and gone out along with the great seed of granule from the discharge gate probability.

The conical screening net comprises an annular net body, an inner net frame and an outer net frame are correspondingly arranged on the inner side and the outer side edge of the net body, the inner side of the inner net frame forms the discharge hole, the outer side of the outer net frame abuts against the inner wall of the outer barrel body, the inner net frame and/or the outer net frame are/is provided with the vibrator, and an elastic supporting structure is at least arranged below the net frame provided with the vibrator. Through setting up interior screen frame and outer screen frame, make the net body can the centre gripping between two screen frames, increased the stability of toper screening net in motion and screening process from top to bottom.

Drawings

FIG. 1 is a schematic view of a crop seed screening apparatus according to the present invention;

FIG. 2 is a cross-sectional view of FIG. 1;

FIG. 3 is a top view of the sieve box of FIG. 1;

FIG. 4 is a top view of the conical screen of FIG. 1;

in the figure: 1-a bottom plate; 2-a support leg; 3, fixing a plate; 4-outer cylinder; 5-a first connecting rod; 6-a spring; 7-outer net frame; 8-a roller; 9-a second connecting rod; 10-a transverse plate; 11-a drive motor; 12-a gear; 13-screening barrel; 14-seed screening wells; 15-connecting blocks; 16-conical screening plates; 17-screening holes; 18-a circular ring; 19-a turntable; 20-a sieve box diversion pipeline; 21-a net body; 22-a guide support bar; 23-a first fixing block; 24-a stop block; 25-a second fixed block; 26-a screening element draft tube; 27-a vibrator; 28-a first holding tank; 29-a second holding tank; 30-teeth; 31-a valve; 32-inner screen frame; 33-a reinforcing rod; 34-conical baffles.

Detailed Description

The following further describes embodiments of the present invention with reference to the drawings.

As shown in fig. 1 and 2, the crop seed screening device of the present invention includes a base and an outer cylinder 4 disposed on the base, the base includes a bottom plate 1, a leg 2 is fixedly disposed on an upper side of the bottom plate 1, a fixing plate 3 is fixedly disposed at an upper end of the leg 2, the outer cylinder 4 is fixedly disposed on the fixing plate 3, a feed inlet is disposed at an upper end of the outer cylinder 4, and an impurity screening structure, a screening box, and a conical screening member are sequentially disposed in the outer cylinder 4 along an up-down direction.

Specifically, as shown in fig. 2, the impurity screening structure includes a screening barrel 13 and a rotary table 19 fixedly mounted on the screening barrel 13, the screening barrel 13 is assembled on the outer barrel 4 by the rotary table 19 along the circumferential direction of the outer barrel 4, wherein the upper end opening of the screening barrel 13 forms the feed inlet. In this embodiment, all be equipped with seed screening hole 14 on the bottom of screening bucket 13 and its circumference lateral wall, be equipped with the seed screening hole 14 that link up the extension along screening bucket 13 axial promptly in the bottom of screening bucket 13, be equipped with the seed screening hole 14 that radially link up the extension along screening bucket 13 on the circumference lateral wall of screening bucket 13 to the seed that guarantees to enter into in the screening bucket 13 can be fast screened out from impurity. Of course, in other embodiments, the seed screening holes may be provided only on the bottom or circumferential side wall of the screen cylinder, where the screening efficiency is low. In other embodiments, the screening barrel can be designed to have a downward convex conical structure, so that the screening barrel can screen relatively small amount of seeds at one time.

In this embodiment, a transverse plate 10 is fixedly disposed on the outer cylinder wall of the outer cylinder 4, a driving mechanism, preferably a driving motor 11, is disposed on the transverse plate 10, and a gear 12 is connected to an output shaft of the driving motor 11 in a transmission manner. The outer circumferential surface of the rotary table 19 is provided with teeth 30, and the teeth 30 are engaged with the gear 12, so that the driving motor 11 drives the rotary table 19 to rotate, and further drives the screening barrel 13 to rotate. In other embodiments, the driving motor may not be disposed on the outer cylinder, but a special supporting structure is disposed to support the driving motor, so that an acting force generated by the gravity of the driving motor on the circumferential side wall of the outer cylinder can be avoided, and the stability of the outer cylinder is ensured.

In this embodiment, be equipped with ring 18 on the up end of outer barrel 4, be equipped with the annular that is used for placing ring 18 on the carousel 19, through the cooperation of ring 18 with the annular, make carousel 19 can slide on outer barrel 4 under driving motor 11's drive, wherein, ring 18 can be earlier when the assembly in the annular of carousel 9 is adorned to ring 18, then at the notch welding apron of annular to it is spacing on carousel 9 with ring 18. In other embodiments, in order to enable the rotary disc to be rotatably transferred on the outer cylinder, a bearing can be arranged between the rotary disc and the outer cylinder, the inner side of the bearing is fixedly assembled with the outer cylinder, and the outer side of the bearing is fixedly assembled with the rotary disc.

As shown in fig. 2 and 3, the bottom of the screening barrel 13 is fixedly connected with a screen box through a connecting block 15, the screen box can rotate in the outer barrel 4 along with the screening barrel 13, wherein the diameter of the screening barrel 13 is smaller than the maximum diameter of the screen box. Of course, in other embodiments, the screen box can be directly driven to rotate by the driving motor, and the screen barrel does not rotate; or a driving mechanism is not arranged, and the seeds are screened only by the gravity of the seeds. Specifically, the sieve box comprises an upward convex conical sieve plate 16 and a downward convex conical guide plate 34, wherein the conical sieve plate 16 and the conical guide plate 34 are arranged in the up-down direction, the conical sieve plate 16 forms an upper top plate, and the conical guide plate 34 forms a lower bottom plate. The edges of the conical screening plate 16 and the conical guide plate 34 are connected to form an inner cavity of the screen box, the conical screening plate 16 is provided with an upper screening hole 17 extending along the axial direction of the outer cylinder 4, and the upper screening hole 17 is communicated with the inner cavity of the screen box; the conical guide plate 34 is connected with a screen box guide pipeline 20 communicated with the inner cavity of the screen box, the lower part of the screen box guide pipeline 20 is provided with a valve 31, and an upper blanking channel for seeds falling from the conical screening plate 16 to fall downwards onto the conical screening part is arranged between the screen box and the outer cylinder 4.

In this embodiment, the border position of sieve case has second connecting rod 9 along its circumference interval arrangement, the one end that second connecting rod 9 was sieved the case dorsad is equipped with gyro wheel 8, be equipped with the annular groove on the inside wall of outer barrel 4, gyro wheel 8 sliding assembly is in the annular groove, wherein, during the assembly of gyro wheel 8, can assemble gyro wheel 8 in the annular groove earlier, then the notch welding apron of annular groove again, with spacing gyro wheel 8 on outer barrel 4, wherein, the quantity of gyro wheel can be more than three, in order to increase the stability of sieve case rotation in-process. In other embodiments, a bearing may be disposed between the second connecting rod and the outer cylinder, an outer ring of the bearing is fixedly disposed on an inner sidewall of the outer cylinder, and an inner ring of the bearing is fixedly connected to the second connecting rod.

As shown in fig. 2 and 4, the conical screening member is a conical screening net slidably assembled in the outer cylinder 4 in the up-down direction, the conical screening net is arranged in a downward convex manner, and a vibrator 27 is arranged on the conical screening net.

Specifically, toper screen cloth includes annular net body 21, and net body 21 has down the screening hole, and the inboard of net body 21 is equipped with interior net frame 32, and the outside of net body 21 is equipped with outer net frame 7, is equipped with between outer net frame 7 and the interior net frame 32 along the stiffener 33 of outer barrel 4 radial extension to guarantee that the net body is difficult for taking place to warp, wherein, outer net frame 7's outside butt is on the inside wall of outer barrel 4, and the inboard of interior net frame forms the discharge gate. In other embodiments, after the net body is fixed by the outer net frame and the inner net frame, if the tension force is large enough, the reinforcing rods are not needed.

In this embodiment, be equipped with screening part draft tube 26 through first connecting rod 5 fixed mounting on the inside wall of outer barrel 4, screening part draft tube 26 is located the below of discharge gate to be used for accepting the seed of landing on the follow toper screening part, wherein screening part draft tube 26 includes the major diameter section on upper portion, the minor diameter section of lower part and the middle toper section, the major diameter section on upper portion is convenient for the entering of seed, the minor diameter section of lower part is favorable to the seed to fall into in the collecting vat. In other embodiments, the screening part guide cylinder is not arranged, a collecting bag is directly arranged at the discharge port during screening, and a valve is arranged on the screen box guide pipeline to prevent seeds in the screen box guide pipeline from flowing into the collecting bag; or the sieve box does not rotate, and a sieve box diversion pipeline can be led out from the outer cylinder on the outer side wall above the conical screening piece.

The screening part guide cylinder 26 is sleeved outside the screening box guide pipeline 20, the screening part guide cylinder 26 and the screening box guide pipeline 20 enclose a material guide channel for guiding seeds flowing out of the discharge port, and a material falling channel for allowing the seeds screened from the lower screening holes to pass through is arranged between the screening part guide cylinder 26 and the outer cylinder 4. In this embodiment, the sieve box flow guide pipeline 20 is connected to the center of the conical flow guide plate 34, and the sieve box flow guide pipeline 20 is connected to the center of the conical flow guide plate 34, so that seeds in the sieve box can conveniently flow into the sieve box flow guide pipeline 20, and the seeds are prevented from staying in the sieve box; meanwhile, the size of the discharge port can be reduced, and the size of the conical screening piece can be correspondingly increased, so that the conical screening piece can sufficiently screen seeds. In other embodiments, the sieve box diversion pipeline may be disposed at a position on the conical diversion plate deviated from the center thereof, and the size of the discharge port needs to be designed to be larger in order to avoid interference between the sieve box diversion pipeline and the discharge port.

As shown in fig. 2, a first fixing block 23 is arranged on the inner side wall of the outer cylinder 4, a guide support rod 22 is mounted on the first fixing block 23 in a penetrating manner, a spring 6 is sleeved on the guide support rod 22, the upper end of the guide support rod 22 is fixedly connected to the outer screen frame 7, and a stop block 24 is arranged at the lower end of the guide support rod; the outer side wall of the screening part guide cylinder 26 is provided with a second fixed block 25, a guide support rod 22 penetrates through the second fixed block 25, the guide support rod 22 is sleeved with a spring 6, the upper end of the guide support rod 22 is fixedly connected to the inner net frame 32, and the lower end of the guide support rod 22 is provided with a stop block 24. The guide support rod 22, the spring 6, the stop 24 and the corresponding fixing block form an elastic support structure. In other embodiments, the resilient support structure may be provided only beneath the inner frame or beneath the outer frame, where the vibration effect is relatively poor. In the present embodiment, since the space at the inner frame 32 is large, the vibrators 27 are provided on the inner frame 32 so as to facilitate mounting of the vibrators 27, wherein the vibrators 27 are symmetrically arranged in two. In other embodiments, the outer screen frame may be enlarged along the radial dimension of the outer cylinder, and at this time, only the vibrator may be disposed on the outer screen frame, or the vibrator may be disposed on both the outer screen frame and the inner screen frame.

In this embodiment, a first collecting tank 28 is disposed on the bottom plate 1, and a second collecting tank 29 is disposed in the first collecting tank 28, wherein the first collecting tank 28 is located below the outer cylinder 4 for collecting seeds falling through the falling material channel, and the second collecting tank 29 is located below the screening guide cylinder 26 for collecting seeds falling through the material guide channel. In other embodiments, the first collecting tank and the second collecting tank may not be provided, during screening, a small-sized collecting bag is directly sleeved on the lower portion of the screening element guide cylinder, a large-sized collecting bag is sleeved on the lower portion of the outer sleeve, and at this time, the valve on the screen box guide pipeline is in a closed state. In other embodiments, the sieve box diversion pipeline may not be provided with a valve, the second collection tank is provided with a third collection tank, and the notch of the third collection tank is opposite to the lower nozzle of the sieve box diversion pipeline, but the third collection tank is relatively small, and only a small amount of seeds can be screened at a time.

It should be noted that the diameter of the seed screening holes is larger than the diameter of the seeds, but smaller than the diameter of the impurities; the diameters of the upper screening holes and the lower screening holes are equivalent.

In the present embodiment, the driving motor 11 and the vibrator 27 are electrically connected to an external power supply (not shown). Among them, the vibrator 27 is a mature product in the prior art.

During screening, the driving motor 11 and the vibrator 27 are firstly connected with an external power supply, and the switch is turned on to work. The seeds of crops are poured into the screening barrel 13 from the upper end opening of the screening barrel 13, the driving motor 11 drives the screening barrel 13 to rotate through the gear 12 and the rotary table 19, so that the seeds shake in the screening barrel 13 and fall into the outer barrel 4 through the seed screening holes 14, and impurities such as straws in the seeds are blocked in the screening barrel 13 and are cleaned out by workers. At the moment, the sieve box and the sieve barrel 13 synchronously rotate, seeds falling into the outer barrel 4 fall onto the sieve box, and a part of seeds with smaller particles enter an inner cavity of the sieve box through the upper sieve holes 17 of the conical sieve plate 16 and enter a sieve box flow guide pipeline 20 for collection through the flow guide of the conical flow guide plate 34; meanwhile, the other part of seeds roll to the edge of the screen box along the conical screening plate 16 and fall on the conical screening net through an upper blanking channel, the conical screening net jolts on the elastic supporting structure through vibration of the vibrator, the seeds further roll down along the conical screening net in the jolting process, the seeds with smaller particles fall into the first collecting tank 28 through a lower screening hole and a lower blanking channel, and the seeds with larger particles fall into the screening part guide cylinder 26 through the discharge hole and fall into the second collecting tank 29 through a guide channel for collection. After the screening is completed, the second collecting tank 29 is taken out from the first collecting tank 28, and then the valve 31 is opened, so that the seeds with smaller particles in the screen box diversion pipeline 20 fall into the first collecting tank 28 for collection, and the seed collecting process is completed.

Through twice screening of sieve case and toper screening piece, avoided once screening can not effectively partd the problem with the seed of different particle sizes, need not carry out screening work once more, improved the efficiency of screening.

Claims

1. Crops seed sieving mechanism, including the outer barrel that has the feed inlet, its characterized in that:

a screening box and a downward convex conical screening part are arranged in the outer cylinder body;

the screening box and the conical screening piece are arranged along the up-down direction;

the upper top plate of the sieve box is an upwards-convex conical sieve plate, the conical sieve plate is provided with upper sieve holes, the upper sieve holes are communicated with the inner cavity of the sieve box, and the lower bottom plate of the sieve box is connected with a sieve box flow guide pipeline communicated with the inner cavity of the sieve box;

an upper blanking channel for seeds falling from the conical screening plate to fall downwards onto the conical screening piece is arranged between the screening box and the outer cylinder;

the conical screening piece is provided with a lower screening hole, the edge of the conical screening piece is abutted against the inner wall of the outer cylinder body, and the bottom of the conical screening piece is provided with a discharge hole;

the lower bottom plate of the sieve box is a conical guide plate protruding downwards, and a sieve box guide pipeline is connected to the central position of the conical guide plate;

a screening part guide cylinder for receiving seeds falling from the conical screening part is fixedly arranged below the discharge port in the outer cylinder body, the screening box guide pipeline penetrates through the discharge port of the conical screening part at intervals and extends into the screening part guide cylinder so as to form a guide channel for guiding the seeds flowing out of the discharge port together with the screening part guide cylinder, and a falling material channel for allowing the seeds screened from the lower screening hole to pass is arranged between the screening part guide cylinder and the outer cylinder body;

the sieve box flow guide pipeline is provided with a valve for cutting off the sieve box flow guide pipeline, a first collecting tank for collecting seeds falling through the falling material guide channel is arranged below the outer cylinder, and a second collecting tank for collecting seeds falling through the material guide channel is arranged below the screening part flow guide cylinder in the first collecting tank.

2. The crop seed screening apparatus of claim 1, wherein: the screen box rotates around the central axis of outer barrel and assembles at the urceolus internally, crops seed sieving mechanism is including being used for driving screen box pivoted actuating mechanism.

3. The crop seed screening apparatus of claim 1, wherein: the outer barrel body is further provided with an impurity screening structure above the screen box, and the impurity screening structure is provided with seed screening holes.

4. The crop seed screening apparatus of claim 3, wherein: impurity screening structure and sieve case fixed mounting, impurity screening structure and sieve case wind the central axis of outer barrel rotates the assembly and is in it is internal that the urceolus, crops seed sieving mechanism is including being used for driving impurity screening structure and sieve case pivoted actuating mechanism.

5. The crop seed screening apparatus of claim 4, wherein: impurity screening structure includes the screening bucket and sets firmly the carousel on the screening bucket, and impurity screening structure rotates through the carousel around the central axis of outer barrel and assembles in the urceolus, is equipped with on the bottom of screening bucket and/or the circumference lateral wall seed screening hole, the upper end opening of screening bucket constitutes the feed inlet.

6. The crop seed screening apparatus of claim 1 or 2, wherein: the conical screening piece is a conical screening net which can be assembled in the outer cylinder body in a sliding mode in the up-down direction, and a vibrator is arranged on the conical screening net.

7. The crop seed screening apparatus of claim 6, wherein: the conical screening net comprises an annular net body, an inner net frame and an outer net frame are correspondingly arranged on the inner side and the outer side edge of the net body, the inner side of the inner net frame forms the discharge hole, the outer side of the outer net frame abuts against the inner wall of the outer barrel body, the inner net frame and/or the outer net frame are/is provided with the vibrator, and an elastic supporting structure is at least arranged below the net frame provided with the vibrator.