CN117323858A - High-sealing stirring and dispersing main shaft and stirring and dispersing machine - Google Patents

Abstract

The invention relates to the technical field of stirring and dispersing equipment, in particular to a high-sealing stirring and dispersing main shaft and a stirring and dispersing machine, and aims to solve the problem that an existing dispersing shaft is poor in sealing effect. The invention provides a high-sealing stirring dispersion main shaft, which comprises a main shaft body, a bearing assembly and a dry gas sealing assembly, wherein the bearing assembly comprises a lower bearing piece, the dry gas sealing assembly comprises a sealing cavity, a movable ring piece, a static ring piece and a fixed structure are arranged in the sealing cavity, the movable ring piece is provided with a plurality of hydrodynamic grooves, the sealing cavity is provided with an air inlet, the air inlet is positioned at the side part of the movable ring piece, the fixed structure is fixedly arranged in the sealing cavity, and the static ring piece is arranged on the fixed structure by means of a spring piece, so that the static ring piece can be abutted against a sealing surface of the movable ring piece under the action of the spring piece and can be separated from the sealing surface of the movable ring piece under the combined action of the spring piece and air entering from the air inlet.

Description

High-sealing stirring and dispersing main shaft and stirring and dispersing machine

Technical Field

The invention relates to the technical field of stirring and dispersing equipment, and particularly provides a high-sealing stirring and dispersing main shaft and a stirring and dispersing machine.

Background

Various types of stirring and dispersing machines are widely used in the fields of fine industry and other chemical industry to stir and disperse solid-liquid mixed slurry and the like. The bearing of the stirring and dispersing main shaft of the existing stirring and dispersing machine can be soaked with a certain amount of lubricating oil, and if the lubricating oil of the stirring and dispersing main shaft leaks and drops into the dispersing cavity, the materials in the dispersing cavity can be polluted.

In order to solve the problem that the lubricating oil of the bearing is easy to leak, patent document with publication number CN219663397U discloses a seal protection structure of a dispersed shaft, which mainly seals the shaft end of the dispersed shaft through mechanical seal, and particularly, strengthens the sealing performance mainly through a mode of combining mechanical structures to form multiple seals. The mechanical seal is a contact seal, and although the sealing effect can be improved to a certain extent, the effect is limited; in addition, the contact seal has the disadvantage of wear, requiring frequent inspection, maintenance and replacement, which is time-consuming and laborious.

Accordingly, there is a need in the art for a new solution to the above-mentioned problems.

Disclosure of Invention

The invention aims to solve the technical problem that the sealing effect of the existing dispersion shaft is poor.

In a first aspect, the present invention provides a high-sealing stirring dispersion spindle, the stirring dispersion spindle includes a spindle body, a bearing assembly and a dry gas seal assembly, the bearing assembly includes a lower bearing member, the lower bearing member is sleeved on the periphery of the spindle body, the dry gas seal assembly is located below the lower bearing member so as to seal a lower end face of the lower bearing member, the dry gas seal assembly includes a seal cavity, the seal cavity is internally provided with a moving ring member, a static ring member and a fixed structure, the moving ring member is sleeved and fixed on the periphery of the spindle body, a plurality of fluid dynamic pressure grooves which are annularly arranged with the axis of the spindle body as a center are formed on an end face of the moving ring member facing the lower bearing member, the seal cavity is provided with an air inlet, the air inlet is located on a side portion of the moving ring member and can be communicated with any fluid dynamic pressure groove in a rotating process of the moving ring member, the fixed structure is fixedly arranged in the seal cavity, the static ring member is arranged on the periphery of the spindle body by means of a spring member, so that the static ring member can be abutted against the air inlet and the fixed ring member can be separated from the seal face of the moving ring member.

In the above preferred technical solution of the high-sealing stirring dispersion main shaft, the static ring member includes an upper static ring member and a lower static ring member, the spring member includes an upper spring member and a lower spring member, the upper static ring member is located above the moving ring member, and is disposed on the fixing structure by means of the upper spring member, so that the upper static ring member abuts against an upper sealing surface of the moving ring member under the action of the upper spring member, and the lower static ring member is located below the moving ring member, and is disposed on the fixing structure by means of the lower spring member, so that the lower static ring member abuts against a lower sealing surface of the moving ring member under the action of the lower spring member.

In the above preferred technical scheme of the high-sealing stirring dispersion main shaft, the fixing structure comprises a static ring support member, an upper gland and a lower gland, the static ring support member is fixedly arranged in the sealing cavity, the upper gland is fixedly arranged on the upper side of the static ring support member, the upper spring member is arranged on the upper gland, the lower gland is fixedly arranged on the lower side of the static ring support member, and the lower spring member is arranged on the lower gland.

In the above preferred technical solution of the high-sealing stirring dispersion spindle, the sealing cavity is provided with an upper shaft through hole and a lower shaft through hole, the spindle body is sleeved with an upper sealing ring and a lower sealing ring, the upper sealing ring is arranged in the upper shaft through hole and sleeved on the spindle body so that the outer peripheral surface of the spindle body and the inner peripheral surface of the upper shaft through hole are sealed by the upper sealing ring, and the lower sealing ring is arranged in the lower shaft through hole and sleeved on the spindle body so that the outer peripheral surface of the spindle body and the inner peripheral surface of the lower shaft through hole are sealed by the lower sealing ring.

In the above preferred technical solution of the high-sealing stirring dispersion main shaft, the bearing assembly further includes a bearing support member and an upper bearing member, and when the installation is completed, the bearing support member is sleeved on the outer periphery of the main shaft body and is located between the upper bearing member and the lower bearing member, when the axial direction of the main shaft body is observed.

In the preferable technical scheme of the high-sealing stirring dispersion main shaft, the upper bearing piece is an angular contact ball bearing; and/or the lower bearing member is a cylindrical roller bearing.

In the above preferred technical solution of the high-sealing stirring and dispersing main shaft, the stirring and dispersing main shaft further includes a coupling, and one end of the main shaft body far away from the dry gas sealing assembly is connected with the coupling.

In the above preferred technical scheme of the high-sealing stirring and dispersing main shaft, the stirring and dispersing main shaft further comprises a water cooling assembly, the water cooling assembly comprises a water cooling jacket, the water cooling jacket is sleeved on the periphery of the main shaft body by means of the bearing assembly, and the water cooling jacket is located above the sealing cavity.

In the above preferable technical scheme of the high-sealing stirring dispersion main shaft, the water-cooling jacket is internally provided with a water-cooling channel, and the water-cooling channel is spirally arranged along the axial direction of the main shaft body.

In a second aspect, the present invention also provides a stirring and dispersing machine comprising a high seal stirring and dispersing spindle according to any one of the first aspects above.

Under the condition that any preferable technical scheme is adopted, the dry gas sealing assembly is arranged, so that the dry gas sealing, namely the non-contact sealing, can be formed below the lower bearing piece, and the sealing effect of the stirring dispersion main shaft is improved.

Drawings

Preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a high seal stirring dispersion main shaft of the present invention.

Fig. 2 is an enlarged view of the area a in fig. 1.

Fig. 3 is an enlarged view of region C in fig. 2.

Fig. 4 is an enlarged view of region B in fig. 1.

FIG. 5 is a plan view of the moving ring of the present invention.

List of reference numerals:

1-a main shaft body;

a 2-bearing assembly; 21-an upper bearing member; 22-a lower bearing member; 23-bearing support;

3-dry gas seal assembly; 31-a moving ring; 311-hydrodynamic grooves; 321-upper stationary ring member; 322-lower stationary ring member; 333-static ring supports; 334-capping; 335-lower gland; 341-upper spring member; 342-lower spring member; 35-sealing the cavity; 351-sealing the shell; 3511—an air inlet; 3512-air outlet; 3513-upper shaft through hole; 3514-upper seal ring; 352-sealing cover; 3521-lower shaft through hole; 3522-lower seal ring;

41-a water-cooling jacket; 411-water cooling channel; 4111-inlet; 4112-outlet;

5-shaft coupling.

Detailed Description

Preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are merely for explaining the technical principles of the present invention, and are not intended to limit the scope of the present invention.

It should be noted that, in the description of the present invention, terms such as "upper," "lower," "inner," "outer," and the like, which indicate a direction or a positional relationship, are based on the direction or the positional relationship shown in the drawings, which are merely for convenience of description, and do not indicate or imply that the apparatus or element must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.

Furthermore, it should be noted that, in the description of the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; the two components can be mechanically connected, can be directly connected or can be indirectly connected through an intermediate medium, and can be communicated with each other. The specific meaning of the above terms in the present invention can be understood by those skilled in the art according to the specific circumstances. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

As shown in fig. 1 to 5, the stirring and dispersing main shaft provided by the embodiment of the invention comprises a main shaft body 1, a bearing assembly 2 and a dry gas sealing assembly 3.

As shown in fig. 1, the main shaft body 1 sequentially passes through the bearing assembly 2 and the dry gas sealing assembly 3, and the main shaft body 1 can rotate under the drive of a driving piece.

As shown in fig. 1 and 4, a bearing assembly 2 is sleeved on the outer periphery of the main shaft body 1, the bearing assembly 2 includes an upper bearing member 21, a lower bearing member 22 and a bearing support member 23, and the bearing assembly 2 is used for connecting the main shaft body 1 and a water cooling jacket 41 in the water cooling assembly. As shown in fig. 4, the upper bearing member 21 and the lower bearing member 22 are fitted around the outer periphery of the main shaft body 1, and the bearing support member 23 is fitted around the outer periphery of the main shaft body 1 between the upper bearing member 21 and the lower bearing member 22 as viewed in the axial direction of the main shaft body 1 in a state where the installation is completed, so that not only the supporting action on the water cooling jacket 41 can be enhanced, but also the upper bearing member 21 and the lower bearing member 22 can be restrained in the axial direction.

In some specific embodiments, the upper bearing member 21 is an angular contact ball bearing; and/or the lower bearing member 22 is a cylindrical roller bearing. The angular contact ball bearing can bear radial load and axial load at the same time. The cylindrical rollers of the cylindrical roller bearing are in line contact with the roller path, have large radial load capacity, are suitable for bearing heavy load and impact load, and can be used for a high-speed rotating scene.

As shown in fig. 1 to 3, the dry gas seal assembly 3 is located below the lower bearing member 22 so as to seal the lower end surface of the lower bearing member 22, thereby preventing leakage of lubricating oil of the bearing assembly 2.

As shown in fig. 2 and 3, the dry gas seal assembly 3 includes a seal cavity 35, and a moving ring 31, a stationary ring, and a fixed structure are provided inside the seal cavity 35.

As shown in fig. 2, the seal chamber 35 has an air inlet 3511 and an air outlet 3512, the air inlet 3511 being located at a side portion of the movable ring 31 and capable of communicating with any hydrodynamic grooves 311 on the movable ring 31 during rotation of the movable ring 31, air being able to enter the interior of the seal chamber 35 through the air inlet 3511, and seal air being able to be discharged from the interior of the seal chamber 35 to the outside through the air outlet 3512.

In some embodiments, a gas inlet 3511 is provided with a gas inlet nozzle, gas is introduced into the sealed chamber 35 from the gas inlet 3511 through the gas inlet nozzle, a gas outlet 3512 is provided with a gas outlet nozzle, and gas is discharged from the interior of the sealed chamber 35 to the outside through the gas outlet 3512 through the gas outlet nozzle.

As shown in fig. 2, the sealing cavity 35 is provided with an upper shaft through hole 3513 and a lower shaft through hole 3521, the spindle body 1 is sleeved with an upper sealing ring 3514 and a lower sealing ring 3522, the upper sealing ring 3514 is arranged on the upper shaft through hole 3513 and sleeved on the spindle body 1, so that the outer peripheral surface of the spindle body 1 and the inner peripheral surface of the upper shaft through hole 3513 are sealed by the upper sealing ring 3514, and the lower sealing ring 3522 is arranged on the lower shaft through hole 3521 and sleeved on the spindle body 1, so that the outer peripheral surface of the spindle body 1 and the inner peripheral surface of the lower shaft through hole 3521 are sealed by the lower sealing ring 3522. By the above arrangement, the sealing effect of the seal cavity 35 is improved.

In some specific embodiments, the upper seal 3514 is a skeletal oil seal and the lower seal 3522 is a skeletal oil seal.

In some specific embodiments, as shown in fig. 2, the sealing cavity 35 includes a sealing case 351 and a sealing cap 352, a bottom end cap of the sealing case 351 is coupled to the sealing cap 352 to form the sealing cavity 35, an outer circumference of the sealing case 351 has an air inlet 3511 and an air outlet 3512, an upper shaft through hole 3513 is further formed at an upper end of the sealing case 351, and a lower shaft through hole 3521 is formed at a lower end of the sealing cap 352.

As shown in fig. 3 and 5, the moving ring 31 is annular, and the moving ring 31 is fitted around and fixed to the outer periphery of the main shaft body 1, and the inner circumferential surface thereof is interference fit with the outer circumferential surface of the main shaft body 1 so that it can rotate with the main shaft body 1. As shown in fig. 5, a plurality of hydrodynamic grooves 311 are formed on the end surface of the movable ring 31 facing the lower bearing member 22 and annularly spaced about the axial center of the main shaft body 1, and the gas inlet 3511 of the seal chamber 35 is located on the side of the movable ring 31 and can communicate with any hydrodynamic groove 311 on the movable ring 31 during rotation of the movable ring 31, and gas can enter the interior of the seal chamber 35 through the gas inlet 3511. The hydrodynamic grooves 311 form a sealed air film by hydrodynamic effects generated when the movable ring 31 and the stationary ring rotate relatively.

As shown in fig. 2 and 3, the fixed structure is fixedly disposed in the sealing cavity 35, and the stationary ring is disposed in the fixed structure by means of a spring member, so that the stationary ring can be abutted against the sealing surface of the moving ring 31 under the action of the spring member and can be separated from the sealing surface of the moving ring 31 under the combined action of the spring member and the air entering from the air inlet 3511. By the above arrangement, the dry gas seal, that is, the noncontact seal can be formed under the lower bearing member 22, thereby improving the sealing effect of the stirring dispersion main shaft.

As shown in fig. 3, the fixing structure includes a stationary ring support 333, an upper gland 334 and a lower gland 335, the stationary ring support 333 is fixedly disposed at the seal cavity 35, the upper gland 334 is fixedly disposed at an upper side of the stationary ring support 333, the upper spring 341 is disposed at the upper gland 334, the lower gland 335 is fixedly disposed at a lower side of the stationary ring support 333, and the lower spring 342 is disposed at the lower gland 335.

As shown in fig. 3, the stationary ring member includes an upper stationary ring member 321 and a lower stationary ring member 322, and the spring members include an upper spring member 341 and a lower spring member 342. Specifically, the upper stationary ring 321 is located above the moving ring 31, and is disposed in a fixed structure by means of an upper spring 341, so that the upper stationary ring 321 abuts against an upper sealing surface of the moving ring 31 under the action of the upper spring 341 and can be separated from the sealing surface of the moving ring 31 under the combined action of the upper spring 341 and air entering from the air inlet 3511; when the acting force of the upper spring member 341 and the restoring force of the air entering the air inlet 3511 reach the force balance, an upper sealing air film is formed between the upper static ring member 321 and the upper end sealing surface of the moving ring member 31, and the upper static ring member 321 is separated from the upper end sealing surface of the moving ring member 31, so that almost no abrasion exists between the upper static ring member 321 and the upper end sealing surface of the moving ring member 31, and meanwhile, a dry air seal is formed; the lower stationary ring member 322 is located below the moving ring member 31 and is disposed in a fixed structure by means of a lower spring member 342, so that the lower stationary ring member 322 abuts against a lower side sealing surface of the moving ring member 31 under the action of the lower spring member 342 and can be separated from the sealing surface of the moving ring member 31 under the combined action of the lower spring member 342 and air entering from the air inlet 3511. When the restoring force of the lower spring member 342 and the air force entering the air inlet 3511 reach the force balance, a lower sealing air film is formed between the lower static ring member 322 and the lower end sealing surface of the moving ring member 31, and the lower static ring member 322 is separated from the lower end sealing surface of the moving ring member 31, so that almost no abrasion exists between the lower static ring member 322 and the lower end sealing surface of the moving ring member 31, and dry air sealing is formed; by the arrangement, the upper end sealing surface and the lower end sealing surface of the movable ring 31 can form dry gas sealing, so that the sealing performance of the stirring dispersion main shaft is further improved, and lubricating oil leakage is prevented.

The dry gas seal assembly 3 has the following specific working principle:

1) In the initial state, the static ring member is abutted against the sealing surface of the moving ring member 31 under the elastic force of the spring member, that is, the static ring member is abutted against the sealing surface of the moving ring member 31.

2) When the movable ring 31 rotates following the main shaft body 1 and sealing gas is injected into the hydrodynamic groove 311 through the gas inlet 3511, the sealing gas is extruded in the hydrodynamic groove 311, and further applies pneumatic force to the stationary ring, so that the stationary ring has a tendency to be far away from the sealing surface of the movable ring 31 under the pneumatic force, and the stationary ring is separated from the sealing surface of the movable ring 31 to achieve a non-contact effect. Wherein the sealing gas is nitrogen.

3) When the restoring force of the spring member and the force of the air entering the air inlet 3511 reach the force balance, the static ring member and the sealing surface of the moving ring member 31 are kept in a relatively stable state, and a sealing air film is formed between the static ring member and the sealing surface of the moving ring member 31, so that the static ring member and the sealing surface of the moving ring member 31 are not contacted any more, and almost no abrasion is caused between the static ring member and the sealing surface of the moving ring member 31, and meanwhile, a dry air seal is formed.

As shown in fig. 4, the stirring dispersion main shaft further comprises a water cooling assembly, the water cooling assembly comprises a water cooling jacket 41, the water cooling jacket 41 is sleeved on the periphery of the main shaft body 1 by means of the bearing assembly 2, cooling liquid for cooling can be introduced into the water cooling jacket 41, and the water cooling jacket 41 is located above the sealing cavity 35. The water cooling jacket 41 is internally provided with a water cooling channel 411, the water cooling channel 411 is spirally arranged along the axial direction of the main shaft body 1, the water cooling channel 411 is provided with a liquid inlet 4111 and a liquid outlet 4112, cooling liquid is introduced into the water cooling channel 411 through the liquid inlet 4111, and is discharged from the water cooling channel 411 through the liquid outlet 4112. By introducing the coolant into the water-cooling jacket 41, the coolant can absorb heat of the bearing assembly 2, and the phenomenon that the main shaft body 1 is excessively heated due to rotation can be avoided.

The water cooling assembly further includes a water cooling transfer pump in communication with the water cooling channel 411, the water cooling transfer pump being capable of providing power to the cooling fluid so as to cause the cooling fluid to pass into the interior of the water cooling channel 411 at a rate and to cause it to circulate.

As shown in fig. 1, the stirring dispersion main shaft further comprises a coupling 5, one end of the main shaft body 1, which is far away from the dry gas seal assembly 3, is connected with the coupling 5, and one end of the main shaft body 1, which is far away from the dry gas seal assembly 3, can be in driving connection with the rotating shaft of the driving member by means of the coupling 5.

The embodiment of the invention also provides a stirring and dispersing machine, which comprises the high-sealing stirring and dispersing main shaft in any one of the above embodiments.

Thus far, the technical solution of the present invention has been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of protection of the present invention is not limited to these specific embodiments. Equivalent modifications and substitutions for related technical features may be made by those skilled in the art without departing from the principles of the present invention, and such modifications and substitutions will fall within the scope of the present invention.

Claims (10)

1. The high-sealing stirring dispersion main shaft is characterized by comprising a main shaft body (1), a bearing assembly (2) and a dry gas sealing assembly (3), wherein the bearing assembly (2) comprises a lower bearing piece (22), the lower bearing piece (22) is sleeved on the periphery of the main shaft body (1), the dry gas sealing assembly (3) is positioned below the lower bearing piece (22) so as to seal the lower end face of the lower bearing piece (22), the dry gas sealing assembly (3) comprises a sealing cavity (35), the sealing cavity (35) is internally provided with a movable ring piece (31), a static ring piece and a fixed structure, the movable ring piece (31) is sleeved and fixed on the periphery of the main shaft body (1), a plurality of fluid dynamic grooves (311) which are annularly arranged at intervals with the axis of the main shaft body (1) as the center are formed on the end face of the lower bearing piece (22), the sealing cavity (3511) is provided with an air inlet, the movable ring piece (31) is arranged in the fixed structure in a rotary way, the movable ring piece (31) can be fixed on the side part of the movable ring piece (31) by means of a spring, the movable ring piece (31) can be fixed in the fixed structure, so that the stationary ring member can be abutted against the sealing surface of the moving ring member (31) under the action of the spring member and can be separated from the sealing surface of the moving ring member (31) under the combined action of the spring member and the air entering from the air inlet (3511).

2. The high-sealing stirring dispersion main shaft according to claim 1, characterized in that the stationary ring comprises an upper stationary ring (321) and a lower stationary ring (322), the spring comprises an upper spring (341) and a lower spring (342), the upper stationary ring (321) is located above the moving ring (31) and is arranged on the fixed structure by means of the upper spring (341) so that the upper stationary ring (321) is abutted against an upper side sealing surface of the moving ring (31) under the action of the upper spring (341), the lower stationary ring (322) is located below the moving ring (31) and is arranged on the fixed structure by means of the lower spring (342) so that the lower stationary ring (322) is abutted against a lower side sealing surface of the moving ring (31) under the action of the lower spring (342).

3. The high-sealing stirring dispersion main shaft according to claim 2, wherein the fixing structure comprises a static ring support (333), an upper gland (334) and a lower gland (335), the static ring support (333) is fixedly arranged in the sealing cavity (35), the upper gland (334) is fixedly arranged on the upper side of the static ring support (333), the upper spring part (341) is arranged on the upper gland (334), the lower gland (335) is fixedly arranged on the lower side of the static ring support (333), and the lower spring part (342) is arranged on the lower gland (335).

4. The high-sealing stirring dispersion main shaft according to claim 1, wherein the sealing cavity (35) is provided with an upper shaft through hole (3513) and a lower shaft through hole (3521), the main shaft body (1) is sleeved with an upper sealing ring (3514) and a lower sealing ring (3522), the upper sealing ring (3514) is arranged on the upper shaft through hole (3513) and sleeved on the main shaft body (1), so that the outer peripheral surface of the main shaft body (1) and the inner peripheral surface of the upper shaft through hole (3513) are sealed through the upper sealing ring (3514), and the lower sealing ring (3522) is arranged on the lower shaft through hole (3521) and sleeved on the main shaft body (1), so that the outer peripheral surface of the main shaft body (1) and the inner peripheral surface of the lower shaft through hole (3521) are sealed through the lower sealing ring (3522).

5. The high-seal stirring dispersion main shaft according to claim 1, wherein the bearing assembly (2) further comprises a bearing support member (23) and an upper bearing member (21), and the bearing support member (23) is sleeved on the outer periphery of the main shaft body (1) and is located between the upper bearing member (21) and the lower bearing member (22) as viewed in the axial direction of the main shaft body (1) in the mounted state.

6. The high-seal stirring dispersion main shaft according to claim 5, characterized in that said upper bearing member (21) is an angular contact ball bearing; and/or

The lower bearing member (22) is a cylindrical roller bearing.

7. The high-seal stirring dispersion main shaft according to claim 1, further comprising a coupling (5), wherein an end of the main shaft body (1) remote from the dry gas seal assembly (3) is connected to the coupling (5).

8. The high-seal stirring dispersion main shaft according to any one of claims 1 to 7, characterized in that the stirring dispersion main shaft further comprises a water cooling assembly comprising a water cooling jacket (41), the water cooling jacket (41) is sleeved on the periphery of the main shaft body (1) by means of the bearing assembly (2), and the water cooling jacket (41) is positioned above the seal cavity (35).

9. The high-sealing stirring dispersion main shaft according to claim 8, wherein the water-cooling jacket (41) is internally provided with a water-cooling channel (411), and the water-cooling channel (411) is spirally arranged along the axial direction of the main shaft body (1).

10. A stirring disperser, characterized in that it comprises a high-seal stirring dispersing main shaft as claimed in any one of claims 1 to 9.