JP2012136340A - Air supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air supply device which can accurately and stably convey a glass sheet.SOLUTION: The air supply device includes: a housing 10 whose inside is hollow and an upper side is open; an air fan 20 mounted on the inner bottom surface of the housing 10; a filter 30 disposed at the upper part of the housing 10 above the air fan 20; and a cover 40 closely contacted to the upper surface of the filter 30 to cover the upper side of the housing, and having air discharge holes 41 formed on its surface. Air partitioning parts 50, air-discharge adjustment parts, and air-generation adjustment parts are provided, so that the air is generated for each partition space. The generated air is evened and is discharged upwardly by each partition space, or the amount of the air is increased and is discharged to another adjacent partition space instead of blocking the air discharging from the specific partition space.

Description

  The present invention relates to an air supply apparatus, and more particularly to an apparatus for supplying air to an internal space of a housing.

  Conventionally, on the inspection equipment for inspecting the defect of thin plate glass used for LCD, PDP, etc., it is used to transport the plate glass to the inspection section side or to transport it to other process lines A roller transport device is used in which a plurality of transport rollers for supporting and transporting the bottom surface of a sheet glass on a plurality of rotating shafts arranged at regular intervals on a work table are axially coupled. It was.

  However, since the plate glass is transported after the sheet glass and the outer peripheral surface of the transport roller are basically brought into contact with each other, the sheet glass transport device using such a transport roller basically looks like shaking or vibration due to contact friction. Such a fine tremor phenomenon is not completely prevented, and such a tremor causes a problem that the defect rate cannot be accurately measured when inspecting the plate glass, and the accuracy of the inspection is lowered.

  In order to solve such problems, for example, an air floating part is provided at the center of the workbench to float the platen in the air, and the both sides of the platen glass are supported on both sides in the width direction of the workbench. The conveyance apparatus which is provided with the conveyance roller part to make it convey in a desired direction in the state which air-lifted the plate glass to the fixed height was shown.

  However, such a conventional sheet glass conveying device is a system in which the sheet glass is levitated by the strength of air discharge from the air floating portion arranged at the center of the work table. Since it is almost concentrated only in the center, the central part of the plate glass swells, and both sides of the plate glass on the roller conveyance part side are dented, so the so-called satiety situation is generated and basically the conveyance of the plate glass is not properly done, and further the damage of the plate glass In addition, since air discharge is uniformly generated upward, air control such as intensive air supply to a desired part, such as a fine drop of the plate glass, is totally impossible. There was a problem of becoming possible.

  The present invention has been devised in order to solve such a problem, and is provided between an air compartment section that divides the internal space of the housing into a large number of spaces in the longitudinal direction, an air fan, and a filter. An air discharge adjusting section that divides the air and an air generation adjusting section that adjusts the amount of air generated by the air fan itself with respect to the width direction of the housing so that air is generated in each partition space. May be discharged upward in line with each partition space, or instead of blocking air discharge from a specific partition space, it may be discharged by increasing the amount of air to another adjacent partition space In addition, in the case of a plate glass conveying device, the air generating direction can be adjusted with respect to the width direction of the housing. The air supply can be adjusted to a desired portion of the flat glass plate having a thin flat plate structure to be conveyed so that the flatness with respect to the glass plate being conveyed can be maintained constant. An object of the present invention is to provide an air supply device that enables conveyance of plate glass.

  In order to achieve the above object, the air supply device of the present invention includes a housing that is vacant inside and opened upward; an air fan provided on an inner bottom surface of the housing; an opening of the housing above the air fan; And a cover that is in close contact with the upper surface of the filter and covers the upper portion of the housing, and has an air discharge hole formed on the surface.

  Also, in the air supply device according to the present invention, a plurality of the air fans are provided at regular intervals along the longitudinal direction of the housing, and the air fans are separated between the air fans in order to partition the air fans. Preferably, a plurality of air compartments are provided inside the housing.

  In the air supply device according to the present invention, a through hole is provided in one side wall surface of the housing in which the air partition portion is provided. The air partition portion includes a partition plate that partitions the corresponding internal space of the housing, and the partition plate. Preferably, the fixing plate is fixed to the housing by another fastener while being exposed to the outside of the through hole and in close contact with the outer wall surface of the housing.

  In the air supply device according to the present invention, it is preferable that the air supply device further includes another sealing plate for sealing the through hole of the housing in a state where the air partition portion is removed.

  Further, in the air supply device according to the present invention, the air partition portion is a partition plate that partitions the corresponding internal space of the housing; the partition plate is disposed at a central portion in the vertical direction of the partition plate, and both end portions thereof define both side walls of the housing. A rotating shaft that penetrates; and a knob that is coupled to both ends of the rotating shaft that is exposed to the outside of the housing and communicates with both side spaces of the housing that are partitioned by rotating the partition plate by a rotating operation. Preferably it consists of:

  Also, in the air supply device according to the present invention, an air discharge adjusting unit for adjusting the air generated from the air fan in the internal space of the housing between the air fan and the filter so that the air is discharged and blocked to the filter. Is preferably further provided.

  Further, in the air supply device according to the present invention, the air discharge adjusting portion includes a plurality of auxiliary units arranged continuously along the longitudinal direction of the housing in order to define a corresponding internal space of the housing between the air fan and the filter. A partition plate; disposed at the center in the vertical direction of each auxiliary partition plate, and both ends of the rotation shaft penetrating both side walls of the housing; and both ends of the rotation shaft exposed to the outside of the housing; It is preferable to include a knob for communicating the space between the air fan and the filter of the housing which is partitioned by rotating each of the auxiliary partition plates by rotating operation.

  Further, in the air supply device according to the present invention, an air discharge adjusting unit for adjusting the air generated from the air fan in the inner space of the housing between the air fan and the filter so that the air is discharged and blocked by the filter. Is preferably further provided.

  Further, in the air supply device according to the present invention, the air discharge adjusting portion includes a plurality of auxiliary units arranged continuously along the longitudinal direction of the housing in order to define a corresponding internal space of the housing between the air fan and the filter. A partition plate; disposed at the center in the vertical direction of each auxiliary partition plate, and both ends of the rotation shaft penetrating both side walls of the housing; and both ends of the rotation shaft exposed to the outside of the housing; It is preferable to include a knob for communicating the space between the air fan and the filter of the housing which is partitioned by rotating each of the auxiliary partition plates by rotating operation.

  In the air supply device according to the present invention, it is preferable that an air generation adjusting unit for covering the air fan and adjusting an air generation amount of the air fan itself is further provided.

  Further, in the air supply device according to the present invention, the air generation adjusting unit has an auxiliary housing that covers the outside of the air fan and has an open hole that is open on the upper side; An opening / closing plate for partitioning the inside and outside space of the door; a rotating shaft disposed at a central portion of the opening / closing plate and having both end portions penetrating both side walls of the auxiliary housing; and a rotating shaft exposed to the outside of the auxiliary housing It is preferable to include a knob that is connected to both ends of the auxiliary housing and communicates with the internal air fan of the auxiliary housing that is blocked by rotating the opening and closing plate by a rotating operation.

  Further, in the air supply device according to the present invention, the opening and closing plates are continuously arranged along the width direction of the opening hole, and a plurality of the opening and closing plates are individually operated to rotate to adjust the amount of air generated in the width direction of the housing. It is preferable to be provided.

  In the air supply device according to the present invention, it is preferable that the lower side of the housing has a right-angle structure that is perpendicular to the entire longitudinal direction.

  Further, in the air supply device according to the present invention, it is preferable that the both side corners of the housing have a straight inclined surface structure that is inclined at a predetermined angle over the entire longitudinal direction.

  In the air supply device according to the present invention, it is preferable that the lower side of the housing has a curved surface structure rounded with a constant curvature over the entire longitudinal direction.

  As described above, the air supply device according to the present invention includes an air partition section that partitions the internal space of the housing into a number of spaces in the longitudinal direction, an air discharge adjustment section that partitions between the air fan and the filter, and an air. An air generation control unit that adjusts the air generation amount of the fan itself in the width direction of the housing is provided so that air is generated for each partition space, and the generated air is separated for each partition space. Instead of blocking air discharge from a specific partition space, it can be discharged by increasing the amount of air to another adjacent partition space, and the width of the housing By making it possible to adjust the direction of air generation relative to the direction, for example, in the case of a plate glass transport device, a thin flat plate positioned above the cover and transported along the horizontal direction The air supply can be adjusted to the desired part of the plate glass of the rate structure, and the flatness with respect to the plate glass being conveyed can be kept constant, thereby enabling accurate and stable conveyance of the plate glass, etc. An effect is obtained.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIGS. 1 to 12, the air supply device of the present invention has a housing 10 that is empty inside and open upward, an air fan 20 provided on the inner bottom surface of the housing 10, and an upper side of the air fan 20. A filter 30 disposed above the housing 10 and a cover 40 which is in close contact with the upper surface of the filter 30 to cover the top of the housing and has an air discharge hole 41 formed on the surface.

  The housing 10 is formed in a rectangular square box shape that extends long along the longitudinal direction (preferably, a length corresponding to the entire longitudinal direction of a work table such as a plate glass conveying device) and is opened upward.

  The air fan 20 has a so-called roller fan structure that is provided on the inner bottom surface of the housing 10 and discharges air.

  The filter 30 has a square block shape disposed above the housing 10 above the air fan 20 so as to remove foreign matters contained in the discharged air or to increase the strength of air discharge. It has functions such as how much to relax.

  The cover 40 is in close contact with the upper surface of the filter 30 to cover the upper portion of the housing, and a plurality of air discharge holes 41 formed in the oblique direction are provided on the surface.

  Various embodiments of the air supply apparatus of the present invention having such a structure are as follows.

  As shown in FIGS. 1 to 3, in the first embodiment, a plurality of the air fans 20 are provided at regular intervals (equal intervals) along the longitudinal direction of the housing 10. In order to partition 20, a plurality of air partition portions 50 are provided inside the housing 10 between the air fans 20.

  Here, a through hole 11 is formed in one side wall surface of the housing 10 where the air partition 50 is provided, and the air partition 50 includes a square plate-like partition plate 51 that partitions the corresponding internal space of the housing 10, An alphabetic character comprising a fixed plate 53 connected to one end portion of the partition plate 51 and exposed to the outside of the through hole 11 and fixed to the housing 10 by another fastener 52 while being in close contact with the outer wall surface of the housing 10. It consists of a T structure.

  The air supply device according to the first embodiment of the present invention having such a configuration immediately rises with the air partition portion 50 where the same air discharge amount generated for each partition space is fixedly installed as a boundary. The glass sheet is discharged to the outside through the air discharge holes 41 of the cover 40 which is discharged and disposed above, and the plate glass or the like is allowed to float on the air.

  On the other hand, in the first embodiment, the air partition portion 50 can be removed so as to communicate with the adjacent space portion. At this time, the penetration of the housing 10 with the air partition portion 50 removed is performed. The hole 11 can be sealed with another sealing plate 55.

  As shown in FIGS. 4 and 5, the second embodiment shows a structure in which only the air partition 60 is deformed in the first embodiment.

  The air partition portion 60 is disposed at a square plate-shaped partition plate 61 that partitions the corresponding internal space of the housing 10 and a central portion in the vertical direction of the partition plate 61, and both end portions thereof define both side walls of the housing 10. Both side space portions of the housing 10 which are coupled to both ends of the long rod-shaped rotating shaft 62 and the rotating shaft 62 exposed to the outside of the housing 10 and are partitioned by rotating the partition plate 61 by a rotating operation. It has a structure including a knob 63 having a handle function for communicating with each other.

  In the air supply device according to the second embodiment of the present invention having such a structure, the same air discharge amount generated for each partition space is immediately discharged upward with the air partition portion 60 as a boundary and disposed above. Can be discharged outside through the air discharge hole 41 of the cover 40 so that the plate glass or the like can be floated on the air, or the adjacent partition spaces can be adjusted by rotating the knob 63 in order to adjust the air supply amount to a necessary portion. The air can be shared by communicating with each other, and the amount of air to be shared can also be adjusted by adjusting the inclination of the partition plate 61.

  As shown in FIGS. 6 to 8, in the third embodiment, the air generated from the air fan 20 is filtered in the internal space of the housing 10 between the air fan 20 and the filter 30 in the second embodiment. 30 shows a structure in which an air discharge adjusting unit 70 for adjusting discharge and discharge blocking is further added.

  The air discharge adjusting unit 70 includes a plurality of square plate-like auxiliary compartments that are continuously arranged along the longitudinal direction of the housing 10 in order to define a corresponding internal space of the housing 10 between the air fan 20 and the filter 30. A plate 71, a long rod-shaped rotary shaft 72 that is disposed at the center in the vertical direction of each auxiliary partition plate 71 and whose both ends penetrate both side walls of the housing 10, and a rotary shaft exposed to the outside of the housing 10 72, and has a handle function for communicating the space portion between the air fan 20 and the filter 30 of the housing 10 which is coupled by rotating the auxiliary partition plate 71 by a rotation operation. The structure includes a knob 73.

  Here, the length of the auxiliary partition plate 71 in the width direction is such that when the auxiliary partition plate 71 is rotated horizontally so as to be sealed between the air fan 20 and the filter 30, It is preferable to have a length that allows the plate surfaces to overlap each other.

  In the air supply device according to the third embodiment of the present invention having such a configuration, the same air discharge amount generated for each partition space is immediately discharged upward with the air partition portion 60 as a boundary, and is disposed above. The glass can be discharged to the outside through the air discharge holes 41 of the cover 40, or the plate 73 can be floated on the air, or the knob 73 of the auxiliary partition plate 71 can be rotated to adjust the air supply amount to a necessary part. Then, after changing the direction of the air to another adjacent partition space, the air can be shared by communicating with each other, and at the same time, the auxiliary partition plate 71 is inclined by adjusting the inclination of the corresponding auxiliary partition plate 71 It is also possible to make the air flow have directionality by allowing it to flow along the inclined surface of the plate 61.

  As shown in FIGS. 9 to 12, in the fourth embodiment, the configuration of the air partition section 60 of the third embodiment is deleted, and the air fan 20 is turned on again with only the air discharge adjusting section 70 provided. The structure which the air generation adjustment part 80 for covering and adjusting the air generation amount of air fan 20 itself is further provided is shown.

  Here, the air generation adjusting unit 80 covers the outside of the air fan 20 and blocks the rectangular box-shaped auxiliary housing 81 having an open hole 81a opened upward, and the open hole 81a of the auxiliary housing 81. A rectangular plate-shaped opening / closing plate 82 for partitioning the inside and outside space of the auxiliary housing 81, and a long rod-like shape that is disposed at the center of the opening / closing plate 82 and whose both end portions penetrate both side walls of the auxiliary housing 81. The air fan 20 inside the auxiliary housing 81 is coupled to both ends of the rotary shaft 83 and the both ends of the rotary shaft 83 exposed to the outside of the auxiliary housing 81 and is blocked by rotating the opening / closing plate 82 by a rotating operation. And a knob 84 having a handle function for communicating with the external space.

  The opening / closing plate 82 is continuously arranged along the width direction of the opening hole 81a, and a plurality of the opening / closing plates 82 are provided so that each of the opening / closing plates 82 can be individually rotated to adjust the amount of air generated in the width direction of the housing 10.

  In the air supply device according to the fourth embodiment of the present invention having such a configuration, each air discharge adjusting unit 70 is opened upright, and the air generated by the air fan 20 is immediately discharged upward and disposed above. The plate glass or the like can be discharged to the outside through the air discharge holes 41 of the cover 40, and the air to the air fan 20 can be closed by closing the open / close plate 82 with respect to the corresponding air fan 20. The discharge can be blocked or the knob 73 of the auxiliary partition plate 71 is rotated to adjust the air direction to other adjacent partition spaces in order to adjust the air supply amount to a necessary portion. After the conversion, the air amount can be shared by communicating with each other, and at the same time, the inclination of the auxiliary partition plate 71 is adjusted, and the air flows along the inclined surface of the auxiliary partition plate 61 inclined. In this way, the flow of air along the longitudinal direction can be directional, and at the same time, the opening inclination of the opening / closing plate 82 can be adjusted to adjust the direction of air discharge in the width direction. It can also be adjusted so that multiple air discharges are possible.

  In this way, the air supply device having various embodiments of the present invention is installed in a plate glass transport device or a clean tunnel unit to correct the flatness imbalance in which both side portions of the plate glass and the like are lowered, It can be conveyed accurately and stably.

  FIG. 13 shows a state where the air supply device of the present invention is applied to a plate glass conveying device, and FIG. 14 shows a state where the air supply device of the present invention is applied to a clean tunnel unit.

  15 and 16 show another embodiment of the housing 10 in the air supply apparatus of the present invention. The structure of the straight inclined surface 12 in which the lower end of the housing 10 is inclined at a predetermined angle over the entire longitudinal direction. Alternatively, the both sides of the lower end of the housing 10 may have a curved surface 13 rounded with a constant curvature over the entire length. If the lower end of the housing 10 has a curved surface 13 structure, the air generated by the air fan 20 naturally occurs along the curved surface instead of generating friction in the process of changing the wind direction due to the structure of the inclined surface. It can be discharged upward.

  As described above, the present invention has been described with reference to the above-described preferred embodiments. However, the scope of the present invention is not limited to the modified examples in which such embodiments are simply applied in combination with the prior art. Of course, all the techniques that can be easily modified and used by those skilled in the art to which the present invention belongs are included in the scope of the present invention.

It is a disassembled perspective view which shows the air supply apparatus by the 1st Embodiment of this invention. It is a principal part expansion perspective view which shows the air division part of the air supply apparatus by the 1st Embodiment of this invention. It is a principal part expansion perspective view which shows the state by which the sealing board was installed after the partition board of the air supply apparatus by the 1st Embodiment of this invention was removed. It is a disassembled perspective view which shows the air supply apparatus by the 2nd Embodiment of this invention. It is a principal part expansion perspective view which shows the air division part of the air supply apparatus by the 2nd Embodiment of this invention. It is a disassembled perspective view which shows the air supply apparatus by the 3rd Embodiment of this invention. It is the schematic which shows the state by which the air discharge adjustment part of the air supply apparatus by the 3rd Embodiment of this invention was open | released. It is the schematic which shows the state by which the air discharge adjustment part of the air supply apparatus by the 3rd Embodiment of this invention partly closed and partly inclined for the direction change of air discharge. It is a disassembled perspective view which shows the air supply apparatus by the 4th Embodiment of this invention. It is a principal part schematic diagram which shows the air generation adjustment part of the air supply apparatus by the 4th Embodiment of this invention. It is the schematic which shows the state by which the air discharge adjustment part of the air supply apparatus by the 4th Embodiment of this invention was open | released. It is the schematic which shows the state by which the air discharge adjustment part of the air supply apparatus by the 4th Embodiment of this invention was partially closed and partly inclined for the direction change of air discharge. It is a schematic perspective view which shows the state by which the air supply apparatus by this invention was applied to the plate glass conveying apparatus. It is a schematic perspective view which shows the state by which the air supply apparatus by this invention was applied to the clean tunnel unit. It is a schematic perspective view which shows other embodiment of a housing in the air supply apparatus of this invention. It is a schematic perspective view which shows other embodiment of a housing in the air supply apparatus of this invention.

DESCRIPTION OF SYMBOLS 10: Housing 11: Through-hole 12: Directly inclined surface 13: Curved surface 20: Air fan 30: Filter 40: Cover 41: Air discharge hole 50: Air partition part 51: Partition plate 52: Fastener 53: Fixing plate 55: Sealing Plate 60: Air partition 61: Partition plate 62: Rotating shaft 63: Knob 70: Air discharge controller 71: Auxiliary partition plate 72: Rotating shaft 73: Knob 80: Air generation controller 81: Auxiliary housing 81a: Open hole 82 : Open / close plate 83: Rotating shaft 84: Knob

Claims (15)

A housing 10 that is empty inside and open at the top;
An air fan 20 provided on the inner bottom surface of the housing 10;
A filter 30 provided above the air fan 20 that is open above the housing 10; and a cover that is in close contact with the upper surface of the filter 30 and covers the top of the housing, and is provided with an air discharge hole 41 on the surface. 40 and;
An air supply device comprising:   A plurality of the air fans 20 are provided at regular intervals along the longitudinal direction of the housing 10, and a plurality of air fans 20 are provided inside the housing 10 between the air fans 20 to partition each air fan 20. The air supply device according to claim 1, wherein partition portions are provided. A through hole 11 is provided on one side wall surface of the housing 10 where the air partition 50 is provided
The air partition 50 is connected to a partition plate 51 that partitions the corresponding internal space of the housing 10 and one end of the partition plate 51, is exposed to the outside of the through hole 11, and is in close contact with the outer wall surface of the housing 10. The air supply device according to claim 2, further comprising a fixing plate 53 fixed to the housing 10 by another fastener in a state where the air supply device is in a closed state.   The air supply device according to claim 3, further comprising another sealing plate 55 for sealing the through hole 11 of the housing 10 in a state where the air partition portion 50 is removed. The air compartment 60 is
A partition plate 61 that partitions the corresponding internal space of the housing 10;
The partition plate 61 is provided at a central portion in the vertical direction, and both end portions thereof are coupled to the rotation shafts 62 penetrating both side walls of the housing 10; and both ends of the rotation shaft 62 exposed to the outside of the housing 10. A knob 63 for communicating the both side spaces of the housing 10 partitioned by rotating the partition plate 61 by a rotation operation;
The air supply device according to claim 2, comprising:   An air discharge adjusting unit 70 is further provided in the internal space of the housing 10 between the air fan 20 and the filter 30 to adjust the air generated from the air fan 20 to be discharged to or blocked from the filter 30. The air supply device according to claim 5. The air discharge adjusting unit 70
A plurality of auxiliary partition plates 71 arranged continuously along the longitudinal direction of the housing 10 to partition the corresponding internal space of the housing 10 between the air fan 20 and the filter 30;
A rotary shaft 72 provided at the center of each auxiliary partition plate 71 in the vertical direction, and both ends of the auxiliary partition plate 71 penetrating both side walls of the housing 10; and both ends of the rotary shaft 72 exposed to the outside of the housing 10 A knob 73 that is coupled and communicates with a space between the air fan 20 of the housing 10 and the filter 30 by rotating the respective auxiliary partition plates 71 by a rotation operation;
The air supply device according to claim 6, comprising:   An air discharge adjusting unit 70 is further provided in the internal space of the housing 10 between the air fan 20 and the filter 30 to adjust the air generated from the air fan 20 to be discharged to or blocked from the filter 30. The air supply device according to claim 1. The air discharge adjusting unit 70
A plurality of auxiliary partition plates 71 arranged continuously along the longitudinal direction of the housing 10 to partition the corresponding internal space of the housing 10 between the air fan 20 and the filter 30;
A rotary shaft 72 provided at the center of each auxiliary partition plate 71 in the vertical direction, and both ends of the auxiliary partition plate 71 penetrating both side walls of the housing 10; and both ends of the rotary shaft 72 exposed to the outside of the housing 10 A knob 73 that is connected and communicates with a space between the air fan 20 and the filter 30 of the housing 10 that is partitioned by rotating each auxiliary partition plate 71 by a rotation operation;
The air supply device according to claim 8, comprising:   The air supply device according to claim 9, further comprising an air generation adjusting unit 80 that covers the air fan 20 and adjusts an air generation amount of the air fan 20 itself. The air generation adjusting unit 80 includes:
An auxiliary housing 81 that covers the outside of the air fan 20 and has an open hole 81a opened upward;
An opening / closing plate 82 for blocking the open hole 81a of the auxiliary housing 81 to partition the inside and the outside of the auxiliary housing 81;
A rotary shaft 83 disposed at a central portion of the opening / closing plate 82 and having both ends thereof penetrating both side walls of the auxiliary housing 81; and both ends of the rotary shaft 83 exposed to the outside of the auxiliary housing 81; A knob 84 for connecting the air fan 20 inside the auxiliary housing 81 and the outside space portion, which is blocked by rotating the opening / closing plate 82 by a rotation operation;
The air supply device according to claim 10, comprising:   The opening / closing plate 82 is continuously arranged along the width direction of the opening / closing hole 81a, and a plurality of the opening / closing plates 82 are provided so that each of the opening / closing plates 82 can be individually rotated to adjust the amount of air generated in the width direction of the housing 10. The air supply device according to claim 11.   2. The air supply device according to claim 1, wherein the lower end of the housing has a right-angle structure that is perpendicular to the entire longitudinal direction.   2. The air supply device according to claim 1, wherein both sides of the lower end of the housing have a straight inclined surface 12 structure that is inclined at a predetermined angle over the entire longitudinal direction.   2. The air supply device according to claim 1, wherein both sides of the lower end of the housing have a curved surface 13 structure rounded with a constant curvature over the entire longitudinal direction.