JP2011035971A - Grommet for inserting liner body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a harmful deformation of a bellows portion and an interference thereof with a liner body when a rotating body such as a back door moves. <P>SOLUTION: A grommet 1 for inserting linear body has an intermediate bellows portion 4 for inserting a linear body 8 and fixing portions 2, 3 on both the sides, fixes the fixing portions to hole portions 14a, 15a of panels 14, 15 respectively, and bends the bellows portion in accordance with the rotation of one panel 14. In the grommet 1, protrusions portion 5 of a mount-like longitudinal cross section protruding outside a diameter direction from the other portions of the bellows portion are formed on an intermediate portion of an axial direction of the bellows portion 4, and a portion as the inside of bending of the protruding portions when the bellows portion is bent is protruded outside of the diameter direction while being compressed in the axial direction. A portion as the outside of bending of the protrusions portion 5 when the bellows portion 4 is bent like a dog leg shape in longitudinal and cross section while elongating in the axial direction. The bellows portion 4 comprises the intermediate protruding portion 5 and at least small-diameter mount portions 6, 7 each of which continues to both the sides of the axial direction of the protruding portion. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a grommet for passing through a linear body for wiring a linear body such as a wire harness through a panel of an automobile, for example.

  FIG. 4 shows an embodiment of a conventional linear body penetrating grommet (see Patent Document 1).

  The grommet 51 is made of synthetic rubber and includes an intermediate small bellows portion 52 and large-diameter fixing portions 53 (only one of them is shown) at both ends. The bellows portion 52 is freely bendable, and each fixing portion 53 has a circumferential groove 55 that fits into a hole portion 54a of each panel 54 of the automobile.

  A wire harness (not shown) is inserted into the grommet 51 and passes through the panel hole 54a. For example, the grommet 51 is routed from the engine room side to the vehicle compartment side or from the vehicle body side to the door side. Power is supplied to the electrical equipment on the side and the auxiliary equipment. The fixing portion 53 of the grommet 51 is in close contact with the hole portion 54a of the panel 54 to provide waterproofing. A wire harness is generically called a linear body.

  FIG. 5 shows another embodiment of a conventional linear body penetrating grommet (see Patent Document 2).

  The grommet 61 is composed of a synthetic rubber grommet main body 62 and a synthetic resin hard inner member 63 mounted inside the grommet main body 62.

  The grommet main body 62 has an intermediate bellows portion 64 and a terminal fixing portion 65, and the fixing portion 65 has an inner circumferential groove 66 and a tip lip 68 that is in close contact with the panel 67. The inner member 63 has a flange portion 69 that fits into the circumferential groove 65 and a lock arm 70 that engages with the panel hole 67a. The wire harness 71 passes through the grommet body 61, the inner member 63, and the panel hole 67a, and is connected to an auxiliary machine or the like inside the panel 67.

  FIG. 6 shows an application in which a conventional linear body penetrating grommet 81 is disposed between a back door panel 82 and a vehicle body panel 83 of an automobile and power is supplied from the vehicle body side to an auxiliary machine on the back door side. An example is given.

  The grommet 81 includes approximately four mountain bellows portions 84 and fixing portions 85 and 86 that are integrally connected to both ends of the bellows portion 84. The fixing portions 85 and 86 at both ends of the grommet 81 or the inner members (not shown) in the fixing portions are locked in the holes of the panels 82 and 83, and for example, as shown in FIG. In this state, the wire harness 87 is inserted (penetrated) from the hole of the vehicle body panel 83 through the grommet 81 to the hole of the back door panel 82.

JP-A-10-191536 (FIG. 9) JP 2008-218110 A (FIG. 4)

  However, in the conventional linear body penetrating grommet, for example, the number of the bellows portions 84 is small as in the example of FIG. 6, and after fixing the grommet 81 to both panels 82 and 83, the wire harness 87 is In the case of passing from one panel hole to the other panel hole through the grommet 81, the bellows portion 84 of the grommet 81 is bent when the back door 82 is opened or closed (when the back door is rotated). Since the bellows portion 84 protrudes radially inward (inside the harness insertion space) on the bent inner side, the harness insertion space in the grommet is narrowed, and there is a problem that the workability of the wire harness 87 is lowered.

  Further, after the grommet 81 is mounted between the panels 82 and 83, the wire harness 87 is passed through the grommet 81, or after the wire harness 87 is passed through the grommet in advance, When the fixing portions 85 and 86 of the grommet 81 are locked to the panel holes by penetrating from the panel hole to the other panel hole, the grommet 81 is arranged between the two panels, and the wire harness 87 is connected to each panel hole. In the case of passing through the panel hole and the grommet 81, when the back door 82 is opened and closed, the bellows portion 84 bends, and the bellows portion 84 protrudes inward particularly inside the bend to interfere with the wire harness 87, The smooth bending operation of the grommet 81 is not performed, and the wire harness 87 and the grommet 81 are worn. There was a concern that doubles as occur.

  These problems and concerns apply not only to the back door 82 but also to the case where a linear body 87 such as a wire harness is routed from a fixed structure such as a vehicle body to a rotating body such as a front door, trunk or bonnet. Can occur.

  In view of the above points, the present invention provides a grommet disposed between a rotating body such as a back door and a fixed structure body such as a vehicle body. An object of the present invention is to provide a grommet for penetrating a linear body that prevents interference with the linear body, improves the workability of penetrating the linear body, and allows the bellows part to bend smoothly.

  In order to achieve the above object, a grommet for penetrating a linear body according to claim 1 of the present invention has an intermediate bellows part that penetrates the linear body and fixing parts at both ends, and the fixing parts are each panel. In the grommet for penetrating a linear body that is fixed to the hole part of the linear body, and the bellows part bends as one of the panels rotates, the axially intermediate part of the bellows part has another part than the other part of the bellows part. A projecting portion having a mountain-shaped longitudinal section that protrudes greatly outward in the radial direction is formed, and when the bellows portion is bent, the portion that is the bent inner side of the protruding portion protrudes radially outward while being compressed in the axial direction. Features.

  With the above configuration, for example, when one panel is a door panel and the other panel is a vehicle body panel, when the bellows is bent as the door is opened and closed (the door panel rotates), By projecting radially outward while being compressed in the axial direction (grommet longitudinal direction) on the inner side of the bend, a wide space for inserting the linear body in the grommet is secured, and harmful deformation such as bending of the projecting portion is prevented. In addition, interference with the linear body is prevented, and the bellows portion can be smoothly bent. The bellows portion may have a small-diameter crest as another portion in addition to the protruding portion, or may have a flat peripheral wall instead of the small-diameter crest.

  A linear body penetrating grommet according to claim 2 is the longitudinal cross section of the linear body penetrating grommet according to claim 1, wherein a portion that is outside the bent portion of the projecting portion is extended in the axial direction when the bellows portion is bent. It is characterized by bending in a U-shape.

  With the above configuration, when the bellows portion is bent, the bent outer portion of the protruding portion does not bend or protrude inward, and the bellows portion is smoothly bent in the longitudinal direction in the shape of a square cross section so that the bellows portion can be bent smoothly. .

  The linear body penetrating grommet according to claim 3 is the linear body penetrating grommet according to claim 1 or 2, wherein the bellows part continues at least between the projecting part in the middle and both axial sides of the projecting part. It is characterized by comprising one small-diameter ridge.

  With the above configuration, as one panel rotates, one fixed part that follows one panel rotates, and one small-diameter peak that follows one fixed part bends in the rotating direction. The large-diameter projection that follows the peak bends. The protruding portion is sandwiched between the ridges on both sides on the bent inner side and maintains a state of protruding outward. Thereby, the inward bending and protrusion of the protrusion are reliably prevented.

  The linear body penetrating grommet according to claim 4 is the linear body penetrating grommet according to any one of claims 1 to 3, wherein the bellows portion and the fixing portion are formed in an oblong cross section. It is characterized by.

  With the above configuration, the bending direction of the bellows portion is regulated in the short direction in the cross section, and the protruding portions on both sides in the short direction become the bent inner portion and the bent outer portion. A plurality of wire harnesses and a plurality of types of linear bodies including the wire harness can be inserted in the longitudinal direction in the cross section of the bellows portion. In the cross section of the protrusion, the end in the longitudinal direction may be the same as the shape of the protrusion in the short direction, or may have a smaller diameter than the protrusion in the short direction.

  According to the first aspect of the present invention, since the bent inner portion of the protruding portion protrudes radially outward when the bellows portion is bent, the space inside the bellows portion is widely secured, so the bellows portion is bent. In this state, a linear body such as a wire harness can be smoothly inserted into the bellows part, and the penetration workability of the linear body is improved. Further, since the protruding portion does not bend inward, the bellows portion can be smoothly bent with a small force, and interference with the linear body can be prevented. For example, the back door panel of an automobile is repeatedly opened and closed. Will not damage the bellows or the linear body, improve the waterproof and dustproof reliability of the panel holes and the reliability of power supply etc. by the linear body, and smoothly open and close the back door panel without catching Can be made.

  According to the invention described in claim 2, when the bellows portion is bent, the bent outer portion of the protruding portion is bent in a vertical cross-sectional shape while protruding outward in the radial direction, thereby ensuring a large space inside the bellows portion. Therefore, a linear body such as a wire harness can be smoothly inserted into the bellows part in a state where the bellows part is bent, and the penetration workability of the linear body is improved. Further, since the protruding portion does not bend inward, the bellows portion can be smoothly bent with a small force, and interference with the linear body can be prevented. For example, the back door panel of an automobile is repeatedly opened and closed. As a result, the bellows part is not damaged, and the reliability of the waterproof and dustproofing of the panel hole and the reliability of power feeding by the linear body can be improved, and the back door panel can be opened and closed smoothly without being caught. .

  According to the invention described in claim 3, when the bellows portion is bent, the large-diameter protruding portion is sandwiched between the small-diameter ridges on both sides in the axial direction on the inner side of the bending, and maintained in a state protruding outward. The effect of the invention of item 1 is promoted.

  According to the invention of claim 4, when the horizontally long bellows portion is bent, the horizontally long protrusion portions uniformly protrude radially outward over the entire length in the horizontal direction, so that a plurality of types of lines to the horizontally long bellows portion can be obtained. It is possible to penetrate the rod-like body with good workability, and it is possible to prevent damage caused by repeated bending of the horizontally long bellows portion and interference with each linear body.

It is a longitudinal cross-sectional view which shows one Embodiment of the grommet for linear body penetration which concerns on this invention. It is a bottom view top view which similarly shows a grommet (the AA cross section of FIG. 2 is FIG. 1). It is a longitudinal cross-sectional view which similarly shows the bending state of a grommet. It is a longitudinal cross-sectional view which shows one form of the conventional grommet for linear body penetration. It is a longitudinal cross-sectional view which shows the other form of the conventional grommet for linear body penetration. It is a perspective view which shows the other form of the conventional grommet for linear body penetration.

  1 to 3 show an embodiment of a linear body penetrating grommet according to the present invention.

  As shown in FIG. 1, the linear body penetrating grommet 1 has an upper and lower fixed portions 2 and 3 and an intermediate short bellows portion 4 connecting the fixed portions 2 and 3 in a free state. The central portion in the axial direction of the portion 4 protrudes greatly outward, and the protruding portion 5 protrudes outward while being compressed in the axial direction when the grommet 1 in FIG. 3 is bent. ) 8 (FIG. 3) insertion space 9 is widely secured.

  The grommet 1 is formed in a horizontally long shape as shown in FIG. 2 (bottom view), and has an oblong (flat) harness insertion space 9. 1 is a cross-sectional view taken along line AA in FIG. The left and right end portions 10 of the grommet 1 are formed in a semicircular shape, and the front and rear wall portions 11 are formed in parallel.

  As shown in FIG. 1, the grommet 1 of this example includes an elastic grommet main body 12 made of synthetic rubber, and a hard inner member 13 made of synthetic resin that is fitted to and fixed to the fixing portions 2 and 3 at both ends of the grommet main body 12. (The lower inner member is not shown). The inner member 13 is for fixing the fixing portions 2 and 3 to the hole portions 14a and 15a of the panels 14 and 15, and the fixing portion (2, 3) itself is the panel as in the conventional example of FIG. It is not necessary when fitting into the holes 14a, 15a.

  A fixing portion 2 on one side (upper side) of the grommet main body 12 in FIG. 1 is tapered from an annular circumferential wall 17 having a substantially U-shaped longitudinal section having a circumferential groove 16 on the inner side and a horizontal upper wall portion 17 a of the circumferential wall 17. And an annular lip 18 projecting diagonally upward. The inner end of the horizontal lower wall portion 17 b of the peripheral wall 17 continues to the valley portion 19 at the upper end of the bellows portion 4. Since the other (lower) annular portion 3 has the same configuration (vertical symmetry) as the one annular portion 2, description thereof is omitted.

  The vertical side wall portion 17 c of the peripheral wall 17 is located slightly outside the tip end of the lip 18 in the radial direction. The crest portion 6 at the upper end of the bellows portion 4 is located radially inward of the side wall portion 17 c along the lower wall portion 17 b of the peripheral wall 17 (the crest portion 6 at the upper end is about half the protruding length of the peripheral wall 17. Projecting outward in length).

  A horizontal flange 21 of the inner member 13 is fitted in an annular circumferential groove 16 in the peripheral wall 17. The inner member 13 includes an annular flange 21, a vertical peripheral wall 22 raised from the flange 21, and a locking projection 23 provided on the outer surface of the peripheral wall 22. The flange portion 21 has a die-cutting hole for forming the protrusion 23. The inner member 13 is formed horizontally long like the grommet body 12 of FIG. The protrusion 23 is located radially inward of the lip 18 and slightly protrudes above the lip 18. The position and number of the protrusions 23 are appropriately set, but are preferably provided on the front, rear, left and right.

  The protruding wall 24 of the grommet body 12 is provided on the radially inner side of the protrusion 23 adjacent to the right and left of the protrusion 23, and the wire harness (linear body) 8 (FIG. 3) faces upward along the inner surface of the protruding wall 24. Derived. The lower inclined surface (locking surface) of the protrusion 23 engages with the hole portion 14a of the back door panel 14, and at the same time, the lip 23 is compressed and bent to elastically adhere to the surface of the panel 14.

  As described above, when the inner member 13 is excluded and the fixing portions (2, 3) of the grommet body 12 (in this case simply referred to as grommet) are fitted into the panel holes, the conventional example of FIG. Similarly, for example, the peripheral wall 16 is eliminated to eliminate the peripheral groove 16 inside the peripheral wall 17, and a horizontal peripheral wall (not shown) for engaging the peripheral edge of the panel hole 14 a with the side wall portion 17 c of the peripheral wall 17 is provided. The lip (23) is formed in the circumferential groove. This is the same in the upper and lower fixing portions 2 and 3.

  As shown in FIG. 1, the bellows portion 4 of the grommet body 12 includes a small-diameter ridge portion 6 at the upper end, a large-diameter ridge portion (projecting portion) 5 at the middle (center in the height direction), and a small-diameter ridge portion 7 at the lower end. It consists of and. The diameters of the upper and lower peaks 6 and 7 are the same. The intermediate peak 5 continues integrally with the adjacent peaks 6, 7 through valleys 19, 20, that is, through the folded portion on the skirt side of the peak 5. The upper and lower peak portions 6 and 7 continue to intersect the lower wall portion 17b or the upper wall portion of each peripheral wall 17 at upper and lower valley portions 19 'and 20'.

  The outer diameter of the intermediate peak part (projection part) 5 is larger than the outer diameter of the peripheral wall 17 of the fixed parts 2 and 3, for example, the dimension obtained by adding the protrusion height of the upper and lower peak parts 6 and 7 to the outer diameter of the peripheral wall 17. Slightly smaller than. The outer diameter of the protrusion 23 of the inner member 13 is substantially equal to the outer diameter of the upper and lower peaks 6, 7. An inner diameter of the peripheral wall 22 of the inner member 13 is approximately the same as the inner diameter of the valley portions 19 and 20. The inner diameters of the valleys 19 and 20 are equal.

  The vertical width of the middle peak 5 is approximately twice as large as the vertical width of the upper peaks 6 and 7. Conventionally, two small peaks similar to the upper and lower peaks 6 and 7 are arranged in parallel instead of the middle peak 5. The upper inclined wall 25 and the lower inclined wall 26 of the middle peak 5 are inclined at the same angle, forming an isosceles triangle shape in the longitudinal section, and the inclination angles of the upper and lower inclined walls 25 and 26 are vertical. It is steeper than the inclination angle of each inclined wall above and below the peak portions 6 and 7. The tip portions of the peaks 5 to 7 and the valleys 19 and 20 are bent in a circular arc shape. The plate | board thickness of the bellows part 4 is the same in each peak part 5-7 and the trough parts 19 and 20. FIG.

  As shown in FIG. 2 (showing the lower surface of the grommet main body 12), the grommet main body 12 is oblong with a flat shape in the front-rear direction and a longitudinal direction in the left-right direction. It continues in a ring. In the left and right semicircular end portions 10, the protruding height of the intermediate peak portion 5 can be the same as the height of the upper and lower peak portions 6 and 7. This is because the grommet body 12 bends only in the front-rear direction as the back door is opened and closed.

  As shown in FIG. 3, the grommet main body 12 bends in the front-rear direction (forward or rearward), that is, in the short direction as the back door is opened and closed (opened or closed), and the bent inner side of the bellows portion 4 (the left portion in FIG. 3) ), The peak portion 5 in the middle of the bellows portion 4 is compressed in the axial direction, and the upper and lower inclined walls (wall portions) 25 and 26 are overlapped with each other and project outward in the radial direction in a flat shape. In this example, the intermediate peak 5 is inclined slightly downward from the horizontal, and the inclination direction is directed to the intersection of the virtual extension lines of the upper and lower panels 14 and 15.

  The base end on the trough side of the upper wall portion 25 of the intermediate peak portion 5 is folded back and continues to the lower inclined wall 6a of the upper peak portion 6, and the upper wall portion 25 is connected to the lower inclined wall 6a. Similarly, the base end on the valley side of the lower wall portion 26 of the intermediate peak portion 5 is folded back and continues to the inclined wall 7a on the upper side of the lower peak portion 7 in the same manner. The side wall portion 26 overlaps with (in contact with) the upper inclined wall 7a.

  The tip of the intermediate peak portion 5 protrudes radially outward from the peripheral wall 17 of the lower fixing portion 3, and protrudes largely radially outward to substantially the same extent as the peripheral wall 17 of the upper fixing portion 2. Since the intermediate peak 5 protrudes radially outward while being compressed in the axial direction, the upper and lower peaks 6, 7 are also positioned slightly protruding in the radial direction while being slightly compressed according to the intermediate peak 5. Protrusion of the portions 5 to 7 inward in the radial direction is prevented. Further, the intermediate peak portion 5 is sandwiched between the upper and lower peak portions 6 and 7 and is maintained in a state of protruding radially outward.

  As a result, a large through space 9 for the linear body 8 such as a wire harness is secured in the grommet body 12, and the penetration workability of the linear body 8 is enhanced. In addition, each of the peak portions 5 to 8 is smoothly compressed with a beautiful shape without bending, and the inner linear body 8 and the peak portions 5 to 8 do not interfere with each other, so that the grommet body 12 is opened and closed when the back door is opened and closed. The bending of the grommet body 12 due to repeated bending is prevented, and the wear of the linear body 18 due to interference is prevented.

  On the outer side of the bent portion of the bellows portion 4 (the portion on the right side in FIG. 3), the intermediate peak portion 5 is stretched in the axial direction in the shape of a vertical cross section, and the intermediate peak portion 5 inside the bent portion is the starting point. The longitudinal section is widened in the axial direction in a substantially fan shape. The lower inclined wall 26 is inclined with a steep slope slightly outward from the vertical, and the upper inclined wall 25 is inclined in the direction opposite to the inclination direction of the lower inclined wall 26. The upper and lower inclined walls 25, 26 smoothly follow the upper and lower mountain parts 6, 7 without bending. The upper and lower ridges 6 and 7 are maintained in a state of being slightly pulled in the axial direction and protruding outward in the radial direction without being bent.

  Since the peak portions 5 to 7 do not enter or bend radially inside the bellows portion 4 as well, the linear body 8 such as a wire harness is formed in the grommet body 12 in the same manner as the inside of the bend. A large penetration space 9 is secured, the workability of penetrating the linear body 8 is enhanced, the grommet body 12 is smoothly bent when the door is opened and closed, and the interference with the linear body 8 is prevented. Wear and damage of the grommet body 12 due to bending, wear of the linear body 8 due to interference, and the like are prevented.

  In the above-described embodiment, the bellows portion 4 is configured by the three peak portions 5 to 7 including the upper and lower small peak portions 6 and 7 and the intermediate large peak portion 5. For example, the number of upper and lower small ridges 6 and 7 may be two or more. Further, it is preferable that the position of the intermediate large-diameter ridge portion 5 is in the middle (center) in the longitudinal (axial) direction of the grommet body 12, but for example, two small ridge portions 6 on the upper side are formed, It is also possible to form one small ridge 7 on the lower side via the large ridge 5. In those cases, the total length of the grommet body 12 is longer than the example of FIG.

  Further, if the fixed portions 2 and 3 do not interfere with each other at the time of bending, the large-diameter ridge portion 5 is directly connected to either one of the fixed portions 2, and one or more small-diameter ridge portions 7 are connected to the large-diameter ridge portion 5. It is also possible to make the other fixing part 3 continuous via Further, the bellows portion 4 is formed as a flat cylindrical peripheral wall portion (not shown) by removing the upper and lower small-diameter ridge portions 6 and 7, and the intermediate large-diameter ridge portion 5 is continued to the flat peripheral wall portion. (The bellows portion 4 may be constituted by one large crest portion 5 and a flat peripheral wall portion).

  In the above embodiment, as shown in FIG. 2, the intermediate peak portion 5 is formed on the considerably long grommet body 12. For example, the lateral length of the grommet body 12 is shortened to about half that of the example of FIG. 2. It is also possible to do. Since the grommet 1 in the example of FIG. 2 is horizontally long, different types of wire harnesses (a plurality of electric wires), a washer hose for a back door wiper, an antenna cable, and the like can be inserted and routed at the same time.

  Further, as described above, the inner member 13 is for improving the workability and reliability of the locking of the grommet in the panel hole, so there is no direct relationship with the present invention, and the inner member 13 is excluded. It is also possible to form a grommet with only the grommet body 12 and fit and lock the fixing portions (2, 3) of the grommet into the panel holes. In the claims, the fixing part of the grommet includes the fixing part (2, 3) of the grommet body 12 or the inner member 13.

  Moreover, in the said embodiment, although the shape of the upper and lower fixing parts 2 and 3 of the grommet main body 12 was made the same, the upper and lower fixing parts 2 and 3 are made into a different shape, or the inner member 13 is provided only in one fixing part 2. It is also possible to use.

  Moreover, in the said embodiment, although the example which arrange | positions the grommet 1 standing upright substantially vertically between the back door panel 14 and the vehicle body panel 15 of a motor vehicle was demonstrated, for example, the front door panel of a motor vehicle, a vehicle body panel, When it arrange | positions between, the grommet 1 is leveled and arrange | positioned in the front-back direction.

  Further, the present invention is effective not only as the linear body penetrating grommet 1 but also as a linear body penetrating grommet mounting structure, bending structure, or the like.

  The grommet for penetrating a linear body according to the present invention supplies power and signals from a vehicle body (fixed structure) side to a rotating body such as a back door, front door, trunk, bonnet, etc. It can be used for communication or the like.

1 Grommet for penetrating linear object 2,3 Fixed part 4 Bellows part 5 Large diameter peak part (protrusion part)
6,7 Small-diameter peak 8 Linear body 14,15 Panel 14a, 15a Hole

Claims (4)

  It has an intermediate bellows part that penetrates the linear body, and fixed parts at both ends. The fixed part is fixed to the hole of each panel, and the bellows part bends as one of the panels rotates. In the grommet for penetrating a linear body, a projecting portion having a mountain-shaped vertical section that protrudes more radially outward than the other portions of the bellows portion is formed at an axially intermediate portion of the bellows portion. A linear body penetrating grommet characterized in that, when bent, a portion on the bent inner side of the protruding portion protrudes radially outward while being compressed in the axial direction.   2. The linear body penetrating grommet according to claim 1, wherein when the bellows portion is bent, a portion that is the outer side of the protruding portion is bent in a longitudinal cross-section while being elongated in the axial direction.   The linear body penetration according to claim 1 or 2, wherein said bellows part is constituted by said intermediate projecting part and at least one small-diameter ridge part continuing on both axial sides of said projecting part. Grommet for.   The linear body penetrating grommet according to any one of claims 1 to 3, wherein the bellows part and the fixing part are formed in an oblong cross section.

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