Self-tightening type anti-loosening thread fastening kit

Abstract

The utility model discloses a self-tightening type anti-loosening thread fastening kit which comprises a bolt, a nut and an elastic gasket. A clamping structure is arranged on the end face of the nut. The gasket is formed by punching a plate, a plurality of radial slots are formed in the circumferential surface of the gasket, circumferential slots are formed in at least one of the bottoms of the radial slots, the radial slots and strip-shaped parts separated by the circumferential slots on the corresponding sides form warped pieces, the warped pieces on the corresponding sides are obliquely turned up towards the same surface of the gasket, and the warped pieces on the corresponding sides are rotationally and symmetrically distributed; the bolt is a second bolt free of slotting. The clamping structure is at least one spiral gentle slope surface which is arranged on at least one end surface of the nut and is close to the peripheral edge part; the inner ring surface of the gasket is a complete circular inner ring surface; when the nut is unscrewed, the outer end of at least one warped piece relatively displaces towards the slope top direction of the corresponding gentle slope surface; a limiting protruding ring is arranged on the end face of the nut close to the middle shaft part. The reliability is higher, and the production cost is lower.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of standard parts, and relates to a self-tightening anti-loose threaded fastening kit. BACKGROUND

[0002] Threaded fastening kits are the most important category of standard parts, and are widely used in various fields. There are many series of products of standardized threaded fastening kits, which usually include bolts, nuts and gaskets used in combination.

[0003] Threaded fastening kits using such technology can of course be used normally in conventional application scenarios, but are not suitable for scenarios such as high-speed rail tracks where vibration is large and frequent and high reliability is required, and special designed anti-loose threaded fastening kits must be used. Due to the large amount of use and high requirements, whether it can be used must also consider the manufacturing cost, installation and maintenance cost and reliability under the premise of meeting the hard technical requirements of anti-loose.

[0004] For example, the technical solution disclosed in the Chinese patent application with the application number 202421958985.4 and the name "an anti-loose threaded fastening kit easy to mass-produce" of the applicant's prior application has a structure as shown in Figure 1 、 Figure 2 、 Figure 3 , which includes a bolt 3A, a nut 1A and an elastic gasket. The bolt 3A is provided with a positioning groove 6 in the axial direction. The nut 1A is provided with a plurality of anti-slip teeth 2 symmetrically distributed on at least one end face. The inner ring of the elastic gasket is provided with a positioning block 4 matched with the positioning groove 6. The elastic gasket is a circular ring-shaped special-shaped gasket 5A. At least one radial slit J with a length smaller than the width of the ring part of the gasket 5A is formed on the circumferential surface of the gasket 5A along the radial direction of the gasket. A circumferential slit Z is formed on one side of the circumferential surface of the gasket 5A along the circumferential direction of the gasket 5A from the bottom of the radial slit J as a starting point. The L-shaped slits formed by the radial slit J and the circumferential slit Z are separated into a strip-shaped part, which constitutes an elastic flap K. The elastic flap K is obliquely turned up at an acute angle in the same direction of the gasket 5A. The gasket 5A is formed by one-time stamping of an equal-thickness plate.

[0005] The anti-loose threaded fastening kit using such technology can of course achieve the technical purpose of anti-loose and easy mass production, but has the following disadvantages:

[0006] A, since its anti-loose principle is through the positioning groove 6 on the bolt 3A and the positioning block 4 on the A washer 5A cooperation to prevent the A washer 5A and bolt 3A between the angular displacement, and then through the elastic tab K on the A washer 5A on the nut 1A bottom anti-skid teeth 2, thereby preventing the nut 1A and bolt 3A between the angular displacement, once the elastic tab K and anti-skid teeth 2 between the original card position loose will further exacerbate the loose, because there is no self-tightening function, the nut 1A and bolt 3A between the further loose, the reliability is not high enough;

[0007] B, since the need to open the positioning groove 6 on the bolt 3A, in addition to the production cost is increased, the mechanical strength of the bolt 3A will be affected to a certain extent, also relatively not easy to replace popularization, reliability will be affected to a certain extent;

[0008] In summary, the reliability of the prior art is not high enough, the production cost is relatively high, and the use effect is not ideal. Utility model content

[0009] In order to overcome the deficiencies of the prior art, the utility model provides a self-tightening anti-loose threaded fastening assembly, which is higher in reliability and lower in production cost.

[0010] The utility model discloses a kind of self-tightening anti-loose threaded fastening assembly, including bolt, nut, elastic washer;At least one end surface of nut is equipped with clamping structure;Elastic washer is the round ring shaped gasket that equal-thickness plate piece is punched and formed, multiple radial slits with slit length less than gasket ring part width are opened on the circumference of gasket along the radial direction of the gasket, the slit bottom of radial slit is taken as starting point, and at least one side of the circumference of gasket is opened with circumferential slit, corresponding strip part separated on gasket body by corresponding L-shaped slit formed by radial slit and corresponding side circumferential slit constitutes corresponding side tab, corresponding side tab is obliquely turned up with acute angle to the same face direction of gasket, and corresponding side tab is distributed with gasket center as axis of rotation symmetry;The bolt is the bolt without slot in the axial direction of shank;The clamping structure is at least one end surface of nut, and at least one spiral ramp surface is equipped on the outer circumferential edge portion close to the spiral ramp surface;The inner ring surface of gasket is complete circular inner ring surface;When nut is loosened, the outer end of at least one tab is relatively displaced towards the top of corresponding ramp surface and is further pressed down by the ramp surface;The end surface of nut close to the middle axis is equipped with limiting convex ring higher than all ramp surfaces.

[0011] The nut is the nut, and the outer circumferential edge portion close to the spiral ramp surface is rotationally symmetrical on at least one end surface of the nut, and multiple ramp surfaces are provided, and the terminal top of each ramp surface is integrally connected with the initial bottom of the adjacent ramp surface through a transition steep slope.

[0012] The nut is a propylene nut, and a twisted annular slope surface is arranged on at least one end surface of the propylene nut close to an outer peripheral edge portion.

[0013] The gasket is an ethylene gasket, a plurality of radial slits with a slit length smaller than a ring portion width of the gasket are arranged on a peripheral surface of the ethylene gasket along a radial direction of the gasket, a circumferential slit is arranged on one side of the gasket along a circumferential direction of the gasket from a bottom of the radial slit, a strip portion separated by the L-shaped slit formed by the radial slit and the circumferential slit on the gasket body forms an elastic flap, the elastic flap is obliquely turned up at an acute angle toward the same surface direction of the gasket, and the elastic flaps are rotationally symmetrically distributed about the gasket center.

[0014] The gasket is a propylene gasket, a plurality of radial slits with a slit length smaller than a ring portion width of the gasket are arranged on a peripheral surface of the propylene gasket along a radial direction of the gasket, circumferential slits are arranged on both sides of the gasket along a circumferential direction of the gasket from a bottom of the radial slit, one side is an alpha circumferential slit, and the other side is a beta circumferential slit; a strip portion separated by the L-shaped slit formed by the radial slit and the alpha circumferential slit on the gasket body forms an alpha elastic flap; a strip portion separated by the L-shaped slit formed by the radial slit and the beta circumferential slit on the gasket body forms a beta elastic flap; the alpha elastic flap is obliquely turned up at an acute angle toward one surface direction of the gasket; the beta elastic flap is obliquely turned up at an acute angle toward the other surface direction of the gasket; and the flaps on the corresponding sides are rotationally symmetrically distributed about the gasket center.

[0015] The utility model discloses a beneficial effect is: because adopt above technical scheme, on the structure has a self -force type increase friction force and then prevent further loosening's force feedback mechanism, thereby realize self -tightening type anti -loosening, and the reliability of anti -loosening is higher, and the strength on the reliability is relatively higher, and the production cost is relatively lower, and the use effect is more ideal. BRIEF DESCRIPTION OF DRAWINGS

[0016] The utility model will be further explained in connection with the drawings and examples. Among them:

[0017] Figure 1 It is the schematic diagram of prior art anti -loosening thread fastening kit;

[0018] Figure 2 It is the schematic diagram of prior art alpha gasket 5A part;

[0019] Figure 3 It is the schematic diagram of prior art alpha gasket 5A part another view;

[0020] Figure 4 It is the schematic diagram of the utility model;

[0021] Figure 5is a schematic view of the part of the second nut 1B in the utility model;

[0022] Figure 6 is a schematic view of the part of the third gasket 5C in the utility model;

[0023] Figure 7 is an omitted schematic view of the utility model;

[0024] Figure 8 is a schematic view of the part of the third nut 1C in the utility model;

[0025] Figure 9 is a schematic view of the part of the second gasket 5B in the utility model;

[0026] Figure 10 is a schematic view of the part of the third gasket 5C in the utility model from another view direction;

[0027] The mark number in the drawing is explained as follows: the first nut 1A, the second nut 1B, the third nut 1C, the anti-skid tooth 2, the first bolt 3A, the second bolt 3B, the positioning block 4, the first gasket 5A, the second gasket 5B, the third gasket 5C, the positioning groove 6, the limiting convex ring 7, the elastic flaps K, the first elastic flap K1, the second elastic flap K2, the radial slit J, the circumferential slit Z, the first circumferential slit Z1, the second circumferential slit Z2, the gentle slope surface P, the steep slope surface T DETAILED DESCRIPTION

[0028] The first embodiment of the utility model is shown as follows, Figure 4 、 Figure 5 、 Figure 7 、 Figure 9 A self-tightening type anti-loose threaded fastening kit, comprising a bolt, a nut and an elastic gasket, at least one end face of the nut is provided with a clamping structure, the elastic gasket is a round ring shaped special-shaped gasket punched and formed by an equal-thickness plate, a plurality of radial slits J with a slit length less than the width of the gasket ring part are formed on the circumferential surface of the gasket along the radial direction of the gasket, a circumferential slit Z is formed along at least one side of the gasket circumferential surface from the bottom of the radial slit J as a starting point, the corresponding L-shaped slit formed by the radial slit J and the corresponding circumferential slit Z on the gasket body is divided into a corresponding strip-shaped part, and the corresponding flaps on the corresponding side are obliquely turned up at an acute angle towards the same face direction of the gasket, and the corresponding flaps on the corresponding side are rotationally symmetrically distributed with the gasket center as an axis; the bolt is a second bolt 3B with an axially free slot; the clamping structure is a disc spiral gentle slope surface P provided on at least one end face of the nut close to the outer circumferential edge; the inner ring surface of the gasket is a complete circular inner ring surface; when the nut is loosened, the outer end of at least one flap is relatively displaced towards the top of the corresponding gentle slope surface P and is further pressed down by the gentle slope surface P; the end face of the nut close to the central axis is provided with a limiting convex ring 7 higher than all the slope surfaces.

[0029] The nut is a nut 1B, and a plurality of gentle slope surfaces P are rotationally symmetrically arranged on at least one end surface of the nut 1B close to an outer peripheral edge portion.

[0030] The gasket is a gasket 5B, a plurality of radial slits J with a slit length smaller than a gasket ring portion width are formed on a peripheral surface of the gasket 5B along a radial direction of the gasket, a circumferential slit Z is formed on one side of the gasket along a circumferential direction of the gasket from a slit bottom of the radial slit J as a starting point, and corresponding L-shaped slits formed by the radial slit J and the circumferential slit Z on the corresponding side form corresponding strip portions separated on a gasket body, and the corresponding strip portions form elastic flaps K, the elastic flaps K are obliquely turned up at an acute angle in the same surface direction of the gasket, and the elastic flaps K are rotationally symmetrically distributed around a gasket center.

[0031] The second embodiment of the utility model, such as Figure 5 、 Figure 6 、 Figure 10 And reference Figure 4 、 Figure 7 , a self-tightening anti-loose threaded fastening kit, comprising a bolt, a nut, an elastic gasket, at least one end surface of the nut is provided with a clamping structure, the elastic gasket is a round ring-shaped special-shaped gasket punched and formed by an equal-thickness plate, a plurality of radial slits J with a slit length smaller than a gasket ring portion width are formed on a peripheral surface of the gasket along a radial direction of the gasket, a circumferential slit Z is formed on at least one side of the gasket along a circumferential direction of the gasket from a slit bottom of the radial slit J as a starting point, corresponding L-shaped slits formed by the radial slit J and the circumferential slit Z on the corresponding side form corresponding strip portions separated on a gasket body, and the corresponding strip portions form flaps on the corresponding side, the flaps on the corresponding side are obliquely turned up at an acute angle in the same surface direction of the gasket, and the flaps on the corresponding side are rotationally symmetrically distributed around a gasket center, the bolt is a shaft-axial slot-free nut 3B, the clamping structure is at least one spiral gentle slope surface P arranged on an end surface of the nut close to an outer peripheral edge portion, an inner ring surface of the gasket is a complete circular inner ring surface, when the nut is loosened, an outer end of at least one flap is relatively displaced towards a slope top direction of the corresponding gentle slope surface P and is further pressed down by the gentle slope surface P, and an end surface of the nut close to a central shaft portion is provided with a limiting convex ring 7 higher than all slope surfaces.

[0032] The nut is a nut 1B, and a plurality of gentle slope surfaces P are rotationally symmetrically arranged on at least one end surface of the nut 1B close to an outer peripheral edge portion.

[0033] The gasket is a propeller gasket 5C, a plurality of radial slits J with a slit length less than the width of the gasket ring part are formed on the circumferential surface of the propeller gasket 5C along the radial direction of the gasket, a circumferential slit Z is formed on at least one side of the gasket along the circumferential direction of the gasket from the bottom of the radial slit J, one side is an alpha circumferential slit Z1, and the other side is a beta circumferential slit Z2; the L-shaped slit formed by the radial slit J and the alpha circumferential slit Z1 separates a strip part on the gasket body to form an alpha elastic flap K1; the L-shaped slit formed by the radial slit J and the beta circumferential slit Z2 separates a strip part on the gasket body to form a beta elastic flap K2; the alpha elastic flap K1 is obliquely turned up at an acute angle towards one side of the gasket; the beta elastic flap K2 is obliquely turned up at an acute angle towards the other side of the gasket; and the flaps on the corresponding sides are distributed in rotational symmetry with the center of the gasket as the axis.

[0034] A third embodiment of the utility model is shown in Figure 8 、 Figure 9 A self-tightening anti-loose threaded fastening kit, including a bolt, a nut, and an elastic gasket, at least one end surface of the nut is provided with a clamping structure, the elastic gasket is an equal-thickness plate stamping formed annular special-shaped gasket, a plurality of radial slits J with a slit length less than the width of the gasket ring part are formed on the circumferential surface of the gasket along the radial direction of the gasket, a circumferential slit Z is formed on at least one side of the gasket along the circumferential direction of the gasket from the bottom of the radial slit J, the corresponding strip part separated on the gasket body by the corresponding L-shaped slit formed by the radial slit J and the circumferential slit Z on the corresponding side forms the flap on the corresponding side, the flaps on the corresponding sides are obliquely turned up at an acute angle towards the same side of the gasket, and the flaps on the corresponding sides are distributed in rotational symmetry with the center of the gasket as the axis, the bolt is a shaft-axial non-slotted beta bolt 3B, the clamping structure is at least one spiral ramp surface P provided on the end surface of the nut close to the outer circumferential edge, the inner ring surface of the gasket is a complete circular inner ring surface, when the nut is loosened, the outer end of at least one flap is relatively displaced towards the top of the corresponding ramp surface P and is further pressed down by the ramp surface P, and the end surface of the nut close to the middle shaft part is provided with a limiting convex ring 7 higher than all the ramp surfaces.

[0035] The nut is a propeller nut 1C, at least one end surface of the propeller nut 1C is provided with a twisted annular ramp surface P close to the outer circumferential edge, and the ramp surface of the annular ramp surface P is half a circle raised and half a circle lowered and closed at the head and tail.

[0036] The gasket is gasket 5B, a plurality of radial slits J with slit length less than the width of the gasket ring are formed on the circumference of gasket 5B along the radial direction of the gasket, a circumferential slit Z is formed along one side of the circumference of the gasket from the bottom of the radial slit J, the corresponding L-shaped slit formed by the radial slit J and the circumferential slit Z forms a corresponding strip on the gasket body, and the corresponding strip forms an elastic flap K, the elastic flap K is obliquely turned up at an acute angle in the same direction of the gasket, and the elastic flap K is rotationally symmetrically distributed about the center of the gasket.

[0037] The fourth embodiment of the utility model, as shown in Figure 6 、 Figure 8 、 Figure 10 A self-tightening anti-loose threaded fastening kit, comprising a bolt, a nut and an elastic gasket, at least one end face of the nut is provided with a clamping structure, the elastic gasket is an equal-thickness plate-shaped punched annular special-shaped gasket, a plurality of radial slits J with slit length less than the width of the gasket ring are formed on the circumference of the gasket along the radial direction of the gasket, a circumferential slit Z is formed along at least one side of the circumference of the gasket from the bottom of the radial slit J, the corresponding L-shaped slit formed by the radial slit J and the circumferential slit Z on the corresponding side forms a corresponding strip on the gasket body, the corresponding flap on the corresponding side is obliquely turned up at an acute angle in the same direction of the gasket, and the corresponding flap on the corresponding side is rotationally symmetrically distributed about the center of the gasket, the bolt is a shaft-axially-unslotted bolt 3B, the clamping structure is at least one spiral ramp surface P provided on the end face of the nut close to the outer circumferential edge, the inner annular surface of the gasket is a complete circular inner annular surface, when the nut is loosened, the outer end of at least one flap is relatively displaced toward the top of the corresponding ramp surface P and is further pressed down by the ramp surface P, and the end face of the nut close to the middle shaft is provided with a limiting convex ring 7 higher than all the ramp surfaces.

[0038] The nut is nut 1C, at least one ramp surface P close to the outer circumferential edge is provided on at least one end face of nut 1C, the ramp surface of the annular ramp surface P is half a circle raised and half a circle lowered and closed at the head and tail.

[0039] The gasket is a propylene gasket 5C, a plurality of radial slits J with a slit length smaller than the width of the gasket ring are formed on the circumferential surface of the propylene gasket 5C along the radial direction of the gasket, a circumferential slit Z is formed on the circumferential surface of the gasket from the bottom of the radial slit J to one side, and a circumferential slit Z is formed on the circumferential surface of the gasket from the bottom of the radial slit J to the other side; the L-shaped slit formed by the radial slit J and the circumferential slit Z1 on one side forms a strip-shaped part separated on the gasket body, and the strip-shaped part forms an elastic flap K1; the L-shaped slit formed by the radial slit J and the circumferential slit Z2 on the other side forms a strip-shaped part separated on the gasket body, and the strip-shaped part forms an elastic flap K2; the elastic flap K1 on one side is obliquely turned up at an acute angle towards one side of the gasket; the elastic flap K2 on the other side is obliquely turned up at an acute angle towards the other side of the gasket; and the flaps on the corresponding sides are respectively distributed in rotational symmetry with the center of the gasket as the axis.

[0040] Further description of the utility model:

[0041] A, the action principle of the self-tightening anti-loosening device is as follows: when the utility model is applied, the whole surface of the bottom surface of the gasket is pressed against the circumferential surface of the corresponding hole of a device, the middle part of the top surface of the gasket is pressed against the limiting convex ring 7 on the bottom surface of the nut, but the elastic flap K area of the outer circle of the top surface of the gasket is only elastically pressed against the gentle slope P point line on the bottom surface of the nut, therefore, the pressing area of the bottom surface of the gasket is larger, the friction force received is larger, when loosening occurs, the nut and the gasket will loosen first, therefore, the gasket will not loosen together with the nut at this time. When the nut begins to slightly loosen, at least one elastic flap K (or the elastic flap K1 on one side or the elastic flap K2 on the other side) will be further pressed against the corresponding gentle slope P, the elastic force is increased, the friction force between the nut and the gasket is automatically increased, the further loosening of the nut is prevented, a self-tightening anti-loosening feedback mechanism is formed, and the self-tightening anti-loosening is realized. Once the initial clamping between the elastic flap K and the anti-skid tooth 2 of the traditional anti-loosening structure begins to loosen, the anti-loosening structure will "loosen all at once".

[0042] B, the limiting convex ring 7 is arranged to prevent the elastic flap from losing elasticity due to being pressed too tightly against the nut for a long time, so that the feedback mechanism is invalid, and the pressing distance of the elastic flap on the nut and the gasket is limited.

[0043] C, the nut and the gasket are provided with two arbitrary general embodiments, which are a kind of "fool-proof design" when manually operated, and can simplify the positioning unit mechanism of the automatic installation mechanism when the automatic installation mechanism is used.

[0044] D, the sample of the utility model has been detected by a national authoritative detection department, and is intentionally detected with a higher requirement than the relevant standard, and still achieves the detection result of residual / initial = 98.9% after butter is added.

[0045] E, two kinds of using the ethyl nut 1B embodiment, suitable for the application scene of higher requirement; two kinds of using the prop nut 1C embodiment, then suitable for the application scene of relatively lower requirement.

[0046] F, the terminal end of each gentle slope surface P and the starting slope bottom of the adjacent gentle slope surface P are integrally connected through a transition steep slope surface T, which can be directly adjacent to the slope end, or can be connected through the insertion of a moderate arc surface transition.

[0047] G, since the utility model makes no structural change to the bolt, the utility model is more easily promoted and used.

[0048] H, the utility model can fully utilize the traditional production line to produce, the nut production, because the non-standard clamping structure on the nut needs to be punched out at the same time, the mold needs to be changed accordingly, and the rest of the process is the same as the production process of the traditional nut part; the gasket production uses steel coil plate as raw material and can be continuously produced on the traditional punching production line; when the mold is designed, a combined mold can be used to punch, bend and shape once to form a shape; the produced bolts, nuts and gaskets can be uniformly heat treated in batches.

Claims

1. A self-tightening anti-loosening threaded fastener kit, comprising a bolt, a nut, and an elastic washer; at least one end face of the nut is provided with a locking structure; the elastic washer is a circular annular irregular washer formed by stamping a sheet of equal thickness, and a plurality of radial slits with a slit length less than the width of the annular portion of the washer are formed along the radial direction of the washer on the circumference of the washer; a circumferential slit is formed along at least one side of the circumference of the washer, with the radial slits and the corresponding circumferential slits forming corresponding L-shaped slits on the washer body, which divide the corresponding strip-shaped portions into corresponding side flaps; the corresponding side flaps are tilted at an acute angle towards the same surface of the washer, and the corresponding side flaps are symmetrically distributed about the center of the washer; characterized in that: The bolt is a slotless bolt for the axial direction of the rod body; the clamping structure is that at least one spiral-shaped gentle slope is provided on at least one end face of the nut near the outer periphery; the inner ring surface of the washer is a complete circular inner ring surface; when the nut is loosened, the outer end of at least one pry bar is displaced relative to the top of the corresponding gentle slope and is further pressed down by the gentle slope; the end face of the nut near the central axis is provided with a limiting protrusion higher than all slopes.

2. The self-tightening anti-loosening threaded fastener according to claim 1, characterized in that: The nut is a type B nut, and at least one end face of the B nut has multiple gently sloping surfaces near the outer periphery that are rotationally symmetrically provided. The terminal top of each gently sloping surface is connected to the starting bottom of the adjacent gently sloping surface by a transition steep slope that forms an integral connection.

3. The self-tightening anti-loosening thread fastener according to claim 1, characterized in that: The nut is a C-nut, and at least one end face of the C-nut has a twisted annular gentle slope near the outer periphery. The slope of the annular gentle slope is half a circle rising and half a circle falling and closed at both ends.

4. A self-tightening anti-loosening threaded fastener according to claim 1, 2, or 3, characterized in that: The gasket is a type B gasket. Multiple radial slits with a length less than the width of the gasket's ring are formed along the radial direction of the gasket. A circumferential slit is formed along one side of the gasket's circumference, starting from the bottom of the radial slit. The corresponding L-shaped slits formed by the radial and circumferential slits divide the corresponding strips on the gasket body, forming elastic flaps. The elastic flaps are tilted at an acute angle towards the same side of the gasket, and are distributed symmetrically about the center of the gasket.

5. A self-tightening anti-loosening threaded fastener according to claim 1, 2, or 3, characterized in that: The gasket is a C-type gasket. Multiple radial slits, each shorter than the width of the gasket's circumference, are formed along the circumference of the C-type gasket. Starting from the bottom of each radial slit, circumferential slits are formed on both sides of the gasket's circumference: one is circumferential slit A, and the other is circumferential slit B. The L-shaped slit formed by the radial slits and circumferential slit A creates strip-shaped portions on the gasket body, forming elastic flap A. The L-shaped slit formed by the radial slits and circumferential slit B creates strip-shaped portions on the gasket body, forming elastic flap B. Elastic flap A is angled upwards at an acute angle towards one side of the gasket; elastic flap B is angled upwards at an acute angle towards the other side of the gasket. The flaps on corresponding sides are symmetrically distributed about the center of the gasket.

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