JP6920925B2 - Vibration welding method, vibration welding jig and interior parts for vehicles - Google Patents

Description

The present invention relates to a vibration welding method, a vibration welding jig used in the vibration welding method, and an interior product for a vehicle.

Conventionally, for example, Patent Document 1 discloses synthetic resin parts used for interior parts for vehicles. This synthetic resin part is formed by vibrating welding the first molded body and the second molded body to each other. By the way, at the time of vibration welding, it is inevitable that these molded bodies rub against each other and so-called hair burrs are generated. The synthetic resin component of Patent Document 1 is formed with a guide portion that guides hair burrs so that they do not protrude to the outside of the synthetic resin component.

Japanese Unexamined Patent Publication No. 2016-137682

However, since Patent Document 1 does not suppress the occurrence of hair burrs themselves, if the generated hair burrs are not guided as intended, the hair burrs may protrude to the outside of the synthetic resin part. there were.

By the way, in order to improve the design of the molded product to be vibration-welded, it is required to color-code the molded product into a plurality of colors. At this time, if the coating is performed before the vibration welding, the coated surface must be brought into contact with the vibration welding jig, so that the coating may be peeled off by the vibration at the time of welding. On the other hand, when painting is performed after welding, a large-scale masking equipment is required.

Therefore, as the molded body, for example, it is conceivable to use a molded body that is divided into a plurality of color-coded members and the divided members are joined at the contact portion. However, when the molded body divided into the plurality of members and the other molded body are subjected to vibration welding, a difference in vibration occurs between the plurality of members and the contact portion between the plurality of members rubs in the vibration direction. As a result, hair burrs occur as described above.

The present invention has been made in view of the above points, and an object of the present invention is to divide into a plurality of members and perform vibration welding by devising a vibration welding method, a vibration welding jig, and an interior product for a vehicle. The purpose is to improve the design of vehicle interior parts by suppressing the occurrence of hair burrs during vibration welding in the panel.

In order to achieve the above object, in the present invention, at the time of vibration welding, the portion where the divided members come into contact with each other is deformed to release the contact.

Specifically, the first invention is a vibration welding method for a resin molded product in which a resin outer panel and a resin inner panel are vibrated in a state of being pressed against each other on the back side thereof to be welded and integrated. The outer panel is divided into first and second panel members arranged so as to be adjacent to each other in a direction intersecting the vibration direction at the time of vibration welding, and the first and second panel members are divided into the first and second panel members, respectively. The outer panel is elastically deformed so as to release the contact of the contact portion at the time of vibration welding.

According to the second invention, in the first invention, a fixing portion for fixing the first and second panel members is formed on the back surface of the outer panel at a position different from that of the abutting portion. It is a feature.

In the third invention, in the second invention, in the fixing portion, the intermediate portion of one panel member and the end portion of the other panel member of the first and second panel members are fixed. The contact portion is characterized in that an end portion of one panel member and an intermediate portion of the other panel member are in contact with each other.

According to a fourth aspect of the present invention, in any one of the first to third inventions, the contact portion is provided in a recess recessed toward the inner panel side, and the outer panel is elastically deformed at the corresponding contact portion. This is characterized by releasing the contact of the corresponding contact portion.

A fifth invention is a vibration welding jig used in any one of the first to fourth inventions. The vibration welding jig includes a receiving mold on which the outer panel is mounted, and is vibration welding. Occasionally, the receiving jig presses the contact portion to elastically deform the outer panel, thereby releasing the contact at the contact portion.

According to a sixth aspect of the present invention, in the fifth aspect of the invention, the contact portion is provided in a concave portion recessed toward the inner panel side, and the receiving mold has a convex portion corresponding to the concave portion and said. It is characterized in that the portion of the recess corresponding to the abutting portion is divided with a gap.

A seventh invention is an interior product for a vehicle in which a resin outer panel and a resin inner panel are welded and integrated and fixed to each other on the back side portions of the resin outer panel, and the outer panels are attached to each other in a direction in which the outer panel extends. It is divided into first and second panel members arranged so as to be adjacent to each other, and the first and second panel members are provided with contact portions that are in contact with each other so as to be separable, and are provided on the back surface of the outer panel. Is characterized in that the fixing portion for fixing the first and second panel members to each other is formed at a position different from that of the abutting portion.

In the seventh aspect of the invention, the decorative panel for a vehicle according to the eighth aspect of the invention has, in the seventh invention, the intermediate portion of one panel member and the end portion of the other panel member among the first and second panel members. Is fixed, and the contact portion is characterized in that an end portion of one panel member and an intermediate portion of the other panel member are in contact with each other.

A ninth aspect of the invention is the seventh or eighth aspect of the invention, wherein the outer panel is provided with a recess recessed toward the inner panel side, and the contact portion is formed at the bottom of the recess. It is a feature.

According to the first invention, at the time of vibration welding, the contact between the first panel member and the second panel member is released, and both panel members vibrate in a separated state. As a result, both members do not rub against each other during vibration welding. Therefore, it is possible to suppress the occurrence of hair burrs between the panel members of the outer panel divided into a plurality of members and improve the design of the interior product for the vehicle.

According to the second invention, since the fixed portion is formed at a position different from that of the abutting portion, the abutting portion of the abutting portion is abutted as compared with the case where the fixed portion is formed at the position of the abutting portion. The outer panel is easily elastically deformed so that

According to the third invention, the abutting portion and the fixing portion do not have a complicated structure, and the positions of the fixing portion and the abutting portion can be easily changed.

According to the fourth invention, since the abutting portion is provided in the concave portion, the abutting portion is likely to be elastically deformed in the concave direction. Therefore, it becomes easy to release the contact of the contact portion at the time of vibration welding.

According to the fifth invention, since the receiving mold itself used for vibration welding releases the contact of the contact portion, it is possible to suppress the occurrence of hair burrs during vibration welding without using a special member. can.

According to the sixth invention, since the receiving mold is divided at the portion corresponding to the contact portion to form a gap, the outer panel is deformed along the receiving mold by changing the width of the gap. The pressing force for this can be changed. In addition, the size of the gap generated in the contact portion can be easily adjusted. Therefore, it is possible to release the contact of the contact portion while preventing the surface of the outer panel from being scratched due to the force of pressing the outer panel being too strong.

According to the seventh invention, since the fixed portion is formed at a position different from the contact portion, the contact portion is elastically deformed as compared with the case where the fixed portion is formed at the position of the contact portion. It becomes easier to do. Therefore, when the interior product for a vehicle is formed by vibration welding the outer panel and the inner panel, vibration welding can be easily performed in a state where the contact portion is released from contact. Therefore, it is possible to suppress the occurrence of hair burrs on the outer panel. Further, since the fixing portion is formed on the back surface of the outer panel, the fixing portion is not exposed on the surface of the outer panel, and it is possible to prevent deterioration of the design of the interior product for the vehicle.

According to the eighth invention, the abutting portion and the fixing portion do not have a complicated structure, and the positions of the fixing portion and the abutting portion can be easily changed.

According to the ninth invention, the abutting portion becomes difficult to see from the surface of the outer panel, and it is possible to prevent the design of the vehicle interior product from being deteriorated. Further, when the interior product for a vehicle is formed by vibrating and welding the outer panel and the inner panel, it becomes easy to guide and guide the contact portion by the concave portion to release the contact of the contact portion.

It is a perspective view which shows the glove box as an interior article for a vehicle which concerns on embodiment of this invention. It is a front view which looked at the outer panel from the back side. It is sectional drawing of the part in the glove box where the fixed part is not formed. It is a figure corresponding to FIG. 3 of the part where the fixed part is formed. It is sectional drawing which shows the state which set the outer panel and the inner panel in the vibration welding jig. It is a partially enlarged view which shows the state just before setting the outer panel in a vibration welding jig. It is a figure corresponding to FIG. 6 which shows the state at the time of vibration welding.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of preferred embodiments is merely exemplary and is not intended to limit the present invention, its applications or its uses.

FIG. 1 shows an automobile glove box 1 as an interior component for a vehicle according to an embodiment of the present invention, and the glove box 1 is attached to an instrument panel (not shown) of a vehicle so as to be openable and closable. The glove box 1 includes an outer panel 3 located on the vehicle interior side and exposed to the vehicle interior, an inner panel 5 located on the front side (back side) of the outer panel 3 and housed in the instrument panel in a closed state, and an outer panel 3 It is equipped with a knob 7 attached to the upper part of the. The outer panel 3 and the inner panel 5 are integrated by vibration welding on the back side portions of each.

As shown in FIG. 2, the outer panel 3 is divided into a first panel member 9 and a second panel member 11 arranged so as to be adjacent to each other in the vertical direction.

The first panel member 9 constituting the upper part of the outer panel 3 is a resin-made substantially rectangular plate-shaped member formed by, for example, injection molding or the like. As shown in FIGS. 3 and 4, the first panel member 9 includes a first main body portion 13, a first contact portion 15 as a contact portion, an edge portion 17, and a fixing piece 19. ing.

The first main body portion 13 constitutes most of the first panel member 9 and is provided so as to face the inside of the vehicle interior. A knob mounting portion 8 to which the knob 7 is mounted is formed on the upper portion of the first main body portion. Further, the lower portion of the first main body portion 13 is slightly bent toward the inner panel 5 side in a curved state. The first contact portion 15 is formed by being further bent in the direction of the inner panel 5 from the lower end portion of the slightly bent first main body portion 13, and extends in the direction of the inner panel 5. The end edge portion 17 is formed by being bent downward at a substantially right angle from the end portion of the first contact portion 15 on the inner panel 5 side, and extends downward substantially parallel to the first main body portion 13. A plurality of temporary fixing holes 21 are partially formed in the edge portion 17. Further, as shown in FIG. 4, the fixing piece 19 is partially provided on the edge portion 17, and is bent on the side opposite to the inner panel 5 from the edge portion 17 and then on the second panel member 11. It has a bottomed box shape with a bottom extending along it, and is formed in, for example, two places. The fixing piece 19 and the intermediate portion on the back surface of the second panel member 11 are fixed by, for example, ultrasonic welding.

On the other hand, the second panel member 11 constituting the lower part of the outer panel 3 is a rectangular plate-shaped member made of resin formed by, for example, injection molding, and is colored in a color different from that of the first panel member 9. .. Further, the vertical width of the second panel member 11 is smaller than the vertical width of the first panel member 9. As shown in FIG. 3, the second panel member 11 includes a second main body portion 23 and a second contact portion 25 as a contact portion.

The second main body 23 constitutes most of the second panel member 11 and is provided so as to face the inside of the vehicle interior together with the first main body 13. Further, the upper portion of the second main body portion 23 is slightly bent toward the inner panel 5 side in a curved state. Further, the second contact portion 25 is formed by being further bent in the direction of the inner panel 5 from the upper end portion of the bent second main body portion 23, and extends in the direction of the inner panel 5. That is, the second contact portion 25 is provided at the upper end portion of the second panel member 11. Further, in the second contact portion 25, at the corresponding position of the temporary fixing hole 21 of the first panel member 9, the temporary fixing protrusion that protrudes in the direction of the inner panel 5 and fits and locks into the temporary fixing hole 21. 27 is formed.

A fixing protrusion 29 is formed on the back surface of the second main body 23, which is an upper and lower intermediate portion of the second panel member 11, and the fixing protrusion 29 and the fixing piece 19 formed at the lower end of the first panel member 9 form a fixing protrusion 29. The fixing portion 31 is configured. In the fixing portion 31, the fixing protrusion 29 penetrates through the through hole 20 at the bottom of the fixing piece 19, and the tip portion of the fixing protrusion 29 is integrated with the fixing piece by melting. That is, on the back surface of the outer panel 3, a fixing portion 31 for fixing the first and second panel members 9 and 11 is formed.

Further, the first contact portion 15 corresponding to the upper and lower intermediate portions of the first panel member 9 and the second contact portion 25 corresponding to the upper end portion of the second panel member 11 extend parallel to the direction of the inner panel 5. They are in contact with each other in the state. Further, the contact portions 15 and 25 can be separated from each other by elastic deformation of the first and second panel members 9 and 11. Due to these structures, the fixing portion 31 and the abutting portions 15 and 25 are formed at different positions on the back surface of the outer panel 3. Further, since the lower end portion of the first main body portion 13 and the upper end portion of the second main body portion 23 are respectively bent toward the inner panel 5, the concave portion 33 that is tapered toward the inner panel 5 side due to these curved portions. Is provided, and the contact portions 15 and 25 are located at the bottom thereof.

The inner panel 5 is a resin member formed by, for example, injection molding. The inner panel 5 includes an inner panel main body 35 provided along the outer panel 3 and a box-shaped box portion 37 that opens upward together with the inner panel main body 35.

On the back surface of the inner panel main body 35, a plurality of welding ribs 36 and reinforcing ribs 38 extending toward the outer panel 3 side are formed. The tip of the welded rib 36 is welded and integrated with the back surface of the outer panel 3 by vibration welding. In this way, the inner panel 5 and the outer panel 3 are integrated with each other by welding the welding ribs 36 on the inner panel 5 side. The reinforcing rib 38 is a rib shorter than the welding rib 36 and prevents the inner panel main body 35 from being deformed.

As shown in FIGS. 1 and 3, the box portion 37 includes a bottom portion 39 extending from the lower end portion of the inner panel main body 35, a back surface portion 41 extending upward from the bottom portion 39, and both end portions of the back surface portion 41 in the vehicle width direction. It is provided with a side wall portion 43 extending from the inner panel main body 35 toward the inner panel main body 35. The box portion 37 and the inner panel main body 35 form a box shape that opens upward.

The procedure for manufacturing the glove box 1 having the above configuration will be described below.

First, the first panel member 9, the second panel member 11, and the inner panel 5 are molded by injection molding.

Next, although not shown, after assembling the knob 7 to the knob mounting portion 8 of the first panel member 9, the temporary fixing hole 21 of the first panel member 9 and the temporary fixing projection 27 of the second panel member 11 are attached. Both panel members 9 and 11 are temporarily fixed by fitting them together. In the state where the outer panel 3 is temporarily fixed in this way, the first and second contact portions 15 and 25 come into contact with each other. Then, in a state where the fixing protrusion 29 formed on the back surface of the second main body 23 is inserted through the through hole 20 formed in the fixing piece 19, the fixing protrusion 29 and the fixing piece 19 are superposed by an ultrasonic welding horn. The fixed portion 31 is formed by ultrasonic welding. The outer panel 3 is formed in this way.

Next, as shown in FIG. 5, the inner panel 5 and the outer panel 3 are set on the vibration welding jig 45. The vibration welding jig 45 includes a receiving mold 47 on which the outer panel 3 is placed and a vibration type 49 that presses and vibrates the inner panel 5, and receives the vibration welding type 49 in an raised state. Set the inner panel 5 and the outer panel 3 on the mold 47. Further, as shown in FIG. 6, in the receiving mold 47, the receiving surface is formed to imitate the surface shape of the outer panel 3, and the first receiving tool 51 on which the first panel member 9 of the outer panel 3 is placed is placed. And a second receiver 53 on which the second panel member 11 is placed. Further, a gap S1 is formed between the first and second receivers 51 and 53 corresponding to the first and second contact portions 15 and 25. The upper surface of the end edge portion of the first and second receivers 51 and 53 on the gap S1 side is inclined in a curved shape toward the upper side (seismic type 49 side) toward the gap S1 side. The edge portion forms a convex portion 55 that bulges toward the outer panel 3 side in a tapered shape along the concave portion 33 of the outer panel 3. That is, the receiving mold 47 has a convex portion 55 corresponding to the concave portion 33 of the outer panel, and has a gap S1 in a portion corresponding to both the contact portions 15 and 25 of the concave portion 33, and the first receiving tool 51 and the second receiver 51 and the second. It is divided into a receiver 53.

Then, the vibration type 49 is lowered to receive the inner panel 5 and the outer panel 3 and press them against the type 47. Then, as shown in FIG. 7, the receiving mold 47 conversely presses the outer panel 3 against the inner panel 5. At this time, the tip of the welding rib 36 is in pressure contact with the back surface of the outer panel 3. Further, the convex portion 55 of the receiving mold 47 having the gap S1 enters the concave portion 33 and presses the side surface of the concave portion 33, and the concave portion 33 is expanded to elastic the outer panel 3 so as to follow the shape of the convex portion 55. Transform. As a result, a gap S2 is formed between the contact portions 15 and 25 that have been in contact with each other until then, and the contact between the contact portions 15 and 25 is released.

The width of the gap S1 of the receiving mold 47 can be changed. The width of the gap S1 is such that the contact between the contact portions 15 and 25 is released and the surface of the outer panel 3 is not scratched while the inner panel 5 and the outer panel 3 are pressed against the mold 47. Is set to act on the side surface of the recess 33.

In this state, the vibration type 49 is vibrated in the vehicle width direction (depth direction in FIG. 5) of the glove box 1, so that the outer panel 3 and the inner panel 5 are welded and integrated at the tip of the welding rib 36. At this time, as described above, since the sizes of the first panel member 9 and the second panel member 11 are different, the vibrations of the first panel member 9 and the second panel member 11 are different from each other. For this reason, if the contact portions 15 and 25 are in contact with each other, hair burrs are likely to occur, but as in this embodiment, the contact portions 15 and 25 vibrate in a separated state, so that the hair The generation of burrs is suppressed.

Then, after welding, when the welded and integrated glove box 1 is removed from the vibration welding jig 45, the elastic deformation of the outer panel 3 by the receiving mold 47 disappears, and the contact portions 15 and 25 come into contact with each other again. ..

Therefore, according to the present embodiment, as described above, the contact between the first panel member 9 and the second panel member 11 is released at the time of vibrational vibration welding. As a result, both members do not rub against each other in the vibration direction during vibration welding between the outer panel 3 and the inner panel 5. Therefore, for example, even in the glove box 1 having the outer panel 3 divided into a plurality of panel members 9 and 11 having different colors, it is possible to suppress the occurrence of hair burrs between the panel members 9 and 11, and the design is good. High glove box 1 can be obtained.

Further, since the fixing portion 31 between the first panel member 9 and the second panel member 11 is formed at a position different from the abutting portions 15 and 25, the fixing portion 31 is formed on the abutting portions 15 and 25. Compared with the case where the outer panel 3 is formed at the position, the outer panel 3 is more likely to be elastically deformed so that the contact between the contact portions 15 and 25 is released. Further, in the fixing portion 31, the fixing protrusion 29 formed in the intermediate portion of the second panel member 11 and the fixing piece 19 formed in the lower end portion of the first panel member 9 are fixed, and the second panel member 11 is fixed. The second contact portion 25 provided at the upper end portion of the above and the first contact portion 15 formed in the intermediate portion of the first panel member 9 are in contact with each other. Therefore, the contact portions 15, 25 and the fixing portion 31 do not have a complicated structure, and the positions of the contact portions 15, 25 and the fixing portion 31 can be easily changed.

Further, since the contact portions 15 and 25 are provided at the bottom of the recess 33, the contact portions 15 and 25 are likely to be elastically deformed in the recessed direction. Therefore, it becomes easy to release the contact between the contact portions 15 and 25 at the time of vibration welding.

Further, in the vibration welding jig 45 of the present embodiment, since the receiving mold 47 used for vibration welding releases the contact between the contact portions 15 and 25, the vibration welding does not require a separate special member. It is possible to suppress the occurrence of hair burrs.

Further, in the receiving mold 47, a gap S1 is formed in a portion corresponding to both the contact portions 15 and 25, and the outer panel 3 acts to be deformed along the receiving mold 47 only by changing the width of the gap S1. The pressing force to be applied can be changed. In addition, the size of the gap generated between the abutting portions 15 and 25 can be easily adjusted. Therefore, it is possible to easily set the receiving mold 47 capable of releasing the contact between the contact portions 15 and 25 without damaging the surface of the outer panel 3 because the force for pressing the outer panel 3 is too strong.

Further, according to the outer panel 3 of the present embodiment, since the fixing portion 31 is formed on the back surface of the outer panel 3, the fixing portion 31 is not exposed on the surface of the outer panel 3 to prevent deterioration of the design of the glove box 1. be able to.

Further, since the recess 33 is formed between the first panel member 9 and the second panel member 11 and the contact portions 15 and 25 are formed at the bottom thereof, the contact portions 15 and 15 are formed from the surface of the outer panel 3. 25 becomes difficult to see, and it is possible to prevent deterioration of the design of the glove box 1. Further, at the time of vibration welding between the outer panel 3 and the inner panel 5, the recesses 33 guide and guide the contact portions 15 and 25 to be easily released from the contact.

(Other embodiments)
In the above embodiment, the first panel member 9 and the second panel member 11 are fixed by the fixing portion 31 by ultrasonic welding with an ultrasonic welding horn, but both panel members 9 and 11 are fixed by fastening or the like. You may.

In the above embodiment, the first panel member 9 and the second panel member 11 are colored in different colors, but they may be the same color. In that case, the design of the interior product for the vehicle can be improved by making the pattern or the like different between the first panel member 9 and the second panel member 11.

In the above embodiment, the glove box 1 is mentioned as an interior product for a vehicle, but the present invention is not limited to this. For example, it can be applied to various interior parts for vehicles such as console boxes.

In the present invention, it is useful to obtain a highly designed interior product for a vehicle by suppressing the occurrence of hair burrs during vibration welding in a panel that is vibration-welded divided into a plurality of members.

1 Glove box (vehicle interior)
3 Outer panel 5 Inner panel 9 1st panel member 11 2nd panel member 15 1st contact part (contact part)
25 Second contact part (contact part)
31 Fixed part 33 Concave part 45 Vibration welding jig 47 Receiving type 55 Convex part S1 Gap

Claims (9)

This is a vibration welding method for resin molded products, in which the resin outer panel (3) and the resin inner panel (5) are vibrated while being pressed against each other on the back side of each to be welded and integrated.
The outer panel (3) is divided into first and second panel members (9, 11) arranged so as to be adjacent to each other in a direction intersecting the vibration direction at the time of vibration welding.
The first and second panel members (9, 11) are provided with contact portions (15, 25) that are in contact with each other so as to be separable.
A vibration welding method characterized by elastically deforming the outer panel (3) so as to release the contact of the contact portions (15, 25) at the time of vibration welding. In the vibration welding method according to claim 1,
On the back surface of the outer panel (3), a fixing portion (31) for fixing the first and second panel members (9, 11) to each other is formed at a position different from the contact portion (15, 25). A vibration welding method characterized by being In the vibration welding method according to claim 2,
In the fixing portion (31), of the first and second panel members (9, 11), the intermediate portion of one panel member and the end portion of the other panel member are fixed.
In the contact portion (15, 25), a vibration welding method characterized in that an end portion of one panel member and an intermediate portion of the other panel member are in contact with each other. In the vibration welding method according to any one of claims 1 to 3,
The contact portion (15,25) is provided in a recess (33) recessed toward the inner panel (5) side, and the outer panel (3) is elastically deformed at the corresponding contact portion (15,25). A vibration welding method characterized by releasing the contact of the corresponding contact portion (15, 25). A vibration welding jig used in the vibration welding method according to any one of claims 1 to 4.
The vibration welding jig (45) is provided with a receiving mold (47) on which the outer panel (3) is placed.
At the time of vibration welding, the receiving mold (47) presses the contact portion (15, 25) to elastically deform the outer panel (3), thereby releasing the contact at the contact portion (15, 25). A vibration welding jig characterized by being used. The vibration welding jig according to claim 5.
The contact portion (15, 25) is provided in a recess (33) recessed toward the inner panel (5) side.
The receiving mold (47) has a convex portion (55) corresponding to the concave portion (33), and a gap (S1) is provided in a portion of the concave portion (33) corresponding to the abutting portion (15, 25). A vibration welding jig characterized by being divided by a space. A resin of the outer panel (3) and the inner panel (5) made of resin and has a vehicle interior trim which is fixed by welding integrally with the back sides portions,
The outer panel (3) is divided into first and second panel members (9, 11) arranged so as to be adjacent to each other in the direction in which the outer panel (3) extends.
The first and second panel members (9, 11) are provided with contact portions (15, 25) that are in contact with each other so as to be separable.
On the back surface of the outer panel (3), a fixing portion (31) for fixing the first and second panel members (9, 11) to each other is formed at a position different from that of the contact portion (15, 25). Interior products for vehicles that are characterized by being In the vehicle interior product according to claim 7.
In the fixing portion (31), of the first and second panel members (9, 11), the intermediate portion of one panel member and the end portion of the other panel member are fixed.
The abutting portion (15, 25) is an interior product for a vehicle, characterized in that an end portion of one panel member and an intermediate portion of the other panel member are in contact with each other. In the vehicle interior product according to claim 7 or 8.
The outer panel (3) is provided with a recess (33) that is recessed toward the inner panel (5).
An interior product for a vehicle, characterized in that the contact portion (15, 25) is formed at the bottom of the recess.

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