JP6395321B2 - Grommet - Google Patents

Description

  The present invention relates to a grommet for attaching an article, and more particularly to a grommet used together with a screw member such as a tapping screw.

  FIG. 8 shows a grommet disclosed in Patent Document 1. The grommet 1 is provided on a flange (head) 2 that covers a mounting square hole (mounting hole) 6 a of a substrate 6 that is a member to be mounted, a pair of leg pieces 3 that are provided below the flange, and the flange 2. And the insertion holes 4 for guiding the tapping screw S between the leg pieces, and each leg piece 3 is temporarily fixed by being inserted into the square hole 6a with a displacement in the diameter reducing direction. Further, the grommet 1 is permanently fixed by screwing a tapping screw S into the board 6 between the leg pieces from the through hole and the insertion hole 4 of the mounting member 7. In the fixed state, the mounting member 7 is fixed to the substrate 6 in such a manner that it is sandwiched between the flange 2 and the head of the tapping screw S.

  It should be noted that the grommet 1 includes a metal piece 5 with a screw hole 5a or a hard resin piece provided in the flange 2 to increase the tightening force of the tapping screw S or to maintain the tightening force. It is in the point which enabled it.

Japanese Utility Model Publication No. 60-99313

  In the above-described grommet, the pair of leg pieces are disposed to face each other, and are temporarily fixed by being inserted with a displacement in the reduced diameter direction into the rectangular rectangular hole of the attached member. Each of FIG. 5 to FIG. 7B is a schematic diagram showing the conventional grommet 10 in order to clarify the problems associated with the temporary fixing structure. In each figure, the R processed portion of the outer shape of the leg piece is omitted for easy visual recognition. Each leg piece 30 is disposed on the lower surface of the flange 20 so as to face each other with a gap S therebetween. The outer side surface of each leg piece 30 constitutes the base side and can be engaged with the corresponding inner side surface of the rectangular hole 8a. The lower planar side surface portion 15 is inclined so as to gradually protrude outward as it approaches. Reference numeral k 3 is a boundary between the planar side surface portion 14 and the planar side surface portion 15. The boundary k3 extends most horizontally outward and extends substantially horizontally, and becomes a temporary fixing portion that is most strongly pressed against the corresponding inner side surface of the square hole in the process of inserting the leg piece 30 into the square hole 8a.

  By the way, in the operation of temporarily fixing the grommet 10 to the square hole 8a, the insertion force or the pressing force becomes the highest at the boundary k3 that protrudes most to the outside of the leg piece 30, that is, in the vicinity where the temporary fixing portion passes through the square hole 8a. . Depending on the application, it may be desirable to maintain the designed temporary fixing force and to keep the insertion force and pressing force in the temporary fixing operation somewhat low. This is particularly required when the insertion resistance is high due to the state of the hole edge of the square hole, that is, the burr formed at the hole edge.

  However, in the conventional structure, when the insertion force or the pressing force in the temporary fixing operation is lowered, the temporary fixing force is also reduced in proportion, and the grommet temporarily fixed to the square hole is easily removed. The above-mentioned problems are caused by the cross-sectional L shape (step) between the boundary k3 and the root as well as the shape of the flat side surface portion 14 slightly inclined toward the gap S from the boundary k3 toward the root as shown in FIG. The same is true for the structure formed (see, for example, Japanese Utility Model Publication No. 6-2016).

  The object of the present invention is to eliminate the above-described problems, suppress a decrease in the temporary fixing force, and reduce the insertion force or pressing force into the square hole of the leg piece in the temporary fixing operation. It is to improve the performance. Other purposes will be clarified in the description below.

In order to achieve the above object, the present invention is specified with reference to each of FIGS. 5A to 7A. The flange 2 covers the mounting square hole 8a of the mounted member 8, and the flange is provided below the flange. A pair of leg pieces 3 and an insertion hole 11 formed in the flange 2 for guiding the screw member 6 between the leg pieces, each leg piece 3 being reduced in diameter with respect to the square hole 8a. is temporarily fixed by being inserted with the displacement, is the stop by screwing between the adjacent leg of the screw member 6 from the through-hole 9a and the insertion hole 11 of the mounting member 9, and the mounting member 9 The grommet 1 is fixed to the mounted member 8 while being sandwiched between the flange 2 and the head 6a of the screw member, and the outer surface of the leg piece 3 constitutes the root side to form the corner A planar side surface portion 4 engageable with a corresponding inner side surface of the hole 8a, and the planar side surface portion; And a arcuate side surface portion 5 formed in an arc shape the shape of the plate width direction to constitute a more distal end side is maximum overhang portion substantially intermediate portion of the plate width, the maximum protruding portion, the object to be attached The operation of temporarily fixing the member 8 is to contact the corresponding inner surface of the square hole 8a .

  In the present invention described above, the “attached member” is a member such as a panel or a substrate of various apparatuses or devices. The “attachment member” is a member such as a device or a part that is retrofitted to the attached member. “Temporary fixing” means that the rectangular hole cannot be removed carelessly by vibration or the like. The “planar shape” includes, for example, an aspect in which a part of the plane is provided with a recess or a protrusion. This is also true for “arc”.

The present invention as described above is more preferably embodied as specified in claims 2-5.
(A) The arc-shaped side surface portion is configured to be inclined so as to gradually increase the protruding amount as it approaches the planar side surface portion from the protruding end of the leg piece (Claim 2).
(A) The arc-shaped side surface portion is formed in the process of inserting the leg piece into the square hole by forming a substantially middle portion vertically longer than both sides of the plate width as the planar side surface portion. The temporary fixing part that is most strongly pressed against the corresponding inner side surface is provided at a position displaced below the upper end of the arc on both sides of the plate width (Claim 3).

(C) As shown in FIG. 6, the temporary fixing portion is at the boundary between the planar side surface portion and the arc-shaped side surface portion and is located in the middle of the left and right sides (Claim 4).
(D) The boundary is formed in a downwardly convex arc shape in which the left and right intermediate portions are displaced downward as compared with both sides of the plate width (Claim 5).
(E) a portion of the planar side surface portion and the arc-shaped side surface portion that is above the horizontal line passing through the downwardly convex arc-shaped apex is a section where the arc hole corresponds to the corresponding inner surface of the square hole; The plate width intermediate portion of the portion is an area that becomes a spot with respect to the corresponding inner side surface of the square hole (Claim 6).

  According to the first aspect of the present invention, the outer side surface of each leg piece is located on the root side and can be engaged with the corresponding inner side surface of the square hole. The shape of the direction has an arcuate side surface portion in which a substantially intermediate portion of the plate width is formed in an arc shape that becomes a maximum projecting portion. Of these, the arc-shaped side surface portion in FIG. 7 (a) is the left and right intermediate portion of the arc shape that is the maximum projecting portion of the boundary k between the planar side surface portion 4 and the arc-shaped side surface portion 5. As a contact point that hits the corresponding inner surface of the square hole when passing through the square hole, it becomes a temporary fixing portion that receives the largest insertion resistance. On the other hand, in the conventional grommet, in FIG. 7B, the upper planar side surface portion 14 in which the outer surface of each leg piece 30 is located on the root side and can be engaged with the corresponding inner surface of the square hole 8a; Since it has the lower planar side surface part 15 which is located on the tip side from the planar side surface part and increases the amount of protrusion as it approaches the planar side surface part 14 from the protruding end, the planar side surface part 14 and the planar surface part When the boundary k3 with the side surface portion 15 passes through the square hole 8a, it becomes a contact area of a predetermined length and becomes a temporary fixing portion that receives the largest insertion resistance.

  Therefore, in the temporary fixing operation of the grommet to the mounted member, the invention grommet is inserted into the square hole of the mounted member, and when the leg is inserted and pressed, the grommet has a corner until the temporary fixing portion k1 reaches at least the upper edge of the rectangular hole. It is pushed into the corresponding inner surface of the hole in a spot-like manner, so that the insertion resistance is also reduced. Compared to this, the conventional grommet is a contact area in which the part excluding the temporary fixing part, that is, the R part on both sides of the boundary k3, hits the corresponding inner side surface of the square hole, so that the grommet is pushed more than the structure that is pushed in in a spot-pointed state. The insertion resistance increases and a relatively large insertion load is required. Further, in the temporarily fixed state, the invention and the conventional grommets are engaged with the base portions of the base-side planar side surfaces of the leg pieces with respect to the square holes, so that the temporary fixing force becomes substantially the same. Thereby, in this invention, the fall of temporary fixing force can be suppressed, and the insertion force or pressing force to the square hole of a leg piece can be lowered | hung in temporary fixing operation, Thereby, temporary fixing operability can be improved.

  In the invention of claim 2, since the arcuate side surface portion is inclined so as to gradually increase the protruding amount as it approaches the planar side surface portion from the protruding end of the leg piece, in addition to the reduction of the insertion resistance due to the above-mentioned point hitting, Good insertability of each leg piece into the square hole is maintained.

  In the invention of claim 3, the planar side surface portion 4 is formed so that a substantially middle portion is vertically longer than both sides of the plate width (specifically, the planar side surface portion 4 is formed in a U or V shape), In the process of inserting the piece 3 into the square hole 8a, the temporary fixing portion k1 that is most strongly pressed against the corresponding inner surface of the square hole is located below the upper end u of the arc on both sides of the plate width. In this configuration, for example, each leg piece 3 is displaced from the maximum in the diameter reducing direction in the square hole 8a as shown in FIG. When pushed in until it passes, the force of the contact portion is easily dispersed by the presence of the upper end u of the arc extending upwardly from the boundary k without suddenly hitting the plane as in the conventional case. It is difficult for the piece to be caught, and good insertability is maintained.

  The inventions of claims 4 and 5 clarify the above configuration more positively. That is, the temporary fixing portion k1 is positioned at the left and right intermediate portions at the boundary k between the planar side surface portion 4 and the arc-shaped side surface portion 5 as in claim 3, or the boundary k is on both sides of the plate width as in claim 4. Compared with the downwardly convex arcs with the left and right intermediate portions displaced downward, the leg pieces 3 are gradually lined up from the point when the leg pieces 3 are inserted into the square holes as shown in FIG. Since it shifts to, it can transfer to the end well without being caught.

  The invention of claim 6 clarifies the structure of claims 4 and 5 in more detail, and when each leg piece 3 is inserted into the square hole, the arc shape hits a spot as shown in FIG. 6 (a). Since the transition is gradually made from the area of the plate width intermediate portion y1 of the side surface portion 5 to the upper portion y2 from the horizontal line passing through the downward convex arcuate apex, the transition can be made satisfactorily without being caught.

It is a whole block diagram which shows the relationship with each member at the time of using the grommet of an example. The detail of the said grommet is shown, (a) is a top view, (b) is a side view, (c) is a bottom view. (A) is a front view of the said invention grommet, (b) is the sectional view on the AA line of FIG. 2 (a), (c) is sectional drawing on the BB line of FIG.2 (b). (A) is sectional drawing which shows the operation | movement when temporarily fixing the grommet of FIG.2 and FIG.3 to the square hole of a to-be-attached member, (b) is permanently fixing from the temporarily-fastened state, and an attachment member is to be attached It is sectional drawing which shows the action | operation when fixing to. (A) is the external appearance perspective view of the invention grommet which simplifies and shows the said grommet, (b) is an external appearance perspective view which shows a conventional grommet in the same state. (A) is operation | movement explanatory drawing which shows the structure characteristic of the invention grommet of Fig.5 (a), (b) is operation | movement explanatory drawing which shows the structure characteristic of the conventional grommet of FIG.5 (b). (A) is a schematic diagram which shows the action | operation when temporarily fixing the invention grommet of FIG.5 and FIG.6 (a), (b) is a schematic diagram which shows the said conventional grommet in the state similar to (a). The grommet of patent documents 1 is shown, (a) is a perspective view of the grommet, and (b) is a sectional view showing the state where the attachment member was fixed to the attachment member using the grommet.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. In this description, after clarifying the structure, reference is made to the operating features. 5 to 7, in order to clarify the essential operation of the grommet shown in FIG. 1 to FIG. 4, the R processing of the outer portions on both sides of the leg pieces is omitted for easy viewing. It is shown with various types of conventional grommets.

(Structure) A grommet 1 according to an embodiment is provided with a flange 2 that covers a square hole 8a of a member 8 to be attached such as a panel or a substrate, a pair of leg pieces 3 that are provided below the flange 2, and a flange 2 that is formed in the flange 2. An insertion hole 11 for guiding the screw member 6 between the leg pieces is provided, and each leg piece 3 is temporarily fixed by being inserted into the square hole 8a with a displacement in the reduced diameter direction. Further, the grommet 1 is permanently fixed by screwing the screw member 6 between the leg pieces from the through hole 9a and the insertion hole 11 of the mounting member 9 . In the fixed state, the mounting member 9 is fixed to the mounted member 8 in such a manner that the mounting member 9 is sandwiched between the flange 2 and the head 6a of the screw member. Reference numeral 7 denotes a washer with a through hole 7a. These are the same as before. The difference is that the outer surface of each leg piece 3 forms the root side as the shape of the outer surface of the leg piece 3 in order to reduce the insertion force or pressing force in the temporary fixing operation without lowering the temporary fixing force. The present invention has a flat side surface portion 4 and an arc-shaped side surface portion 5 in which a substantially intermediate portion of the plate width constituting the tip side is formed in an arc shape serving as a maximum projecting portion. Details of this will be clarified below.

The grommet 1 is made of a resin injection molded body. The flange 2 has a disk shape and a size that covers the rectangular hole 8 a of the attached portion 8 . The shape of the flange 2 may be a rectangle or a polygon as long as the square hole 8a can be covered. The flange 2 has a cylindrical portion 12 projecting from the center of the upper surface. The cylindrical portion 12 is a portion that is cylindrical and is inserted into the through hole 9 a of the attachment member 9. Moreover, the cylinder part 12 is in the state divided into two by the pair of vertical grooves 12a. The vertical groove 12a is located above the gap S between the leg pieces 3 arranged to face each other.

  The insertion hole 11 passes through the flange 2 from the inside of the cylindrical portion 12 and communicates with the gap S. The hole diameter of the insertion hole 11 is larger on the upper side than on the lower side. This configuration facilitates deformation of each leg piece 3 in the diameter-expanding direction according to the hole diameter of the insertion hole 11 when the screw member 6 is screwed into the insertion hole as shown by the one-dot chain line in FIG. . Similarly, the cylindrical portion 12 is easily deformed by expanding its diameter by screwing the screw member 6 due to the presence of the vertical groove 12a, and can be mounted without rattling with respect to the inner periphery of the through hole 9a.

  As shown in FIG. 3, each leg piece 3 has a base end 3 a connected to a substantially central portion of the lower surface of the flange 2 and a protruding end with a flat tip 3 b. On the inner surface side of each leg piece 3, a guide groove 3 c is provided from the tip to the insertion hole 11. The screw member 6 is screwed from the insertion hole 11 along the guide groove 3c.

  The outer surface of each leg piece 3 is composed of an upper planar side surface portion 4 and a lower arc-shaped side surface portion 5. As shown in FIGS. 2 to 4, the planar side surface portion 4 and the arc-shaped side surface portion 5 are R processed on both sides in the plate width direction, and both side portions 4 a and 5 a and both side portions 4 a and 5 a which are R processed portions. It consists of intermediate parts 4b and 5b which comprise between. The symbol k indicates the boundary between the planar side surface portion 4 and the arc-shaped side surface portion 5. 5 to 7, both side portions 4a and 5a are omitted.

The planar side surface portion 4, that is, the both side portions 4a and the intermediate portion 4b are portions that are located on the base side of the base end 3a or the leg piece and can be engaged with the corresponding inner side surface of the square hole 8a, and are bordered from the base end 3a. It inclines so that it may protrude gradually toward an external direction toward k. Further, the planar side surface portion 4 is substantially U-shaped or V-shaped with a substantially intermediate portion formed vertically longer than both sides of the plate width.
In this configuration, in the process in which the leg piece 3 is pushed into the square hole 8a, the temporary fixing portion k1 that is most strongly pressed against the corresponding inner side surface of the square hole 8a is shown in the left diagram of FIG. As shown in the drawing, it is a substantially middle portion of the left and right sides of the plate width, and is located considerably below the downwardly convex arcuate upper end u on both sides.

  On the other hand, the arc-shaped side surface 5, that is, the both side portions 5 a and the intermediate portion 5 b gradually increase in the amount of protrusion as the shape in the vertical direction approaches the planar side surface portion 4 from the tip 3 b or the protruding end. The shape of the direction is formed in an arc shape in which a substantially intermediate portion of the plate width is a maximum projecting portion. In other words, the arc-shaped side surface portion 5 in FIG. 7A is the left and right intermediate portion of the arc shape that is the maximum overhanging portion of the boundary k between the planar side surface portion 4 and the arc-shaped side surface portion 5. When k1 passes through the square hole 8a, it hits the corresponding inner surface of the square hole 8a, that is, a temporary fixing portion that receives the largest insertion resistance. Of course, the outer diameter of the temporary fixing portion k1 is larger than the inner diameter of the square hole 8a. That is, the distance a between the temporary fixing part k1 of the one leg piece 3 and the temporary fixing part k1 of the other leg piece 3 is larger than the distance b between the opposing inner surfaces of the square holes 8 where the temporary fixing part side abuts. It is getting longer.

  Further, the boundary k is formed in a downwardly convex arc shape in which the left and right intermediate portions are displaced downward as compared with both sides of the plate width. This boundary k is a part of the planar side surface portion 4 below the square hole 8a in a state where each leg piece 3 is pushed into the square hole 8a to the final stage as shown by a one-dot chain line in FIG. Is exposed. In this configuration, of the planar side surface portion 4 and the arc-shaped side surface portion 5, the upper portion y2 above the horizontal line passing through the downwardly convex arc-shaped apex is an area where the corresponding inner side surface of the square hole 8a is in contact with the line. The plate width intermediate portion y1 of the side surface portion 5 is an area that becomes a spot with respect to the corresponding inner surface of the square hole 8a.

(Operation) The grommet 1 described above can reduce the insertion force or the pressing force as compared with the conventional grommet 1 by the following operation in the temporary fixing operation to the square hole 8a of the mounted member 8.

(A) The grommet 1 is a plate in which the temporary fastening portion k1 that is most strongly pressed against the corresponding inner side surface of the square hole 8a is the plate of the boundary k in the process in which the leg piece 3 is pushed into the rectangular square hole 8a of the mounted member. It is a substantially middle portion of the width, and is below the upper end u of the arcs on both sides. For this reason, in this structure, for example, each leg piece 3 has a planar side surface portion as shown in FIG. 6A from a state where the leg pieces 3 are displaced to the maximum in the diameter reducing direction in the square hole 8a as shown in FIG. When being pushed in until it passes through the square hole 8a, the force of the contact portion is easily dispersed by the presence of the upper ends u on both sides extending upward in the boundary k without suddenly hitting the plane as before. This distributed operation functions to reduce the pressing force of the leg 3 against the square hole 8a.

(A) In other words, the arc-shaped side surface portion 5 is an arc-shaped left and right intermediate portion which is the maximum projecting portion of the boundary k between the planar side surface portion 4 and the arc-shaped side surface portion 5 in FIG. When k1 in the figure passes through the square hole 8a, it hits the corresponding inner surface of the square hole 8a, that is, becomes a temporary fixing portion that receives the largest insertion resistance. Accordingly, in the operation of temporarily fixing the grommet 1 to the attached member 8, when the grommet 1 inserts each leg portion 3 into the square hole 8a of the attached member 8 and presses the grommet 1, the temporary fastening portion k1 becomes at least the square hole 8a. Until it reaches the upper edge, it is pushed into the corresponding inner surface of the square hole 8a in a spotted state, and as a result, the insertion resistance is also reduced. In this regard, in the conventional grommet, since the portion excluding the temporary fixing portion, that is, the R portions on both sides of the boundary k3, is a contact area that hits the corresponding inner side surface of the square hole, it is inserted rather than a configuration that can be pushed in in a spot-pointed state. Resistance increases and a relatively large insertion load is required.

(C) The temporary fixing portion k1 described above is located at the left and right intermediate portions at the boundary k, or the boundary k is formed in a downwardly convex arc shape with the left and right intermediate portions displaced downward as compared to both sides of the plate width. As a result, when the leg pieces 3 are inserted into the square holes as shown in FIG. 6A, the points gradually move from the point hits to the line hits. That is, in this configuration, the force of the contact portion is easily dispersed particularly by the presence of the upper ends u on both sides extending upward in the boundary k, and the transmission of the insertion load is upward in the middle portion as shown by the arrows in FIG. By controlling the direction and the diagonally upward direction on both sides, the leg piece 3 is hardly caught in the square hole 8a, and good insertability can be maintained. In the conventional grommet 10, the insertion load is transmitted upward as indicated by arrows in FIG. 5B and the horizontal directions on both sides, so that the leg pieces 3 are easily caught by the square holes 8a. Yes.

(D) In the temporarily fixed state, the invention and the conventional grommets are engaged with the base end side of the planar side surface 4 of the leg piece 3 with respect to the square hole 8a, so that the temporary fixing force is approximately the same. Thereby, in this invention, the fall of temporary fixing force can be suppressed, and the insertion force or pressing force to the square hole of a leg piece can be lowered | hung in temporary fixing operation, Thereby, temporary fixing operability can be improved.

  In addition, the grommet of this invention should just be equipped with the structure specified by Claim 1, and a detail can be changed or developed with reference to a form example, a well-known example, etc. For example, a washer may be omitted as a usage mode of the grommet, or a seal member may be interposed between the flange and the attached member.

  Further, a metal piece with a screw hole or a hard resin piece is provided in the flange as in Patent Document 1 to increase the tightening force of the screw member, or the mounting member as in Japanese Utility Model Publication No. 6-2016. In order to absorb the thickness variation, the flange forms a thin piece by the depression on the upper surface, and a thin portion formed by a groove is provided at the connection portion with the thin piece, and the thin piece is deformed upward by screwing of the screw member. The leg piece is pulled up and the attached member is pressed against the lower surface of the flange.

1 ... Grommet 2 ... Flange (11 is an insertion hole)
3... Leg piece 4... Planar side surface portion (4 a is both sides of the plate width, 4 b is a substantially middle portion of the plate width)
5... Arc-shaped side surfaces (5a is both sides of the plate width, 5b is a substantially middle portion of the plate width)
6. Screw member (6a is the head)
7 ··· Washer (7a is a through hole)
8 ... Attached member (8a is a square hole)
9 ... Mounting member (9a is a through hole)
10 ... Conventional grommet (20 is flange, 30 is leg piece)
DESCRIPTION OF SYMBOLS 11 ... Insertion hole 12 ... Tube part k ... Border k1 ... Temporary stop k3 ... Boundary (temporary stop)

Claims (6)

A flange that covers the mounting square hole of the member to be mounted; a pair of leg pieces provided on the flange; and an insertion hole that is formed in the flange to guide the screw member between the leg pieces. The leg pieces are temporarily fixed by being inserted into the square holes with a displacement in the direction of the diameter reduction, and screw members are screwed between the leg pieces from the through holes of the mounting members and the insertion holes. A grommet that is fixedly secured and fixed to the mounted member in a state where the mounting member is sandwiched between the flange and the head of the screw member,
The outer side surface of the leg piece forms a base side and can be engaged with a corresponding inner side surface of the square hole, and has a shape in the plate width direction that forms a tip side from the flat side surface portion. An arc-shaped side surface formed in an arc shape that is a maximum projecting portion of the substantially intermediate portion of the plate width,
The grommet, wherein the maximum overhanging portion contacts a corresponding inner side surface of the square hole in an operation of temporarily fixing to the attached member .   2. The grommet according to claim 1, wherein the arc-shaped side surface portion is inclined so as to gradually increase a protruding amount as it approaches the planar side surface portion from a protruding end of the leg piece.   The arc-shaped side surface portion is formed as a flat side surface portion having a substantially middle portion that is vertically longer than both sides of the plate width, so that the corresponding inner surface of the square hole is inserted in the process of inserting the leg piece into the square hole. The grommet according to claim 1, wherein the temporary fixing portion that is most strongly pressed against the slab is provided at a position displaced below the upper end of the arc on both sides of the plate width.   The grommet according to claim 3, wherein the temporary fixing part is located at a middle part between the left and right sides of the planar side part and the arc-shaped side part.   The grommet according to claim 4, wherein the boundary is formed in a downwardly convex arc shape in which the left and right intermediate portions are displaced downward as compared with both sides of the plate width.   Of the flat side surface portion and the arc-shaped side surface portion, the upper portion of the horizontal line passing through the downwardly convex arc-shaped apex is an area where the corresponding side surface of the square hole comes into contact with the line, and the plate width of the arc-shaped side surface portion The grommet according to claim 5, wherein the intermediate portion is an area that is spotted with respect to a corresponding inner surface of the square hole.

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