JP6013783B2 - Adjuster - Google Patents

Description

  The present invention relates to an adjustment tool capable of adjusting the length or tension of a string-like body.

  Adjustment tools applied to outdoor goods, clothes, shoes, etc. include those that adjust the length and tension of the band-like body, and those that adjust the length and tension of the string-like body, but both the band-like body and the string-like body Few adjustment tools that can be applied have been developed.

  For example, a string-like adjuster described in Patent Document 1 includes a first bar that hangs a single belt-like body and a second bar that hangs a single cord member. The strip and the cord member can be indirectly connected via the adjuster.

US Pat. No. 7150079

  On the other hand, the usage of the adjustment tool tends to be diversified, and there may be a case where a plurality of cord members are attached. For example, when both ends of a cord member are hung on the second bar of the adjusting tool described above to connect both ends of one cord member and one belt-like body, both ends of the cord hung on the second bar Depending on how the tension is applied, it is assumed that the second bar may vary or cross over. If the positions of both ends of the cord vary on the second bar or cross each other, for example, one end portion may be loosened, tension may be applied to both ends of the cord unevenly, and tightening at both ends of the cord may also be uneven.

  This invention is made | formed in view of the said problem, The objective is to provide the adjustment tool which can hang a set of string-like bodies, suppressing dispersion | variation.

A string-like adjuster that solves the above problems includes a frame having a shaft hole, a first cross bar that is supported by the pair of string-like members so as to reciprocate in the shaft hole, and a belt-like shape. The first crossbar is provided with a second crossbar around which the body is wound, and the first crossbar is provided with a recess at an end surface where the string-like body is folded back and symmetrical with respect to the central axis.

According to the said structure , an adjustment tool is provided with the 1st crossbar by which a pair of string-like bodies are hung, and the 2nd crossbar by which a strip | belt-shaped body is hung. For this reason, a pair of string-like bodies and belt-like bodies can be connected via the adjusting tool. In addition, the end surface of the first crossbar is provided with a recess, and the recess is symmetrical with respect to the central axis. For this reason, a set of string-like bodies can be arrange | positioned in a symmetrical position with respect to a center axis | shaft by converging a string-like object to a recessed part. Further, since the first cross bar can reciprocate with respect to the frame, a part of the tension can be absorbed. Moreover, even if tension is applied to one string-like body, the tension applied to each string-like body can be equalized by causing the other string-like body to also follow the first crossbar.

  About the said adjustment tool, it is preferable to provide a rib in the center of a said 1st crossbar, and to provide the said recessed part in the both sides of this rib.
  According to the said structure, since the recessed part is provided in the both sides of the rib of a 1st crossbar, a set of string-like bodies can be converged on the both sides of a rib. For this reason, even if the string-like body is converged at the center of the first crossbar, the string-like bodies can be prevented from crossing or tangling on the first crossbar.

  About the said adjustment tool, it is preferable that the end of the said rib protrudes toward the said frame from the end surface of the said 1st crossbar in which the said recessed part was formed.

  According to the above configuration, since one end of the rib protrudes from the end surface of the first crossbar, when the first crossbar moves, one end of the rib contacts the frame first, and the end surface of the first crossbar A gap is formed between the frame and the frame. For this reason, the first crossbar moves to the frame side.
The string-like body can be accommodated in the gap. Therefore, it is possible to prevent the movement of the first crossbar from being hindered by the string-like body being sandwiched between the first crossbar and the frame.

  A string-like body adjustment tool that solves the above-described problems is a string-like body adjustment tool that includes a first crossbar on which a pair of string-like bodies are hung and a second cross-band-like body. A crossbar, wherein the first crossbar includes a rib at the center, and is provided with a concave portion at a position symmetrical to the both sides of the rib and the central axis, the cord-like body being folded back. The gist.

  According to the said structure, an adjustment tool is provided with the 1st crossbar by which a pair of string-like bodies are hung, and the 2nd crossbar by which a strip | belt-shaped body is hung. For this reason, a pair of string-like bodies and belt-like bodies can be connected via the adjusting tool. In addition, the end surface of the first crossbar is provided with a recess, and the recess is symmetrical with respect to the central axis. For this reason, a set of string-like bodies can be arrange | positioned in a symmetrical position with respect to a center axis | shaft by converging a string-like object to a recessed part. Since the recesses are provided on both sides of the ribs of the first crossbar, a set of string-like bodies can be converged on both sides of the ribs. For this reason, even if the string-like body is converged at the center of the first crossbar, the string-like bodies can be prevented from crossing or tangling on the first crossbar.

  About the said adjustment tool, it is preferable that the said rib is provided ranging from the surface of the said 1st crossbar to the back surface.
  According to the said structure, since the rib is provided from the surface of the 1st crossbar to the back surface, the crossing of a string-like body can be prevented in the front and back of a 1st crossbar.

  About the said adjustment tool, it is preferable that the said recessed part of a said 1st crossbar is equipped with the inclined surface which inclines so that the depth of the said recessed part may become large as it approaches the said central axis.
  According to the above configuration, when tension is applied to the string-like body, the folded portion of the string-like body slides on the inclined surface of the concave portion, so that each string-like body can be guided to the central axis side. For this reason, one set of string-like bodies can be converged on the central axis side.

The perspective view of the backpack to which the adjustment tool of this invention was applied. It is 1st Embodiment which actualized the adjustment tool of this invention, Comprising: The perspective view is shown. The side view of the adjustment tool. The top view of the adjustment tool. The perspective view which looked at the adjustment tool from the bottom side. It is a top view when a string-like body and a strip-like body are hung around the adjustment tool, and shows a state where no tension is applied to the string-like body. A side view when a string-like object and a belt-like object are hung around the adjustment tool. It is a top view when a string-like object and a belt-like object are hung around the adjustment tool, and shows a state where tension is applied to the string-like object. It is 2nd Embodiment which actualized the adjustment tool of this invention, Comprising: The perspective view is shown. The top view which decomposed | disassembled the adjustment tool. (A)-(d) is the modification which actualized the adjustment tool of this invention, Comprising: The top view is each shown.

(First embodiment)
Hereinafter, an embodiment embodying the adjusting tool of the present invention will be described with reference to FIGS. In this embodiment, the adjustment tool of the present invention will be described as an adjustment tool applied to a backpack.

  As shown in FIG. 1, the adjuster 10 indirectly connects the string-like body S hung on the backpack P and the band-like body B provided on the side surface of the backpack P, and It is provided to adjust the length or tension.

  The string-like body S is hung on the front surface that is on the outside when the backpack P is carried by the user. The starting end portion of the string-like body S is inserted through the adjusting tool 10 in a state where an arbitrary length is pulled out. The string-like body S is stretched across the front surface of the backpack P in a zigzag manner while being inserted through a plurality of loop-like belt-like bodies B provided on the side surface of the backpack P. Moreover, the terminal part of the string-like body S is inserted through the adjuster 10 in a state where an arbitrary length is drawn. And the fastening force with respect to the backpack P by the string-like body S can be increased by lengthening the pull-out amount of the string-like body S from the adjusting tool 10. Further, by shortening the pull-out amount of the string-like body S, the tightening by the string-like body S can be loosened.

  As shown in FIG. 2, the adjustment tool 10 includes a flat frame 11 that is rectangular in plan view. A pair of side frames 12 extending in the longitudinal direction of the frame 11 is formed with a long hole 13 as a shaft hole. The longitudinal direction of the long hole 13 is parallel to the longitudinal direction of the side frame 12.

  Both ends of the first cross bar 15 are inserted into the long holes 13 of the side frame 12, respectively. A first end S1 and a terminal end S2 of the string-like body S are hung on the first crossbar 15 while being pulled out from the adjusting tool 10 by an arbitrary length. The starting end S <b> 1 is hung around the upper and lower surfaces of the first crossbar 15 from below the third crossbar 17 in the short direction of the frame 11, and is pulled out from below the third crossbar 17 again. The end portion S2 is also wound around similarly to the start end portion S1.

  As shown in FIG. 3, the shaft portions 22 at both ends of the first crossbar 15 are inserted in a state where there is play in each of the long holes 13. For this reason, when tension is applied to at least one of the start end portion S1 and the end end portion S2 hung around the first cross bar 15, the first cross bar 15 slides along the long hole 13, and the long hole 13 It moves until it contacts the left end in FIG.

As shown in FIG. 4, the first crossbar 15 includes a slide portion 20 having a substantially rectangular shape in plan view, and a rib 21 erected vertically to the upper surface of the slide portion 20. The rib 21 is provided at the center in the longitudinal direction of the slide portion 20 and extends in parallel with the short direction of the slide portion 20. The tip of the rib 21 protrudes from the end surface of the slide portion 20. The protruding amount of the rib 21 is about the diameter of the string S. Furthermore, as shown in FIG. 5, the rib 21 is provided from the upper surface of the slide portion 20 to the middle of the back surface of the slide portion 20 via the end surface of the first crossbar 15 .

  On both sides of the rib 21, the start end S1 and the end end S2 of the string S are hung. By separating the start end S1 and the end S2 by the rib 21, it is possible to prevent the string-like bodies S on the first crossbar 15 from crossing or tangling.

  Moreover, as shown in FIG. 4, the recessed part 23 is each provided in the end surface where the start end part S1 and the termination | terminus part S2 of the string-like body S of the slide part 20 are return | folded. In plan view, the recesses 23 are provided on both sides of the base end portion of the rib 21 and have a substantially U shape or a substantially V shape, respectively. Each of these recesses 23 is formed in a position and shape symmetrical with respect to the central axis X1 parallel to the moving direction of the first crossbar 15.

  Each recessed part 23 has a small inclined surface toward the rib 21 side from the bottom part 23a used as the most depressed position. The position where the inclined surface and the rib side surface are connected is located on the far side from the end surface of the slide portion 20. Each concave portion 23 has a gentle and long inclined surface 23b that continues from the end surface of the slide portion 20 toward the opposite side of the rib 21 from the bottom portion 23a. That is, the recess 23 has a shape that is asymmetrical with respect to the bottom 23 a, and the bottom 23 a is biased toward the rib 21.

  These recesses 23 extend in a groove shape on the end surface of the first cross bar 15 from the upper surface to the lower surface of the slide portion 20. By providing these recesses 23, when a tension is applied to the string-like body S hung around the first crossbar 15, the start end S <b> 1 and the end end S <b> 2 are guided to the rib 21 side.

  As shown in FIG. 2, the side opposite to the direction in which the string-like body S is drawn out of the short direction of the frame 11 constitutes the second crossbar 16 around which the belt-like body B is wound. ing. An opening (not shown) around which the strip B is hung is formed on the second crossbar 16 side of the frame 11, and the strip B hung on the second crossbar 16 is pulled out from the opening. Thus, the belt-like body B is attached to the adjustment tool 10. That is, the starting end S1 and the terminal end S2 of the string-like body S and the band-like body B are connected to each other via the adjusting tool 10 with their longitudinal directions parallel to each other. For this reason, the thickness (height) of the adjustment tool 10 can be reduced. Moreover, since the string-like body S is folded around the first cross bar 15, the number of parts is smaller than that of an adjustment tool that penetrates the string-like body S into the hole of the casing and is fixed by a spring. can do.

Next, the operation of the adjustment tool 10 will be described.
First, a description will be given of a case where tension is not applied to the string-like body S, such as when the string-like body S is attached or when no luggage is contained in the backpack P. As shown in FIG. 6, the first end portion S <b> 1 and the end portion S <b> 2 of the string-like body S are hung around the first cross bar 15 in a state where the first end portion S <b> 1 is drawn from below the third cross bar 17. . At this time, the string-like body S is folded back at the end portion of the first crossbar 15 where the concave portion 23 is formed. When no tension is applied to the string S, the positions of the start end S1 and the end S2 on the first crossbar 15 are not necessarily symmetrical with respect to the ribs 21. In addition, a loop-shaped band B is wound around the second cross bar 16.

  As shown in FIG. 7, when tension is applied to the string-like body S due to factors such as loading of the luggage into the backpack P after attaching the string-like body S and the band-like body B to the adjustment tool 10 in this manner, The first crossbar 15 moves. The first crossbar 15 is movable until the shaft portion 22 contacts the end portion 13A of the long hole 13. At this time, for example, even when a tension is applied only to the start end S1, the first crossbar 15 moves, and even when a tension is applied only to the end S2, the first crossbar 15 moves. For this reason, even if tension is applied to one of the start end S1 and the end S2, it is possible to prevent the other from loosening. Moreover, a part of tension | tensile_strength can be absorbed by the 1st crossbar 15 moving, with the amount of drawer | drawing-out constant.

On the other hand, when tension is applied to the belt-like body B, the first cross bar 15 moves to the second cross bar 16 side, and when the tip of the rib 21 comes into contact with the second cross bar 16, the tip of the rib 21 becomes a slide part. Since it protrudes from the end face 20, a gap is formed between the recess 23 and the second crossbar 16 . Since the string-like body S is accommodated in the gap, the string-like body S is not sandwiched between the first crossbar 15 and the second crossbar 16 .

  When tension is applied to the string-shaped body S, the string-shaped body S is symmetrical on the first crossbar 15 in the state before the tension is applied to the string-shaped body S. 8, the folded portions S3 and S4 are accommodated in the bottom 23a while sliding on the inclined surface 23b of the recess 23 as shown in FIG. In other words, the start end S1 and the end S2 are guided to the bottom 23a of the recess 23 by the inclined surface 23b. As a result, the start end S <b> 1 and the end end S <b> 2 are arranged at positions that are symmetrical with respect to the rib 21 in the center of the first crossbar 15. For this reason, variations such as one of the start end S1 and the end S2 being loosened or being biased toward the end of the first crossbar 15 are suppressed, and tension can be applied uniformly to the start end S1 and the end S2. . Accordingly, for example, the tension applied to the terminal end S2 is suppressed from becoming extremely large as compared with the starting end S1, so that the tightening force on the backpack P can be made uniform in the front. For this reason, it is possible to suppress a situation in which the backpack P is evenly tightened while receiving the load and the load is biased to the lower portion of the backpack P.

According to the first embodiment, the following effects can be obtained.
(1) In the first embodiment, the adjuster 10 is attached to the first crossbar 15 around which the start end S1 and the end end S2 of the string-like body S are wound, and the belt-like body B on the backpack P side. 2 crossbars 16. For this reason, the start end part S1 and the terminal end part S2 of the string-like body S and the band-like body B can be connected via the adjusting tool 10. In addition, the first crossbar 15 is provided with a recess 23 at a position symmetrical to the central axis X1 on the end face where the start end S1 and the end end S2 are folded back. For this reason, since the start end S1 and the end S2 accommodated in the recess 23 are disposed at positions symmetrical with respect to the central axis X1, the start end S1 and the end S2 are located on the first crossbar 15. Can be suppressed. That is, when the backpack P is packed with a load and tension is applied to the string-like body S due to the swelling of the backpack P, it is possible to apply a uniform tension to the start end S1 and the end end S2. For this reason, it is possible to apply a tightening force evenly to the backpack P.

  (2) In 1st Embodiment, the recessed part 23 of the 1st crossbar 15 is provided with the inclined surface which inclines toward the central axis X1. Accordingly, when tension is applied to the string S, the folded portions of the start end S1 and the end S2 slide in the direction of descending the inclined surface of the recess 23, so that each string S is moved to the central axis side. Can be guided. For this reason, the dispersion | variation in each string-like body S hung around the 1st crossbar 15 can be suppressed.

  (3) In the first embodiment, the rib 21 is provided in the center of the first cross bar 15, and the recesses 23 are provided on both sides of the rib 21. For this reason, it is possible to prevent the starting end S1 and the terminal end S2 of the string-like body S from crossing or getting entangled on the first crossbar 15.

  (4) In the first embodiment, the first cross bar 15 is pivotally supported in the elongated hole 13 of the frame 11 so as to be able to reciprocate. For this reason, part of the tension applied to the string S can be absorbed by the reciprocating motion of the first crossbar 15. Further, for example, even if tension is applied only to the start end S1, the end S2 is also driven by the first crossbar 15 so that the tension applied to the start S1 and the end S2 can be equalized.

(5) In the first embodiment, the tip of the rib 21 protrudes from the end surface of the first crossbar 15 toward the second crossbar 16. Therefore, when the first cross bar 15 moves, one end of the rib 21 comes into contact with the second cross bar 16 first, and a gap is formed between the end surface of the first cross bar 15 and the second cross bar 16. Is done. For this reason, when the 1st crossbar 15 moves to the 2nd crossbar 16 side, the string-like body S can be accommodated in the clearance gap. Therefore, it is possible to suppress the movement of the first crossbar 15 from being hindered by the string-like body S being sandwiched between the first crossbar 15 and the second crossbar 16 .

  (6) In the first embodiment, the rib 21 is provided from the surface of the first crossbar 15 to the back surface through the end surface on which the recess 23 is formed. For this reason, it is possible to prevent a cross line of the string-like body on the front and back of the first crossbar 15.

(Second Embodiment)
Next, a second embodiment of the adjusting tool embodying the present invention will be described with reference to FIGS. In addition, since 2nd Embodiment is a structure which applied the adjustment tool of 1st Embodiment only to what is called a side release buckle, the detailed description is abbreviate | omitted about the same part.

As shown in FIG. 9, the buckle 50 includes a socket 51 and a plug 55 inserted into the socket 51.
The socket 51 includes an insertion port 52 formed on the front surface through which the plug 55 is inserted, an opening 53 formed through the side surface, and a belt-like cross bar 54 around which the belt-like body B is hung. The belt-like cross bar 54 is provided on the back surface opposite to the insertion port 52.

  As shown in FIG. 10, the plug 55 includes a frame-shaped frame portion 61 and a rotating piece 60 provided at the tip of the frame portion 61. The frame portion 61 includes a side frame 62 that extends substantially in the longitudinal direction. The side frame 62 is formed with a long hole (not shown), and the shaft portion of the first crossbar 15 is loosely inserted into the long hole. The first crossbar 15 has the same configuration as that of the first embodiment, and includes a slide portion 20, a rib 21, and a concave portion 23.

  The rotating piece 60 has a shape such that the width increases from the base end to the tip in plan view. In addition, the rotating pieces 60 are connected by an extendable part 63. The stretchable part 63 is substantially U-shaped in plan view. When the plug 55 is inserted into the insertion port 52 of the socket 51 and the rotating pieces 60 are rotated in the directions close to each other, the expansion / contraction part 63 contracts.

  The effect | action of the buckle 50 of this embodiment is demonstrated. As shown in FIG. 9, the start end S <b> 1 and the end end S <b> 2 of the string-like body S are folded back around the first crossbar 15 by the recess 23. Moreover, since the start end part S1 and the termination | terminus part S2 are hung on the both sides of the rib 21, they are not mixed. By adjusting the drawing amount of the string-like body S from the plug 55, the tension of the string-like body S can be adjusted. Further, the band B is hung around the band cross bar 54 of the socket 51.

  When the plug 55 is fastened to the socket 51, the tip of the rotating piece 60 is inserted from the insertion port 52 of the socket 51. Then, the side surface of the rotating piece 60 and the inner side surface of the socket 51 come into contact with each other, so that the rotating piece 60 rotates in a direction close to each other. Further, when the plug 55 is inserted to a position where the rotating piece 60 faces the opening 53 of the socket 51, the rotating piece 60 is rotated outward by its own elastic force, and the socket 51 is connected via the opening 53. Project a part of it outward. As a result, the plug 55 is fastened to the socket 51.

  Similarly to the first embodiment, when tension is applied to the string-like body S, the start end portion S1 and the end end portion S2 that are hung around the first crossbar 15 slide toward the recess 23 and It is arranged at a symmetrical position. For this reason, when tension is applied to the string S, it is possible to apply tension equally to the start end S1 and the end S2.

Thus, since the string-like body S and the strip-like body B are connected via the adjustment tool 10 in a state where the longitudinal directions thereof are parallel, the thickness (height) of the adjustment tool 10 can be reduced.
When releasing the fastening of the socket 51 and the plug 55, the rotating piece 60 of the plug 55 protruding from the socket 51 is pressed toward the inside of the socket 51. As a result, due to the elastic force of the rotating piece 60 and the expansion / contraction part 63, the plug 55 is urged in the direction of coming out of the socket 51, and the fastening between the socket 51 and the plug 55 is released.

Therefore, according to the second embodiment, the following effects can be obtained in addition to the effects (2) to (6) described in the first embodiment.
(7) In 2nd Embodiment, the adjustment tool 10 which comprises a side release buckle is the 1st crossbar 15 in which the start end part S1 and termination | terminus part S2 of the string-like body S are wound, and the crossbar 54 for strip | belt-shaped bodies The first crossbar 15 includes end portions S1 and end portions S2 that are folded back, and has a recess 23 at a position that is symmetrical with respect to the central axis. For this reason, since the start end S1 and the end S2 accommodated in the recess 23 are arranged at positions symmetrical with respect to the central axis, the start end S1 and the end S2 are located on the first crossbar 15. Variations can be suppressed. That is, when the backpack P is packed with a load and tension is applied to the string-like body S due to the swelling of the backpack P, it is possible to apply a uniform tension to the start end S1 and the end end S2. For this reason, it is possible to apply a tightening force evenly to the backpack P.

In addition, you may change each said embodiment as follows.
-The recessed part 23 formed in the 1st crossbar 15 may have shapes other than the above, as long as it is formed in the symmetrical position via the central axis. For example, as shown to Fig.11 (a), the recessed part 23A which consists only of the inclined surface which descend | falls toward a central axis may be sufficient. Moreover, as shown in FIG.11 (b), the most depressed bottom part may be the recessed part 23B which is not biased to the rib 21 side. Further, the end portion on the rib 21 side of the recess 23 </ b> B may have a shape protruding (higher) than the end portion on the side frame 12 side. Furthermore, as shown in FIG. 11 (c), the first crossbar 15 may have a shape in which the ribs 21 are omitted. Under the present circumstances, if the protrusion 23D higher than the bottom part of each recessed part 23C is provided between the recessed parts 23C, the crossing of a string-like body can be suppressed. Moreover, as shown in FIG.11 (d), the 1st crossbar 15 may be integrally provided in the flame | frame 11, and you may comprise so that a slide movement is impossible. Even in this case, the length and tension of the string S can be adjusted using the first crossbar 15 and the frame.

  In each of the above embodiments, the pair of string-like bodies S that are hung around the first crossbar 15 are configured by the start end S1 and the end end S2 of one string-like body S. You may comprise from the one end part. In short, as long as there is one set of string-like bodies that are hung around the first crossbar 15, the string-like bodies may be loop-shaped or not loop-shaped.

  The second crossbar 16 around which the belt-like body B is hung may have an adjuster function for the belt-like body B. That is, by forming a slit slightly wider than the width of the band B in the second crossbar 16, and by winding the drawn band B so as to meander around the slit, the length of the band B, and The tightening state may be changed.

  -In each above-mentioned embodiment, although the adjustment tool of this invention was applied to the backpack P, you may apply to other things, and not only adjusting the fastening state of a string-like body but adjusting the length. It may be used as a thing. For example, the present invention may be applied to shoes as an adjustment tool that adjusts the tightening state of shoelaces, or may be applied as an adjustment tool that adjusts the length or tightening state of a string attached to clothes. Or you may apply as an adjustment tool which adjusts the clamp | tightening state of the string provided in outdoor goods, such as a tent. Or you may apply as an adjustment tool which adjusts the length etc. of the cord connected to electrical appliances.

  DESCRIPTION OF SYMBOLS 10 ... Adjuster, 11 ... Frame, 13 ... Long hole as shaft hole, 15 ... 1st cross bar, 16 ... 2nd cross bar, 21 ... Rib, 23, 23A, 23B, 23C, 23E ... Recessed part, 23b ... Inclined surface, B ... strip-like body, S ... string-like body, X1 ... central axis.

Claims (6)

A string adjuster,
A frame having a shaft hole;
A first crossbar that is wound around a pair of string-like bodies and supported in the shaft hole so as to be reciprocally movable ;
A second crossbar around which the belt-like body is wound,
The first crossbar is
An adjustment tool comprising a concave portion at an end surface where the string-like body is folded back and symmetrical with respect to the central axis. A rib at a center of the first cross bar, adjuster according to claim 1 comprising the recess on both sides of the rib. The adjustment tool according to claim 2 , wherein one end of the rib projects toward the frame from an end surface of the first crossbar in which the concave portion is formed. A string adjuster,
A first crossbar around which a pair of string-like bodies are wound;
A second crossbar around which the belt-like body is wound,
The first crossbar is
A rib in the center, a facet in which the string-like body is folded back, adjuster characterized by comprising a recess in symmetrical positions with respect to both sides and the center axis of said rib. The said rib is an adjustment tool of any one of Claims 2-4 provided over the back surface from the surface of the said 1st crossbar. The adjustment tool according to any one of claims 1 to 5 , wherein the concave portion of the first crossbar includes an inclined surface that is inclined so that the depth of the concave portion increases as the central axis approaches the central axis .

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