CN117628061A - Miniature linear slide rail - Google Patents

Abstract

The invention discloses a miniature linear slide rail which comprises a rail, a sliding block, at least one circulating accessory and a retainer. The slide block is arranged on the track, the circulation fitting is arranged on the track and is connected with the slide block, a circulation channel for balls to run is formed among the circulation fitting, the track and the slide block, the circulation fitting is provided with a plurality of steering convex parts, the retainer is provided with a plate part and two retaining parts, two ends of each retaining part are respectively connected with the plate part by a positioning part, the plate parts of the retaining parts are adjacent to the slide block, the positioning parts of the retainer are abutted to the steering convex parts, the retaining parts of the retainer provide retaining effects for the balls in running, and the width of the plate parts of the retainer is smaller than the distance between the steering convex parts of the circulation fitting. Therefore, the miniature linear slide rail can optimize the assembly efficiency, and further realize the purpose of automatic assembly.

Description

Miniature linear slide rail

Technical Field

The invention relates to the technical field of linear slide rails, in particular to a miniature linear slide rail capable of optimizing assembly efficiency.

Background

The retainer disclosed in japanese patent JP 2632126 B2 is a closed curve formed by two locking portions and two straight portions, and is made of a metal wire rod by means of segment forming and then welding or bonding, which is troublesome in manufacturing, and is also difficult to take and assemble due to weak overall configuration, and is easy to damage and deform, resulting in poor retaining effect, and even possibly to press the balls to cause unsmooth operation.

The retainer disclosed in taiwan patent TW I440784 is composed of a retaining portion and two hooks, wherein each end cap is provided with a fastening slot corresponding to the hook and a guiding surface adjacent to the fastening slot, and the guiding surface has an inclination angle with respect to the end cap, so that the assembly resistance is reduced by the arrangement of the inclination angle. However, the retainer itself is too small to be easily taken out, and the resistance to the addition of the distal end of the guide surface is still large, resulting in difficulty in assembly. In addition, the retainers are in a multi-segment curved configuration, are easily entangled with each other, and often require additional steps to separate, thereby increasing the cost of the invisible article.

The retainer disclosed in US 5544954 includes a straight line portion and two arc locking portions, and is difficult to be taken out due to the fact that the retainer is a thin steel wire, and in addition, when the retainer is mounted in the arc grooves of the two end covers by the arc locking sections at the two ends, the retainer is difficult to align and needs to be pressed in by applying a certain force, so that the retainer is inconvenient to assemble.

On the other hand, for the micro linear guide (Miniature Linear Guide) having a height of about 1cm and a width of about 2cm (even smaller), manual work is relied upon for assembling the retainer, but the assembly efficiency and productivity are still to be improved due to the smaller size and the limitation of the manual work.

Disclosure of Invention

The invention mainly aims to provide a miniature linear slide rail which can optimize the assembly efficiency so as to realize the aim of automatic assembly.

In order to achieve the above-mentioned main objective, a micro linear guide of the present invention comprises a rail, a slider, at least one circulation fitting, a plurality of balls, and a retainer. The sliding block is arranged on the track in a sliding manner and is provided with an abdomen and two side parts which are oppositely connected with the abdomen; the circulating fitting is slidably arranged on the rail and is connected with the sliding block, so that a circulating channel is formed among the circulating fitting, the rail and each side part of the sliding block, and in addition, the circulating fitting is provided with a plurality of turning convex parts; the retainer has a plate portion, a plurality of positioning portions, and two retaining portions, both ends of each retaining portion are respectively connected with the plate portion by one positioning portion, the plate portion of the retainer abuts against the abdomen portion of the slider, the positioning portions of the retaining portions abut against the turning protrusions of the circulation fittings, and each retaining portion of the retainer abuts against the balls, wherein the width of the plate portion of the retainer is smaller than the distance between the turning protrusions of each circulation fitting.

From the above, the micro linear slide rail of the present invention is capable of improving the assembly efficiency and reducing the assembly cost, thereby achieving the purpose of automated assembly.

Preferably, the two sides of the rail are respectively provided with a first rolling groove and a holding groove adjacent to the first rolling groove, each side of the sliding block is provided with a second rolling groove, the second rolling grooves of the sliding block correspond to the first rolling grooves of the rail one to one, so that a load channel is respectively formed between the second rolling grooves of the sliding block and the first rolling grooves of the rail, each side of the sliding block is also provided with a non-load channel, and each non-load channel penetrates through two opposite end surfaces of one side. The number of the circulating accessories is two, each circulating accessory is arranged on two opposite end surfaces of the sliding block and is provided with two steering convex parts and two return grooves, each return groove is adjacent to one steering convex part, and two ends of each return groove are connected with one end of the load channel and one end of the non-load channel, so that one load channel, one non-load channel and two return grooves jointly form one circulating channel. Each of the retaining portions of the retainer is located in the retaining groove of the rail and abuts against the balls passing through one of the load channels.

Preferably, two side surfaces of the rail are respectively provided with a first rolling groove and a holding groove adjacent to the first rolling groove, each side part of the sliding block is provided with two second rolling grooves parallel to each other and two opposite first reflux grooves, and a load channel is respectively formed between one second rolling groove of each side part of the sliding block and one first rolling groove of the rail. The number of the circulating accessories is one, the circulating accessories are also provided with two opposite sleeving grooves and four steering convex parts, a third rolling groove and two opposite second reflux grooves are arranged around each sleeving groove, the second reflux grooves are connected with two ends of the third rolling groove, one second rolling groove of each side part of the sliding block corresponds to one first rolling groove of the sliding rail, the other second rolling groove of each side part of the sliding block corresponds to one third rolling groove of the circulating accessories, and the first reflux grooves of each side part of the sliding block correspond to the second reflux grooves of the circulating accessories, so that one first rolling groove, the second rolling grooves, the third rolling grooves, the first reflux grooves and the second reflux grooves jointly form a circulating channel; each second return groove is adjacent to one of the turning convex parts, and each second return groove is connected with one of the load channels, and each retaining part of the retainer is positioned in the retaining groove of the track and is abutted against the balls passing through one of the load channels.

Preferably, the bottom surface of the abdomen of the slider has a concave part, the top surface of the plate part of the retainer has a convex part, and the retainer is embedded in the concave part of the slider by the convex part, so that the positioning effect between the two can be improved.

Preferably, each circulation fitting further has a plurality of positioning blocks, each positioning block protrudes from one of the steering protruding portions into one of the accommodating grooves along the extending direction of the rail, and each positioning portion of the retainer is clamped to one of the positioning blocks of each circulation fitting, so that a positioning effect between the two positioning blocks can be improved.

Preferably, the retainer further has a plurality of wing portions, each of which extends from one of the positioning portions in a direction away from the plate portion and abuts against an outer end surface of one of the circulation fittings to promote structural stability of the retainer.

Preferably, the outer end surface of each circulation fitting is provided with a plurality of positioning posts, each wing part of the retainer is provided with a positioning hole, and the retainer is clamped with the positioning posts of the circulation fittings through the positioning holes, so that the positioning effect between the two can be improved.

Preferably, the retainer further has a plurality of wing portions, each of which extends upward from one end of the retainer portion and abuts against an outer end surface of the circulation fitting to promote structural stability of the retainer.

Preferably, the holding portion has a rectangular cross-sectional shape, and the holding portion has a width-to-thickness ratio of not less than 1.5, so that it is ensured that the holding portion has sufficient structural strength without being deformed easily to provide a good holding effect.

Preferably, each positioning portion has a rectangular cross-sectional shape, and the length-to-thickness ratio of each positioning portion is not less than 1.5, so that each positioning portion can be ensured to have sufficient structural strength without being deformed easily, so as to provide a good positioning effect.

The detailed construction, features, assembly or use of the micro linear guide provided by the present invention will be described in the detailed description of the embodiments that follow. However, those of ordinary skill in the art will realize that these specific embodiments, as well as the specific embodiments that are illustrated in the present application, are intended to be illustrative of the present invention and are not intended to limit the scope of the present application.

Drawings

Fig. 1 is a perspective view of a micro linear guide according to embodiment 1 of the present invention.

Fig. 2 is an exploded perspective view of a micro linear guide according to embodiment 1 of the present invention.

Fig. 3 is a cross-sectional view of fig. 1 taken along line 3-3.

Fig. 4 is a cross-sectional view of fig. 1 taken along line 4-4.

Fig. 5 is a partially exploded perspective view of a miniature linear guide rail according to embodiment 1 of the present invention.

Fig. 6 is a combination diagram of fig. 5.

Fig. 7 is a bottom view of the omitted track of the micro linear guide rail of embodiment 1 of the present invention.

Fig. 8 is a perspective view of a holder provided by a micro linear guide according to embodiment 1 of the present invention.

Fig. 9 is a cross-sectional view of fig. 8 taken along line 9-9.

Fig. 10 is a cross-sectional view of fig. 8 taken along line 10-10.

Fig. 11 is a partially exploded perspective view of a micro linear guide rail according to embodiment 2 of the present invention.

Fig. 12 is a cross-sectional view of a micro linear guide rail omitted track according to embodiment 2 of the present invention.

Fig. 13 is a partial perspective view of a omitted track of a micro linear guide according to embodiment 3 of the present invention.

Fig. 14 is a perspective view of a holder provided by a micro linear guide according to embodiment 4 of the present invention.

Fig. 15 is a perspective view of a omitted track of a micro linear guide according to embodiment 4 of the present invention.

Fig. 16 is an exploded perspective view of a omitted track of a micro linear guide according to embodiment 5 of the present invention.

Fig. 17 is a perspective view of a omitted track of a micro linear guide according to embodiment 5 of the present invention.

Fig. 18 is a perspective view of a holder provided by a micro linear guide according to embodiment 6 of the present invention.

Fig. 19 is a perspective view of a omitted track of a micro linear guide according to embodiment 6 of the present invention.

Fig. 20 is an exploded perspective view of a omitted track of a micro linear guide according to embodiment 7 of the present invention.

Fig. 21 is a perspective view of a omitted track of a micro linear guide according to embodiment 7 of the present invention.

Fig. 22 is a perspective view of a micro linear guide according to embodiment 8 of the present invention.

Fig. 23 is an exploded perspective view of a omitted track of a micro linear guide according to embodiment 8 of the present invention.

FIG. 24 is a cross-sectional view of FIG. 22 taken along line 24-24.

Fig. 25 is a cross-sectional view of fig. 22 taken along line 25-25.

[ reference numerals description ]

10 miniature linear slide rail

20 track

22 first rolling groove

24 holding groove

30 sliding block

31 abdomen portion

32 side portions

33 second rolling groove

34 non-load path

35 concave portion

40 circulation fittings

41 steering boss

D distance between the steering protrusions

42 reflux groove

43 containing groove

44 positioning block

45 outer end face

46 positioning column

50:ball

52 load path

54 circulation channel

56 non-load path

60 retainer

61 plate portion

W1 width of plate portion

62 positioning part

L length of the positioning part

Thickness of the positioning portion T2

63 holding part

W2 width of holding portion

Thickness of the holding portion T1

64 convex part

65 wing portion

66 positioning hole

70 sliding block

71 abdomen part

72 side portions

73 second rolling groove

74 first reflux groove

80 circulation fittings

81 socket groove

82 third rolling groove

83 second reflux groove

84 turning convex part

Detailed Description

The present invention will be further described in detail below with reference to specific embodiments and with reference to the accompanying drawings, in order to make the objects, technical solutions and advantages of the present invention more apparent.

Applicant hereby gives notice that throughout this specification, including the examples presented below and the claims of the claims, directional terms are used to refer to the orientation of the drawing figures. Next, in the embodiments to be described below and the drawings, the same reference numerals denote the same or similar elements or structural features thereof.

Referring first to fig. 1, a micro linear slide 10 (Miniature Linear Guide) of embodiment 1 of the present invention is suitable for use in miniaturized precision equipment or space-constrained applications, and is about 1cm in size, in height, and about 2cm in width. With continued reference to fig. 1 and 2, the micro linear guide 10 of embodiment 1 of the present invention comprises a rail 20, a slider 30, two-cycle fittings 40, a plurality of balls 50, and a retainer 60.

The rail 20 has a first rolling groove 22 and a holding groove 24 adjacent to the first rolling groove 22 on both left and right sides thereof.

The slider 30 has a web 31 and two opposite side portions 32 connected to the web 31, the inner side of each side portion 32 has a second rolling groove 33, the slider 30 is slidably assembled on the rail 20, such that the second rolling grooves 33 of the slider 30 correspond to the first rolling grooves 22 of the rail 20 in a one-to-one manner, and thus a load channel 52 is formed between the second rolling grooves 33 of the slider 30 and the first rolling grooves 22 of the rail 20, respectively. As shown in fig. 2 and 3, each side portion 32 further has a non-load passage 34, and the non-load passage 34 penetrates through both front and rear end surfaces of the side portion 32.

These circulation fittings 40 are provided on both front and rear end surfaces of the slider 30. The left and right ends of each circulation fitting 40 are respectively provided with a turning protrusion 41 and a return groove 42 adjacent to the turning protrusion 41, and the two ends of each return groove 42 are connected with one end of the load channel 52 and one end of the non-load channel 34, so that the load channel 52, the non-load channel 34 and the front and rear return grooves 42 together form a circulation channel 54 (shown in fig. 3) for the balls 50 to run. In addition, as shown in fig. 5, each circulation fitting 40 further has a receiving groove 43 adjacent to the turning protrusions 41.

The holder 60 is a one-piece structure made of a metal material by press working. As shown in fig. 2, the retainer 60 has a plate portion 61, four positioning portions 62 and two holding portions 63, wherein the plate portion 61 is rectangular, and the width W1 of the plate portion 61 is smaller than the distance D (as shown in fig. 7 and 8) between the turning protrusions 41, and the positioning portions 62 are connected to four corners of the plate portion 61 on the one hand and to both ends of the holding portions 63 on the other hand. In assembly, as shown in fig. 5 and 6, since the width W1 of the plate portion 61 is smaller than the distance D between the turning protrusions 41, the retainer 60 can be directly pressed into the slider 30 in a single direction to complete assembly, and after the completion of assembly, as shown in fig. 3 and 4, the plate portion 61 of the retainer 60 abuts against the web 31 of the slider 30, and the positioning portions 62 of the retaining portions 63 abut against the turning protrusions 41 of the circulation fittings 40 and are positioned in the receiving grooves 43 of the circulation fittings 40, so that the retainer 60 is positioned, and the retaining portions 63 of the retainer 60 are positioned in the retaining grooves 24 of the rail 20 and abut against the balls 50 passing through the load channels 52, so that the retainer 60 provides a retaining effect on the balls 50 passing through the load channels 52.

On the other hand, as shown in fig. 8 and 9, the cross-sectional shape of the holding portion 63 is rectangular, and the aspect ratio of the holding portion 63 is not less than 1.5, so that it is possible to ensure that the holding portion 63 has sufficient structural strength without being deformed easily, to provide a good holding effect; as shown in fig. 8 and 10, the cross-sectional shape of each positioning portion 62 is rectangular, and the length-thickness ratio of each positioning portion 62 is not less than 1.5, so that each positioning portion 62 has sufficient structural strength and is not easy to deform, and a good positioning effect is provided.

To further improve the structural stability of the holder 60, the slider 30, the circulation fitting 40 and the holder 60 are positioned in cooperation with each other with different structural variations in the following embodiments.

As shown in fig. 11, in embodiment 2 of the present invention, the bottom surface of the abdomen 31 of the slider 30 has a rectangular concave portion 35, the retainer 60 integrally protrudes upward from the plate portion 61 to form a rectangular convex portion 64, and when the retainer 60 is pressed into the slider 30, the convex portion 64 of the retainer 60 is simultaneously embedded in the concave portion 35 of the slider 30, as shown in fig. 12, so that the positioning effect between the two can be enhanced.

As shown in fig. 13, in embodiment 3 of the present invention, each circulation fitting 40 further has two positioning blocks 44, each positioning block 44 protrudes from the rotation protruding portion 41 into the accommodating groove 43 along the extending direction of the track 20, and when the retainer 60 is assembled, the positioning portions 62 of the retainer 60 are clamped to the positioning blocks 44 of the circulation fitting 40 in a one-to-one manner, so that the positioning effect between the two can be improved.

In embodiment 4 of the present invention, as shown in fig. 14, the retainer 60 further has four wing portions 65, each wing portion 65 extends horizontally from the positioning portion 62 in a direction away from the plate portion 61, and when the retainer 60 is assembled, as shown in fig. 15, the wing portions 65 of the retainer 60 abut against the outer end surfaces 45 of the circulation fittings 40, so that the retainer 60 has a clamping effect. As shown in fig. 16 and 17, in embodiment 5 of the present invention, the outer end surface 45 of each circulation fitting 40 further provides two positioning posts 46, each wing portion 65 of the retainer has a positioning hole 66, and the retainer is clamped to the positioning posts 46 of the circulation fittings 40 in a one-to-one manner by the positioning holes 66 of each wing portion 65, so as to enhance the positioning effect therebetween.

However, the number and positions of the wing portions 65 may be changed, as shown in fig. 18, in embodiment 6 of the present invention, the retainer 60 further has two wing portions 65, the wing portions 65 extend upward from both ends of the retaining portion 63, and when the retainer 60 is assembled, as shown in fig. 19, the two wing portions 65 of the retainer 60 abut against the outer end surfaces 45 of the circulation fittings 40, so that the retainer 60 can also have a clamping effect. In addition, as shown in fig. 20 and 21, in embodiment 7 of the present invention, the outer end surface 45 of each circulation fitting 40 has a positioning post 46, each wing portion 65 of the retainer 60 has a positioning hole 66, and the retainer 60 is clamped to the positioning post 46 of the circulation fitting 40 by the positioning hole 66 of the wing portion 65, so as to enhance the positioning effect therebetween.

On the other hand, the number of the circulation parts is two in the above embodiments, and in fact, the number of the circulation parts may be only one according to the different configuration of the sliding rail, and further referring to fig. 22 and 23, the micro linear guide 10' of the 8 th embodiment of the present invention includes a rail 20, a slider 70, a circulation part 80, a plurality of balls 50, and a retainer 60.

The rail 20 has a first rolling groove 22 and a holding groove 24 adjacent to the first rolling groove 22 on both sides thereof.

Each side 72 of the slider 70 has two parallel second rolling grooves 73 and two opposite first return grooves 74, and the first return grooves 74 are adjacent to two ends of the second rolling grooves 73. The slider 70 is assembled to the track 20, such that a load channel 52 (as shown in fig. 24) is formed between one of the second rolling grooves 73 of each side 72 of the slider 70 and the first rolling groove 22 of the track 20.

The circulation fitting 80 has two opposite socket grooves 81, and a third rolling groove 82 and two opposite second return grooves 83 are disposed around each socket groove 81, and these second return grooves 83 are connected to two ends of the third rolling groove 82. The side portions 72 of the slider 70 are assembled in the socket grooves 81 of the circulation fitting 80, such that a non-load channel 56 is formed between the second rolling groove 73 of the side portions 72 of the slider 70 and the third rolling groove 82 of the circulation fitting 80, and such that the first reflow grooves 74 of the side portions 72 of the slider 70 correspond to the second reflow grooves 83 of the circulation fitting 80. Thus, as shown in fig. 25, the load path 52, the non-load path 56, the first return grooves 74 and the second return grooves 83 together form a circulation path 54 through which the balls 50 travel. Further, as shown in fig. 23, the circulation fitting 80 further has four turning protrusions 84, and each turning protrusion 84 abuts one second return groove 83.

After the assembly is completed by directly pressing the retainer 60 into the slider 30 in a single direction, as shown in fig. 24 and 25, the plate portion 61 of the retainer 60 abuts against the web portion 71 of the slider 70, the positioning portions 62 of the retainer 60 abut against the turning protrusions 84 of the circulation fitting 80, positioning the retainer 60, and the holding portions 63 of the retainer 60 are positioned in the holding grooves 24 of the rail 20 and abut against the balls 50 passing through the load channel 52, so that the retainer 60 provides a holding effect on the balls 50 passing through the load channel 52.

In summary, the retainer 60 provided by the present invention is pressed in along a single direction to complete the assembly with the slider 30, which is relatively easy to assemble, reduces the assembly process, and can be matched with different structural designs to improve the positioning effect, so that the assembly efficiency can be effectively improved, the assembly cost can be reduced, and the purpose of automatic assembly can be further achieved.

The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the invention thereto, but to limit the invention thereto, and any modifications, equivalents, improvements and equivalents thereof may be made without departing from the spirit and principles of the invention.

Claims (10)

1. A micro linear slide comprising:

a track;

the sliding block is slidably arranged on the track and is provided with an abdomen part and two side parts, and the side parts are connected with two opposite side edges of the abdomen part;

at least one circulation fitting slidably disposed on the rail and connected to the slider such that a circulation channel is formed between the circulation fitting, the rail and each of the sides of the slider, the circulation fitting having a plurality of diverting protrusions;

a plurality of balls arranged in the circulation channels; and

a retainer having a plate portion, a plurality of positioning portions and two retaining portions, both ends of each retaining portion being connected to the plate portion with one of the positioning portions, respectively, the plate portion of the retainer abutting against the web portion of the slider, and the positioning portions of the retaining portions abutting against the turning protrusions of the circulation fittings, and each retaining portion of the retainer abutting against the balls, wherein a width of the plate portion of the retainer is smaller than a distance between the turning protrusions of each circulation fitting.

2. The micro linear slide of claim 1, wherein the two sides of the rail are respectively provided with a first rolling groove and a holding groove adjacent to the first rolling groove, each side of the slider is provided with a second rolling groove, the second rolling grooves of the slider correspond to the first rolling grooves of the rail one to one, so that a load channel is respectively formed between the second rolling grooves of the slider and the first rolling grooves of the rail, each side of the slider is also provided with a non-load channel, and each non-load channel penetrates through two opposite end surfaces of one side; the number of the circulating accessories is two, each circulating accessory is arranged on two opposite end surfaces of the sliding block and is provided with two steering convex parts and two return grooves, each return groove is adjacent to one steering convex part, and two ends of each return groove are connected with one end of one load channel and one end of one non-load channel, so that one load channel, one non-load channel and two return grooves jointly form one circulating channel; each of the retaining portions of the retainer is located in the retaining groove of the rail and abuts against the balls passing through one of the load channels.

3. The micro linear slide of claim 1, wherein the two sides of the rail are respectively provided with a first rolling groove and a holding groove adjacent to the first rolling groove, each side of the slider is provided with two second rolling grooves parallel to each other and two opposite first reflux grooves, and a load channel is respectively formed between one second rolling groove of each side of the slider and one first rolling groove of the rail; the number of the circulating accessories is one, the circulating accessories are also provided with two opposite sleeving grooves and four steering convex parts, a third rolling groove and two opposite second reflux grooves are arranged around each sleeving groove, the second reflux grooves are connected with two ends of the three rolling grooves, one second rolling groove of each side part of the sliding block corresponds to one first rolling groove of the sliding rail, the other second rolling groove of each side part of the sliding block corresponds to one third rolling groove of the circulating accessories, and the first reflux grooves of each side part of the sliding block correspond to the second reflux grooves of the circulating accessories, so that one first rolling groove, the second rolling grooves, the third rolling grooves, the first reflux grooves and the second reflux grooves jointly form a circulating channel; each second return groove is adjacent to one of the turning convex parts, and each second return groove is connected with one of the load channels, and each retaining part of the retainer is positioned in the retaining groove of the track and is abutted against the balls passing through one of the load channels.

4. The micro linear guide of claim 1, wherein the bottom surface of the web portion of the slider has a recess, and the retainer integrally forms a protrusion from the plate portion, the protrusion being engaged in the recess.

5. The micro linear slide of claim 1, wherein the circulation assembly further comprises a plurality of positioning blocks, each of the positioning blocks protrudes from one of the steering protrusions along the extending direction of the rail, and each of the positioning portions of the retainer is engaged with one of the positioning blocks of each of the circulation assemblies.

6. The micro linear slide of claim 1, wherein the retainer further comprises a plurality of wings, each of the wings extending from one of the positioning portions in a direction away from the plate portion and abutting an outer end surface of the circulation fitting.

7. The micro linear slide of claim 6, wherein the outer end surface of the circulation assembly has a plurality of positioning posts, and each of the wings of the retainer has a positioning hole that is snapped into the positioning posts.

8. The micro linear slide of claim 1, wherein the retainer further has a plurality of wings, each of the wings extending upwardly from one end of the retainer and abutting an outer end surface of the circulation fitting.

9. The micro linear slide according to claim 1, wherein each of the holding portions has a rectangular cross-sectional shape, and the width-to-thickness ratio of each of the holding portions is not less than 1.5.

10. The micro linear slide according to claim 1, wherein each of the positioning portions has a rectangular cross-sectional shape, and the aspect ratio of each of the positioning portions is not less than 1.5.