Safety mechanism

Abstract

To provide a safety mechanism capable of covering a gap between an insert body and a through hole.SOLUTION: A safety mechanism is a safety mechanism of a device in which an insert body 93 moves inside a through hole 87. The safety mechanism comprises a cover 3 that covers the through hole 87 and is rotatably supported by the insert body 93, and a guide 5 that rotates the cover 3 in a state of covering the through hole 87 by movement of the insert body 93.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a safety mechanism for a device in which an inserted body moves inside a through hole.

Background Art

[0002] In a device in which an inserted body moves inside a through hole, a safety mechanism is provided to prevent hands or foreign objects from entering between the inserted body and the through hole. As a safety mechanism, "a head portion 1 that supports a part gripping portion and moves along a predetermined orbit having a curved portion, a drive portion that moves the head portion 1 along the predetermined orbit, and a cover 2 having a cover main body 4 and a rotating cover 5 are provided. The cover main body 4 has a partition plate portion 4a parallel to the plane in which the predetermined orbit is located. The partition plate portion 4a has an orbit hole 6 along the predetermined orbit. The rotating cover 5 is sized to cover the orbit hole 6 and is rotatably provided in parallel with the partition plate portion 4a. It has a radially long notch 8. The head portion 1 is inserted through the orbit hole 6 and the notch 8 and is movable along the orbit hole 6. The notch 8 allows the head portion 1 to move along the longitudinal direction while restricting movement in the short hand direction" mechanism has been proposed (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above mechanism, as shown in Fig. 6 (a) of Patent Document 1, depending on the position of the head portion (inserted body) 1, there are cases where the gap between the head portion (inserted body) 1 and the orbit hole (through hole) 6 is not covered by the rotating cover (cover). Here, the terms in () are the terms used in the present invention. The problem to be solved by the present invention is to provide a safety mechanism with a simple structure that can cover the gap between the inserted body and the through hole.

Means for Solving the Problem

[0005] A safety mechanism according to an aspect of the present invention is a safety mechanism of a device in which an inserted body moves in a through hole, and includes a cover that covers the through hole and is rotatably supported by the inserted body, and a guide that rotates the cover in a state of covering the through hole by the movement of the inserted body.

Effect of the Invention

[0006] According to the present invention, a gap between the inserted body and the through hole can be covered with a simple structure.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0008] <Summary> A first safety mechanism according to an aspect of the present invention is a safety mechanism for a device in which an insertion body moves in a through hole. The first safety mechanism includes a cover that covers the through hole and is rotatably supported by the insertion body, and a guide that rotates the cover in a state of covering the through hole by the movement of the insertion body. Thereby, even when the insertion body moves, the cover is guided in a state of covering the through hole. A second safety mechanism according to another aspect of the present invention is the first safety mechanism. The guide is arranged on at least one side of both sides in a direction intersecting the moving direction of the insertion body. An end face of the cover on the side facing the guide is configured such that as the insertion body moves, the cover rotates around the insertion body in a state of covering the through hole. Thereby, it can be implemented by configuring the opposing portion between the movable cover and the guide so that the cover rotates in a state of covering the through hole, and it can be implemented with a simple configuration. A third safety mechanism according to another aspect of the present invention is that in the first or second safety mechanism, the insert body moves between a first position and a second position in the through hole, and the cover extends toward the second position and covers the through hole when the insert body is located at the first position, and a first region, and a second region that extends toward the first position and covers the through hole when the insert body is located at the second position, and one angle between the first region and the second region is less than 180 degrees. Thereby, the dimension in the direction connecting the first position and the second position in the cover can be reduced. A fourth safety device according to another aspect of the present invention is that the through hole is arc-shaped and long in a first direction when viewed from the insertion direction of the insert body, and the guide is provided on one side between the first region and the second region, and has an arc region that is arc-shaped when viewed from the insertion direction on a surface facing the end face on the guide side of the cover. Thereby, the cover can be smoothly guided.

[0009] <Embodiment> The safety mechanism 1 according to the embodiment will be described in detail with reference to the drawings as an example provided in a conveying device 7 that uses a chain member or a belt member and conveys an object to be conveyed. Note that the safety mechanism 1 is not provided in FIGS. 1 and 2.

[0010] 1. Overall Configuration As an example, the safety mechanism 1 is provided in a conveying device 7 that uses a chain member. Here, the direction in which the object to be conveyed is conveyed is defined as the conveying direction. As shown in FIG. 1, the conveying device 7 includes one or a plurality of conveyor units 70, a drive unit 72 for driving the conveyor unit 70, and a tension applying mechanism 74. There are two conveyor units 70 spaced apart in a direction orthogonal to the conveying direction and are connected by a connecting member 76. Here, the conveyance direction of the object to be conveyed is also referred to as the longitudinal direction of the conveyance device 7 or simply the longitudinal direction, the direction in which the drive shaft 78 of the drive unit 72 extends or the direction in which the two conveyor units 70 are arranged side by side is also referred to as the width direction of the conveyance device 7 or simply the width direction, and the direction orthogonal to the longitudinal direction and the width direction of the conveyance device 7 is also referred to as the vertical direction.

[0011] 2. Each part (1) Conveyor unit, etc. The conveyor unit 70 includes a frame 80 extending in the conveyance direction, a sprocket (not shown in the figure) provided on one end (drive unit 72) side of the frame 80 in the conveyance direction, a driven roller 82 provided at the other end of the frame 80 in the conveyance direction (see (b) of FIG. 2), and a chain member 84 that winds around the sprocket and the driven roller 82 and moves in a circulating manner. Note that the driven roller 82 is rotatably fixed to the frame 80 via a pair of plates 86, respectively. Note that the chain member 84 has an inner link and an outer link connected thereto, but in the figure, it is in a belt shape for convenience.

[0012] (2) Tension applying mechanism The tension applying mechanism 74 applies tension to the chain member 84 that moves in a circulating (orbiting) manner. As shown in FIG. 2, the tension applying mechanism 74 includes a clutch unit 90 having a one-way clutch that allows rotation in one direction around the clutch shaft, an arm 92 connected to the clutch shaft of the clutch unit 90 and rotatable around the clutch shaft, and a tension pulley 94 rotatably supported by the arm 92 and applying tension to the chain member 84. Thereby, the arm 92 can rotate only in the first direction, which is the direction in which tension is applied, around the clutch shaft. The tension pulley 94 is rotatably supported by a fixed shaft 93 (see (b) of FIG. 3) fixedly supported by a pair of arms 92. As shown in FIG. 1, the pair of arms 92 are arranged outside the pair of plates 86. That is, the fixed shaft 93 (corresponding to an example of the “inserted body” of the present invention) passes through the long holes 87 (corresponding to an example of the “through holes” of the present invention) of the pair of plates 86 and is fixed to the arm 92 by screws 96 outside the plate 86.

[0013] (3) Safety mechanism Mainly, it will be described with reference to FIG. 3. The safety mechanism 1 mainly has a function of preventing fingers, foreign objects, etc. from being pinched between the long hole 87 of the plate 86 (see FIG. 1) and the fixed shaft 93 moving in the long hole 87. The safety mechanism 1 has a cover 3 that covers the long hole 87 and is rotatably supported by the fixed shaft 93, and a guide 5 that rotates the cover 3 in accordance with the movement of the fixed shaft 93. Thus, the safety mechanism 1 is configured with a simple structure. Here, the fixed shaft 93 moves in one direction (the direction in which the tension acts) between one end (upper end) and the other end (lower end) in the longitudinal direction of the long hole 87 (the moving direction of the fixed shaft 93 in the long hole 87). The upper end corresponds to an example of the “first position” of the present invention, and the lower end corresponds to an example of the “second position” of the present invention, respectively. The guide 5 is arranged on at least one side, i.e., the clutch unit 90 side, of both sides in a direction intersecting the moving direction of the fixed shaft 93. In other words, the guide is arranged on one side in the direction sandwiching the long hole 87.

[0014] (3-1) Cover The cover 3 is made of a metal plate, a resin plate, or the like. The cover 3 has an insertion portion 30 through which the fixed shaft 93 passes. Here, the insertion portion 30 is formed by a through hole. Note that the reference numeral of the through hole is also “30”. Thereby, the cover 3 is rotatably supported by the fixed shaft 93. Here, the fixed shaft 93 has a cylindrical shape, and the through hole 30 also has a substantially circular shape of the same size. Thereby, the rotation of the cover 3 around the fixed shaft 93 becomes smooth. Cover 3 has a first region 31 that extends toward the lower end (the other end) of the long hole 87 and covers the long hole 87 in a state where the fixed shaft 93 passing through the through hole 30 is located at the upper end (one end) of the long hole 87 (refer to the state in FIG. 4(a)), a second region 32 that extends toward the upper end (one end) of the long hole 87 and covers the long hole 87 in a state where the fixed shaft 93 passing through the through hole 30 is located at the lower end (the other end) of the long hole 87 (refer to the state in FIG. 4(c)), and an intermediate region 34 located between the first region 31 and the second region 32. Note that the through hole 30 is provided in the intermediate region 34. Here, the first region 31 and the second region 32 have substantially the same length and shape.

[0015] The angle between the first region 31 and the second region 32 is configured to be less than 180 degrees. Here, the long hole 87 is in an arc shape that is long in the vertical direction. The first region 31 and the second region 32 extend in a range where the angle therebetween is 100 to 120 degrees. That is, when viewed from the extending direction of the fixed shaft 93 (the thickness direction of the cover), the cover 3 as a whole has a "V" shape, a "U" shape, an arc shape, or a shape similar thereto (hereinafter referred to as an arc shape). Here, a guide 5 is provided between the first region 31 and the second region 32 where the angle is 100 to 120 degrees. The end face 35 on the guide 5 side of the cover 3 is configured such that the cover 3 rotates around the fixed shaft 93 in a state where the cover 3 covers the long hole 87 as the fixed shaft 93 moves. Here, when viewed from the insertion direction of the fixed shaft 93, the end face 36 on the guide 5 side of the intermediate region 34 is arc-shaped, the end face 37 on the guide 5 side of the first region 31 is linear and extends in the tangential direction from the end face 36 of the intermediate region 34, and the end face 38 on the guide 5 side of the second region 32 is linear and extends in the tangential direction from the end face 36 of the intermediate region 34. Note that the end faces 37 and 38 on the guide 5 side of the first region 31 and the second region 32 may be curved instead of linear. The end face 39 on the side of the cover 3 opposite to the guide 5 is configured not to interfere with the surrounding members when the cover 3 rotates as the fixed shaft 93 moves. Here, it is arc-shaped as a whole.

[0016] The cover 3 and the guide 5 are configured such that in a state where the fixed shaft 93 is located at the upper end of the long hole 87 (refer to the state in FIG. 4(a)), the tip (the end opposite to the fixed shaft 93) of the first region 31 is located outside the long hole 87 in the longitudinal direction thereof (i.e., the extending direction of the first region 31) with respect to the guide 5 (lower side in FIG. 4(a)), and the tip (the end opposite to the fixed shaft 93) of the second region 32 is located outside the long hole 87 in the direction orthogonal to the longitudinal direction thereof (i.e., the extending direction of the second region 32) with respect to the guide 5 (left side in FIG. 4(a)). The cover 3 and the guide 5 are configured such that in a state where the fixed shaft 93 is located at the lower end of the long hole 87 (refer to the state in FIG. 4(c)), the tip (the end opposite to the fixed shaft 93) of the first region 31 is located outside the long hole 87 in the direction orthogonal to the longitudinal direction thereof (i.e., the extending direction of the first region 31) with respect to the guide 5 (left side in FIG. 4(c)), and the tip (the end opposite to the fixed shaft 93) of the second region 32 is located outside the long hole 87 in the longitudinal direction thereof (i.e., the extending direction of the second region 32) with respect to the guide 5 (upper side in FIG. 4(c)).

[0017] (3-2) Guide The guide 5 guides the cover 3 rotatably supported by the fixed shaft 93 to rotate around the fixed shaft 93 as the fixed shaft 93 moves in a state where the long hole 87 is covered. Specifically, the guide 5 performs a guiding function by contacting the end face 35 of the cover 3. The guide 5 is plate-shaped and fixed to the plate 86. The end face of the guide 5 on the cover 3 side is configured such that as the fixed shaft 93 moves, the cover 3 rotates around the fixed shaft 93 in a state where the cover 3 covers the long hole 87. The guide 5 is configured not to interfere with the second region 32 of the cover 3 when the fixed shaft 93 is located at the first position (the state in FIG. 4(a)), and is configured not to interfere with the first region 31 of the cover 3 when the fixed shaft 93 is located at the second position (the state in FIG. 4(c)). Here, when viewed from the insertion direction of the fixed shaft 93, the end face 51 of the guide 5 has an arc region 53 that is arc-shaped on the cover 3 side. Both ends of the arc region 53 are located on the side opposite to the cover 3 from the intersection points with the virtual line passing through the center of the arc and extending along the longitudinal direction of the long hole 87. In other words, the central angle of the arc region 53 is 180 degrees or more. The end face 51 of the guide 5 has a linear region 55 extending along the long hole 87 on the side opposite to the cover 3.

[0018] 3. Operation The operation of the tension pulley 94 moving from the upper end (the first position) to the lower end (the second position) along the long hole 87 of the plate 86 will be described with reference to FIG. 4. Here, the movement of the tension pulley 94 will be described as the movement of the fixed shaft 93. (1) The state where the fixed shaft 93 is located at the upper end of the long hole 87 is the state shown in (a) of FIG. 4. In this state, the first region 31 of the cover 3 extends downward, the second region 32 extends in the lateral direction orthogonal to the downward direction, and the end face 35 of the cover 3 abuts against the guide 5. In this state, the long hole 87 is completely covered by the first region 31 and the intermediate region 34. (2) When the fixed shaft 93 moves downward from the upper end within the long hole 87, as the fixed shaft 93 moves, the cover 3 rotates while the end face 35 of the cover 3 is guided by the guide 5. Here, the direction of rotation is clockwise. Furthermore, when the fixed shaft 93 moves downward, eventually, the fixed shaft 93 is located at approximately the center in the longitudinal direction of the long hole 87. This state is the state shown in (b) of FIG. 4. In this state, the end face 35 on the intermediate region 34 side of the cover 3 abuts against the guide 5. Also, in this state, the cover 3 is inclined such that the first region 31 extends downward toward the side where the guide 5 is located. Even in this state, the long hole 87 is completely covered by the first region 31, the second region 32, and the intermediate region 34. (3) When the fixed shaft 93 moves downward from the center within the long hole 87, as the fixed shaft 93 moves, the cover 3 rotates while the end face 35 of the cover is guided by the guide 5. Furthermore, when the fixed shaft 93 moves downward, eventually the fixed shaft 93 is positioned at the lower end of the long hole 87. This state is the state shown in (c) of FIG. 4. In this state, the cover 3 is inclined so that the second region 32 extends upward along the long hole 87. Even in this state, the long hole 87 is completely covered by the second region 32 and the intermediate region 34. (4) In this way, even when the fixed shaft 93 moves from the upper end to the lower end of the long hole 87, the gap between the fixed shaft 93 and the long hole 87 is covered by the cover 3 without being exposed.

[0019] 4. Size of the Cover When the long hole 87 is long in the first direction (here, the vertical direction), the difference in size between the cover that only moves in the first direction and the cover 3 described in the embodiment will be described with reference to FIG. 5. The vertically long cover 903 is sized to be able to cover all of the long hole 87, as shown in FIGS. 5(a) and 5(b). When the fixed shaft 93 is positioned at the upper end of the long hole 87, as shown in FIG. 5(a), the arc-shaped cover 3 has its second region 32 extending laterally. Therefore, when comparing the extension amount upward from the fixed shaft 93, the arc-shaped cover 3 can be made shorter by L1 compared to the vertically long cover 903. When the fixed shaft 93 is positioned at the lower end of the long hole 87, as shown in FIG. 5(b), the arc-shaped cover 3 has its first region 31 extending laterally. Therefore, when comparing the extension amount downward from the fixed shaft 93, the arc-shaped cover 3 can be made shorter by L2 compared to the vertically long cover 903. In this way, the cover 3 described in the embodiment can have a smaller dimension in the vertical direction compared to the cover 903 that is long in the vertical direction, in other words, that only moves in the vertical direction. Thereby, the space for accommodating the safety mechanism can be made smaller.

[0020] 5. Others (1) Long Hole (Through-Hole) The safety mechanism 1 was provided in the arc-shaped long hole 87 that is long in the first direction (vertical direction), but it can also be provided for through-holes of other shapes. As another shape, there is an oblong hole that is long in the first direction, which will be described with reference to FIG. 6. The plate is provided with an oblong hole 87A extending in the first direction, and an inserted body 93 moves along the first direction within the oblong hole 87A. The cover 3A has a first region 31A, a second region 32A, and an intermediate region 34A, and has an insertion portion (through hole) in the intermediate region 34A. The angle between the first region 31A and the second region 32A is in the range of 80 to 130 degrees. The first region 31A and the second region 32A are configured to cover the oblong hole 87A even when the cover 3A rotates around the inserted body 93. The end face 35A on the guide 5A side of the cover 3A is arc-shaped at the portion corresponding to the intermediate region 34A, and the portions corresponding to the first region 31A and the second region 32A are configured to extend in a tangential direction from the arc of the intermediate region 34A. The guide 5A is cylindrical or disk-shaped here and is provided on the side where the angle between the first region 31A and the second region 32A is small.

[0021] (2) Guide position The safety mechanism 1 is arranged between the first region 31 and the second region 32 on the side where the angle between the first region 31 and the second region 32 is small, but it may also be arranged between the first region and the second region on the side where the angle is large, which will be described with reference to FIG. 7. The oblong hole 87 is long in the first direction and is curved in an arc shape here, and the inserted body 93 moves within the oblong hole 87. The cover 3B has a first region 31B, a second region 32B, and an intermediate region 34B, and has an insertion portion (through hole) in the intermediate region 34B. The angle between the first region 31B and the second region 32B is in the range of 80 to 130 degrees. The first region 31B and the second region 32B are configured to cover the oblong hole 87 even when the cover 3B rotates around the inserted body 93. The guide 5B is provided on the side where the angle between the first region 31B and the second region 32B is large. The end face 35B on the guide 5B side in the cover 3B and the end face 53B on the cover 3B side in the guide 5B are configured to rotate around the insertion body 93 with the cover 3B covering the long hole 87B as the insertion body 93 moves within the long hole 87. Here, the end face 35B of the cover 3B and the end face 53B of the guide 5B are arc-shaped. Note that the shape of the guide 5B only needs to have an end face 53B that allows the cover 3B to rotate as the insertion body 93 moves, and the shape of the end face that does not face the cover 3B is not particularly limited. Considering the size of the safety mechanism 1B, shapes such as "L" shape, arc shape, etc. as shown in FIG. 7 are preferable.

[0022] (3) Shape of the cover The covers 3, 3A, 3B were in the shapes of "V" shape, "U" shape, "L" shape, arc shape, or shapes similar thereto, but other shapes may also be acceptable. As other shapes, as shown in FIG. 8, circular shape, elliptical shape, or shapes similar thereto may also be acceptable. As shown in FIG. 8(a), the cover 3C has a through hole 30C, and the guide 5C is arranged in the through hole 30C. Also in this case, the cover 3C has a first region 31C, a second region 32C, and an intermediate region 34C. In the cover 3C, the opening end face 35C on the side opposite to the insertion body 93 of the through hole 30C becomes a guide surface guided by the guide 5C. The opening end face 35C in the cover 3C and the end face 53C on the side opposite to the insertion body 93 in the guide 5C are configured to rotate around the insertion body 93 with the cover 3C covering the long hole 87 as the insertion body 93 moves within the long hole 87. As shown in FIG. 8(b), the cover 3D has a first region 31D, a second region 32D, and an intermediate region 34D. In the cover 3D, the end face 35D on the side where the angle between the first region 31D and the second region 32D is large becomes a guide surface guided by the guide 5D. The end face 35D in the cover 3D and the end face 53D on the cover 3D side in the guide 5D are configured to rotate around the insertion body 93 with the cover 3D covering the long hole 87 as the insertion body 93 moves within the long hole 87.

[0023] <Modification example> The safety mechanism 1 according to the embodiments has been described above. However, the present invention is not limited to these embodiments, and for example, the following modifications may be made. Also, combinations of embodiments and modifications may be used, or combinations of modifications may be used. Further, the present invention includes examples not described in the embodiments or modifications and design changes that do not depart from the gist. 1. Device In the embodiment, an example in which the safety mechanism 1 is provided in the tension mechanism of a conveying device that uses a chain member or a belt member and conveys an object to be conveyed has been described. However, a safety mechanism can be provided for any device in which an inserted body moves within a through hole. As such a device, in addition to the conveying device, there is a stacking and unstacking device 101 or the like that moves a loaded object such as a container up and down between a pair of frames 103 as shown in FIG. 9. The stacking and unstacking device 101 has a structure in which a shaft body 107 with a hook 105 for supporting a loaded object attached to its tip is inserted through a long through hole 109 that is long in the vertical direction of the frame 103 from the inside to the outside of the frame 103 and is supported by a plate 111 outside the frame 103. A safety mechanism can be provided between the through hole 109 of such a stacking and unstacking device 101 and the shaft body 107.

[0024] 2. Moving Direction of Inserted Body (1) The inserted body 93 moved only in one direction in which tension acts within the long hole 87. However, the inserted body may move in both directions along the longitudinal direction of the long hole, or may move only in the direction opposite to the one direction. (2) The inserted body 93 was made movable between one end (upper end) and the other end (lower end) of the long hole 87. However, it may move in one direction (including upward and downward) or in both directions between a position on the other end side (the first position) of the long hole 87 than one end and a position on the one end side (the second position) of the long hole 87 than the other end.

[0025] 3. Cover (1) The insertion part 30 was constituted by a circular through-hole, but it suffices that the cover 3 can rotate around the insertion body 93. For example, it may be a through-hole having a polygonal shape such as a square shape, an elliptical shape, a pentagonal shape, or a shape similar thereto, or a shape in which a part of a circular shape, a square shape, an elliptical shape, a polygonal shape, or a shape similar thereto is missing. (2) The first region 31 and the second region 32 were of the same shape, size, and thickness, but they may have different shapes, different sizes, and different thicknesses. (3) The cover 3 was arranged inside the plate 86, but it may be provided outside the plate 86 (the side with the arm), or may be provided on both sides. (4) Through-holes were provided in the pair of plates 86, and there were two combinations of the through-holes and the insertion body, and the safety mechanism 1 was provided for the two combinations. However, the combination of the through-holes and the insertion body may be one set or three sets or more, and the safety mechanism 1 may be provided at a location where a person's finger or foreign object is likely to enter.

[0026] 4. Guide (1) The guides 5, 5B were arranged on one side in a direction intersecting the moving direction of the fixed shaft 93, but if the cover can be configured to rotate while covering the through-hole as the insertion body moves, they may be arranged on both sides in the intersecting direction. However, from the viewpoints of the number of parts, the number of assembly steps, and the weight, it is preferable to arrange them on one side in the intersecting direction. Also, the position, size, etc. of the guides may be determined in consideration of the space of the device provided with the safety mechanism. (2) The end face of the guide 5 had a linear region 55 (see FIG. 3) on the side opposite to the cover 3 side, but the guide may have an overall circular shape or a crescent (arc-shaped) shape. The crescent has an arc-shaped end face on the cover 3 side and an arc-shaped end face on the side opposite to the cover 3.

Explanation of Reference Numerals

[0027] 1 Safety mechanism 3 Cover 3a Through-hole 5 Guide 86 Plate 87 Long hole (through-hole) 93 Fixed shaft (inserted body)

Claims

1. In a safety mechanism of a device in which an inserted body moves within a through hole, a cover that covers the through hole and is rotatably supported by the inserted body, and a guide that rotates the cover in a state of covering the through hole by the movement of the inserted body are provided, a safety mechanism.

2. The guide is arranged on at least one side of both sides in a direction intersecting the moving direction of the inserted body, and an end face on the side of the cover facing the guide is configured such that as the inserted body moves, the cover rotates around the inserted body in a state of covering the through hole. The safety mechanism according to Claim 1.

3. The inserted body moves between a first position and a second position in the through hole, and the cover has a first region that extends toward the second position and covers the through hole when the inserted body is at the first position, and a second region that extends toward the first position and covers the through hole when the inserted body is at the second position, and one angle between the first region and the second region is less than 180 degrees. The safety mechanism according to Claim 1 or 2.

4. When viewed from the insertion direction of the inserted body, the through hole has an arc shape that is long in a first direction, the guide is provided on the one side between the first region and the second region, and has an arc region that is arc-shaped when viewed from the insertion direction on a surface facing the end face on the guide side of the cover, The safety mechanism according to Claim 3.

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