Connecting links and chains

Abstract

A connecting link comprises a connecting pin, a first link plate, a second link plate, and a nut member. The connecting pin has an external thread portion and a frustum-shaped portion. The first link plate has holes at one end and the other end in the longitudinal direction. At least one of the holes at one end and the other end of the first link plate constitutes a first pin hole. The second link plate has holes at one end and the other end in the longitudinal direction. At least one of the holes at one end and the other end of the second link plate constitutes a second pin hole. The nut member can be screwed into the external thread portion of the connecting pin. According to the connecting link of the present invention, unnecessary elongation of the chain after cutting and reconnecting can be suppressed.

Description

Technical Field

[0001] The present invention relates to a connecting link for cutting and reconnecting a chain and a chain cut and reconnected using the connecting link. Background Art

[0002] In the past, for example, a transmission chain described in Japanese Patent Laid-Open No. 2011-94660 is known. This transmission chain includes inner link plates and outer link plates that are alternately arranged in the longitudinal direction of the chain. The inner link plates and the outer link plates are arranged in series so that the ends of the inner link plates overlap with the ends of the outer link plates in the width direction of the chain. The inner link plates and the outer link plates that are adjacent to each other in the longitudinal direction of the chain are connected to each other at their ends via connecting pins so that they can rotate freely. The end of the connecting pin is pressed into the pin hole of the outer link plate. In other words, the connecting pin is in a so-called interference fit state in which it is non-rotatably engaged with the pin hole of the outer link plate. Summary of the Invention

[0003] Drive chain users sometimes cut the chain to the desired length on site before splicing it. In this case, if the connecting pin has a clearance fit with the pinhole of the outer link plate, allowing the pin to rotatably engage, the user can easily insert the end of the connecting pin into the pinhole. However, with this clearance fit, the inner circumference of the pinhole and the outer circumference of the connecting pin slide against each other. Consequently, wear over time can cause the pinhole diameter to expand, leading to unnecessary stretching of the chain after cutting and splicing.

[0004] In contrast, if the connecting pin is fitted into the pin hole of the outer link plate in a so-called interference fit, where the connecting pin is non-rotatably engaged in the pin hole, the inner circumference of the pin hole and the outer circumference of the connecting pin will not slide. This prevents unnecessary stretching of the chain after the splice is cut or reconnected. However, to achieve this so-called interference fit, the connecting pin's end must be pressed into the pin hole using a hydraulic machine or hammered into the hole. Therefore, while this interference fit can prevent unnecessary stretching of the chain after the splice is cut or reconnected, it also presents the problem of requiring significant effort and labor to insert the connecting pin during the splice.

[0005] A connecting link for solving the above-mentioned problem, which is used for cutting and reconnecting a chain, wherein the chain is composed of a plurality of links arranged in series in the longitudinal direction of the chain, wherein the links adjacent to each other in the longitudinal direction are connected to each other via a connecting pin so as to be freely rotatable, and the connecting link comprises: a connecting pin having an external threaded portion at a front end and a frustum-shaped portion on a base end side closer to the external threaded portion, wherein the frustum-shaped portion is formed so that the cross-sectional area gradually increases toward the base end side; a first link plate having holes at one end and the other end in the longitudinal direction for inserting the connecting pin, and At least one of the hole at the one end and the hole at the other end constitutes a first pin hole in which the base end of the connecting pin is non-rotatably embedded; a second link plate has holes at one end and the other end in the length direction through which the connecting pin can be inserted, and at least one of the hole at the one end and the hole at the other end constitutes a second pin hole in which the external threaded portion of the connecting pin can pass and the inner side surface is formed in a concave conical surface shape corresponding to the outer side surface of the frustum-shaped portion; and a nut member that can be screwed into the external threaded portion of the connecting pin.

[0006] The chain that solves the above-mentioned problem comprises: a plurality of chain links arranged in series along the length direction of the chain; a connecting pin that connects the chain links adjacent to each other in the length direction so that they can rotate freely; and the connecting chain link, which is located midway in the length direction of the chain and connects the chain link adjacent to the connecting chain link on one side of the length direction with the chain link adjacent to the other side. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a perspective view showing a partially exploded view of a chain according to one embodiment.

[0008] Figure 2 This is a plan view showing the partially broken-away portion of the connecting link in the chain.

[0009] Figure 3 It will Figure 2 A top sectional view showing an enlarged portion of FIG.

[0010] Figure 4 This is a perspective view showing a portion of the connecting link in an exploded manner.

[0011] Figure 5 This is a perspective view showing a portion of the connecting link of the first modified example in an exploded manner.

[0012] Figure 6 This is a perspective view showing a portion of an exploded connection link according to a second modification.

[0013] Figure 7This is a plan cross-sectional view showing an enlarged portion of a connecting link according to a third modified example. DETAILED DESCRIPTION

[0014] Hereinafter, embodiments of the connecting link and the chain will be described with reference to the drawings.

[0015] <Overall composition>

[0016] like Figure 1 As shown, the chain 11 of this embodiment includes a plurality of inner links 12 and a plurality of outer links 13 arranged in series along the longitudinal direction X of the chain 11, and a connecting link 14. Specifically, the chain 11 is a chain 11 that has been cut and reconnected by a user of the chain 11, for example, at the site of use of the chain 11. Therefore, the chain 11 has a connecting link 14 midway along its longitudinal direction X. When viewed from the position of the connecting link 14, inner links 12 are located on one side and the other side of the chain 11 in the longitudinal direction X. The connecting link 14 then connects the inner link 12 adjacent to one side of the chain 11 in the longitudinal direction X with the inner link 12 adjacent to the other side of the chain 11 in the longitudinal direction X.

[0017] The inner links 12 and outer links 13 are arranged alternately in the longitudinal direction X of the chain 11. Each inner link 12 has a pair of inner link plates 15 that are spaced apart and face each other in the width direction Y. The width direction Y is perpendicular to the longitudinal direction X of the chain 11. Each outer link 13 has a pair of outer link plates 16 that are arranged to sandwich the inner link plates 15 adjacent to the inner link 12 in the longitudinal direction X of the chain 11 from the outside in the width direction Y. The inner link plates 15 and outer link plates 16 are formed, for example, from steel through forging, stamping, or the like. Each inner link plate 15 and outer link plate 16 is formed into a generally rectangular plate shape that extends in the longitudinal direction X of the chain 11.

[0018] Circular bushing holes 17 are formed at both ends of the inner link plates 15 in the longitudinal direction, extending through the thickness of the inner link plates 15. A cylindrical bushing 18 is then assembled between each pair of opposing inner link plates 15, maintaining a spacing in the width direction Y between the opposing inner link plates 15. Specifically, both ends of the bushing 18 are non-rotatably fitted into the bushing holes 17 of the paired inner link plates 15. Furthermore, a roller 19, having a larger diameter than the bushing 18, is rotatably fitted onto the bushing 18. In other words, the roller 19 is supported in a so-called loose fit, rotatably relative to the bushing 18.

[0019] At both ends of the outer link plate 16 in the longitudinal direction, circular pin holes 20 having a diameter slightly smaller than the inner diameter of the bushing 18 are formed so as to penetrate the outer link plate 16 in the thickness direction. Both ends of a substantially cylindrical connecting pin 21 are press-fitted into the pin holes 20 of the paired outer link plates 16. The connecting pin 21 is rotatably inserted into the bushing 18, which serves as the pin insertion portion of the inner link 12. Then, as shown in FIG. Figure 1 As shown, the inner link 12 and the outer link 13 are rotatably connected via a connecting pin 21 in a state where the ends of the inner link plate 15 and the outer link plate 16 adjacent to each other in the longitudinal direction X of the chain 11 overlap. The connecting pin 21 has a flange-shaped base end ( Figure 1 The base end of the connecting pin 21 is locked to the outer surface of the outer link plate 16 on one side of each pair. The tip end of the connecting pin 21 protrudes outward from the pin hole 20 of the outer link plate 16 on the other side of each pair. In this state, the fixing pin 22 is attached to the tip end protruding outward from the pin hole 20 of the outer link plate 16 to prevent the connecting pin 21 from being removed from the pin hole 20.

[0020] <Connecting links>

[0021] like Figure 1 、 Figure 2 and Figure 3 As shown, the connecting link 14 includes a first link plate 31, a second link plate 32, a connecting pin 33, and a nut member 34. The first link plate 31 and the second link plate 32 have the same generally rectangular plate shape as the outer link plate 16. The connecting pin 33 has the same generally cylindrical shape as the connecting pin 21. Like the inner link plate 15 and the outer link plate 16, the first link plate 31 and the second link plate 32 are formed from steel by forging, stamping, or the like.

[0022] <Connecting pin>

[0023] First, the connecting pin 33 has a shaft portion 35, an external thread portion 36, and a frustum-shaped portion 37. The external thread portion 36 is provided at the front end of the connecting pin 33. The outer diameter of the external thread portion 36 is smaller than the outer diameter of the shaft portion 35. The frustum-shaped portion 37 is located closer to the base end side than the external thread portion 36 of the connecting pin 33, that is, between the shaft portion 35 and the external thread portion 36. The cross-sectional area of ​​the frustum-shaped portion 37 gradually increases toward the base end side. The frustum-shaped portion 37 is formed in a frustum-shaped shape in which the outer side surface 37a is in the shape of a frustum-shaped cone in such a way that the cross-sectional shape of the front end is a circle slightly larger than the cross-sectional shape of the external thread portion 36 and the cross-sectional shape of the base end is a circle of the same size as the cross-sectional shape of the shaft portion 35.

[0024] <First link plate>

[0025] like Figure 4As shown, the first link plate 31 has first pin holes 39 at one and other ends of its longitudinal direction, through which the shaft portion 35 of the connecting pin 33 is inserted and into which the base end portion 38 of the connecting pin 33 is non-rotatably fitted. The first pin holes 39 have a pair of planar inner side surfaces 39a extending along the longitudinal direction of the first link plate 31 and a pair of concavely curved inner side surfaces 39b connecting the ends of the two planar inner side surfaces 39a. The width of the opening of the first pin hole 39 along the short side of the first link plate 31, which corresponds to the distance between the two opposing planar inner side surfaces 39a, is approximately equal to the outer diameter of the shaft portion 35 of the connecting pin 33. Furthermore, the width of the opening of the first pin hole 39 along the long side of the first link plate 31, which corresponds to the longest distance between the two opposing concavely curved inner side surfaces 39b, is greater than the outer diameter of the shaft portion 35 of the connecting pin 33.

[0026] <Rotation restriction section>

[0027] like Figure 4 As shown, the base end 38 of the connecting pin 33, which is non-rotatably engaged with the first pin hole 39, is formed to have a cross-sectional shape identical to the opening of the first pin hole 39. Specifically, the base end 38 of the connecting pin 33 includes a pair of planar outer side surfaces 38a that, when inserted into the first pin hole 39, make surface contact with the planar inner side surface 39a of the first pin hole 39; and a pair of convexly curved outer side surfaces 38b that connect the ends of the two planar outer side surfaces 38a. Furthermore, the convexly curved outer side surfaces 38b make surface contact with the concavely curved inner side surface 39b of the first pin hole 39 when the base end 38 of the connecting pin 33 is inserted into the first pin hole 39. Furthermore, the base end 38 of the connecting pin 33 is formed so that its axial length is longer than the thickness of the first link plate 31. Therefore, in this embodiment, the planar inner surface 39a of the first pin hole 39 of the first link plate 31 constitutes a rotation restricting portion, which restricts relative rotation of the connecting pin 33 relative to the first pin hole 39 by abutting against the planar outer surface 38a of the base end portion 38 of the connecting pin 33.

[0028] like Figure 1 As shown, the connecting pin 33 is supported on the first link plate 31 in a so-called cantilevered state, with the base end 38 of the connecting pin 33 press-fitted into the first pin hole 39 of the first link plate 31. In this case, the connecting pin 33 is integrally connected to the first link plate 31 in a so-called interference fit, with the base end 38 non-rotatably engaged with the first pin hole 39. In other words, when the chain 11 is cut or reconnected, the first link plate 31 connecting the links 14 is used with a pair of connecting pins 33 assembled in a cantilevered state into a pair of first pin holes 39 formed at one and the other longitudinal ends of the first link plate 31.

[0029] <Second link plate>

[0030] like Figure 1 、 Figure 2 and Figure 4 As shown, the second link plate 32 has fitting holes 40 formed through it at one and other ends in its longitudinal direction. These fitting holes 40 are circular, with a diameter larger than the shaft portion 35 of the connecting pin 33. A cylindrical connecting bushing 41 is fixed in engagement with the fitting holes 40. The axial length of the connecting bushing 41 is slightly greater than the thickness of the second link plate 32. Furthermore, the axial length of the connecting bushing 41 can be the same as the thickness of the second link plate 32, or slightly less. For example, the connecting bushing 41 is formed from a material, such as stainless steel, that is harder than the steel used to make the second link plate 32. In other words, the connecting bushing 41, a separate component from the second link plate 32, is made of a different material than the second link plate 32. In other words, the connecting bushing 41 and the second link plate 32 differ in their materials, at least including their surface properties, and, as an example, in their hardness. A second pin hole 42 is formed through the connecting bushing 41 in the axial direction, and the external thread portion 36 of the connecting pin 33 can pass through the second pin hole 42. The inner side surface 42a of the second pin hole 42 is formed in a concave truncated cone shape, which is a type of concave conical surface shape, corresponding to the outer side surface 37a of the truncated cone-shaped portion 37 of the connecting pin 33.

[0031] <Nut component>

[0032] like Figure 1 and Figure 2 As shown, the nut member 34 is configured to be screwed with the external thread portion 36 at the front end of the connecting pin 33. When the front end portion of the connecting pin 33, which is cantilevered and integrated with the first link plate 31, is inserted into the second pin hole 42 of the connecting bushing 41 of the second link plate 32, the external thread portion 36 of the connecting pin 33 protrudes from the second pin hole 42. The nut member 34 is screwed with the external thread portion 36 of the connecting pin 33 protruding from the second pin hole 42. Figure 1 and Figure 2 In addition to the illustrated embodiment, that is, the embodiment in which the threaded hole penetrates, a form in which one side in the axial direction is closed and the threaded hole does not penetrate, such as a cap nut, may be employed.

[0033] <Function>

[0034] Next, the effects of this embodiment will be described.

[0035] And say, when using connecting link 14 to cut off the connecting chain 11, as Figure 1As shown, the connecting link 14 is disassembled and disposed at a location where two inner links 12 are adjacent to each other with a gap in the longitudinal direction X of the chain 11. As viewed from this location, the tips of a pair of connecting pins 33 extending in a cantilevered manner from the first link plate 31 are inserted through the bushings 18 of the inner links 12 on one side and the inner link 12 on the other side in the longitudinal direction X of the chain 11. The tips of the connecting pins 33, which extend through the bushings 18, are inserted into the second pin holes 42 of the connecting bushings 41 of the second link plate 32.

[0036] like Figure 3 As shown in the enlarged image, the connecting pin 33 has its tip inserted into the second pin hole 42. The externally threaded portion 36 at its tip passes through the second pin hole 42, and the frustum-shaped portion 37 between the externally threaded portion 36 and the shaft portion 35 engages with the second pin hole 42 in a concave-convex manner. This results in the outer side surface 37a of the frustum-shaped portion 37 making surface contact with the inner side surface 42a of the second pin hole 42. In this state, the nut member 34 is screwed onto the externally threaded portion 36 of the connecting pin 33 protruding from the second pin hole 42 and tightened. This results in the outer side surface 37a of the frustum-shaped portion 37 of the connecting pin 33 being frictionally engaged and tightly fitted against the inner side surface 42a of the second pin hole 42, nesting in a manner equivalent to an interference fit.

[0037] Furthermore, when the nut member 34, which is screwed onto the externally threaded portion 36 of the connecting pin 33, is tightened, friction with the rotating nut member 34 could cause wear on the end surface of the portion of the second link plate 32 corresponding to the second pin hole 42, i.e., the end surface of the connecting bushing 41. However, since the connecting bushing 41 is made of a material having a higher hardness than the second link plate 32 and other materials, this wear can be suppressed. Furthermore, in this embodiment, compared to a case where the second pin hole 42 is formed through the second link plate 32, there is no need to use a high-hardness material throughout the second link plate 32. Consequently, an increase in material cost is also suppressed.

[0038] Furthermore, the chain 11, which has been disconnected and reconnected by the connecting link 14, may become loose due to long-term use of the nut member 34. In this case, the connecting pin 33 may rotate, wearing away the inner surfaces of the first and second pin holes 39, 42, thereby increasing the hole diameters and causing the chain 11 to stretch unnecessarily after disconnection. In this regard, the connecting pin 33 of this embodiment has the planar outer surface 38a of the base end portion 38 abut against the planar inner surface 39a of the first pin hole 39, restricting rotation and thus alleviating this potential concern.

[0039] Effects

[0040] Next, the effects of this embodiment will be described.

[0041] (1) In the connecting pin 33, the frustum-shaped portion 37 is inserted into the second pin hole 42 of the second link plate 32 in a close fit, equivalent to a so-called interference fit, without requiring excessive time and effort. In this state, the outer surface 37a of the frustum-shaped portion 37 at the front end of the connecting pin 33, whose base end 38 is pressed into the first pin hole 39 of the first link plate 31, does not slide against the inner surface 42a of the second pin hole 42 of the second link plate 32. This prevents the diameters of the first and second pin holes 39, 42 from increasing due to wear over time, thereby preventing unnecessary elongation of the chain 11 after the chain is cut or connected.

[0042] (2) Since the hardness of the connecting bushing 41 is high, when the nut member 34 screwed to the external thread portion 36 of the connecting pin 33 is tightened, the concern that the connecting bushing 41, which is a portion corresponding to the second pin hole 42 of the second link plate 32, may be worn due to friction with the nut member 34 can be reduced.

[0043] (3) The material of only the connecting bushing 41, which is a separate member from the second link plate 32 and has the second pin hole 42 for closely contacting the frustum-shaped portion 37 of the connecting pin 33, can be made of a special material that has excellent close contact with the frustum-shaped portion 37. Therefore, it is not necessary to make the entire second link plate 32 of a special material that has excellent close contact with the frustum-shaped portion 37, thereby increasing the range of material choices for the second link plate 32.

[0044] (4) In the event that the nut member 34 becomes loose relative to the external thread portion 36 of the connecting pin 33, the planar inner surface 39a of the first pin hole 39 functions as a rotation limiting portion, thereby limiting the connecting pin 33 from accidentally rotating relative to the first pin hole 39 and the second pin hole 42.

[0045] Furthermore, the above-mentioned embodiment can be modified according to the following modified examples. Furthermore, the configurations included in the embodiment and the configurations included in the following modified examples can be arbitrarily combined, and the configurations included in the following modified examples can be arbitrarily combined with each other.

[0046] Can be used Figure 5 The connecting link 14 of the first modified example is shown. This connecting link 14 is configured with a block-shaped protrusion 51 formed near the opening edge of the first pin hole 39 of the first link plate 31. For example, the protrusion 51 is in the shape of a vertically elongated rectangular parallelepiped, with the side facing the first pin hole 39 being a flat side surface 51a. In this case, the first pin hole 39 of the first link plate 31 is formed to have the same diameter as the cylindrical shaft portion 35 of the connecting pin 33, or approximately the same diameter as that of the cylindrical shaft portion 35, taking into account dimensional tolerances.

[0047] On the other hand, the base end 38 of the connecting pin 33 is formed into a flange with a larger diameter than the first pin hole 39, and a notched flat surface 38c is provided at one point on its outer periphery. Specifically, when the connecting pin 33 is press-fitted into the first pin hole 39, the outer peripheral surface 35a of the shaft portion 35 frictionally engages the inner peripheral surface 39c of the first pin hole 39, and the notched flat surface 38c of the base end 38 abuts against the flat side surface 51a of the block-shaped protrusion 51, thereby restricting rotation. In other words, in this first variation, the rotation restricting portion is formed by the flat side surface 51a of the block-shaped protrusion 51 formed near the opening edge of the first pin hole 39 in the first link plate 31. In this case, the rotation restricting portion can be configured to abut against the notched flat surface 38c of the base end 38 of the connecting pin 33 to restrict rotation. For example, at least one abutting protrusion may be provided.

[0048] · Figure 5 The connecting link 14 of the first modified example shown may not have a structure in which the base end portion 38 of the connecting pin 33 is formed into a flange shape having a diameter larger than the first pin hole 39, but may also have a structure in which a notched flat surface portion 38c is formed in one or more locations on the outer periphery having the same diameter as the shaft portion 35. In this case, a block-shaped protrusion 51 that abuts against the notched flat surface portion 38c of the base end portion 38 of the connecting pin 33 is formed in the opening edge of the first pin hole 39 of the first link plate 31 at a position corresponding to the notch shape of the notched flat surface portion 38c and partially blocks the first pin hole 39. Then, the base end portion 38 of the connecting pin 33 is moved from Figure 5 The inner side of the left side in the width direction Y is pressed into the first pin hole 39, and the notch plane portion 38c passes through Figure 5 The outer side of the right side is in contact with the protrusion 51 and the portion having the same diameter as the shaft portion 35 is in an unrotatable fitted state.

[0049] Can be used Figure 6The second modified example shown is a connecting link 14. In this connecting link 14, the base end 38 of the connecting pin 33 is formed into a cylindrical shape with a larger diameter than the shaft 35. The thickness of the first link plate 31 is thicker than in the aforementioned embodiment and the first modified example, and the first pin hole 39 is formed with a diameter equal to the larger diameter of the base end 38 of the connecting pin 33. The length of the base end 38 of the connecting pin 33 is longer than the thickness of the first link plate 31. In this second modified example, the outer circumferential surface 38d of the base end 38 of the connecting pin 33 frictionally engages with the inner circumferential surface 39d of the first pin hole 39, whose inner circumferential surface area is larger than in the embodiment and the first modified example, thereby limiting the rotation of the connecting pin 33. In other words, in this second modified example, the rotation limiting portion is formed by the inner circumferential surface 39d of the first pin hole 39, which has a relatively wide contact area with the outer circumferential surface 38d of the base end 38 of the connecting pin 33. Furthermore, the base end portion 38 of the connecting pin 33 may be formed into a cylindrical shape having the same diameter as or a smaller diameter than the shaft portion 35 . In this case, the first pin hole 39 is formed into the same diameter as the base end portion 38 of the connecting pin 33 .

[0050] Can be used Figure 7 The third modified example of the connecting link 14 is shown. In this connecting link 14, the second pin hole 42 is formed directly in the second link plate 32. In this case, the entire second link plate 32 or the portion of the second link plate 32 where the second pin hole 42 is formed is preferably made of a high-hardness material such as stainless steel. In short, the portion of the second link plate 32 where the second pin hole 42 is formed can be made of a material with a higher hardness than other portions of the second link plate 32.

[0051] ·exist Figure 4 In the connecting link 14 of the illustrated embodiment, the first pin hole 39 of the first link plate 31 can be configured such that its opening is shaped, for example, D-shaped or rectangular, and a flat inner surface 39a is formed at one or three or more locations on its inner surface. Furthermore, the first pin hole 39 of the first link plate 31 of this embodiment can have the flat inner surface 39a extending along the short side of the first link plate 31. Furthermore, the first pin hole 39 of the first link plate 31 of this embodiment can be configured such that the longest distance between two opposing concavely curved inner surfaces 39b is equal to the outer diameter of the shaft portion 35 of the connecting pin 33, while the distance between the opposing flat inner surfaces 39a is less than the outer diameter of the shaft portion 35 of the connecting pin 33. In this case, the cross-sectional shape of the base end portion 38 of the connecting pin 33 is preferably also formed to match the opening shape of the first pin hole 39.

[0052] The gap between the first pin hole 39 of the first link plate 31 and the shaft portion 35 or the base end portion 38 of the connecting pin 33 press-fitted into the first pin hole 39 may be filled with adhesive so that the adhesive force of the adhesive can function as a rotation restricting portion.

[0053] The material of the connecting bushing 41 may be the same as that of the second link plate 32 . However, even in this case, it is preferable that the material of the connecting bushing 41 has a higher hardness than that of the nut member 34 .

[0054] In each connecting link 14 of the aforementioned embodiment, first modification, and second modification, the connecting bushing 41 and the second link plate 32 may be configured such that only the surface properties of the connecting bushing 41 and the second link plate 32 differ. Similarly, the connecting link 14 of the third modification may be configured such that only the surface properties of the second link plate 32 where the second pin hole 42 is formed differ from those of the other portions of the second link plate 32. In other words, only the hardness and adhesion, as examples of surface properties, may differ. In this case, the surface properties may initially be the same, and then, for example, the hardness and other surface properties may be made different through different heat treatments.

[0055] Each connecting link 14 in the above-described embodiment, first modification, and second modification may be configured such that at least the surface hardness of the connecting bushing 41 is lower than at least the surface hardness of the second link plate 32. Similarly, the connecting link 14 in the third modification may be configured such that at least the surface hardness of the portion of the second link plate 32 where the second pin hole 42 is formed is lower than at least the surface hardness of portions other than the portion where the second pin hole 42 is formed.

[0056] The frustum-shaped portion 37 of the connecting pin 33 is not limited to a circular frustum and may also be a frustum-shaped pyramid, such as a triangular frustum or a quadrangular frustum. In this case, the second pin hole 42 preferably has a concave frustum-shaped surface, wherein the inner side surface 42a thereof can be engaged with the outer side surface 37a of the frustum-shaped portion 37 in a concave-convex manner.

[0057] The chain 11 of this embodiment is a so-called flat-type chain, meaning that the spacing between the inner link plates 15 and outer link plates 16 of the inner links 12 and outer links 13, which are staggered in the longitudinal direction X, is equal on one side and the other side of the longitudinal direction X. However, the chain 11 may also be a so-called offset-type chain, meaning that the spacing between the link plates facing each other in the width direction Y of a plurality of links connected in series in the longitudinal direction X is different on one side and the other side of the longitudinal direction X. In this case, the first link plates 31 and the second link plates 32 of the connecting links 14 preferably have a curved portion at their respective longitudinal midpoints, curved toward the opposing link plates in the width direction Y. Furthermore, the holes formed at one and the other longitudinal ends of the first and second link plates 31 and 32, where the spacing from the opposing link plates in the width direction Y is narrower, are preferably holes through which the shaft portion 35 of the connecting pin 33 is rotatably inserted. That is, these holes are not the first pin holes 39 nor the second pin holes 42 , but may be circular holes having a diameter slightly larger than the shaft portion 35 of the connecting pin 33 .

[0058] The connecting pin 33 of the connecting link 14 may be prevented from coming out of the first pin hole 39 by cutting the base end portion 38 exposed to the outside from the first pin hole 39 of the first link plate 31 and then crimping it.

[0059] Description of Reference Numerals

[0060] 11 Chain

[0061] 12 inner links

[0062] 13 outer links

[0063] 14 connecting links

[0064] 15 Inner link plate

[0065] 16 outer link plates

[0066] 17 Bushing hole

[0067] 18 Bushing

[0068] 19 rollers

[0069] 20 pin hole

[0070] 21 Connecting pin

[0071] 22 Fixing pin

[0072] 31 First link plate

[0073] 32 Second link plate

[0074] 33 Connecting pin

[0075] 34 Nut component

[0076] 35 shaft

[0077] 35a outer surface

[0078] 36 External thread

[0079] 37 Cone-shaped portion

[0080] 37a Lateral surface

[0081] 38 base end

[0082] 38a Flat outer surface

[0083] 38b Convex curved outer surface

[0084] 38c notched flat surface

[0085] 38d outer surface

[0086] 39 First pin hole

[0087] 39a Flat inner surface

[0088] 39b Concave inner surface

[0089] 39c inner circumference

[0090] 39d inner week

[0091] 40 fitting holes

[0092] 41 Connecting bushing

[0093] 42 Second pin hole

[0094] 42a medial surface

[0095] 51 bulge

[0096] 51a Flat side

[0097] X length direction

[0098] Y width direction

Claims

1. A connecting link for cutting and reconnecting a chain, wherein the chain is configured such that, among a plurality of links arranged in series in the longitudinal direction of the chain, adjacent links in the longitudinal direction are rotatably connected to each other via a connecting pin, the connecting link comprising: a connecting pin having an external thread portion at a distal end and a frustum-shaped portion on a proximal side relative to the external thread portion, wherein the frustum-shaped portion is formed so that a cross-sectional area gradually increases toward the proximal side; a first link plate having holes at one end and the other end in the longitudinal direction through which the connecting pin can be inserted, and at least one of the hole at the one end and the hole at the other end constituting a first pin hole into which the base end of the connecting pin is non-rotatably fitted; a second link plate having holes at one end and the other end in the longitudinal direction through which the connecting pin can be inserted, wherein at least one of the hole at the one end and the hole at the other end is a fitting hole; a connecting bushing that is non-rotatably fitted into the fitting hole of the second link plate and has a second pin hole through which the external thread portion of the connecting pin can pass; and a nut member capable of being threadedly engaged with the external thread portion of the connecting pin, The inner side surface of the second pin hole has a portion formed in a concave tapered shape corresponding to the outer side surface of the frustum-shaped portion and a portion formed in a shape different from the concave tapered shape. The portion formed into a shape different from the shape of the concave tapered surface opens at the end surface of the connecting bushing, When the nut member is screwed into the external thread portion protruding from the second pin hole and tightened, the nut member comes into contact with the end surface of the connecting bushing.

2. The connecting link according to claim 1, wherein: The connecting bushing and the second link plate have at least surface properties that differ from each other.

3. The connecting link according to claim 1, wherein: The connecting bushing is made of a material having a higher hardness than the second link plate.

4. The connecting link according to any one of claims 1 to 3, wherein: The first link plate is provided with a rotation restricting portion that restricts relative rotation of the connecting pin with respect to the first pin hole.

5. A chain, characterized in that: have: a plurality of chain links arranged in series along the length of the chain; a connecting pin for connecting the chain links adjacent to each other in the longitudinal direction so as to be freely rotatable; as well as The connecting link according to any one of claims 1 to 4, The connecting link is located midway along the length of the chain. The connecting link connects the link adjacent to one side of the connecting link in the longitudinal direction and the link adjacent to the other side.

Images