Connecting link and chain

Abstract

A connecting link (14) is provided with a connecting pin (33), a first link plate (31), and a second link plate (32). The connecting pin (33) has a first male screw part (36) at the base end. Furthermore, the connecting pin (33) has a first frustum-shaped section (38), which is formed such that the cross-sectional area gradually increases toward the base end side, on the tip side of the first male screw section (36). The first link plate (31) has, at both longitudinal ends thereof, holes through which the connecting pins can be inserted. At least one of the holes in the two end portions forms a first pin hole (44), and the first pin hole (44) is provided with a female thread portion into which the first male thread portion can be screwed and an inner side surface (44a) which corresponds to an outer side surface (38a) of the first frustum-shaped portion and has a concave conical surface shape. The second link plate (32) has, at both longitudinal ends thereof, holes through which the connecting pins can be inserted. At least one of the holes in the two end parts forms a second pin hole (48) into which the tail end part of the connecting pin can be embedded.

Description

Technical Field

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

[0002] As described in Patent Document 1, for example, a chain includes inner link plates and outer link plates that are alternately arranged in the length direction of the chain. The end portions of the inner link plates and the outer link plates are arranged in series so as to overlap in the width direction of the chain. The end portions of the inner link plate and the outer link plate adjacent to each other in the length direction of the chain are rotatably connected via a connecting pin. In this case, the end portion of the connecting pin is press-fitted into the pin hole of the outer link plate. That is, the connecting pin is in a so-called press-fit state in which it is non-rotatably fitted into the pin hole of the outer link plate. Prior Art Documents Patent Documents

[0003] Patent Document: Japanese Unexamined Patent Application Publication No. 2011-94660 Summary of the Invention Technical Problem to be Solved by the Invention

[0004] A chain sometimes needs to be cut and reconnected to a required length dimension at the use site according to the user of the chain. In this case, if the fitting state of the connecting pin with respect to the pin hole of the outer link plate is a so-called clearance fit state in which the connecting pin is rotatably fitted into the pin hole, the user can easily pull out the end portion of the connecting pin from the pin hole or insert it into the pin hole. However, in such a so-called clearance fit state, the inner peripheral surface of the pin hole and the outer peripheral surface of the connecting pin slide. Therefore, there is a possibility that the diameter of the pin hole expands due to wear caused by long-term use, resulting in unnecessary elongation of the chain after cutting and reconnecting.

[0005] On the other hand, if the fitting state of the connecting pin with respect to the pin hole of the outer link plate is a so-called press-fit state in which the connecting pin is non-rotatably fitted into the pin hole, the inner peripheral surface of the pin hole and the outer peripheral surface of the connecting pin do not slide. Therefore, unnecessary elongation of the cut and reconnected chain can be suppressed. However, for setting the end portion of the connecting pin with respect to the pin hole of the outer link plate to the so-called press-fit state, an operation of pressing the connecting pin into the pin hole using a hydraulic machine or the like, or knocking the connecting pin into the pin hole using a sledgehammer is required. Therefore, in the so-called press-fit state, although unnecessary elongation of the cut and reconnected chain can be suppressed, on the other hand, there is the following technical problem: a great deal of time and labor are required for the operation of inserting and pulling out the connecting pin at the time of cutting and reconnecting. Technical Solution for Solving the Technical Problem

[0006] The connecting link of the first embodiment of the present invention is used for cutting and reconnecting a chain in which a plurality of links arranged in series in the length direction of the chain are rotatably connected to each other via a connecting pin. The connecting link includes: a connecting pin having an external thread portion at the base end and a frustum-shaped portion on the end side closer to the base end than the external thread portion, and the frustum-shaped portion is formed such 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 length direction through which the connecting pin can be inserted, and at least one of the holes at the one end and the holes at the other end constitutes a first pin hole, the first pin hole having an internal thread portion that can be screwed with the external thread portion and an inner side surface having a concave frustum shape corresponding to the outer side surface of the frustum-shaped portion; and a second link plate having 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 holes at the one end and the holes at the other end constitutes a second pin hole, the second pin hole being configured to fit the end portion of the connecting pin.

[0007] The connecting link of the second embodiment of the present invention is used for cutting and reconnecting a chain in which a plurality of links arranged in series in the length direction of the chain are rotatably connected to each other via a connecting pin. The connecting link includes: a connecting pin having a first external thread portion at the base end, a second external thread portion at the end, and a first frustum-shaped portion on the end side closer to the base end than the first external thread portion, and the first frustum-shaped portion is formed such 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 length direction through which the connecting pin can be inserted, and at least one of the holes at the one end and the holes at the other end constitutes a first pin hole, the first pin hole having an internal thread portion that can be screwed with the first external thread portion and an inner side surface having a concave frustum shape corresponding to the outer side surface of the first frustum-shaped portion; a second link plate having 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 holes at the one end and the holes at the other end constitutes a second pin hole, the second pin hole being configured to allow the second external thread portion to pass through; and a nut member configured to be screwed with the second external thread portion of the connecting pin.

[0008] A chain according to an embodiment of the present invention includes: a plurality of links arranged in series in the length direction of the chain; a connecting pin rotatably connecting the adjacent links in the length direction to each other; and the connecting link, the connecting link being located in the middle of the length direction of the chain, and the connecting link connecting the link adjacent to the connecting link on one side in the length direction and the link adjacent to the connecting link on the other side. Description of the Drawings

[0009] Figure 1 This is a perspective view showing a partial disassembly of a chain of one embodiment. Figure 2 This is a top view showing a partial break of the cut and rejoined part of a chain using a connecting link. Figure 3 This is a perspective view showing the position alignment step during cut and rejoining. Figure 4 This is a top view showing a partial break of the pin insertion step during cut and rejoining. Figure 5 This is a top view showing a partial break of the connecting link of a modification example. Figure 6 This is a top view showing a partial break of the connecting link of another modification example. Detailed Embodiment

[0010] Hereinafter, with reference to the drawings, embodiments of the connecting link and the chain will be described. <Overall Structure> As Figure 1 shown, the chain 11 of the present embodiment includes a plurality of inner links 12 and a plurality of outer links 13 that are arranged in series in an alternating manner in the length direction X of the chain 11. In addition, the chain 11 has a connecting link 14 disposed in the middle of its length direction X. When observed from the position of the connecting link 14, an inner link 12 as an example of another link adjacent to the connecting link 14 is provided on each of one side and the other side in the length direction X of the chain 11. Then, the inner link 12 adjacent to the connecting link 14 on one side in the length direction X of the chain 11 and the inner link 12 adjacent to the connecting link 14 on the other side are connected via one connecting link 14. That is, the chain 11 is configured such that, for example, at the usage site of the chain 11, etc., the user of the chain 11 can cut and rejoin the length dimension of the chain 11 by using the connecting link 14.

[0011] Each inner link 12 has a pair of inner link plates 15 that face each other with a gap therebetween in the width direction Y orthogonal to the length direction X of the chain 11. Each outer link 13 has a pair of outer link plates 16 that are arranged to sandwich a pair of inner link plates 15 of adjacent inner links 12 in the length direction X of the chain 11 from the outside in the width direction Y. The inner link plates 15 and the outer link plates 16 are formed, for example, from steel materials through forging, stamping, etc. The inner link plates 15 and the outer link plates 16 are each formed in a substantially rectangular plate shape extending along the length direction X of the chain 11.

[0012] At one end and the other end in the longitudinal direction of the inner link plate 15, circular bushing holes 17 are respectively formed so as to penetrate the thickness direction of the inner link plate 15. Then, between the inner link plates 15 opposed to each other in the width direction Y of the inner link 12, a cylindrical bushing 18 is installed in such a manner as to maintain the interval in the width direction Y between the opposed inner link plates 15. That is, both axial ends of the bushing 18 are non-rotatably fitted into the bushing holes 17 of the paired inner link plates 15. Further, a roller 19 having a diameter larger than that of the bushing 18 is externally fitted rotatably to the bushing 18. That is, the roller 19 is supported in a so-called loose fit state rotatable relative to the bushing 18.

[0013] At one end and the other end in the longitudinal direction of the outer link plate 16, circular pin holes 20 having a diameter slightly smaller than the inner diameter of the bushing 18 are formed through the thickness direction of the outer link plate 16. 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 that serves as a pin insertion portion at the inner link 12. Then, as Figure 1 shown, the inner link 12 and the outer link 13 are rotatably connected via the connecting pin 21 in a state where the end portions 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 coincide with each other. The connecting pin 21 has a flange-shaped base end portion ( Figure 1 not shown in the figure) and a tip end portion. The base end portion of the connecting pin 21 is fixed to the outer surface of the outer link plate 16 on one side in the width direction Y of the outer link 13. The tip end portion of the connecting pin 21 projects outward from the pin hole 20 of the outer link plate 16 on the other side in the width direction Y of the outer link 13. Then, in this state, by attaching a fixing pin 22 to the tip end portion projecting outward from the pin hole 20 of the outer link plate 16, the connecting pin 21 can be prevented from coming off from the pin hole 20.

[0014] <Connecting Link> As Figure 1 and Figure 2 shown, the connecting link 14 has 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 are formed in a substantially rectangular plate shape similar to the outer link plate 16. The connecting pin 33 is formed in a substantially cylindrical shape similar to the connecting pin 21. In addition, the first link plate 31 and the second link plate 32 are formed of steel or the like by forging, stamping, or the like, similar to the inner link plate 15 and the outer link plate 16.

[0015] <Connecting Pin> The connecting pin 33 has a shaft portion 35, a first external thread portion 36, a second external thread portion 37, a first frustum-shaped portion 38, and a second frustum-shaped portion 39. The first external thread portion 36 is provided at the proximal end of the connecting pin 33. The outer diameter of the first external thread portion 36 is larger than the outer diameter of the shaft portion 35. The second external thread portion 37 is provided at the distal end of the connecting pin 33. The outer diameter of the second external thread portion 37 is smaller than the outer diameter of the shaft portion 35. The first frustum-shaped portion 38 is located on the distal end side with respect to the first external thread portion 36 of the connecting pin 33, that is, between the shaft portion 35 and the first external thread portion 36. The cross-sectional area of the first frustum-shaped portion 38 gradually increases toward the proximal end side. The second frustum-shaped portion 39 is located on the proximal end side with respect to the second external thread portion 37 of the connecting pin 33, that is, between the second external thread portion 37 and the shaft portion 35. The cross-sectional area of the second frustum-shaped portion 39 gradually increases toward the proximal end side.

[0016] The first frustum-shaped portion 38 is formed into a frustum shape in which the cross-sectional shape at its proximal end is a circle slightly smaller than the cross-sectional shape of the first external thread portion 36 and the cross-sectional shape at its distal end is a circle of the same size as the cross-sectional shape of the shaft portion 35. That is, the first frustum-shaped portion 38 is formed into a frustum of a cone shape in which the shape of its outer side surface 38a is a circular cross-sectional shape that becomes smaller toward the distal end side. On the other hand, the second frustum-shaped portion 39 is formed into a frustum shape in which the cross-sectional shape at its distal end is a circle slightly larger than the cross-sectional shape of the second external thread portion 37 and the cross-sectional shape at its proximal end is a circle of the same size as the cross-sectional shape of the shaft portion 35. That is, the second frustum-shaped portion 39 is formed into a frustum of a cone shape in which the shape of its outer side surface 39a is a circular cross-sectional shape that becomes smaller toward the distal end side.

[0017] As Figure 1 and Figure 2 shown, the connecting pin 33 is formed such that, from its distal end to its proximal end, the second external thread portion 37, the second frustum-shaped portion 39, the shaft portion 35, the first frustum-shaped portion 38, and the first external thread portion 36 are continuous with different outer diameters. The second external thread portion 37 at the distal end of the connecting pin 33 is formed to have the smallest outer diameter, and the first external thread portion 36 at the proximal end of the connecting pin 33 is formed to have the largest outer diameter. The shaft portion 35 is formed to have an outer diameter that is intermediate between the outer diameter of the first external thread portion 36 on the proximal end side and the outer diameter of the second external thread portion 37 on the distal end side. In addition, the second frustum-shaped portion 39 is formed to have an outer diameter that is between the outer diameter of the second external thread portion 37 and the outer diameter of the shaft portion 35 and gradually increases toward the proximal end side. Furthermore, the first frustum-shaped portion 38 is formed to have an outer diameter that is between the outer diameter of the shaft portion 35 and the outer diameter of the first external thread portion 36 and gradually increases toward the proximal end side. In other words, the connecting pin 33 is configured such that, in the order starting from the second external thread portion 37 at the distal end, passing through the second frustum-shaped portion 39, the shaft portion 35, and the first frustum-shaped portion 38 and reaching the first external thread portion 36 at the proximal end, the outer diameter increases in order.

[0018] <Pitch of thread> The connecting pin 33 is configured such that the pitch of the thread of the first external thread portion 36 and the pitch of the thread of the second external thread portion 37 are different from each other. For example, the pitch of the thread of the first external thread portion 36 is set to 1 mm, while on the other hand, the pitch of the thread of the second thread portion 37 is set to 2 mm, so that the pitch of the thread of the first external thread portion 36 and the second thread portion 37 are different from each other. In other words, the pitch of the thread of each of the first external thread portion 36 and the second external thread portion 37 is set such that when the connecting pin 33 is rotated once, it moves 1 mm in the axial direction on the side of the first external thread portion 36, while on the other hand, it moves 2 mm in the axial direction on the side of the second external thread portion 37.

[0019] <First link plate> As Figure 1 and Figure 2 shown, first link plate 31 is formed with first fitting holes 40 penetrating through one end portion and the other end portion in its longitudinal direction, and the first fitting holes 40 are formed in a circular shape having a diameter larger than the outer diameter of the first external thread portion 36 of the connecting pin 33. In the first fitting holes 40, a stepped cylindrical first connecting bushing 41 is fixed in a fitted state. The first connecting bushing 41 is formed in a shape in which a small-diameter cylindrical portion 42 having an outer diameter equal to the inner diameter of the first fitting holes 40 and a large-diameter cylindrical portion 43 having an outer diameter larger than the inner diameter of the first fitting holes 40 are stepped and continuous in the axial direction. Then, the first connecting bushing 41 is fixed to the first link plate 31 in a state where the small-diameter cylindrical portion 42 is fitted into the first fitting holes 40 and the stepped surface-shaped end face of the large-diameter cylindrical portion 43 on the side of the small-diameter cylindrical portion 42 abuts against the surface of the first link plate 31.

[0020] In the first connecting bushing 41, a first pin hole 44 through which the connecting pin 33 can be inserted is formed penetrating in the axial direction. The connecting pin 33 is inserted into the first pin hole 44 from one direction in the order of the second external thread portion 37, the second frustoconical portion 39, the shaft portion 35, the first frustoconical portion 38, and the first external thread portion 36. The inner side surface 44a of the first pin hole 44 is composed of a portion having a concave frustoconical shape, which is a kind of concave conical surface shape, corresponding to the outer side surface 38a of the first frustoconical portion 38 of the connecting pin 33 and a cylindrical surface-shaped portion corresponding to the outer peripheral surface of the first external thread portion 36 of the connecting pin 33. Then, an internal thread portion 45 into which the first external thread portion 36 of the connecting pin 33 can be screwed is formed on the inner peripheral surface of the cylindrical surface-shaped portion in the first pin hole 44 corresponding to the outer peripheral surface of the first external thread portion 36 of the connecting pin 33. In addition, as an example, the first connecting bushing 41 is formed of a material having a higher hardness than the steel material of the first link plate 31, such as stainless steel.

[0021] <Second link plate> As Figure 1 andFigure 2 As shown, second link plate 32 is formed with second fitting holes 46 penetrating through one end and the other end in its longitudinal direction. The second fitting holes 46 are formed as circles with a diameter larger than the shaft portion 35 of the connecting pin 33. A cylindrical second connecting bushing 47 is fixed in the second fitting holes 46 in a fitted state. The axial length of the second connecting bushing 47 is only slightly larger than the plate thickness of the second link plate 32. Additionally, the axial length of the second connecting bushing 47 may be the same as the plate thickness of the second link plate 32, or may be slightly smaller than the plate thickness of the second link plate 32.

[0022] In the second connecting bushing 47, a second pin hole 48 is formed penetrating in the axial direction through which the second external thread portion 37 at the end of the connecting pin 33 can pass. The inner side surface 48a of the second pin hole 48 is formed as a concave frustum cone shape, which is a kind of concave conical surface corresponding to the outer side surface 39a of the second frustum cone shaped portion 39 of the connecting pin 33. Similar to the above-mentioned first connecting bushing 41, the second connecting bushing 47 is made of a material harder than steel, such as stainless steel.

[0023] <Nut member> As Figure 1 and Figure 2 shown, the nut member 34 is configured to be able to be screwed with the second external thread portion 37 at the end of the connecting pin 33. When the connecting pin 33 is inserted through the first pin hole 44 of the first link plate 31, the bushing 18 of the inner link 12, and the second pin hole 48 of the second link plate 32, the second external thread portion 37 of the connecting pin 33 protrudes from the second pin hole 48. The nut member 34 is screwed with the second external thread portion 37 of the connecting pin 33 that protrudes from the second pin hole 48. Additionally, in addition to Figure 1 and Figure 2 the form shown, that is, in addition to the form where the threaded hole penetrates, for example, it may also be in the form of a sleeve nut or the like, where one side in the axial direction is closed and the threaded hole does not penetrate.

[0024] <Function> Next, the function of this embodiment will be described. As Figure 3 shown, when using the connecting link 14 to cut and reconnect the chain 11, the connecting link 14 is arranged in a disassembled state at a position where two inner links 12 adjacent to each other are spaced apart in the longitudinal direction X of the chain 11. Additionally, Figure 3 For ease of explanation in , the inner link plate 15 and the roller 19 of the inner link 12 located on the left side in the figure among the two inner links 12 located on the left and right sides of the connecting link 14 are shown by double-dashed lines.

[0025] <Position alignment step> First, a first link plate 31 is disposed on one side in the width direction Y of the inner link 12, and on the other hand, a second link plate 32 is disposed on the other side in the width direction Y of the inner link 12. Then, the first pin hole 44 of the first link plate 31 and the Figure 3 bushing 18 (not shown in the figure) as the pin insertion portion of the inner link 12 and the second pin hole 48 of the second link plate 32 are aligned coaxially. Then, next, the connecting pin 33 is inserted through the first pin hole 44, the bushing 18, and the second pin hole 48 that are aligned in the above-described manner from the side of the first pin hole 44 via the bushing 18 and toward the side of the second pin hole 48.

[0026] <Pin Insertion Step> As Figure 4 shown, in this case, the end portion of the connecting pin 33 passes through the first pin hole 44 of the first link plate 31 and the bushing 18 as the pin insertion portion of the inner link 12 and then reaches the second pin hole 48 of the second link plate 32. In addition, the shaft portion 35 of the connecting pin 33 is in a state of passing through the first pin hole 44 of the first link plate 31 and then being inserted into the bushing 18 of the inner link 12. Furthermore, the base end portion of the connecting pin 33 is in a position state before the first external thread portion 36 at the base end is about to start screwing with the internal thread portion 45 of the first pin hole 44 and before the outer side surface 38a of the first frustum-shaped portion 38 is about to come into surface contact with the inner side surface 44a having a concave conical shape of the first pin hole 44.

[0027] <Thread Tightening Step> Then, next, the connecting pin 33 is rotated in the direction in which the first external thread portion 36 is screwed with the internal thread portion 45 in the first pin hole 44. That is, the connecting pin 33 is rotated in the right direction, for example, as the thread tightening direction. In this way, the connecting pin 33 is rotated while the first external thread portion 36 is screwed with the internal thread portion 45 in the first pin hole 44, and at the same time, it moves in the downward direction in Figure 4 the axial direction, and the first frustum-shaped portion 38 is engaged with the concave conical portion formed in the first pin hole 44 in a concave-convex manner. That is, in the connecting pin 33, the first frustum-shaped portion 38 comes into surface contact with the inner side surface 44a having a concave conical shape in the first pin hole 44.

[0028] Then, from this state, the connecting pin 33 is further rotated in the thread tightening direction, and the first external thread portion 36 is tightened to the internal thread portion 45. In this way, the connecting pin 33 becomes a state in which the outer side surface 38a of the first frustum-shaped portion 38 is frictionally engaged with the inner side surface 44a of the first pin hole 44 in a nested manner and is in close contact. That is, in the connecting pin 33, the first external thread portion 36 at its base end is screwed into the internal thread portion 45 in the first pin hole 44, and the first frustum-shaped portion 38 is inserted into the first pin hole 44 of the first link plate 31 in a close contact state equivalent to a so-called press-fitting state.

[0029] On the other hand, in this case, in the connecting pin 33 in a state where the end portion is inserted into the second pin hole 48 of the second link plate 32, the second external thread portion 37 at the end thereof passes through the second pin hole 48, and the second frustum-shaped portion 39 is engaged with the second pin hole 48 in a concave-convex manner. In this way, the outer side surface 39a of the frustum shape of the second frustum-shaped portion 39 is in surface contact with the inner side surface 48a of the concave frustum shape of the second pin hole 48. Then, in this state, the nut member 34 is screwed onto the second external thread portion 37 of the connecting pin 33 protruding from the second pin hole 48, and the nut member 34 is tightened. In this way, the outer side surface 39a of the second frustum-shaped portion 39 of the connecting pin 33 is frictionally engaged with the inner side surface 48a of the second pin hole 48 in a nested manner to become a close contact state. That is, in the connecting pin 33, the second frustum-shaped portion 39 is inserted into the second pin hole 48 of the second link plate 32 in a close contact state equivalent to a so-called shrink-fit state.

[0030] In addition, as Figure 2 shown, in the chain 11 that is cut and continued by the connecting link 14, there is a possibility that the nut member 34 becomes loose due to long-term use. In addition, in this case, there is also a possibility that an external force that causes the connecting pin 33 to rotate in the loosening direction is applied to the connecting pin 33. In this case, the following situation may occur: the connecting pin 33 rotates and wears the inner surfaces of the first pin hole 44 and the second pin hole 48, causing the hole diameter to expand, and the cut and continued chain 11 undergoes unnecessary elongation. In this regard, in the connecting pin 33 of the present embodiment, the thread pitch of the first external thread portion 36 is different from the thread pitch of the second external thread portion 37, so this risk can be reduced.

[0031] If it is assumed that the thread pitch of the first external thread portion 36 is the same as the thread pitch of the second external thread portion 37, if an external force in the loosening direction acts on the connecting pin 33 after cutting and continuing the chain 11, the connecting pin 33 rotates in the loosening direction and finally detaches. However, in the present embodiment, if the connecting pin 33 rotates in the loosening direction after cutting and continuing, the distance that the connecting pin 33 can move in the axial direction based on the thread pitch of the first external thread portion 36 and the distance that it can move based on the thread pitch of the second external thread portion 37 will be different. Therefore, the movement of the connecting pin 33 in the axial direction is restricted, and as a result, the rotation in the loosening direction is restricted, and the situation of rotating and falling off in the loosening direction after cutting and continuing the chain 11 is suppressed.

[0032] <Effect> Next, the effects of the present embodiment will be described. (1) In the connecting pin 33, the first frustoconical portion 38 on the base end side and the second frustoconical portion 39 on the terminal end side are fitted into the first pin hole 44 of the first link plate 31 and the second pin hole 48 of the second link plate 32 in a close contact state equivalent to a so-called press fit state. Then, in this state, the outer side surface of the connecting pin 33 does not slide on the inner side surface of the first pin hole 44 of the first link plate 31 and the inner side surface of the second pin hole 48 of the second link plate 32. Therefore, unnecessary elongation of the chain 11 after cutting and reconnecting can be suppressed without much effort and labor.

[0033] (2) The connecting pin 33 is configured such that the outer diameter of the connecting pin 33 increases in order from the second external thread portion 37 at the terminal end, passing through the second frustoconical portion 39, the shaft portion 35, and the first frustoconical portion 38 to reach the first external thread portion 36 at the base end. Therefore, the connecting pin 33 can be easily inserted into the first pin hole 44, the bushing 18 as a pin insertion portion, and the second pin hole 48 from one direction in a state where the positions of the first pin hole 44, the bushing 18, and the second pin hole 48 are aligned.

[0034] (3) Since the thread pitches of the first external thread portion 36 and the second external thread portion 37 are different, when an external force in the loosening direction acts on the connecting pin 33 after cutting and reconnecting, the movement of the connecting pin 33 in the axial direction is restricted. As a result, the rotation and detachment of the connecting pin 33 in the loosening direction after cutting and reconnecting of the chain 11 are suppressed.

[0035] In addition, the above-described embodiment can be modified as in the following modification examples. Furthermore, the structures included in the embodiment and the structures included in the following modification examples can be arbitrarily combined, and the respective structures included in the following modification examples can also be arbitrarily combined.

[0036] · It is possible to use Figure 5The connecting link 14 of the modified example shown. In this connecting link 14, the first pin hole 44 is directly formed in the first link plate 31. That is, the first pin hole 44 can be formed through the first link plate 31, and the inner side surface 44a of the first pin hole 44 is composed of a concave frustum cone-shaped portion corresponding to the outer side surface 38a of the first frustum cone-shaped portion 38 of the connecting pin 33 and a cylindrical surface-shaped portion corresponding to the outer peripheral surface of the first external thread portion 36 of the connecting pin 33. In this case, an internal thread portion 45 into which the first external thread portion 36 of the connecting pin 33 can be screwed is formed on the inner peripheral surface of the cylindrical surface-shaped portion in the first pin hole 44 corresponding to the outer peripheral surface of the first external thread portion 36 of the connecting pin 33. In addition, in this case, it is preferable that the plate thickness of the first link plate 31 is thicker than that in the embodiment. Furthermore, in this case, it is preferable that the material of the entire first link plate 31 or the material of the portion of the first link plate 31 where the first pin hole 44 is formed is a high-hardness material such as stainless steel.

[0037] · It is also possible to use Figure 6 The connecting link 14 of another modified example shown. That is, a second pin hole 48 can be formed through the second link plate 32 in the axial direction, and the second pin hole 48 can pass through the second external thread portion 37 at the end of the connecting pin 33 and the inner side surface 48a is formed in a concave frustum cone shape corresponding to the outer side surface 39a of the second frustum cone-shaped portion 39 of the connecting pin 33. In addition, in this case, it is preferable that the material of the entire second link plate 32 or the material of the portion of the second link plate 32 where the second pin hole 48 is formed is a high-hardness material such as stainless steel.

[0038] · As long as the connecting pin 33 is configured to have a first external thread portion 36 and a first frustum cone-shaped portion 38 on its proximal end side, and its distal end portion is a non-rotatable insertion structure that is fitted into the second pin hole 48 of the second link plate 32, etc., it can also have the following structure. That is, the connecting pin 33 can have a structure in which it does not have at least the second frustum cone-shaped portion 39 among the second external thread portion 37 and the second frustum cone-shaped portion 39 at its distal end portion. In other words, the connecting pin 33 can have a structure in which it has a first external thread portion 36 and a first frustum cone-shaped portion 38 on its proximal end side, while on the other hand, it does not have both the second external thread portion 37 and the second frustum cone-shaped portion 39 on its distal end side, or it has a second external thread portion 37 but does not have a second frustum cone-shaped portion 39.

[0039] · Even in this case, the connecting pin 33 is in a state where the first frustoconical portion 38 is inserted into the first pin hole 44 of the first link plate 31 in a close contact state equivalent to a so-called clamped state, and on the other hand, the end portion is non-rotatably fitted into the second pin hole 48 of the second link plate 32. Therefore, the outer side surface of the connecting pin 33 does not slide on the inner side surface of the first pin hole 44 of the first link plate 31 and the inner side surface 48 of the second pin hole 48 of the second link plate 32. Therefore, as in the case of the embodiment, it is possible to suppress unnecessary elongation of the chain 11 after cutting and reconnecting without much effort and labor.

[0040] · The cross-sectional shape of the base end of the second frustoconical portion 39 in the connecting pin 33 may be a circular shape larger than the cross-sectional shape of the shaft portion 35 as long as it allows the first pin hole 44 of the first link plate 31 to pass through. In short, the second frustoconical portion 39 of the connecting pin 33 can be formed into a frustoconical shape with a circular cross-sectional shape at its base end larger than the cross-sectional shape of the shaft portion 35.

[0041] · The first external thread portion 36 and the second external thread portion 37 of the connecting pin 33 may also have the same thread pitch, and one may have a left-handed thread structure and the other may have a right-handed thread structure. According to this structure, the first external thread portion 36 and the second external thread portion 37 form a reverse thread structure with opposite thread tightening directions. Therefore, after cutting and reconnecting the chain 11, when the connecting pin 33 is set to rotate in the loosening direction for one of the first external thread portion 36 and the second external thread portion 37, the rotation direction is the opposite thread tightening direction to the other in the loosening direction. Therefore, the rotation of the connecting pin 33 in this direction is restricted, and as a result, it is possible to suppress the case where the connecting pin 33 falls off due to rotation in the loosening direction after cutting and reconnecting the chain 11.

[0042] · The chain 11 of the embodiment is a so-called flat type chain in which the intervals in the width direction Y of the inner link plates 15 and the outer link plates 16, which are alternately arranged in the length direction X, are equal on one side and the other side in the length direction X. However, the chain 11 can also be a so-called offset type chain, that is, a structure in which the intervals between the link plates facing each other in the width direction Y of a plurality of link plates connected in series in the length direction X are different on one side and the other side in the length direction X. In this case, it is preferable that the first link plate 31 and the second link plate 32 of the connecting link 14 have bending portions that are bent toward the link plate side on the opposite side facing each other in the width direction Y at the middle portions in their respective length directions. In addition, it is preferable that the holes formed on the narrow side of the intervals in the width direction Y of the opposite link plates at one end portion and the other end portion in the length direction of the first link plate 31 and the second link plate 32 are holes through which the shaft portion 35 of the connecting pin 33 can be rotatably inserted. That is, these holes are not the first pin holes 44 nor the second pin holes 48, but only circular holes with a diameter slightly larger than the shaft portion 35 of the connecting pin 33 are sufficient.

Claims

1. A connecting link for severing and reconnecting a chain in which a plurality of links arranged in series in the longitudinal direction of the chain are rotatably connected to each other via a connecting pin, the connecting link being characterized by comprising: A connecting pin having an external thread portion at its proximal end and a frustoconical portion on the end side closer to the distal end than the external thread portion, the frustoconical portion being formed such that its cross-sectional area gradually increases toward the proximal end 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 holes at the one end and the holes at the other end constituting a first pin hole, the first pin hole having an internal thread portion for screwing with the external thread portion and an inner side surface having a concave frustoconical shape corresponding to the outer side surface of the frustoconical portion; and 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, and at least one of the holes at the one end and the holes at the other end constituting a second pin hole, the second pin hole being configured to fit the distal end portion of the connecting pin.

2. A connecting link for severing and reconnecting a chain in which a plurality of links arranged in series in the longitudinal direction of the chain are rotatably connected to each other via a connecting pin, the connecting link being characterized by comprising: A connecting pin having a first external thread portion at its proximal end, a second external thread portion at its distal end, and a first frustoconical portion on the end side closer to the distal end than the first external thread portion, the first frustoconical portion being formed such that its cross-sectional area gradually increases toward the proximal end 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 holes at the one end and the holes at the other end constituting a first pin hole, the first pin hole having an internal thread portion for screwing with the first external thread portion and an inner side surface having a concave frustoconical shape corresponding to the outer side surface of the first frustoconical portion; 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, and at least one of the holes at the one end and the holes at the other end constituting a second pin hole, the second pin hole being configured to allow the second external thread portion to pass through; and A nut member configured to be screwed with the second external thread portion of the connecting pin.

3. The connecting link according to claim 2, wherein The connecting pin has a second frustoconical portion formed on the end side closer to the distal end than the first frustoconical portion and closer to the proximal end than the second external thread portion, with its cross-sectional area gradually increasing toward the proximal end side, The second pin hole of the second link plate has an inner side surface with a concave frustoconical shape corresponding to the outer side surface of the second frustoconical portion.

4. The connecting link according to claim 2 or 3, wherein The thread pitch of the first external thread portion is different from the thread pitch of the second external thread portion.

5. The connecting link according to claim 2 or 3, wherein One of the first external thread portion and the second external thread portion has a left-handed thread structure and the other has a right-handed thread structure.

6. A chain, characterized in that, Comprising: A plurality of link members arranged in series along the length direction of the chain; A connecting pin rotatably connecting the link members adjacent to each other in the length direction; And The connecting link according to any one of claims 1 to 5, The connecting link is located in the middle of the length direction of the chain, The connecting link connects the link adjacent to the connecting link on one side in the length direction and the link adjacent to the connecting link on the other side.

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