Joint links and chains

Abstract

To provide a joint link which can inhibit unwanted extension from occurring in a cut and joined chain without requiring a lot of effort and labor when the chain is cut and joined, and to provide the chain.SOLUTION: A joint link 14 includes: joint pins 33 each having a first male screw portion 36 at a base end and having, on a distal side relative to the first male screw portion, a first frustum-shaped portion 38 whose cross-sectional area gradually increases toward the base end side; a first link plate 31 on which holes, which are located at both longitudinal ends and allow the joint pins to be respectively inserted thereinto, form first pin holes 44 each having a female screw portion which may threadedly engage with the first male screw portion and an inner surface 44a having a recessed cone shape and corresponding to an outer surface 38a of the first frustum-shaped portion; and a second link plate 32 on which holes, which are located at both longitudinal ends and allow the joint pins to be respectively inserted thereinto, form second pin holes 48 in each of which a tip of the joint pin may be fitted.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present invention relates to a joint link used for splicing a chain and a chain that can be spliced using the joint link.

Background Art

[0002] For example, as described in Patent Document 1, a chain includes inner link plates and outer link plates that are alternately positioned in the longitudinal direction of the chain and are arranged in series such that their end portions overlap each other in the width direction of the chain. The adjacent inner link plate and outer link plate in the longitudinal direction of the chain are rotatably connected to each other at their end portions via a connecting pin. In this case, the connecting pin is in a so-called press-fit state in which its end portion is press-fitted into the pin hole of the outer link plate, that is, a state of being non-rotatably fitted to the pin hole.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A chain may be spliced by a user of the chain at the place of use to a required length dimension. In that case, if the fitting state of the connecting pin to the pin hole of the outer link plate is a so-called clearance fit state in which the connecting pin is rotatably fitted to the pin hole, the user can easily remove the end portion of the connecting pin from the pin hole or fit 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 will slide. Therefore, there is a risk that the diameter of the pin hole will increase due to wear over time, causing unnecessary elongation in the chain after splicing.

[0005] In contrast, if the connecting pin is fitted into the pin hole of the outer link plate in an interlocking fit, where the connecting pin is locked into the pin hole so that it cannot rotate, then the inner surface of the pin hole and the outer surface of the connecting pin will not slide against each other. Therefore, it is possible to suppress unnecessary stretching of the spliced ​​chain. However, in order to achieve an interlocking fit at the end of the connecting pin in the pin hole of the outer link plate, it is necessary to press the connecting pin into the pin hole using hydraulic equipment or to hammer the connecting pin into the pin hole with a large hammer. Therefore, while an interlocking fit can suppress unnecessary stretching of the spliced ​​chain, it presents the challenge of requiring considerable time and effort to insert and remove the connecting pin during the splicing process. [Means for solving the problem]

[0006] The following describes various types of connecting links that address the above-mentioned problems. [Aspect 1] A connecting link used for cutting and joining a chain, wherein adjacent links in the longitudinal direction of the chain are rotatably connected to each other via connecting pins, in a plurality of links arranged in series along the length of the chain, A joint pin having a male threaded portion at its base end and a frustum-shaped portion formed on the tip side of the male threaded portion such that the cross-sectional area gradually increases towards the base end, A first link plate having holes at one end and the other end in the longitudinal direction through which the joint pin can be inserted, and the hole at least one of the one end and the other end having a female thread portion into which the male thread portion can be screwed and an inner surface with a concave conical shape corresponding to the outer surface of the frustoconical portion, A second link plate having holes at one end and the other end in the longitudinal direction through which the joint pin can be inserted, wherein the holes at at least one of the one end and the other end constitute a second pin hole into which the tip of the joint pin can be fitted, A connecting link equipped with [a specific feature].

[0007] In this configuration, when the chain is spliced, the splicing pin is inserted through the first pin hole of the first link plate, the pin insertion portion of the other link adjacent to the splicing link, and the second pin hole of the second link plate. In this case, the tip of the splicing pin is inserted through the second pin hole of the second link plate, the shaft is inserted through the pin insertion portion of the other link, and the base end is inserted through the first pin hole of the first link plate. At this time, the male threaded portion of the base end of the splicing pin is in a position where it can begin to screw into the female threaded portion of the first pin hole, and the outer surface of the frustoconical portion is in close proximity to the inner surface of the concave conical shape of the first pin hole, allowing for surface contact.

[0008] Then, in that state, when the connecting pin is rotated in the screw tightening direction, the male threaded portion is screwed into the female threaded portion of the first pin hole and tightened. As a result, the outer surface of the frustoconical portion makes surface contact with the inner surface of the concave conical shape of the first pin hole, and then presses against that inner surface, resulting in a tight fit. In other words, the connecting pin is fitted into the first pin hole of the first link plate in a tight fit, equivalent to an interference fit. The tip of the connecting pin also fits into the second pin hole of the second link plate. In this state, there is no sliding between the outer surface of the connecting pin and the inner surface of the first pin hole of the first link plate and the inner surface of the second pin hole of the second link plate. Therefore, it is possible to suppress unnecessary elongation of the chain after splicing without requiring a great deal of time and effort.

[0009] [Aspect 2] A connecting link used for cutting and joining a chain, wherein adjacent links in the longitudinal direction of the chain are rotatably connected to each other via connecting pins, in a plurality of links arranged in series along the length of the chain, A coupling pin having a first male threaded portion at its base end and a second male threaded portion at its tip, and having a first frustum-shaped portion formed such that the cross-sectional area gradually increases toward the base end, on the tip side of the first male threaded portion, A first link plate having holes at one end and the other end in the longitudinal direction through which the joint pin can be inserted, and the hole at at least one of the one end and the other end having a female thread portion into which the first male thread portion can be screwed and an inner surface having a concave conical shape corresponding to the outer 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 joint pin can be inserted, and the holes at at least one of the one end and the other end constitute a second pin hole through which the second male thread portion can pass; A nut member that can be screwed onto the second male threaded portion of the aforementioned joint pin, A connecting link equipped with [a specific feature].

[0010] In this configuration, when the chain is spliced, the splicing pin is inserted through the first pin hole of the first link plate, the pin insertion portion of the other link adjacent to the splicing link, and the second pin hole of the second link plate. In this case, the tip of the splicing pin is inserted through the second pin hole of the second link plate, the shaft is inserted through the pin insertion portion of the other link, and the base end is inserted through the first pin hole of the first link plate. At this time, the splicing pin is positioned such that the first male threaded portion at the base end can begin to screw into the female threaded portion of the first pin hole, and the outer surface of the first frustoconical portion is close enough to make surface contact with the inner surface of the concave conical shape of the first pin hole. Simultaneously, the second male threaded portion at the tip of the splicing pin is positioned inside the second pin hole.

[0011] Then, in that state, when the joint pin is rotated in the screw tightening direction, the first male threaded portion is screwed into the female threaded portion of the first pin hole and tightened. As a result, the outer surface of the first frustoconical portion makes surface contact with the inner surface of the concave conical shape of the first pin hole, and then presses against that inner surface, resulting in a tight fit. Meanwhile, as the second male threaded portion passes through the second pin hole of the second link plate, the nut member is screwed onto the second male threaded portion. As a result, the portion of the joint pin closer to the base end than the second male threaded portion at its tip is pressed against the second link plate, resulting in a tight fit. In other words, the joint pin is fitted into the first pin hole of the first link plate with the first frustoconical portion in a tight fit equivalent to an interference fit. Furthermore, the tip of the joint pin is inserted into the second pin hole of the second link plate in a way that prevents rotation. In this state, the outer surface of the connecting pin does not slide against the inner surface of the first pin hole in the first link plate, nor against the inner surface of the second pin hole in the second link plate. Therefore, it is possible to suppress unnecessary elongation of the chain after splicing without requiring a great deal of time and effort.

[0012] [Aspect 3] The coupling pin has a second frustum-shaped portion that is located closer to the tip than the first frustum-shaped portion and closer to the base than the second male thread portion, such that its cross-sectional area gradually increases towards the base. The joint link according to [Aspect 2], wherein the second pin hole of the second link plate has an inner surface with a concave conical shape corresponding to the outer surface of the second frustoconical portion.

[0013] With this configuration, the joint pin can be easily inserted from one direction across the first pin hole, the pin insertion portion, and the second pin hole while the first pin hole, the pin insertion portion, and the second pin hole are aligned. Furthermore, when the nut member is screwed onto the second male thread portion, the outer surface of the second frustoconical portion makes surface contact with the inner surface of the concave conical shape of the second pin hole, and then presses against that inner surface, resulting in a tight fit. In other words, the joint pin is fitted into the first pin hole of the first link plate and the second pin hole of the second link plate in a tight fit, equivalent to an interference fit, with the first and second frustoconical portions being the same. As a result, both the base and tip of the joint pin can be fitted into the first and second pin holes through which they are inserted in a non-rotatable manner.

[0014] [Aspect 4] The joint link according to [Aspect 2] or [Aspect 3], wherein the thread pitch of the first male threaded portion and the thread pitch of the second male threaded portion are different from each other.

[0015] If the thread pitch of the first male thread and the thread pitch of the second male thread are the same, then when an external force acting in the loosening direction is applied to the connecting pin after the chain has been spliced, the connecting pin will rotate in the loosening direction and eventually come out. In contrast, with the above configuration, when an external force acting in the loosening direction is applied to the connecting pin, a difference is created between the distance the connecting pin can move axially based on the thread pitch of the first male thread and the distance it can move based on the thread pitch of the second male thread. As a result, the axial movement of the connecting pin is restricted, and consequently, rotation in the loosening direction is restricted. Therefore, it is possible to prevent the connecting pin from rotating in the loosening direction and coming out after the chain has been spliced.

[0016] [Aspect 5] The coupling link according to [Aspect 2] or [Aspect 3], wherein one of the first male threaded portion and the second male threaded portion has a left-hand thread structure and the other has a right-hand thread structure.

[0017] According to this configuration, the first male screw portion and the second male screw portion have a reverse screw structure in which the screw tightening directions are opposite to each other. Therefore, when the joint pin attempts to rotate in the loosening direction for one of the male screw portions after the chain is spliced, the rotation direction is the screw tightening direction opposite to the loosening direction for the other male screw portion. As a result, the rotation of the joint pin in that direction is restricted. Therefore, it is possible to prevent the joint pin from falling out by rotating in the loosening direction after the chain is spliced.

[0018] A mode of the chain for solving the above problems will be described. [Aspect 6] A chain in which adjacent links in the length direction among a plurality of links arranged in series in the length direction are rotatably connected via a connecting pin, The joint link described in any one of [Aspect 1] to [Aspect 5] is located in the middle of the length direction, and the links adjacent on one side and the other side in the length direction are connected via the joint link.

[0019] According to this configuration, the same effects as those achievable with the joint link of the above configuration can be achieved.

Effect of the Invention

[0020] According to the present invention, it is possible to suppress the occurrence of unnecessary elongation in the spliced chain without much labor and effort during the splicing of the chain.

Brief Description of the Drawings

[0021] [Figure 1] A perspective view showing a disassembled part of a chain according to an embodiment. ​​​​​​​​​ [Figure 5] A plan view showing a portion of the joint link in the modified example, with the link broken. [Figure 6] A plan view showing a portion of the joint link in another modification example, with the link broken. [Modes for carrying out the invention]

[0022] An embodiment of a connecting link and chain will be described below with reference to the figures. <Overall Structure> As shown in Figure 1, the chain 11 of this embodiment comprises a plurality of inner links 12 and a plurality of outer links 13 arranged in series so as to be alternately positioned in its longitudinal direction X. The chain 11 also comprises a single connecting link 14 positioned midway along its longitudinal direction X. Viewed from the position of the connecting link 14, one inner link 12, which is an example of another link adjacent to the connecting link 14, is located on both the one side and the other side of the chain 11 in the longitudinal direction X. The inner links 12 adjacent to the connecting link 14 on one side of the chain 11 in the longitudinal direction X and the inner links 12 adjacent to the other side are connected via the single connecting link 14. In other words, the length of the chain 11 can be cut and spliced ​​using the connecting link 14 by the user of the chain 11, for example, at the site where the chain 11 is used.

[0023] Each inner link 12 has a pair of inner link plates 15 that are spaced apart from each other and facing each other in the width direction Y, which is perpendicular to the length direction X of the chain 11. Each outer link 13 has a pair of outer link plates 16 that are positioned 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 outer link plates 16 are formed from, for example, steel by forging, pressing, etc., and each is in the shape of a substantially rectangular plate that extends along the length direction X of the chain 11.

[0024] Circular bushing holes 17 are formed at one and the other end of the inner link plate 15 in the longitudinal direction, penetrating through the thickness direction of the inner link plate 15. A cylindrical bushing 18 is assembled between opposing inner link plates 15 in the width direction Y of the inner link 12, maintaining the distance between the opposing inner link plates 15 in the width direction Y. That is, the axial ends of the bushing 18 are non-rotatably fitted into the bushing holes 17 of the paired inner link plates 15. A roller 19, which has a larger diameter than the bushing 18, is rotatably fitted to the outside of the bushing 18. That is, the roller 19 is supported in a so-called loosely fitted state that allows it to rotate relative to the bushing 18.

[0025] At one end and the other end of the outer link plate 16 in the longitudinal direction, circular pin holes 20, slightly smaller in diameter than the inner diameter of the bushing 18, are formed through the outer link plate 16 in the thickness direction. Both ends of a substantially cylindrical connecting pin 21, which is rotatably inserted into the bushing 18 that serves as the pin insertion portion in the inner link 12, are press-fitted into the pin holes 20. As shown in Figure 1, the inner link 12 and the outer link 13 are rotatably connected via the connecting pin 21, with the ends of adjacent inner link plates 15 and outer link plates 16 overlapping in the longitudinal direction X of the chain 11. The connecting pin 21 has a flange-shaped base end (not shown in Figure 1) that engages with the outer surface of one side of the outer link plate 16 in the width direction Y of the outer link 13, while its tip protrudes outward from the pin hole 20 of the other side of the outer link plate 16. Furthermore, in this state, the connecting pin 21 is prevented from coming out of the pin hole 20 by attaching a retaining pin 22 to the tip that protrudes outward from the pin hole 20 of the outer link plate 16 on the other side.

[0026] <Connecting Link> As shown in Figures 1 and 2, the joint link 14 has a first link plate 31 and a second link plate 32, which are substantially rectangular in shape, similar to the outer link plate 16. The joint link 14 also has a joint pin 33 and a nut member 34, which are substantially cylindrical in shape, similar to the connecting pin 21. The first link plate 31 and the second link plate 32 are formed from steel or the like by forging, pressing, etc., similar to the inner link plate 15 and the outer link plate 16.

[0027] <Connecting pin> The joint pin 33 has a first male threaded portion 36 at its base end, which has a larger outer diameter than the shaft portion 35, while it has a second male threaded portion 37 at its tip, which has a smaller outer diameter than the shaft portion 35. A first frustum-shaped portion 38 is formed on the tip side of the joint pin 33 beyond the first male threaded portion 36, that is, between the shaft portion 35 and the first male threaded portion 36, and its cross-sectional area gradually increases towards the base end. On the other hand, a second frustum-shaped portion 39 is formed on the base side of the joint pin 33 beyond the second male threaded portion 37, that is, between the second male threaded portion 37 and the shaft portion 35, and its cross-sectional area gradually increases towards the base end.

[0028] The first frustum-shaped portion 38 is formed in a frustum shape, where the cross-sectional shape of its base end is a circle slightly smaller than the cross-sectional shape of the first male thread portion 36, and the cross-sectional shape of its tip is a circle of the same size as the cross-sectional shape of the shaft portion 35. In other words, the first frustum-shaped portion 38 has a frustum-like surface shape, where the shape of its outer surface 38a becomes smaller towards the tip. On the other hand, the second frustum-shaped portion 39 is formed in a frustum shape, where the cross-sectional shape of its tip is a circle slightly larger than the cross-sectional shape of the second male thread portion 37, and the cross-sectional shape of its base end is a circle of the same size as the cross-sectional shape of the shaft portion 35. In other words, the second frustum-shaped portion 39 also has a frustum-like surface shape, where the shape of its outer surface 39a becomes smaller towards the tip.

[0029] As shown in Figures 1 and 2, the joint pin 33 is formed so that the second male threaded portion 37, the second frustoconical portion 39, the shaft portion 35, the first frustoconical portion 38, and the first male threaded portion 36 are continuous from the tip to the base, with different outer diameters. The second male threaded portion 37 at the tip has the smallest outer diameter, and the first male threaded portion 36 at the base has the largest outer diameter. The shaft portion 35 has an outer diameter that is intermediate between the outer diameter of the first male threaded portion 36 at the base and the outer diameter of the second male threaded portion 37 at the tip. The second frustoconical portion 39 is formed so that its outer diameter gradually increases towards the base, between the outer diameter of the second male threaded portion 37 and the outer diameter of the shaft portion 35. The first frustoconical portion 38 is formed so that its outer diameter gradually increases towards the base, between the outer diameter of the shaft portion 35 and the outer diameter of the first male threaded portion 36. In other words, the joint pin 33 is configured such that its outer diameter increases sequentially from the second male threaded portion 37 at the tip, through the second frustoconical portion 39, the shaft portion 35, and the first frustoconical portion 38, to the first male threaded portion 36 at the base.

[0030] <Screw pitch> The joint pin 33 is configured such that the screw pitch of the first male threaded portion 36 and the screw pitch of the second male threaded portion 37 are different from each other. For example, the screw pitch of the first male threaded portion 36 may be 1 mm, while the screw pitch of the second male threaded portion 37 may be 2 mm. In other words, the screw pitches of the first male threaded portion 36 and the second male threaded portion 37 are set such that when the joint pin 33 rotates once, the first male threaded portion 36 will attempt to move 1 mm axially, while the second male threaded portion 37 will attempt to move 2 mm axially.

[0031] <First Link Plate> As shown in Figures 1 and 2, the first link plate 31 has a first fitting hole 40 formed through one end and the other end in its longitudinal direction, the first fitting hole 40 being circular in shape and having a diameter larger than the outer diameter of the first male threaded portion 36 of the joint pin 33. A stepped cylindrical first joint bushing 41 is fitted and fixed into the first fitting hole 40. The first joint bushing 41 has a shape in which a small diameter cylindrical portion 42, whose outer diameter is the same as the inner diameter of the first fitting hole 40, and a large diameter cylindrical portion 43, whose outer diameter is larger than the inner diameter of the first fitting hole 40, are continuous with a step in the axial direction. The first joint bushing 41 is fixed to the first link plate 31 with the small diameter cylindrical portion 42 fitted into the first fitting hole 40 and the stepped end surface of the large diameter cylindrical portion 43 on the side of the small diameter cylindrical portion 42 in contact with the surface of the first link plate 31.

[0032] The first joint bushing 41 has a first pin hole 44 formed axially through which a joint pin 33 can be inserted. The joint pin 33 is inserted into this first pin hole 44 from one direction in the following order: second male thread portion 37, second frustoconical portion 39, shaft portion 35, first frustoconical portion 38, and first male thread portion 36. The first pin hole 44 is composed of a concave conical frustoconical surface portion, which is a type of concave conical surface shape, whose inner surface 44a corresponds to the outer surface 38a of the first frustoconical portion 38 of the joint pin 33, and a cylindrical surface portion that corresponds to the outer surface of the first male thread portion 36 of the joint pin 33. A female thread portion 45 is formed on the inner surface of the cylindrical surface portion of the first pin hole 44 that corresponds to the outer surface of the first male thread portion 36 of the joint pin 33, allowing the first male thread portion 36 of the joint pin 33 to be screwed into it. Furthermore, the first joint bushing 41 is, for example, made of a material with higher hardness than the steel material used for the first link plate 31, such as stainless steel.

[0033] <Second Link Plate> As shown in Figures 1 and 2, the second link plate 32 has a second fitting hole 46 formed through one end and the other end in its longitudinal direction, the second fitting hole 46 being circular in shape and having a larger diameter than the shaft portion 35 of the joint pin 33. A cylindrical second joint bushing 47, whose axial length is slightly greater than the thickness of the second link plate 32, is fitted and fixed into the second fitting hole 46. Note that the axial length of the second joint bushing 47 may be the same as the thickness of the second link plate 32, or it may be slightly less than the thickness of the second link plate 32.

[0034] The second joint bushing 47 has a second pin hole 48 formed axially through it, allowing the second male threaded portion 37 at the tip of the joint pin 33 to pass through. The inner surface 48a of this second pin hole 48 has a concave conical shape, which is a type of concave conical surface shape, corresponding to the outer surface 39a of the second frustoconical portion 39 of the joint pin 33. Like the first joint bushing 41 described above, this second joint bushing 47 is made of a material with higher hardness than steel, such as stainless steel.

[0035] <Nut component> As shown in Figures 1 and 2, the nut member 34 is configured to be screwed onto the second male threaded portion 37 at the tip of the joint pin 33. When the joint 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 nut member 34 is screwed onto the second male threaded portion 37 of the joint pin 33 that protrudes from the second pin hole 48. Note that the nut member 34 may be in a form other than that shown in Figures 1 and 2, i.e., a form with a through-hole, such as a cap nut, where one side in the axial direction is closed and the screw hole does not go all the way through.

[0036] <effect> Next, the operation of this embodiment will be described. As shown in Figure 3, when the chain 11 is spliced ​​using the connecting link 14, the connecting link 14 is positioned in a disassembled state at a point where two inner links 12 are adjacent to each other with a gap in the longitudinal direction X of the chain 11. In Figure 3, for the sake of explanation, the inner link plate 15 and roller 19 of the inner link 12 located on the left side of the connecting link 14 are shown with a dashed line.

[0037] <Alignment process> First, the first link plate 31 is positioned on one side of the inner link 12 in the width direction Y, while the second link plate 32 is positioned on the other side of the inner link 12 in the width direction Y. Then, the first pin hole 44 of the first link plate 31 and the bush 18 (not shown in Figure 3), which serves as the pin insertion part of the inner link 12, and the second pin hole 48 of the second link plate 32 are aligned coaxially. Next, the coupling pin 33 is inserted through the aligned first pin hole 44, bush 18, and second pin hole 48, from the first pin hole 44 side, through the bush 18, and toward the second pin hole 48 side.

[0038] <Pin insertion process> As shown in Figure 4, in this case, the tip of the joint pin 33 passes through the first pin hole 44 of the first link plate 31 and the bushing 18, which is the pin insertion part of the inner link 12, and then reaches the second pin hole 48 of the second link plate 32. Also, the shaft portion 35 of the joint pin 33 passes through the first pin hole 44 of the first link plate 31 and then is inserted into the bushing 18 of the inner link 12. Furthermore, the base end of the joint pin 33 is in a position where the first male thread portion 36 at the base end is just before screwing into the female thread portion 45 of the first pin hole 44 begins, and the outer surface 38a of the first frustoconical portion 38 is just before surface contact with the inner surface 44a of the concave conical shape of the first pin hole 44.

[0039] <Screw tightening process> Next, the joint pin 33 is rotated in a direction in which the first male threaded portion 36 is screwed into the female threaded portion 45 in the first pin hole 44. That is, the joint pin 33 is rotated, for example, to the right, which is the screw tightening direction. As the joint pin 33 rotates with the first male threaded portion 36 screwed into the female threaded portion 45 in the first pin hole 44, it moves axially downward in Figure 4, and the first frustoconical portion 38 fits into the concave conical shape of the first pin hole 44. That is, the first frustoconical portion 38 of the joint pin 33 makes surface contact with the inner surface 44a of the concave conical shape in the first pin hole 44.

[0040] Then, from that state, the joint pin 33 is further rotated in the screw tightening direction, and the first male threaded portion 36 is tightened against the female threaded portion 45. As a result, the outer surface 38a of the first frustoconical portion 38 of the joint pin 33 becomes tightly fitted to the inner surface 44a of the first pin hole 44 through frictional engagement in a nested manner. In other words, the first male threaded portion 36 at the base end of the joint pin 33 is tightened against the female threaded portion 45 in the first pin hole 44, and the first frustoconical portion 38 is fitted into the first pin hole 44 of the first link plate 31 in a tight fit equivalent to an interference fit.

[0041] On the other hand, in this case, the joint pin 33, which had its tip inserted into the second pin hole 48 of the second link plate 32, has its second male threaded portion 37 at its tip pass through the second pin hole 48, and its second frustoconical portion 39 engages with the second pin hole 48 in a recessed manner. Then, the outer surface 39a of the frustoconical shape of the second frustoconical portion 39 makes surface contact with the inner surface 48a of the concave frustoconical shape of the second pin hole 48. Then, in this state, the nut member 34 is screwed onto the second male threaded portion 37 of the joint pin 33 protruding from the second pin hole 48, and the nut member 34 is tightened. As a result, the outer surface 39a of the second frustoconical portion 39 of the joint pin 33 engages with the inner surface 48a of the second pin hole 48 in a nested frictional engagement, resulting in a tight fit. In other words, the joint pin 33 is fitted into the second pin hole 48 of the second link plate 32 with its second frustoconical portion 39 in a tight fit, which corresponds to an interference fit.

[0042] Furthermore, as shown in Figure 2, the chain 11 spliced ​​with the connecting link 14 may experience loosening of the nut member 34 due to prolonged use. In such a case, an external force may be applied to the connecting pin 33, causing it to rotate in the loosening direction. If this occurs, the connecting pin 33 may rotate, causing wear on the inner surfaces of the first pin hole 44 and the second pin hole 48, enlarging the hole diameter and potentially causing unnecessary elongation in the spliced ​​chain 11. In this respect, the connecting pin 33 in this embodiment has different screw pitches for the first male screw portion 36 and the second male screw portion 37, thus reducing such a risk.

[0043] If the screw pitch of the first male screw portion 36 and the screw pitch of the second male screw portion 37 were the same, then when an external force acting in the loosening direction is applied to the joint pin 33 after the chain 11 has been spliced, the joint pin 33 would rotate in the loosening direction and eventually come out. However, in this embodiment, when attempting to rotate the joint pin 33 in the loosening direction after the chain has been spliced, a difference arises between the distance the joint pin 33 can move axially based on the screw pitch of the first male screw portion 36 and the distance it can move axially based on the screw pitch of the second male screw portion 37. As a result, the axial movement of the joint pin 33 is restricted, which in turn restricts its rotation in the loosening direction, preventing it from rotating in the loosening direction and coming out after the chain 11 has been spliced.

[0044] <Effects> Next, the effects of this embodiment will be described. (1) The joint pin 33 is 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 tight fit, with the first frustoconical portion 38 at the base end and the second frustoconical portion 39 at the tip end being 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 this state, the outer surface of the joint pin 33 does not slide against the inner surface of the first pin hole 44 of the first link plate 31 and the inner surface of the second pin hole 48 of the second link plate 32. Therefore, it is possible to suppress unnecessary elongation of the chain 11 after splicing without requiring a great deal of time and effort.

[0045] (2) The joint pin 33 is configured such that its outer diameter increases sequentially from the second male threaded portion 37 at the tip, through the second frustoconical portion 39, the shaft portion 35, and the first frustoconical portion 38, to the first male threaded portion 36 at the base. Therefore, with the first pin hole 44, the bushing 18 which is the pin insertion portion, and the second pin hole 48 aligned, the joint pin 33 can be easily inserted from one direction across the first pin hole 44, the bushing 18, and the second pin hole 48.

[0046] (3) Because the screw pitches of the first male threaded portion 36 and the second male threaded portion 37 are different, if an external force acting in the loosening direction is applied to the joint pin 33 after cutting and splicing, it is possible to restrict the axial movement of the joint pin 33. As a result, it is possible to suppress the joint pin 33 from rotating in the loosening direction and falling out after cutting and splicing the chain 11.

[0047] The above embodiment may be modified as shown in the following examples of modifications. Furthermore, the configurations included in the embodiment and the configurations included in the following examples of modifications may be combined in any way, or the configurations included in the following examples of modifications may be combined in any way.

[0048] • The modified joint link 14 shown in Figure 5 may be used. In this joint link 14, the first pin hole 44 is formed directly in the first link plate 31. That is, the first pin hole 44 may be formed through the first link plate 31, with the inner surface 44a consisting of a concave frustoconical surface portion corresponding to the outer surface 38a of the first frustoconical portion 38 of the joint pin 33 and a cylindrical surface portion corresponding to the outer circumferential surface of the first male thread portion 36 of the joint pin 33. In this case, a female thread portion 45 is formed on the inner circumferential surface of the cylindrical surface portion in the first pin hole 44 that corresponds to the outer circumferential surface of the first male thread portion 36 of the joint pin 33, allowing the first male thread portion 36 of the joint pin 33 to be screwed in. In this case, it is preferable to make the thickness of the first link plate 31 thicker than in the embodiment. In this case, it is preferable that the overall material of the first link plate 31, or the material of the portion of the first link plate 31 in which the first pin hole 44 is formed, be a high-hardness material such as stainless steel.

[0049] • Other modified examples of the joint link 14 shown in Figure 6 may be used. That is, a second pin hole 48 may be formed axially through the second link plate 32, which allows the second male threaded portion 37 at the tip of the joint pin 33 to pass through, and whose inner surface 48a has a concave frustoconical shape corresponding to the outer surface 39a of the second frustoconical portion 39 of the joint pin 33. 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 in which the second pin hole 48 is formed, be a high-hardness material such as stainless steel.

[0050] The joint pin 33 may also be configured such that it has a first male threaded portion 36 and a first frustoconical portion 38 on its base end, and its tip is inserted so as to be unable to rotate, such as by fitting into the second pin hole 48 of the second link plate 32. That is, the joint pin 33 may be configured such that it does not have at least the second frustoconical portion 39 of the second male threaded portion 37 and the second frustoconical portion 39 on its tip. In other words, the joint pin 33 may have a first male threaded portion 36 and a first frustoconical portion 38 on its base end, while not having either the second male threaded portion 37 or the second frustoconical portion 39 on its tip, or it may have the second male threaded portion 37 but not the second frustoconical portion 39.

[0051] Even in this case, the joint pin 33 is fitted into the first pin hole 44 of the first link plate 31 with its first frustoconical portion 38 in a tight fit, while its tip is non-rotatably fitted into the second pin hole 48 of the second link plate 32. Therefore, the outer surface of the joint pin 33 does not slide against the inner surface of the first pin hole 44 of the first link plate 31 or the inner surface of the second pin hole 48 of the second link plate 32. Consequently, as in the embodiment, it is possible to suppress unnecessary elongation of the chain 11 after splicing without requiring a great deal of time and effort.

[0052] The cross-sectional shape of the base end of the second frustoconical portion 39 of the joint pin 33 may be a larger circular shape than the cross-sectional shape of the shaft portion 35, as long as it is large enough to allow passage through the first pin hole 44 of the first link plate 31. In short, the second frustoconical portion 39 of the joint pin 33 may be formed as a frustoconical shape in which the cross-sectional shape of its base end is a larger circle than the cross-sectional shape of the shaft portion 35.

[0053] The first male threaded portion 36 and the second male threaded portion 37 of the connecting pin 33 may have the same thread pitch, with one being a left-hand thread and the other a right-hand thread. In this configuration, the first male threaded portion 36 and the second male threaded portion 37 have a reverse thread structure with the tightening directions opposite to each other. Therefore, after the chain 11 is spliced, if the connecting pin 33 attempts to rotate in a direction that loosens one of the first male threaded portion 36 and the second male threaded portion 37, the direction of rotation will be the tightening direction opposite to the loosening direction for the other. As a result, the rotation of the connecting pin 33 in that direction is restricted, and it is possible to prevent the connecting pin 33 from falling out due to rotation in the loosening direction after the chain 11 is spliced.

[0054] The chain 11 in the embodiment was a so-called flat type chain in which the spacing in the width direction Y of the inner link plates 15 and outer link plates 16 in the inner links 12 and outer links 13, which are alternately located in the length direction X, is equal on one side of the length direction X and on the other side. However, the chain 11 may also be a so-called offset type chain in which the spacing between opposing link plates in the width direction Y of a plurality of links connected in series in the length direction X is different on one side of the length direction X and on the other side. In this case, it is preferable that the first link plate 31 and the second link plate 32 of the coupling link 14 have a bent portion in the middle of their respective longitudinal directions that bends toward the opposing link plate in the width direction Y. Furthermore, it is preferable that the holes formed on the side of the first link plate 31 and the second link plate 32 where the spacing in the width direction Y from the opposing link plate is narrower, at one end and the other end in the longitudinal direction, are holes through which the shaft portion 35 of the coupling pin 33 is rotatably inserted. In other words, these holes are neither the first pin hole 44 nor the second pin hole 48, but rather circular holes that are slightly larger in diameter than the shaft portion 35 of the coupling pin 33. [Explanation of symbols]

[0055] 11... Chain 12…Internal links 13…External links 14…Connecting links 21…Connecting pin 31…First Link Plate 32…Second Link Plate 33... Joint pin 34... Nut component 35... Shaft 36...First male thread section 37...Second male thread section 38...First frustum-shaped part 38a…Outer surface 39…Second frustum-shaped part 39a…Outer surface 44…First pinhole 44a...Inner surface 45...Female thread section 48…Second pin hole 48a…Inner surface X...Length direction Y...Width direction

Claims

1. A connecting link used for cutting and joining a chain, wherein adjacent links in the longitudinal direction of the chain are rotatably connected via connecting pins, in a plurality of links arranged in series along the length of the chain, A joint pin having a male threaded portion at its base end and a frustum-shaped portion formed on the tip side of the male threaded portion such that the cross-sectional area gradually increases towards the base end, A first link plate having holes at one end and the other end in the longitudinal direction through which the joint pin can be inserted, and the hole at least one of the one end and the other end having a female thread portion into which the male thread portion can be screwed and an inner surface with a concave conical shape corresponding to the outer surface of the frustoconical portion, A second link plate having holes at one end and the other end in the longitudinal direction through which the joint pin can be inserted, wherein the holes at at least one of the one end and the other end constitute a second pin hole into which the tip of the joint pin can be fitted, A connecting link characterized by comprising the following:

2. A connecting link used for cutting and joining a chain, wherein adjacent links in the longitudinal direction of the chain are rotatably connected via connecting pins, in a plurality of links arranged in series along the length of the chain, A joint pin having a first male threaded portion at its base end and a second male threaded portion at its tip, and having a first frustum-shaped portion formed such that the cross-sectional area gradually increases toward the base end, on the tip side of the first male threaded portion, A first link plate having holes at one end and the other end in the longitudinal direction through which the joint pin can be inserted, and the hole at least one of the one end and the other end having a female thread portion into which the first male thread portion can be screwed and an inner surface having a concave conical shape corresponding to the outer surface of the first frustoconical shape portion, A second link plate having holes at one end and the other end in the longitudinal direction through which the joint pin can be inserted, and the holes at at least one of the one end and the other end constitute a second pin hole through which the second male thread portion can pass; A nut member that can be screwed onto the second male threaded portion of the aforementioned joint pin, A connecting link characterized by comprising the following:

3. The coupling pin has a second frustum-shaped portion that is located closer to the tip than the first frustum-shaped portion and closer to the base than the second male thread portion, such that its cross-sectional area gradually increases towards the base end. The coupling link according to claim 2, characterized in that the second pin hole of the second link plate has an inner surface with a concave conical shape corresponding to the outer surface of the second frustoconical portion.

4. The coupling link according to claim 2, characterized in that the screw pitch of the first male screw portion and the screw pitch of the second male screw portion are different from each other.

5. The coupling link according to claim 2, characterized in that one of the first male threaded portion and the second male threaded portion has a left-hand thread structure and the other has a right-hand thread structure.

6. A chain in which multiple links arranged in series along the length direction are rotatably connected to each other via connecting pins, A chain characterized in that a connecting link according to any one of claims 1 to 5 is located in the middle of the longitudinal direction, and adjacent links on one side of the longitudinal direction are connected to adjacent links on the other side via the connecting link.

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