Chain

Abstract

To improve the fatigue performance of a chain.SOLUTION: A chain comprises: a pair of inner link plates 14 which are oppositely arranged; cylindrical bushes inserted into a pair of penetration holes 14a included in the pair of inner link plates 14, respectively; pins rotatably inserted into the bushes; and a pair of outer link plates arranged so as to sandwich the pair of inner link plates 14 from the outside, and arranged at both end parts of the pins. The pair of pins are located between the pair of outer link plates. The inner link plates 14 have tapers 14a1 at opening end parts of the penetration holes 14a at the outer link plate sides, and a ratio (B / A) of depths (B) of the tapers with respect to a distance (A) between centers of the pair of penetration holes 14a is 0.9% or more and 6% or less.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a chain. [Background technology]

[0002] The patent US 5,399,633 describes a chain. 12, the chain 61 includes a pair of inner link plates 62, a pair of bushings 63 press-fitted into the pair of inner link plates 62, a pair of connecting pins 64 loosely fitted into the pair of bushings 63, and a pair of outer link plates 65 into which the pair of connecting pins 64 are press-fitted. The chain 61 is formed by arranging a plurality of the above-mentioned components as one unit in succession. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-105325 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, it is desirable for the chain 61 described in Patent Document 1 etc. to have excellent durability. To achieve excellent durability, improvement in fatigue performance is required. [Means for solving the problem]

[0005] The chain of embodiment 1 comprises a pair of inner link plates arranged opposite each other, cylindrical bushings inserted into a pair of through holes formed in each of the pair of inner link plates, a pin rotatably inserted into the bushings, and a pair of outer link plates arranged to sandwich the pair of inner link plates from the outside and disposed at both ends of the pin, with the pair of pins positioned between the pair of outer link plates, wherein the inner link plates have a taper at an opening end of the through hole facing the outer link plate, and the ratio (B / A) of the taper depth (B) to the distance (A) between the centers of the pair of through holes is 0.9% or greater and 6% or less.

[0006] In a second aspect, in the chain of the first aspect, the inner link plate has a convex portion that is continuous with the taper on a surface facing the outer link plate. A third aspect of the present invention is the chain according to the second aspect, wherein the inner link plate has the taper around the entire circumference of the open end and has the convex portion at a position surrounding the entire circumference of the taper.

[0007] A fourth aspect is the chain according to the second or third aspect, in which the ratio (C / A) of the height (C) of the convex portion to the distance (A) between the centers of a pair of the through holes is 0.05% or more and 0.9% or less. Effect of the Invention

[0008] According to the present invention, the fatigue performance of the chain can be improved. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is an exploded perspective view showing a schematic view of a portion of a chain according to a first embodiment. [Diagram 2] 1 is a cross-sectional view showing a schematic view of a portion of a chain according to a first embodiment. [Diagram 3] FIG. [Figure 4] 4 is a partial cross-sectional view taken along line 4-4 of FIG. 3. [Diagram 5] FIG. 11 is an exploded perspective view showing a schematic view of a portion of a modified chain. [Figure 6] FIG. 11 is a cross-sectional view showing a schematic view of a portion of a modified chain. [Figure 7] FIG. 11 is a perspective view of an inner link plate of the second embodiment. [Figure 8] 8 is a partial cross-sectional view taken along line 8-8 in FIG. 7. [Figure 9] FIG. 11 is a perspective view of an inner link plate according to another modified example. [Figure 10] FIG. 11 is a perspective view of an inner link plate according to still another modified example. [Figure 11] 4 is a graph showing fatigue performance of chains of examples and comparative examples. [Figure 12] 1A and 1B are exploded and perspective views of a portion of a prior art chain; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] First Embodiment A first embodiment of a chain according to the present invention will now be described. 1 and 2, a chain 11 of the first embodiment includes a plurality of inner links 12 and a plurality of outer links 13 arranged in a longitudinal direction X of the chain 11. The plurality of inner links 12 and the plurality of outer links 13 are arranged so as to be alternately positioned in the longitudinal direction X.

[0011] Each inner link 12 includes a pair of inner link plates 14 arranged opposite each other at a distance D1 in a width direction Y perpendicular to the length direction X of the chain 11. Each inner link 12 also includes a cylindrical bushing 16 located between the pair of inner link plates 14 to connect the pair of inner link plates 14 together, and a cylindrical roller 17 rotatably fitted onto the bushing 16.

[0012] The outer link 13 includes a pair of outer link plates 15 arranged opposite to each other at a distance D2 in the width direction Y perpendicular to the length direction X of the chain 11. The outer link 13 also includes a rod-shaped pin 18 rotatably inserted into the bushing 16. The pair of outer link plates 15 are arranged to sandwich the pair of inner link plates 14 from the outside and are arranged at both ends of the pin 18. The pair of pins 18 are located between the pair of outer link plates 15. The distance P1 between the axial centers of adjacent pins 18 is not particularly limited and is, for example, 1 mm or more and 100 mm or less. The distance P2 between the axial centers of adjacent pins 18 in the outer link plates 15 adjacent to each other in the length direction X is also not particularly limited and is, for example, 1 mm or more and 100 mm or less. Hereinafter, the distances P1 and P2 between the axial centers of adjacent pins 18 are also referred to as the pitch of the chain 11.

[0013] The chain 11 will now be described in detail. <Inner link plate> 1 and 2, the inner link plate 14 is made of a plate material. Both longitudinal ends of the inner link plate 14 are semicircular with both longitudinal outer sides convex. The longitudinal center of the inner link plate 14 is curved and narrowed from both lateral sides toward the center.

[0014] The inner link plate 14 has a pair of through holes 14a on both outer sides in the longitudinal direction that sandwich the longitudinal center portion. That is, the inner link plate 14 has two through holes 14a that are parallel to each other along the longitudinal direction of the inner link plate 14.

[0015] The distance between the centers of a pair of through holes 14a in the inner link plate 14 is equal to the distance P2 between the axis centers of adjacent pins 18 in the outer link plates 15 adjacent in the longitudinal direction X. Hereinafter, the distance between the centers of the pair of through holes 14a in the inner link plate 14 is also referred to as distance (A).

[0016] The distance between the centers of adjacent through holes 14a in the inner link plates 14 adjacent in the longitudinal direction X is equal to the distance P1 between the axis centers of adjacent pins 18 in the outer link plates 15.

[0017] As shown in FIG. 2, thickness T1 of inner link plate 14 is not particularly limited, but is preferably 0.1 mm or more and 80 mm or less. The width of the inner link plate 14 is not particularly limited, but is preferably 0.9 mm to 80 mm. The width of the inner link plate 14 refers to the length in the short side of the inner link plate 14, and is the dimension of the point where the length in the short side is the greatest, excluding the narrowed portion.

[0018] The inner diameter of through hole 14a of inner link plate 14 is slightly smaller than the outer diameter of the peripheral wall of bushing 16, which will be described later. As described below, both ends of bushing 16 are press-fitted into through holes 14a of inner link plates 14, so that the pair of inner link plates 14 are disposed opposite each other with a distance D1 therebetween.

[0019] The distance D1 between the pair of inner link plates 14 is not particularly limited, but is preferably 0.6 mm or more and 55 mm or less. As shown in FIG. 2, hereinafter, the direction in which a pair of inner link plates 14 face each other is referred to as the inner side of chain 11, and the opposite direction is referred to as the outer side of chain 11.

[0020] 1 to 4, a pair of through holes 14a in each of the pair of inner link plates 14 has a taper 14a1 around the entire periphery at the outer open end facing the outer link plate 15. In addition, the pair of through holes 14a does not have a taper 14a1 at the inner open end. The inner surface of the inner link plate 14 is a flat surface.

[0021] By providing taper 14a1 around the entire circumference of the opening end of through hole 14a, the inner diameter of through hole 14a at the opening end is slightly larger than the inner diameter of through hole 14a at any other portion than the opening end.

[0022] As shown in FIG. 4, the depth (B) of taper 14a1 extending from the outer surface of inner link plate 14 toward the inside of inner link plate 14 is not particularly limited. The ratio (B / T1) of the depth (B) of taper 14a1 to the thickness T1 of inner link plate 14 is not particularly limited, but is preferably 6% or more and 50% or less, and more preferably 20% or more and 40% or less.

[0023] The inclination angle of taper 14a1 with respect to the thickness direction of inner link plate 14, i.e., the angle of taper 14a1 when the thickness direction of inner link plate 14 is set to 0°, is not particularly limited. The angle of taper 14a1 is preferably 10° or more and 70° or less, more preferably 20° or more and 60° or less, and even more preferably 30° or more and 50° or less. The angle of taper 14a1 can be, for example, 45°.

[0024] The ratio (B / A) of the depth (B) of taper 14a1 to the distance (A) between the centers of a pair of through holes 14a in inner link plate 14 is 0.9% or greater and 6% or less. The ratio (B / A) is preferably 2% or greater and 5.5% or less, and more preferably 3% or greater and 5% or less.

[0025] <Outer link plate> As shown in Figures 1 and 2, the outer link plate 15 is made of a plate material. Both longitudinal ends of the outer link plate 15 are semicircular with both longitudinal outer sides being convex. The longitudinal center of the outer link plate 15 is curved from both lateral sides toward the center.

[0026] The outer link plate 15 has one pin insertion hole 15a on each of the outer sides in the longitudinal direction that sandwich the longitudinal center portion. In other words, the outer link plate 15 has two pin insertion holes 15a that are parallel to each other along the longitudinal direction of the outer link plate 15.

[0027] The thickness T2 of the outer link plate 15 is not particularly limited, but is preferably the same as the thickness T1 of the inner link plate 14 described above. The width of the outer link plate 15 is not particularly limited, but is preferably the same as the width of the inner link plate 14 .

[0028] The inner diameter of the pin insertion hole 15a is slightly smaller than a diameter T5 of the pin 18, which will be described later. As described later, both ends of the pin 18 are press-fitted into the pin insertion holes 15a of the outer link plates 15, so that the pair of outer link plates 15 are arranged facing each other at a distance D2 in the width direction Y perpendicular to the length direction X of the chain 11. The distance D2 is also referred to as the separation distance between the pair of outer link plates 15.

[0029] The distance D2 between the pair of outer link plates 15 is not particularly limited, but is slightly larger than the distance D3 between the outer sides of the pair of inner link plates 14. The distance D2 between the pair of outer link plates 15 is preferably, for example, not less than 0.45 mm and not more than 85 mm.

[0030] <Bush> 1 and 2, the bushing 16 is configured to be cylindrical. Specifically, the bushing 16 has a cylindrical peripheral wall in a cross section along the radial direction.

[0031] The bushing 16 is formed as a separate body from the pair of inner link plates 14, and both axial ends thereof are press-fitted into the through holes 14a of the inner link plates 14, respectively. The thickness of the bushing 16, that is, the thickness T3 of the peripheral wall of the bushing 16, is not particularly limited, but is preferably 0.05 mm or more and 5 mm or less.

[0032] The outer diameter of the bushing 16, that is, the outer diameter of the peripheral wall of the bushing 16, is not particularly limited, but is preferably 0.4 mm or more and 45 mm or less. The inner diameter of the bushing 16, that is, the inner diameter of the peripheral wall of the bushing 16, is not particularly limited, but is preferably 0.3 mm or more and 35 mm or less.

[0033] The length of bushing 16 is not particularly limited, but is preferably the same as distance D3 between the outer sides of a pair of inner link plates 14 or slightly smaller than distance D3. <Laura> 1 and 2, the roller 17 is configured to be cylindrical. Specifically, the roller 17 has a cylindrical peripheral wall in a cross section along the radial direction.

[0034] The roller 17 is rotatably fitted onto the bushing 16. That is, the inner diameter of the peripheral wall of the roller 17 is configured to be larger than the outer diameter of the peripheral wall of the bushing 16, and the roller 17 is loosely fitted onto the bushing 16.

[0035] The thickness of the roller 17, that is, the thickness T4 of the peripheral wall of the roller 17, is not particularly limited, but is preferably 0.1 mm or more and 7 mm or less. The outer diameter of the roller 17, that is, the outer diameter of the peripheral wall of the roller 17, is not particularly limited, but is preferably 0.6 mm or more and 55 mm or less.

[0036] The inner diameter of the roller 17, that is, the inner diameter of the peripheral wall of the roller 17, is not particularly limited, but is preferably 0.4 mm or more and 45 mm or less. The length of roller 17, that is, the axial length of the peripheral wall of roller 17, is slightly smaller than distance D1 between the pair of inner link plates 14.

[0037] <Pin> As shown in Figures 1 and 2, the pin 18 is configured in a rod shape. Specifically, the pin 18 has a cylindrical shape with a circular outer shape in a cross section along the radial direction. Figures 2 and 6 show the pin 18 as viewed from the side.

[0038] The pin 18 has both axial ends inserted into the pin insertion holes 15a of the outer link plates 15 and press-fitted into the pin insertion holes 15a. Furthermore, the tip portions of both axial ends of the pin 18 pass through the pin insertion holes 15a of the pair of outer link plates 15 and protrude outward in the width direction Y of the chain 11.

[0039] Pin 18 is rotatably inserted into bushing 16. That is, diameter T5 of pin 18 is configured to be smaller than the inner diameter of through hole 14a of inner link plate 14 and the inner diameter of the peripheral wall of bushing 16. Pin 18 is configured to be rotatable inside bushing 16.

[0040] The diameter T5 of the pin 18 is not particularly limited, but is preferably 0.3 mm or more and 35 mm or less. The length of the pin 18 is not particularly limited, but is preferably 1.4 mm or more and 350 mm or less.

[0041] The upper limit of the distances P1, P2 between the axial centers of adjacent pins 18, i.e., the upper limit of the pitch, is not particularly limited, but is preferably, for example, 90 mm. The lower limit of the pitch is not particularly limited, but is preferably, for example, 0.9 mm.

[0042] The materials of the components of the chain 11 will now be described. <Materials of each component of the chain> The materials of the components of the chain 11, that is, the inner link plates 14, the outer link plates 15, the bushings 16, the rollers 17, and the pins 18, are not particularly limited, and any material known as the material for the chain 11 can be appropriately used.

[0043] Examples of known materials include metals, resins, etc. Among these, metals are preferred because they can improve mechanical strength. A method for manufacturing the chain 11 will now be described.

[0044] <Chain manufacturing method> The manufacturing method of the chain 11 includes a forming process for forming a metal plate material into a predetermined shape, and an assembly process for assembling each component member obtained in the forming process. Each process will be described below.

[0045] (molding process) In the molding process, each component is molded using a plate material such as a metal plate. When forming the inner link plate 14 and the outer link plate 15, for example, the plate material is punched into a predetermined shape. The through hole 14a of the inner link plate 14 and the pin insertion hole 15a of the outer link plate 15 can also be formed by punching. At the same time as forming the through hole 14a, a taper 14a1 can be formed at the outer opening end of the through hole 14a. In Figure 4, the taper 14a1 is formed with the opening end being C-chamfered.

[0046] Furthermore, when forming the bushing 16 and the roller 17, for example, the plate material is punched into a predetermined shape and then curved into a cylindrical shape. In other words, it is curled into a cylindrical shape. Furthermore, after curling, the ends of the plate material are joined together. Here, joining the ends of the plate material means bringing the ends of the plate material into contact with each other.

[0047] When forming the pin 18, for example, a metal bar is drawn and then cut to a predetermined length. After the molding step, a heat treatment step such as quenching may be carried out.

[0048] (Assembly process) In the assembling process, the respective component parts obtained in the molding process are assembled to produce the chain 11. As shown in FIGS. 1 and 2, first, a plurality of inner link plates 14 are prepared, and bushings 16 are press-fitted into two through holes 14a of each inner link plate 14.

[0049] Here, bushing 16 is press-fitted from the inner open end side of one of the two through holes 14a of inner link plate 14, where taper 14a1 is not formed. Bushing 16 is attached to inner link plate 14 with one axial end side press-fitted into through hole 14a. It is preferable that one axial end side of bushing 16 is located within through hole 14a and does not protrude outward.

[0050] Next, rollers 17 are fitted onto the bushes 16 attached to each inner link plate 14 from the other end side of the bushes 16. Furthermore, another inner link plate 14 is attached to the bushes 16 with the rollers 17 fitted onto them from the other end side of the bushes 16. Specifically, the other end side of the bushes 16 with the rollers 17 fitted onto them is press-fitted into the open end side where the taper 14a1 is not formed, of the two through holes 14a of the other inner link plate 14. It is preferable that the other end side of the bushes 16 is located within the through holes 14a and does not protrude outward.

[0051] By the above procedure, the inner link 12 can be produced. One end and the other end of the bushing 16 are press-fitted into the through holes 14a of the pair of inner link plates 14, so that the through holes 14a formed in the pair of inner link plates 14 are connected by the bushing 16. By repeating the same procedure, multiple inner links 12 can be produced.

[0052] Next, a plurality of outer link plates 15 are prepared, and the pins 18 are press-fitted into the two pin insertion holes 15a of each outer link plate 15. The pins 18 are attached to the outer link plates 15 with the tip portions at one axial end protruding from the pin insertion holes 15a.

[0053] Next, the two inner links 12 produced as described above are prepared. For one of the two inner links 12, one of the two pins 18 attached to the outer link plate 15 is inserted into the bushing 16 of this inner link 12.

[0054] Furthermore, for the other of the two inner links 12, the other of the two pins 18 attached to the outer link plate 15 is inserted into the bushing 16 of this inner link 12. Furthermore, another outer link plate 15 is attached to the two pins 18 inserted into the bushings 16 of the two inner links 12. Specifically, the other end portions of the two pins 18 inserted into the bushings 16 of the two inner links 12 are press-fitted into the two pin insertion holes 15a of the other outer link plate 15.

[0055] Through the above steps, the pins 18 are joined to the two pin insertion holes 15a of each of the pair of outer link plates 15. This completes the manufacture of the outer link 13. Furthermore, the two inner links 12 are connected by one outer link 13.

[0056] The above procedure is repeated to connect the inner links 12 and the outer links 13 so that the inner links 12 and the outer links 13 are alternately positioned in the length direction X. Furthermore, both ends of the inner links 12 and the outer links 13 alternately positioned in the length direction X are connected to each other to make the whole into a ring shape.

[0057] Through the above-mentioned procedure, the chain 11 can be manufactured. The order in which the components of the chain 11 are assembled can be changed as appropriate. <Action and Effects> The operation of the chain 11 of the first embodiment will be described.

[0058] When the chain 11 is in use, stress is applied to the through hole 14a of the inner link plate 14 directly from the bushing 16 press-fitted into the through hole 14a, or indirectly from the pin 18 inserted into the bushing 16. This stress tends to concentrate at the open end of the through hole 14a of the inner link plate 14 on the outer link plate 15 side.

[0059] 3 and 4, inner link plate 14 of the first embodiment has taper 14a1 at the outer open end of through hole 14a, thereby making it possible to prevent stress from concentrating at the open end of through hole 14a. In particular, by setting the ratio (B / A) of the depth (B) of taper 14a1 to the distance (A) between the centers of a pair of through holes 14a to be 0.9% or more and 6% or less, the fatigue performance of chain 11 can be suitably improved even for chains 11 having different distances (A).

[0060] On the other hand, when through hole 14a has taper 14a1, it is easy for the fitting pressure output of bushing 16 to decrease in through hole 14a of inner link plate 14. In chain 11 of the present embodiment, the ratio (B / T1) of depth (B) of taper 14a1 to thickness T1 of inner link plate 14 is 6% or more and 50% or less, thereby suitably suppressing the decrease in the fitting pressure output of bushing 16 in through hole 14a.

[0061] The effects of the chain 11 of the first embodiment will be described. (1-1) Chain 11 includes a pair of inner link plates 14 arranged opposite each other, and a cylindrical bushing 16 inserted into a pair of through holes 14a of each of the pair of inner link plates 14. Chain 11 also includes a pin 18 rotatably inserted into bushing 16, and a pair of outer link plates 15 arranged to sandwich the pair of inner link plates 14 from the outside and arranged at both ends of pin 18. The pair of pins 18 are located between the pair of outer link plates 15. Inner link plate 14 has taper 14a1 at an open end of through hole 14a facing outer link plate 15, and a ratio (B / A) of a depth (B) of taper 14a1 to a distance (A) between the centers of the pair of through holes 14a is 0.9% or more and 6% or less.

[0062] This makes it possible to suitably improve the fatigue performance of the chain 11. By suitably improving the fatigue performance, it is possible to obtain a chain 11 with excellent durability. (1-2) By having taper 14a1 in through hole 14a of inner link plate 14, lubricating oil can be stored in the gap between taper 14a1 and bushing 16. For example, lubricating oil applied between bushing 16 and pin 18 that leaks out from between the two can be stored in the gap. This prevents lubricating oil from leaking out to the outside of chain 11, making it easier to reduce wear on bushing 16 and pin 18.

[0063] <Second embodiment> A second embodiment of a chain according to the present invention will now be described. In the following, configurations different from those of the chain 11 in the first embodiment will be described, and descriptions of the same configurations will be omitted.

[0064] 7 and 8, inner link plate 14 has convex portion 14a2 in the vicinity of taper 14a1. Specifically, inner link plate 14 has convex portion 14a2 at a position that is continuous with taper 14a1 and surrounds the entire circumference of taper 14a1. Note that "continuous with taper 14a1" means that convex portion 14a2 is located on an extension of the surface of taper 14a1. Convex portion 14a2 protrudes outward from inner link plate 14 along the thickness direction of inner link plate 14.

[0065] As shown in Fig. 8, in a cross-sectional view of the inner link plate 14, the convex portion 14a2 has a semicircular cross-sectional shape with the outer side being convex in the protruding direction. The convex portion 14a2 may not only have a completely semicircular cross-sectional shape, but also may have a substantially semicircular cross-sectional shape with the outer side being curved and convex. In addition, the cross-sectional shape of the convex portion 14a2 is not limited to a semicircular shape, and any cross-sectional shape with the outer side being convex may be used.

[0066] The ratio (C / A) of the height (C) of the convex portion to the distance (A) between the centers of a pair of through holes in the inner link plate is not particularly limited, but is preferably 0.05% to 0.9%, more preferably 0.1% to 0.5%, and even more preferably 0.15% to 0.35%.

[0067] The width E of the protrusion 14a2 along the radial direction of the through-hole 14a is not particularly limited, but is preferably 0.05 mm or more and 3 mm or less, and more preferably 0.1 mm or more and 1 mm or less.

[0068] As a method for forming the convex portion, when forming the taper 14a1 by punching in the molding step in the manufacturing method of the chain of the first embodiment, the convex portion 14a2 continuous with the taper 14a1 can be formed at the same time. For example, when forming the taper 14a1, punching is performed under conditions that cause the periphery of the taper 14a1 to rise, so that the taper 14a1 and the convex portion 14a2 can be formed at the same time. There is no particular limitation on the method for forming the convex portion 14a2, and it can be formed by, for example, thermal spraying, welding, forging, etc.

[0069] <Action and Effects> The operation of the chain 11 of the second embodiment will be described. The chain 11 of the second embodiment exhibits the following action in addition to the action of the chain 11 of the first embodiment.

[0070] By having the protrusion 14a2 that protrudes outward from the inner link plate 14 along the thickness direction of the inner link plate 14, excessive interference between the inner link plate 14 and the outer link plate 15 can be suppressed. In other words, the outer surface of the inner link plate 14 and the inner surface of the outer link plate 15 are in point contact or line contact at the top of the protrusion 14a2 rather than surface contact. This reduces the contact area between the outer surface of the inner link plate 14 and the inner surface of the outer link plate 15, thereby suppressing heat generation due to friction between them. By suppressing heat generation, the wear performance of the chain can be improved.

[0071] Furthermore, by making the ratio (C / A) of the height (C) of the convex portion 14a2 to the distance (A) between the centers of a pair of through holes 14a greater than or equal to 0.05% and less than or equal to 0.9%, excessive interference between the inner link plate 14 and the outer link plate 15 can be suitably suppressed even in chains 11 having different distances (A).

[0072] The effects of the chain 11 of the second embodiment will be described. (2-1) The inner link plate 14 has a convex portion 14a2 continuous with the taper 14a1 on the surface facing the outer link plate 15. The presence of the convex portion 14a2 makes it possible to prevent excessive interference between the inner link plate 14 and the outer link plate 15, thereby improving the wear performance of the chain 11. In addition, the sliding between the inner link plate 14 and the outer link plate 15 can be reduced, thereby reducing noise of the chain 11.

[0073] (2-2) The protruding portion 14a2 is continuous with the taper 14a1. Therefore, the protruding portion 14a2 can be utilized as a part of the taper 14a1. In addition, the protruding portion 14a2 and the taper 14a1 can be formed simultaneously, so that the production efficiency of the chain 11 can be improved.

[0074] (2-3) Inner link plate 14 has taper 14a1 around the entire circumference of the open end of through hole 14a facing outer link plate 15, and has protrusion 14a2 at a position surrounding the entire circumference of taper 14a1. By having taper 14a1 and protrusion 14a2 around the entire circumference of through hole 14a, the effects of the second embodiment can be achieved around the entire circumference of through hole 14a.

[0075] (2-4) The ratio (C / A) of the height (C) of the protrusions 14a2 to the distance (A) between the centers of a pair of through holes 14a is 0.05% or more and 0.9% or less. This effectively prevents excessive interference between the inner link plate 14 and the outer link plate 15 located outside the inner link plate 14, thereby improving the wear performance of the chain 11.

[0076] <Example of change> The first embodiment and the second embodiment (hereinafter, collectively referred to as the present embodiment) can be modified as follows. The present embodiment and the following modified examples can be combined with each other to the extent that there is no technical contradiction.

[0077] In this embodiment, the chain 11 has the rollers 17, but the rollers 17 may be omitted. As shown in Figures 5 and 6, for example, the chain 11 may omit the rollers 17, and the inner links 12 of the chain 11 may be composed of a pair of inner link plates 14 and a bushing 16 positioned between the pair of inner link plates 14.

[0078] In the present embodiment, the inner link plate 14 has the protrusion 14a2 continuous with the taper 14a1 on the surface facing the outer link plate 15, but the present invention is not limited to this.

[0079] As shown in Figure 9, inner link plate 14 may have convex portion 14a2 on the surface facing outer link plate 15, adjacent to taper 14a1 but spaced from the periphery of taper 14a1. Having convex portion 14a2 spaced from the periphery of taper 14a1 makes it easy to form taper 14a1 and convex portion 14a2 separately. Forming taper 14a1 and convex portion 14a2 separately makes it easier to improve the dimensional accuracy of each.

[0080] The protrusion 14a2 does not have to be formed continuously along the periphery of the taper 14a1. As shown in Fig. 10, for example, the protrusion 14a2 may be formed discontinuously at a distance from the periphery of the taper 14a1. In Fig. 10, the protrusion 14a2 is formed in a dome shape, in other words, a hemispherical shape. By forming the protrusion 14a2 discontinuously, the protrusion 14a2 can be selectively disposed at a more effective position.

[0081] As shown in Figure 10, it is preferable that convex portion 14a2 is located in a region including the inner diameter of through hole 14a, including taper 14a1, in the longitudinal direction of inner link plate 14, and in a region including both sides in the lateral direction of inner link plate 14 (inside the dashed lines indicated by arrows in Figure 10). Since this region is prone to wear when chain 11 is in use, having convex portion 14a2 at least in this region makes it easier to suppress wear of inner link plate 14 and outer link plate 15.

[0082] In the present embodiment, through hole 14a of inner link plate 14 has taper 14a1 and protrusion 14a2 only at the outer opening end, but is not limited to this. In addition to the outer opening end, through hole 14a may have taper 14a1 and protrusion 14a2 at the inner opening end. In other words, inner link plate 14 may have the same shape on the outer and inner sides.

[0083] When through hole 14a of inner link plate 14 is formed by stamping, taper 14a1 may be provided on the fracture surface of through hole 14a, or taper 14a1 may be provided on the shear surface of through hole 14a.

[0084] In the present embodiment, the taper 14a1 is formed around the entire circumference of the outer opening end of the through hole 14a, but the present invention is not limited to this. The taper 14a1 may be formed on only a part of the outer opening end of the through hole 14a.

[0085] The ratio (B / T1) of the depth (B) of the taper 14a1 to the thickness T1 of the inner link plate 14 is not limited to 6% or more and 50% or less. The ratio (B / T1) may be less than 10% or more than 50%.

[0086] In the present embodiment, the taper 14a1 has a shape in which the opening end of the through hole 14a is chamfered to a C-shape, but is not limited to this. The shape of the taper 14a1 can be selected as appropriate. For example, the taper 14a1 may have a shape in which the opening end of the through hole 14a is chamfered to a R-shape, or may have a stepped shape.

[0087] In this embodiment, the bushing 16 is attached by being press-fitted into the through hole 14a of the inner link plate 14, but the present invention is not limited to this. The bushing 16 may be attached by welding to the through hole 14a of the inner link plate 14, or may be attached using an adhesive. The pin 18 may be attached to the pin insertion hole 15a of the outer link plate 15 in a similar manner.

[0088] In a chain of a different type from the chain 11 of this embodiment, the taper 14a1 may be omitted at the outer opening end of the through hole 14a of the inner link plate 14, and a convex portion 14a2 may be provided contiguous to the opening end or in the vicinity of the opening end. EXAMPLES

[0089] In the following, examples will be given in order to more specifically explain the configuration and effects of the present invention, but the present invention is not limited to these examples. Example 1 An inner link plate 14 was fabricated having a thickness T1 of 3.15 mm, an inner diameter of a pair of through holes 14a of 11.25 mm, a distance (A) between the centers of a pair of through holes 14a of 25.4 mm, and a taper 14a1 at the outer open end of through hole 14a. The depth (B) of taper 14a1 was 0.24 mm, and the ratio (B / A) was 0.94%. Inner link plate 14 had a protrusion 14a2 continuous with taper 14a1, and the height (C) of protrusion 14a2 was 0.025 mm, the ratio (C / A) was 0.1%, and the width E of protrusion 14a2 was 1.6 mm.

[0090] An outer link plate 15 was produced having a thickness T2 of 3.15 mm, an inner diameter of a pair of pin insertion holes 15a of 7.85 mm, and a distance between the centers of the pair of pin insertion holes 15a of 25.4 mm. A bushing 16 was produced having a peripheral wall thickness of 1.65 mm, an inner diameter of 8.1 mm, an outer diameter of 11.4 mm, and a length of 22.6 mm.

[0091] A roller 17 was produced having a peripheral wall thickness of 2.2 mm, an inner diameter of 11.5 mm, an outer diameter of 15.9 mm, and a length of 15.6 mm. A pin 18 was fabricated having a diameter of 7.9 mm and a length of 32.5 mm.

[0092] A chain 11 was produced by assembling a plurality of the above-mentioned components. (Examples 2 to 12, Comparative Examples 1 to 6) A chain was produced in the same manner as in Example 1, except that the depth (B) and ratio (B / A) of the taper 14a1 were changed as shown in Table 1.

[0093] (Fatigue performance evaluation) Fatigue performance was evaluated for the chains of Examples 1 to 7, 9 to 12 and Comparative Examples 1 to 5. Specifically, the effect of the ratio (B / A) of the depth (B) of taper 14a1 to the distance (A) between the centers of a pair of through holes 14a of inner link plate 14 on the fatigue performance of inner link plate 14 was evaluated.

[0094] The fatigue performance was evaluated using a known fatigue testing machine in accordance with the "Fatigue test method for transmission roller chains and leaf chains" described in JIS1811 B 2018. The analytical fatigue safety factor was measured and evaluated according to the following evaluation criteria. The results are shown in Table 1 and Figure 11.

[0095] Fatigue performance evaluation criteria ◎(Good): When the analytical fatigue safety factor is 2.1 or more ○(Acceptable): When the analytical fatigue safety factor is 2.0 or more and less than 2.1 × (Not acceptable): When the analytical fatigue safety factor is less than 2.0 (Evaluation of bushing fitting pressure output) The bushing fitting pressure output was evaluated for the chains of Examples 1 to 12 and Comparative Examples 1 to 6. Specifically, the effect of the ratio (B / T1) of the depth (B) of taper 14a1 to the thickness (T1) of inner link plate 14 on the bushing fitting pressure output was evaluated.

[0096] The bushing fitting pressure force was evaluated using a known tensile tester to measure the fitting pressure force, which is the force exerted when pushing out bushing 16 press-fitted into through hole 14a of inner link plate 14. Evaluation was performed according to the following evaluation criteria. The results are shown in Table 1.

[0097] - Evaluation criteria for bush mating pressure output ◎(Good): When the mating pressure output is 4.0kN or more ○(OK): When the mating pressure output is 3.0kN or more and less than 4.0kN × (Not possible): When the mating pressure output is less than 3.0 kN

[0098] [Table 1] (Evaluation Results) 11, in Comparative Examples 1 to 5, the ratio (B / A) was less than 0.9% or more than 6%, and the fatigue performance was "unacceptable." In contrast, in Examples 1 to 7 and 9 to 12, the ratio (B / A) was 0.9% or more and 6% or less, and the fatigue performance was "fair" or better. In particular, in Examples 5 to 7 and 9 to 11, the ratio (B / A) was 2% or more and 5.5% or less, and the fatigue performance was "good."

[0099] Also, from Table 1, in Comparative Examples 5 and 6, the ratio (B / T1) exceeded 50%, and the fitting pressure output was "not acceptable." In contrast, in Examples 1 to 12, the ratio (B / T1) was 6% or more and 50% or less, and the fitting pressure output was "acceptable" or more. When the fitting pressure output is "acceptable" or more, that is, when the fitting pressure output is 3.0 kN or more, it is possible to suitably prevent bushing 16 from falling out of through hole 14a of inner link plate 14. [Explanation of symbols]

[0100] 11...Chain 12…Internal link 13…External link 14…Inner link plate 14a...Through hole 14a1...Tapered 14a2…Convex part 15…Outer link plate 15a…Pin insertion hole 16…Bush 17…Laura 18…Pin A: Distance between the centers of the through holes B…Taper depth C: Height of the convex part D1,D2…interval D3: Distance between the plates E…Width of the convex part P1, P2: Distance between shaft centers T1, T2, T3, T4…Thickness T5…Diameter

Claims

1. A pair of inner link plates arranged opposite each other; a pair of cylindrical bushings to be inserted into a pair of through holes formed in each of the pair of inner link plates; a pin rotatably inserted into the bushing; a pair of outer link plates disposed on both ends of the pin and sandwiching the pair of inner link plates from the outside, wherein the pair of pins are located between the pair of outer link plates, the inner link plate has a taper at an open end of the through hole facing the outer link plate, A chain characterized in that the ratio (B / A) of the taper depth (B) to the distance (A) between the centers of a pair of the through holes is 0.9% or more and 6% or less.

2. 2. The chain according to claim 1, wherein the inner link plate has a convex portion continuous with the taper on a surface facing the outer link plate.

3. the inner link plate has the taper around the entire circumference of the opening end, 3. The chain according to claim 2, wherein the protrusions are disposed at positions surrounding the entire circumference of the taper.

4. 4. A chain according to claim 2 or 3, wherein the ratio (C / A) of the height (C) of the convex portion to the distance (A) between the centers of a pair of the through holes is 0.05% or more and 0.9% or less.

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