JP2011067851A - Method of manufacturing power transmission chain - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a power transmission chain, by which the variation of the circumferential length of a chain being a finished article is reduced. <P>SOLUTION: The method of manufacturing the power transmission chain includes: as shown in Fig.4, a stage S1 where the table of proper prestressing load when the hardness and the thickness of a link is beforehand prepared; a stage S2 where the hardness of the link is measured before assembling the chain; a stage S3 where the reference load for prestressing is selected in accordance with the hardness of the link; a stage S4 where the plate thickness of the link is measured before assembling the chain; a stage S5 where a correction factor is selected in accordance with the plate thickness; a stage S6 where the endless power transmission chain is assembled; a stage S7 where the prestressing load is calculated by (the reference load×the correction factor) in accordance with the hardness and the plate thickness of the link which is used actually in assembled power transmission chain; a stage S8 where the prestress is performed by loading the calculated prestressing load to the power transmission chain; and a stage S9 where an amount of plastic elongation generated by the prestressing is checked. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a power transmission chain, and more particularly to a method for manufacturing a power transmission chain suitable for a continuously variable transmission (CVT) of a vehicle such as an automobile.

  Conventionally, as a power transmission chain suitable for a continuously variable transmission, a power transmission chain including a plurality of links through which pins are inserted and a plurality of pins connecting links arranged in the chain width direction is known. In order to improve durability, in the manufacturing process, a tensioning device having a configuration similar to that of a continuously variable transmission (actual machine) actually used is used, and tension is applied (pretensioned) to the chain in advance. Thus, it is disclosed that the variation in the circumferential length of the chain is reduced, and an appropriate residual compressive stress is applied to the link to improve the fatigue life.

JP 2007-167931 A

  In the power transmission chain of Patent Document 1, variation in the chain circumference can be reduced by pre-tensioning. However, since the chain circumference is a contributing factor to the gear ratio in the continuously variable transmission, it is further increased. It is desired to suppress variations in the above.

  An object of the present invention is to provide a method of manufacturing a power transmission chain that can reduce variation in the circumference of a finished product chain.

  A method of manufacturing a power transmission chain according to the present invention is a method of manufacturing a power transmission chain including a plurality of links and a plurality of pins connecting links arranged in the width direction of the chain. A step of measuring the thickness, a step of assembling the power transmission chain endlessly, a step of calculating a preload according to the hardness and thickness of the link actually used in the assembled power transmission chain, And a pre-tensioning step by applying a pre-tensioning load to the power transmission chain.

  The link is manufactured by pressing a rolled material, and the thickness of the link varies. The link is also made of steel and is subjected to a required heat treatment to become a finished product. In this process, the hardness also varies.

  In manufacturing such a power transmission chain, in order to suppress variation in the circumference, a process of applying a load before applying it to an actual vehicle, pulling it to plastic deformation, and applying residual compressive stress (in this specification) , Referred to as “pretension”). In the pre-tensioning process, when the link is plastically deformed by applying a pre-tensioning load of a predetermined size based on the relationship between the link elongation amount ε and its stress σ (when unloading) ) Is applied with a load such that the residual compressive stress is about -500 Mpa, for example. When the tension load is constant, when the link hardness and the link plate thickness change within the tolerance range, the circumference after the tension varies. The variations in the link hardness and the link plate thickness are considered to be appropriate if they are within the tolerance range, and have not been taken into consideration in the conventional tensioning process.

  On the other hand, in the manufacturing method according to the present invention, the link hardness and the link plate thickness are actually measured before the assembly of the power transmission chain, and the hardness and plate thickness of the links constituting the chain are grasped for the assembled chain. . On the other hand, as for the pretension condition, an appropriate pretension load corresponding to the link hardness and the link plate thickness is set in advance. For each chain, a preload according to the hardness and thickness of the link constituting the chain is determined, and this preload is applied when the chain is pretensioned.

  More specifically, the manufacturing method includes a step of preparing a table or formula of an appropriate preload when the hardness and thickness of the link are changed, and a step of measuring the hardness of the link before assembling the chain. , A step of selecting a reference load for tension according to the link hardness, a step of measuring the link plate thickness before assembling the chain, a step of selecting a correction factor according to the plate thickness, and endless power The process of assembling the transmission chain, the process of calculating the preload by the standard load x correction factor according to the hardness and thickness of the link actually used in the assembled power transmission chain, and the calculated preload It is assumed that the method includes a step of performing tension by loading the power transmission chain and a step of checking the amount of plastic elongation caused by the tension.

  When setting the tension load, for example, the link hardness tolerance range and the link thickness tolerance range are each divided into a plurality of ranges and tabulated, and a standard load is set for each predetermined link hardness range. The correction coefficient is multiplied for each predetermined link plate thickness range. The preload may be set in the form of a formula such as preload = A × link hardness × link plate thickness + B instead of the form in the table. In any case, when the link hardness and the link plate thickness are relatively large, a relatively large preload is applied and the link hardness and the link plate thickness are relatively small. This means that a relatively small preload is applied, and the variation in plastic elongation of the link between different power transmission chains is suppressed, which reduces the variation in the circumference of the finished product of the power transmission chain. To do.

  Preferably, the links are grouped into a plurality of layers according to the plate thickness, and the same layer group is used for one chain. And in the group with the same plate thickness, the hardness is also grouped by layer, and for one chain, the one in the layer group having the same plate thickness and hardness is used. Even when the thickness and hardness of the links in one chain are different, various measures can be taken by changing the table or formula for setting the preload.

  The above manufacturing method is suitable for manufacturing various power transmission chains that require pre-tensioning, but includes a plurality of links having front and rear insertion portions through which pins are inserted, and a front insertion portion of one link. A plurality of first pins and a plurality of second pins arranged before and after connecting the links arranged in the chain width direction so as to correspond to the rear insertion portions of the other links are provided, and the first pins and the second pins are relatively By rolling contact movement, it is possible to bend the links in the chain length direction, and one of the first pin and the second pin is fixed to the front insertion part of one link by press-fitting and the other The other of the links is movably fitted into the rear insertion portion of one link, and the other is movably fitted into the front insertion portion of one link and fixed to the rear insertion portion of the other link by press-fitting. Manufacture power transmission chain It is more suitable for that. In this case, the press-fitting is preferably performed at the edges (upper and lower edges) of the portion orthogonal to the chain length direction of the insertion portion.

  In the power transmission chain, at least one of the first pin and the second pin comes into contact with the pulley to transmit power by frictional force. In a chain in which one of the pins contacts the pulley, one of the first pin and the second pin is a pin that contacts the pulley when the chain is used in a continuously variable transmission ( In the following, the pin is referred to as “first pin” or “pin”, and the other is referred to as the pin that does not contact the pulley (interpiece or strip). "Peace").

  For example, the link is made of spring steel or carbon tool steel. The material of the link is not limited to spring steel or carbon tool steel, and may of course be other steel such as bearing steel. In the link, the front and rear insertion portions may be independent through holes (links with columns), and the front and rear insertion portions may be one through holes (links without columns). Appropriate steel such as bearing steel is used as the material of the pin.

  According to the power transmission chain manufacturing method of the present invention, the steps of measuring the hardness and thickness of the link before assembling the chain, the step of assembling the power transmission chain endlessly, and the assembled power transmission chain are actually used. Including a step of calculating a preload according to the hardness and thickness of the link, and a step of applying a preload by applying the calculated preload to the power transmission chain. The preload according to the hardness and thickness of the link that composes it is calculated. When the chain is pretensioned, this pretension load is applied, reducing the variation in the circumference of the finished product. be able to. As a result, it is possible to reduce the variation in the gear ratio when used in a continuously variable transmission.

FIG. 1 is a plan view showing a part of one embodiment of a power transmission chain manufactured by the method of manufacturing a power transmission chain according to the present invention. FIG. 2 is an enlarged side view of the link. FIG. 3 is a front view showing a state in which the power transmission chain is attached to the pulley. FIG. 4 is a flowchart showing a method for manufacturing a power transmission chain according to the present invention. FIG. 5 is a table showing an example of the relationship between the link hardness and the link plate thickness used in the method for manufacturing a power transmission chain according to the present invention and the preload. FIG. 6 is a graph showing the amount of variation of the power transmission chain obtained by the method of manufacturing the power transmission chain according to the present invention. FIG. 7 is a graph showing an example of the relationship between the stress and elongation of the link used in the method for manufacturing a power transmission chain according to the present invention.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the top and bottom refer to the top and bottom of FIG.

  FIG. 1 shows a part of a power transmission chain manufactured by using the method of manufacturing a power transmission chain according to the present invention. The power transmission chain (1) is provided at predetermined intervals in the chain length direction. A plurality of pins (11) (21) having the inserted front and rear insertion portions (12) (13) and a plurality of pins (11) (21) arranged in the chain width direction so as to be bendable in the length direction (First pin) (14) and an interpiece (second pin) (15). The interpiece (15) is made shorter than the pin (14), and both are opposed to each other with the interpiece (15) disposed on the front side and the pin (14) disposed on the rear side.

  In the chain (1), three link rows composed of a plurality of links having the same phase in the width direction are arranged in the traveling direction (front-rear direction) to form one link unit, and the link unit composed of the three rows of link rows is the traveling direction. Are connected to each other. In this embodiment, one link unit includes a link row having nine links and two link rows having eight links.

  In the power transmission chain (1) of the present invention, two types of links (11) and (21) are used: a short link (11) and a long link (21). In the short link (11) and the long link (21), the distance between the lines (points in the cross section) where the pin (14) and the interpiece (15) are in contact in the straight region of the chain (1) (FIG. 2). The distance between the point indicated by symbol A and the point indicated by B) = “pitch length” is different.

  As shown in FIG. 2, the front insertion portion (12) of the short link (11) (the same applies to the long link (12)) includes a pin movable portion (16) and an interpiece to which the pin (14) is movably fitted. It consists of an interpiece fixing part (17) to which (15) is fixed, and the rear insertion part (13) is fitted so that the pin fixing part (18) to which the pin (14) is fixed and the interpiece (15) can be moved. It consists of interpiece movable parts (19) to be matched.

  Each pin (14) is wider in the front-rear direction than the interpiece (15), and the upper and lower edges of the interpiece (15) have protruding edges (15a) extending to the respective pins (14) side. ) (15b).

  When connecting the links (11) (21) arranged in the chain width direction, the front insertion part (12) of one link (11) (21) and the rear insertion part (13) of the other links (11) (21) ) And the links (11) and (21) are overlapped so that the pin (14) is fixed to the rear insertion part (13) of one link (11) (21) and the other link (11) (21) is movably fitted to the front insertion part (12), and the interpiece (15) is movably fitted to the rear insertion part (13) of one link (11) (21) and the other It is fixed to the front insertion part (12) of the links (11) (21). Then, the pin (14) and the interpiece (15) are relatively rolled and brought into contact with each other, whereby the links (11) and (21) can be bent in the length direction (front-rear direction).

  At the boundary between the pin fixing part (18) of the link (11) (21) and the interpiece movable part (19), the upper and lower concave arcuate guide parts (19a) (19b) of the interpiece movable part (19) Are provided with upper and lower convex arc-shaped holding portions (18a) and (18b) for holding the pin (14) fixed to the pin fixing portion (18). Similarly, at the boundary between the interpiece fixing part (17) and the pin movable part (16), the upper and lower concave arcuate guide parts (16a) and (16b) of the pin movable part (16) are connected to the interpiece fixed part. Upper and lower convex arc-shaped holding portions (17a) and (17b) for holding the interpiece (15) fixed to the portion (17) are provided.

  The locus of the contact position between the pin (14) and the interpiece (15) with respect to the pin (14) is an involute of the circle, and in this embodiment, the rolling contact surface (14a) of the pin (14) Is an involute curve having a base circle of radius Rb and center M in the cross section, and the rolling contact surface (15c) of the interpiece (15) is a flat surface (the cross-sectional shape is a straight line). As a result, when each link (11) (21) moves from the straight region to the curved region of the chain (1) or from the curved region to the straight region, the pin (14) is fixed at the front insertion portion (12). The rolling contact surface (14a) is in contact with the rolling contact surface (15c) of the interpiece (15) while the rolling contact surface (15a) is in contact (including some sliding contact) with respect to the interpiece (15) in the state. In the rear insertion portion (13), the rolling contact surface (15c) is connected to the pin (14) with respect to the pin (14) in a state where the interpiece (15) is fixed in the interpiece movable portion (19). It moves while rolling (including some sliding contact) on the rolling contact surface (14a).

  FIG. 3 shows a power transmission device in which the power transmission chain (1) is attached to a V-type pulley type CVT. In the power transmission device, as shown in FIG. 3, a pulley having a pulley shaft (2e) ( 2) The end face of the pin (14) is the pulley (2) with the end face of the interpiece (15) not in contact with the conical sheave face (2c) (2d) of the fixed sheave (2a) and the movable sheave (2b). ) Contact the conical sheave surfaces (2c) and (2d), and power is transmitted by the frictional force generated by the contact.

  When the movable sheave (2b) of the drive pulley (2) at the position indicated by the solid line in FIG. 3 is moved toward and away from the fixed sheave (2a), the winding diameter of the drive pulley (2) is as shown in FIG. As indicated by the chain line, it is large when approaching and small when separated. In the driven pulley (3), although not shown in the drawing, when the movable sheave moves in the opposite direction to the movable sheave (2b) of the drive pulley (2) and the winding diameter of the drive pulley (2) increases, the driven pulley When the winding diameter of (3) decreases and the winding diameter of the drive pulley (2) decreases, the winding diameter of the driven pulley (3) increases. As a result, U / D (underdrive) where the winding diameter of the drive pulley (2) is the smallest and the winding diameter of the driven pulley (3) is the maximum based on the state where the transmission ratio is 1: 1. A state is obtained, and an O / D (overdrive) state in which the winding diameter of the drive pulley (2) is maximum and the winding diameter of the driven pulley (3) is minimum is obtained.

  This power transmission chain (1) has the necessary number of pins (14) and interpieces (15) held vertically on the assembly jig, and then one or several links (11) and (21). Manufactured by pressing together. This press-fitting is performed between the upper and lower edges of the pin (14) and the interpiece (15) and the upper and lower edges of the pin fixing part (18) and the interpiece fixing part (17). It is set to 0.005 mm to 0.1 mm. Thus, an appropriate tension is applied to the assembled chain (1) in the pre-tensioning process.

  In the above power transmission chain (1), polygonal vibration is caused by repeated vertical movement of the pin, which causes noise, but the pin (14) and the interpiece (15) are relatively rolled and moved in contact. In addition, since the locus of the contact position between the pin (14) and the interpiece (15) with respect to the pin (14) is an involute of the circle, both the contact surfaces of the pin and the interpiece are arcuate surfaces. Compared to the case, vibration can be reduced and noise can be reduced.

  When used in the CVT, the pin (14) and the interpiece (15) are guided by the movable parts (16) and (19) as described above to move in rolling contact with the pulley (2). The pin (14) hardly rotates with respect to the sheave surfaces (2c) and (2d), the friction loss is reduced, and a high power transmission rate is secured.

  In the pre-tensioning step, the link (11) (21) is attached by applying a predetermined load (pre-tensioning load) based on the relationship between the link elongation amount ε and the stress σ shown in FIG. A load is applied such that the residual compressive stress is within a predetermined range when plastically deformed and the load is removed (at the time of unloading).

  In the conventional tensioning process, the variations in link hardness and link plate thickness are appropriate if they are within the tolerance range, and the tensioning load is constant in the power transmission chain (1) with the same specifications. It was. Therefore, since the link hardness and the link plate thickness change within the tolerance range, the variation in the circumferential length after pre-tensioning between the power transmission chains (1) of the finished product is large.

  On the other hand, the manufacturing method of the power transmission chain according to the present invention is as follows, so that variations in link hardness and link plate thickness are taken into consideration.

  As shown in FIG. 4, the method for manufacturing a power transmission chain according to the present invention includes a step (S1) of preparing a table (or formula) of appropriate preload when the hardness and thickness of the link change in advance. , A step of measuring the link hardness before chain assembly (S2), a step of selecting a reference load for pretension according to the link hardness (S3), and a step of measuring the thickness of the link before chain assembly (S4), the step of selecting a correction factor according to the plate thickness (S5), the step of assembling an endless power transmission chain (S6), and the hardness of the link actually used in the assembled power transmission chain A step of calculating a preload according to the reference load × correction coefficient according to the plate thickness (S7), a step of applying a preload by applying the calculated preload to the power transmission chain (S8), Including a step (S9) of checking the amount of plastic elongation generated by It is.

  The appropriate tensile load at the time of tensioning refers to the relationship between the link elongation amount ε and the stress σ shown in FIG. 7, and even if the link hardness and link plate thickness change, the link elongation is Set to be the same.

  Specifically, first, as shown in FIG. 5 (a), the minimum value and the maximum value of the tolerance range of the HRC hardness of the link are divided into a plurality of equal parts (for example, four equal parts). , Reference loads A, B, C and D are associated with each other. Since the pretension load is preferably increased as the hardness increases, the reference load is A <B <C <D (the difference between the reference loads does not need to be constant).

  Further, as shown in FIG. 5B, the link plate thickness t is also divided into a plurality of equal parts (for example, three equal parts) between the minimum value and the maximum value of the tolerance range, and correction is made for each range. Coefficients E, F and G are associated with each other. Since it is preferable to increase the tension load as the link plate thickness increases, the correction coefficient E <F <G (the difference between the correction coefficients need not be constant).

  The HRC hardness of the link and the link plate thickness t are actually measured before the assembly of the power transmission chain by steps (S2) and (S4), whereby the hardness of the links constituting the chain and The thickness is grasped. Thus, for each chain, a pretension load (appropriate pretension load) corresponding to the hardness and thickness of the link constituting the chain is obtained, and this proper pretension load is applied when the chain is pretensioned.

  The reference load based on the link hardness and the correction coefficient based on the link plate thickness are prepared, for example, in the form of a table. For example, the link hardness value is in the second range from the bottom, and the link plate thickness is the first from the top. When it is within the range, the reference load B and the correction coefficient G are used, and the tension of the reference load B × the correction coefficient G is applied.

  In this way, as shown in FIG. 6, in the conventional tension where the preload is 1 level, there is a plastic elongation indicated by a white square, and the variation in plastic elongation per link row is compared. On the other hand, according to the power transmission chain manufacturing method of the present invention in which the preload is 4 levels, the variation in plastic elongation per link row is reduced to about half or less. Of course, the level of the tension load is not limited to 4 levels.

  Thereby, the dispersion | variation in the perimeter between the finished products of a power transmission chain (1) is reduced, and the dispersion | variation in the shift in CVT using this can be reduced.

  The manufacturing method described above is not limited to the shapes of links, pins, and interpieces, and can be applied to various power transmission chains that require pretensioning.

(1) Power transmission chain
(11) Link
(14) Pin (1st pin)
(15) Interpiece (2nd pin)

Claims (1)

A method of manufacturing a power transmission chain comprising a plurality of pins and a plurality of pins connecting links arranged in the chain width direction,
The process of measuring the link hardness and thickness before assembling the chain, the process of assembling the power transmission chain endlessly, and the tension according to the hardness and thickness of the link actually used in the assembled power transmission chain A method of manufacturing a power transmission chain, comprising: a step of calculating a load; and a step of performing a tension by applying the calculated pretension load to the power transmission chain.

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