JP2010060117A - Nitriding tool for metal ring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nitriding tool capable of uniformly performing nitriding of a lateral end face (edge surface) of a metal ring, facilitating attachment/detachment of the metal ring and securely fixing and holding a plurality of metal rings in predetermined positions even when the plurality of metal rings are stored. <P>SOLUTION: The nitriding tool 1 is used to nitride the metal ring W formed to have an endless band shape and an arcuate cross sectional shape bent to project outwardly in the central part along the width direction by using gas. The nitriding tool 1 is provided with a plurality of holding members 3 holding the metal rings W by pressing a plurality of portions of the outer peripheral faces W<SB>1</SB>of the metal rings W to bend them to form an elliptical shape; and abutment recessed parts 6 formed in portions of the holding members 3 abutting on the metal rings W. The abutment recessed part 6 has a shape brought into point contact with at least two portions of the outer peripheral face W<SB>1</SB>of the metal ring W. The holding member 3 has the plurality of abutment recessed parts 6 along the length direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a nitriding jig for holding an endless band-shaped metal ring when nitriding the endless band-shaped metal ring constituting a power transmission belt of a continuously variable transmission such as an automobile with a gas. .

  The power transmission belt of a continuously variable transmission (CVT) used as a transmission of an automobile or the like has a plurality of elements arranged in an annular shape and a plurality of endless metal rings stacked in the thickness direction. It is provided with a configuration that is integrally bound by a laminated ring.

  The metal ring is an endless belt-like ring-shaped member obtained by cutting a cylindrical drum formed by welding ends of thin plates of steel material such as maraging steel or stainless steel to a predetermined width, It is rolled to a predetermined thickness and further subjected to a peripheral length correction to a predetermined peripheral length. The laminated ring is subjected to aging treatment and nitriding treatment on the metal ring whose circumference has been corrected to improve hardness and wear resistance, and then a plurality of metal rings having slightly different circumferences are mutually added. It is formed by laminating in the thickness direction. When the metal rings are laminated as described above, a circular arc shape with a central portion curved outward is provided along the width direction so as not to be displaced from each other. .

  As a nitriding treatment method for the metal ring, a gas nitriding method, a gas soft nitriding method and the like are known. The gas nitriding method or the gas soft nitriding method is performed by using a gas containing a predetermined concentration of ammonia and holding the metal ring in the atmosphere of the gas for a predetermined time. In the gas nitriding method or the gas soft nitriding method, it is preferable that the metal ring is uniformly nitrided by exposing the entire metal ring to the atmosphere.

  Therefore, a nitriding jig 41 shown in FIG. 4A is conventionally known as a jig for holding the metal ring when nitriding the metal ring with the gas containing the predetermined concentration of ammonia ( Patent Document 1). The nitriding jig 41 includes a pair of suspension members 43 provided above and below a standing pole 42 at a predetermined interval, and each suspension member 43 is shown as a side view in FIG. As shown in the figure, a tip member 44 is provided with a holding member 45 having a V-shaped cross-sectional view. The clamping member 45 can press and hold the metal ring W in the width direction by pressing against the inner peripheral surface of the metal ring W, and can hold the metal ring W in a state where tension is applied. Further, a net-like member 46 made of pure Ni that itself does not undergo nitriding is disposed on the pinching member 45, and the pinching member 45 holds the metal ring W via the net-like member 46. It has become.

  According to the conventional nitriding jig, the net-like member 46 made of pure Ni is disposed at the portion where the metal ring W comes into contact with the sandwiching member 45, so that the inside of the metal ring W with which the sandwiching member 45 comes into contact is arranged. It is possible to reduce non-uniform nitriding of the peripheral surface. However, in the nitriding jig, there is a problem that nitriding of the inner peripheral surface of the metal ring W cannot be avoided at all.

  When the metal ring W is used for the power transmission belt of the CVT, a strong tensile load is applied, and the tensile load is particularly applied to the side end surface (edge surface) of the metal ring W. Accordingly, it is not preferable that the nitriding of the inner peripheral surface of the metal ring W constituting the edge surface is not uniform.

  In order to solve the above problem, a nitriding jig 51 shown in FIG. 5A has been proposed (see Patent Document 2). The nitriding jig 51 includes a frame body 52 in which the metal ring W can be freely inserted in the radial direction thereof, and is attached to the frame body 52 and presses the metal ring W at a plurality of locations on the outer peripheral surface. And a plurality of holding members 53 that are held in an elliptical shape.

  The holding member 53 is a round bar extending along the length direction of the rectangular parallelepiped frame body 52, and has a predetermined interval near the center between the two opposite side surfaces of the frame body 52 and the bottom surface. And two are attached. Therefore, as shown by an arrow in FIG. 5B, the metal ring W can be inserted into the frame body 52 from above where the holding member 53 is not disposed. In this way, the nitriding jig 51 can accommodate a plurality of metal rings W along the length direction of the frame body 52.

  Further, as shown in FIG. 5C, the holding member 53 is formed on the outer peripheral surface of the metal ring W provided with a cross-sectional arc shape in which the central portion is curved outwardly along the width direction. Press contact with the arcuate top. Therefore, in the nitriding jig 51, the metal ring W is held in a state in which the edge surface is not in contact with the holding member 53 and the frame body 52 at all, so that the side end face can be nitrided uniformly.

However, in the nitriding jig 51, when the holding member 53 is pressed against the arcuate top portion of the outer peripheral surface of the metal ring W as described above, the holding member 53 is only in one point with respect to the metal ring W. It will come into contact. As a result, the nitriding jig 51 has a disadvantage that the position of the metal ring W is likely to be shifted, and it may be difficult to maintain the arrangement state when a plurality of metal rings W are stored.
Japanese Patent No. 3776306 JP 2004-257462 A

  The present invention eliminates such inconvenience, can uniformly perform nitriding of the side end face (edge surface) of the metal ring, is easy to attach and detach the metal ring, and when a plurality of metal rings are accommodated, It is an object of the present invention to provide a nitriding jig that can securely fix and hold the metal ring at a predetermined position.

  In order to achieve such an object, the present invention performs nitriding treatment with a gas on a metal ring which is formed in an endless belt shape and has a cross-sectional arc shape in which a central portion is curved outwardly along the width direction. A plurality of holding members that hold the metal ring in a state of being bent into an elliptical shape by pressing the metal ring at a plurality of locations on the outer peripheral surface, and the metal ring of the holding member. A contact recess formed in the contact portion, and the contact recess has a shape that makes point contact with at least two locations on the outer peripheral surface of the metal ring.

  The metal ring is usually an annular shape, but is made of a thin plate of steel material such as maraging steel or stainless steel. Can be bent into shape. Further, when the pressing force is released, the metal ring easily returns to an annular shape due to its elastic force.

  Therefore, in the nitriding jig of the present invention, the plurality of holding members press the metal ring at a plurality of locations on the outer peripheral surface to hold the metal ring in a state of being bent into an elliptical shape. According to the nitriding jig of the present invention, after the metal ring is inserted between the plurality of holding members in a state of being bent into an elliptical shape, the bent state is released and returned to an annular shape. Thus, the holding member can be easily held, and the metal ring can be easily extracted by the reverse operation. Therefore, according to the nitriding jig of the present invention, the metal ring can be easily attached and detached.

  Here, the metal ring is formed by rolling an endless belt-shaped ring made of a steel material such as maraging steel or stainless steel to a predetermined thickness and further correcting the peripheral length to a predetermined peripheral length. An arcuate cross-sectional shape in which the central portion is curved outwardly along the center is provided. In the nitriding jig according to the present invention, the holding member includes the concave portion for contact. Therefore, the metal ring held by the holding member is formed into the corresponding concave portion for at least two places on the outer peripheral surface. By the point contact, it is held by the holding member.

  As a result, according to the nitriding jig of the present invention, the metal ring is held by the holding member in a state where the side end surface of the metal ring is not in contact with the holding member at all. Can be uniformly nitrided. The portion of the outer peripheral surface of the metal ring that comes into contact with the recess for contact is considered to be non-nitrided, but the outer peripheral surface of the metal ring is formed by stacking the metal rings on each other. When it does, it will be shielded by the adjacent metal ring and will not be exposed. Therefore, the metal ring can be used without any problem as a CVT power transmission belt.

  Further, according to the nitriding jig of the present invention, the metal ring is held in point contact with the contact recess at at least two locations on the outer peripheral surface, so that the metal ring is securely fixed at a predetermined position. Can be held.

  In the nitriding jig of the present invention, it is preferable that the holding member includes a plurality of the contact concave portions along the length direction. By doing in this way, when hold | maintaining the said several metal ring along the length direction of the said holding member, the arrangement | sequence state of this metal ring can be maintained easily.

  Next, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is a front view of the nitriding jig of the present embodiment, FIG. 2 is a plan view of the nitriding jig of the present embodiment, and FIG. 3 is an enlarged view of the main part of FIG.

  As shown in FIGS. 1 and 2, in the nitriding jig 1 of this embodiment, a plurality of round bar-shaped holding members 3 are erected on a bottom plate 2. The holding members 3 are erected, for example, three rows per row, for example, six rows. The upper end portion of each holding member 3 is inserted into a hole provided in the upper lid 4, and is fixed by screwing the upper lid 4 to the holding member 3 with a bolt 5.

  In the nitriding jig 1, metal rings W are inserted between two rows of holding members 3 adjacent to each other, and the six holding members 3 press the metal rings W at six locations on the outer peripheral surface thereof to form a metal. The ring W is held in an elliptical shape.

As shown in FIG. 3, the holding member 3 includes a plurality of contact recesses 6 along the length direction. The plurality of contact recesses 6 are provided at a predetermined interval from each other. For example, 12 holding recesses 6 are provided in one holding member 3. The contact recess 6 has, for example, an isosceles trapezoidal shape in a sectional view, and the interval between the opening end portions 6 a and 6 a is smaller than the width of the metal ring W. On the other hand, the metal ring W is formed by rolling an endless belt-shaped ring made of a steel material such as maraging steel or stainless steel to a predetermined thickness and further correcting the peripheral length to a predetermined peripheral length along the width direction. central portion is a circular arc cross sectional shape which is convexly curved outward is applied to the outer peripheral surface W ₁ Te.

As a result, the metal ring W is held by the holding member 3 by making two points on the outer peripheral surface W ₁ having the circular arc shape in cross-section contact with the opening end portion 6 a of the contact recess 6, and the side end surface (edge surface) W ₂ is in a state which does not at all contact with the holding member 3.

  Next, a method for using the nitriding jig 1 of this embodiment will be described.

In the nitriding jig 1, first, an annular metal ring W is inserted between two rows of holding members 3 adjacent to each other, and the metal ring W is inserted into the outer peripheral surface W ₁ by the six holding members 3. Are pressed and held in an elliptical shape. At this time, in the metal ring W, the outer peripheral surface W ₁ having the arcuate cross section is engaged with the contact recess 6, and two locations on the outer peripheral surface W ₁ are the open end portions of the contact recess 6. By making point contact with 6a, it is securely fixed and held at a predetermined position. In the nitriding jig 1, in this way, a total of 60 metal rings W are held between the holding members 3 and 3 adjacent to each other, for example, 12 each.

  If a predetermined number of metal rings W are held, the nitriding jig 1 is then accommodated in the nitriding chamber. The nitriding chamber is sealed after the nitriding jig 1 is accommodated, and a gas containing a predetermined concentration of ammonia is introduced. Then, the metal ring W is nitrided by heating the inside of the nitriding chamber to a predetermined temperature and maintaining the chamber at the predetermined temperature for a predetermined time. The nitriding treatment can be performed by a method known per se such as a gas nitriding method or a gas soft nitriding method.

The metal ring W is held by the holding member 3 by contacting abutment recess 6 two points at two locations on the outer peripheral surface W ₁ as described above, the side end face of the metal ring W (edge surface) W ₂ is in a state which does not at all contact with the holding member 3. Therefore, according to the nitriding jig 1, the side end face of the metal ring W can be uniformly nitrided. The metal ring W is considered to be non-nitrided at the portion of the outer peripheral surface W ₁ that contacts the contact recess 6. However, the outer peripheral surface W ₁ of the metal ring W includes a plurality of metal rings W. When a laminated ring is formed by laminating each other, it is shielded by the adjacent metal ring W and is not exposed, so there is no problem in practical use.

  If the nitriding treatment is accommodated, the nitriding jig 1 is taken out of the nitriding treatment chamber and allowed to cool to room temperature, for example. Then, the nitrided metal ring W is taken out from the nitriding jig 1. By removing the metal ring W from the nitriding jig 1, the pressing force by the holding member 3 is released, so that the metal ring W returns to an annular shape by its own elastic force.

  Note that the nitriding jig 1 of this embodiment includes six rows of holding members 3 in each row, but the holding member 3 presses the metal ring W at a plurality of locations on the outer peripheral surface thereof. As long as the metal ring W can be held in an elliptical shape, the number of holding members 3 can be appropriately set according to the size of the metal ring W and the volume of the nitriding chamber. Further, the number of contact recesses 6 formed in one holding member 3 can also be appropriately set according to the volume of the nitriding chamber.

Further, in the nitriding jig 1 of the present embodiment, the contact recess 6 has an isosceles trapezoidal shape in cross-section, but the contact recess 6 has two points on the outer peripheral surface W ₁ of the metal ring W in point contact. The shape is not limited to a trapezoidal shape such as a cross-sectional view. Further, the nitriding treatment apparatus 1 of the present embodiment, the contact recess 6 of the cross section isosceles trapezoid shape, but two places of the outer peripheral surface W ₁ of the metal ring W is as point contact, those The contact recess 6 may have a polygonal shape that is a pentagon or more in a sectional view, and may make point contact at a large number of locations.

The front view which shows the structure of one Embodiment of the jig | tool for nitriding treatment of this invention. FIG. 2 is a plan view of the nitriding jig shown in FIG. 1. The principal part enlarged view of the jig | tool for nitriding treatment shown in FIG. The figure which shows one structural example of the jig | tool for conventional nitriding treatment The figure which shows the other structural example of the conventional jig | tool for nitriding treatment

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Jig for nitriding treatment, 3 ... Holding member, 6 ... Concave part for contact, W ... Metal ring.

Claims (2)

A jig used for nitriding a metal ring formed in an endless belt shape and having a circular arc shape with a central portion curved outwardly along the width direction with a gas,
A plurality of holding members that hold the metal ring in an elliptical shape by pressing the metal ring at a plurality of locations on the outer peripheral surface, and a contact formed on a portion of the holding member that contacts the metal ring And a recess for
The metal ring nitriding jig is characterized in that the contact recess has a shape that makes point contact with at least two locations on the outer peripheral surface of the metal ring.   The jig for nitriding treatment of a metal ring according to claim 1, wherein the holding member includes a plurality of the abutting recesses along a length direction.

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