JPH0641780B2 - Surface treatment method for endless metal strip - Google Patents

Description

TECHNICAL FIELD The present invention relates to a surface treatment method for an endless metal strip in a metal belt used in a torque transmission device such as a continuously variable transmission.

<Prior Art> For example, as a drive belt used in a continuously variable transmission for a vehicle, a laminated metal strip formed by laminating a plurality of endless metal strips, and a circumferential direction on the inner peripheral side of the laminated metal strip. It is known to have a metal block which is arranged along with the metal block and which sequentially contacts the inner surface of the pulley groove. Such a metal belt 1
As shown in FIG. 1, is a pair of V-groove pulleys 2 and 3
It is hung between and transmits power. At this time, the pulleys 2 and 3 are divided into two in the axial direction, and the effective radius of each pulley is changed by varying the width of each pulley groove, so that the relative ratio of the rotational speeds of both pulleys, that is, the gear ratio is not changed. The continuously variable transmission is configured so that it can be changed in stages.

The endless metal strip for constituting such a metal belt needs to have a thin thickness of about 0.1 to 0.2 mm so as to have sufficient durability against repeated bending stress. So, in order to withstand the required tension,
A plurality of endless metal strips are stacked and used.

<Problems to be Solved by the Invention> When a metal belt as described above transmits power, the speed due to the difference in the radius of gyration between the stacked endless metal strips and between the stacked metal strips and the metal block. As a result, a difference occurs, and both end surfaces in the circumferential direction of each endless metal strip and the inner peripheral surfaces of the innermost endless metal strips are pressed against the metal block and slide relative to each other. Here, in particular, the side end faces of the respective endless metal strips have a thin plate thickness and are chamfered in order to avoid stress concentration at the corners, so that the contact surface pressure becomes extremely high. Therefore, there is a problem in that the side surface of each endless metal strip is worn and the durability of the metal belt is impaired.

On the other hand, as the material of the endless metal strip, relatively high strength, high toughness, and also in terms of excellent workability such as good weldability, precipitation hardening type martensitic stainless steel,
Alternatively, maraging steel or the like is suitable. However,
These have the drawback of being somewhat inferior in wear resistance.

On the other hand, it is well known that nitriding is one of the means for improving the wear resistance and fatigue strength of metal materials. However, if a member having a long circumference such as an endless metal strip used for the metal belt is to be entirely nitrided, nitrogen invades and diffuses, resulting in an increase in size and a twist deformation.

In addition, electroless nickel plating is also good for curing,
If this is applied to the whole, there is a problem that a long strip-shaped thin plate causes a dimensional change due to the plating layer.

In view of such inconveniences of the prior art, a main object of the present invention is to provide a simple surface treatment method for obtaining an endless metal strip for a metal belt for a torque transmission device having excellent durability. is there.

[Constitution of the Invention] <Means for Solving the Problems> According to the present invention, a plurality of metal blocks are attached to the inner peripheral side of a laminated metal strip composed of a plurality of layers of endless metal strips. A method for surface treatment of an endless metal strip used for a metal belt for a torque transmission device, wherein at least both end faces along the circumferential direction are subjected to nitriding treatment or electroless nickel plating in a state where the endless metal strips are laminated. It is achieved by providing a surface treatment method for an endless metal strip. In particular, it is preferable to mask the innermost peripheral surface and / or the outermost peripheral surface of the laminated endless metal strips and perform the treatment.

<Operation> In this way, since the overlapping surfaces of the endless metal strips are hidden, the exposed both side end faces in the circumferential direction, the innermost peripheral face, and the outermost peripheral face are hardened. Will be given. Here, the surface of the metal strips located in the innermost peripheral layer and the outermost peripheral layer may be subjected to a hardening treatment, but in particular, a mild steel plate or the like is used as a masking on the inner and outer peripheral surfaces of the laminated metal strips. If they are overlapped with each other, the curing treatment can be applied only to a desired portion. Therefore, the required wear resistance can be imparted to the endless metal strip without causing twisting or dimensional change.

<Embodiment> Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 and 3 show a first embodiment of the metal belt 1 according to the present invention, which comprises a plurality of endless metal strips 4a-4.
The laminated metal strip 4 formed by laminating n is received in the groove 6 defined by the protrusions 5a protruding left and right on the upper surface of the metal block 5 in FIG. Pins 7 press-fitted in the left and right holes provided in 5a prevent the laminated metal strip 4 from being separated from the groove 6.

As shown in FIG. 2, the metal blocks 5 are arranged in the circumferential direction in the circumferential direction with respect to the laminated metal strip 4 with almost no space therebetween, and between the inner circumferential surface of the laminated metal strip 4 and the bottom surface 8 of the groove 6. The bottom surface 8 of the groove 6 has a curved shape that is convex toward the outer circumference so that the contact surface pressure does not become excessive. The side surface of the metal block 5 forms an inclined surface 9 corresponding to the inner surface of the pulley groove 2a of the V-groove pulley 2. As a result, the metal block 5
It does not fall off from the laminated metal strip 4 and is freely movable in the circumferential direction of the laminated metal strip 4. Here, when the driving force is transmitted from one pulley to the metal belt 1, this driving force is transmitted to the other pulley via the aligned metal blocks 5.

4 to 6 show a second embodiment of the metal belt 1 according to the present invention, which is bounded between the protrusions 10a integrally formed on the upper surface of the metal block 10 on the left and right sides. Groove 11
The laminated metal strip 4 is received therein, and the respective ends of the three-dimensionally bent clip 12 are attached to the undercut portions formed on the left and right side portions of the protrusion 10a, whereby the laminated metal strip 4 is formed. Are not allowed to separate from the groove 11.

As shown in FIG. 4, the circumferential end surface of the metal block 10 is formed with a curved surface 13 which is recessed in a substantially arc shape, and a cylindrical roller is provided between the adjacent metal blocks 10. The member 14 is installed. This roller member 14
Is preferably elastically deformable so as to absorb the impact force acting between the metal blocks 10. This allows
As the laminated metal strip 4 is curved according to the given curvature of the pulley, the curved surface 13 of the metal block 10 becomes
Rolling on the outer peripheral surface of 4, the adjacent metal blocks 10 can move according to the deformation of the laminated metal strip 4 without interfering with each other.

As shown well in FIG. 6, the metal block 10 of this embodiment also has a side surface which forms an inclined surface 15 so that it can be brought into close contact with the inner surface of the pulley groove 2a.

In both of the above embodiments, the thickness of each of the endless metal strips 4a to 4n of the laminated metal strip 4 is about 0.1 mm to 0.2 mm, and the nitriding layer by ion nitriding is formed only on both end faces in the circumferential direction. Are formed. A suitable thickness of this nitride layer is 0.5 μ to 30 μ. If a nitride layer having a thickness of more than 30 μ is formed, the rigidity becomes excessively high and the bending stress resistance decreases,
There is a risk of cracking when passing over the pulleys 2 and 3. If the thickness of the nitrided layer is less than 0.5 μm, sufficient wear resistance cannot be obtained, which causes a problem in practical use.

By the way, the ion nitriding is a method of accelerating nitrogen ions by glow discharge in a vacuum atmosphere and colliding them with a base material to deposit them. At this time, by performing ion nitriding in a state where all of the endless metal strips 4a to 4n are stacked,
No nitride layer is formed on the surfaces of the endless metal strips 4a to 4n that overlap each other, and the nitride layers are formed on the exposed both end surfaces, the innermost peripheral surface, and the outermost peripheral surface. Needless to say, if appropriate masking is applied to the innermost peripheral surface and the outermost peripheral surface, it is easy to perform nitriding treatment only on both end surfaces.

The nitride layer thus obtained has high adhesion of the adhesion layer to the base material, is highly durable, and can improve its wear resistance while making the most of the characteristics of the base material.

Such a surface-hardened layer can also be formed by electroless nickel plating. According to this, it is possible to obtain a cured layer in which the hardened layer is not easily peeled off from the base material and which has extremely high surface hardness. In particular, if this is also applied to the innermost peripheral surface, wear due to relative movement between the metal block and the innermost layer of the laminated metal strip can be prevented. Further, the combination of ion nitriding and electroless nickel plating is also effective in improving the wear resistance of the laminated metal strip.

According to an experiment conducted by the inventor, when the conventional laminated metal strip was used for 400 hours under a certain load condition, both end faces in the circumferential direction were worn by 1 to 2 mm. It was confirmed that when the laminated metal strip subjected to the surface hardening treatment was used, the wear was extremely small even after the use for 400 hours, and the durability was significantly improved.

<Effect of the Invention> As described above, according to the present invention, a desired portion can be extremely easily
In particular, since the surface hardening treatment can be applied only to both end faces in the circumferential direction of the endless metal strip, it is possible to inexpensively obtain a laminated metal strip for a metal belt having high wear resistance.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the outline of a belt type torque transmission device to which a metal belt according to the present invention can be applied. FIG. 2 is a longitudinal sectional view showing a first embodiment of the metal belt according to the present invention. FIG. 3 is a sectional view taken along the line III-III in FIG. FIG. 4 is a vertical sectional view showing a second embodiment of the metal belt according to the present invention. FIG. 5 is a partial plan view of FIG. FIG. 6 is a sectional view taken along the line VI-VI in FIG. 1 ... metal belt, 2.3 ... pulley, 2a ... pulley groove, 4 ... laminated metal strip, 4a-4n ... endless metal strip,
5 ... Metal block, 5a ... Projection, 6 ... Groove, 7 ...
Pin, 8 ... bottom surface, 9 ... inclined surface, 10 ... metal block, 10a ... protrusion, 11 ... groove, 12 ... clip,
13 ... curved surface, 14 ... roller member, 15 ... inclined surface

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Chiharu Umezu 1 Shinisogo-cho, Isogo-ku, Yokohama-shi Kanagawa Nihon Hatsujo Co., Ltd. In-house Co., Ltd. (72) Inventor Kiyo Kurimoto, No. 1, Shinisogo-cho, Isogo-ku, Yokohama-shi, Kanagawa Japan In-house Co., Ltd. In-house (56) Bibliographic references Sho 59-7949 (JP, U)

Claims (2)

[Claims] 1. A surface treatment method for an endless metal strip used in a metal belt for a torque transmitting device, comprising a plurality of metal blocks attached to an inner peripheral side of a laminated metal strip composed of a plurality of layers of endless metal strips. A surface treatment method for an endless metal strip, wherein at least both end faces along the circumferential direction are subjected to nitriding treatment or electroless nickel plating in a state where the endless metal strips are laminated. 2. The nitriding treatment or electroless nickel plating is performed by masking the innermost peripheral surface and / or the outermost peripheral surface of the laminated endless metal strips. Surface treatment method for endless metal strip.