JPS60248815A - Manufacture of endless metallic belt - Google Patents

Abstract

PURPOSE:To provide fatigue resistance to an endless belt of a precipitation strengthening alloy by subjecting the belt to soln. heat treatment, plastic deformation by a specified extent and aging. CONSTITUTION:An endless belt of a precipitation strengthening alloy is subjected to soln. heat treatment by heating to 700-900 deg.C. The belt perimeter is stretched between two tension rolls, and it is elongated and deformed plastically by 0.2- 1.9% by moving the tension rolls outward while rotating at least one of the rolls. The belt is then aged by heating at 500 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an endless metal belt with excellent fatigue resistance.

An endless metal belt (hereinafter simply referred to as a belt) is a belt manufactured by connecting the ends of metal band-shaped materials by means such as welding, or by rolling an endless ring-shaped metal material. It is widely used for power transmission, especially as a transmission means for continuously variable transmissions. Since such an endless metal belt is stretched between rotating rollers, when using it as a multilayer belt, for example, a difference in circumferential length of 2π1 (where 1 is the thickness) is required between adjacent belts. It is said that it is necessary to finish the belt circumference with high precision.

On the other hand, the above-mentioned belt exhibits a straight state when running between rollers, and a curved state when running along the curved surface of the rollers, so it must have sufficient strength to withstand bending deformation without such a situation. . For this reason, research is underway on ways to improve fatigue strength, for example, by curving the belt in the same direction with a smaller radius of curvature than the roller radius to cause plastic deformation in the radially outer region of the belt. A method of applying a residual stress in the compressive direction to the outer region and relieving the tensile stress applied to the outer region when the belt is used (Japanese Patent Publication No. 58-4193Q)
is proposed. However, it is still not sufficient.

The present invention has been made as a result of repeated studies under these circumstances, and it is an object of the present invention to provide a method for manufacturing an endless metal belt that has a highly accurate circumference and excellent fatigue resistance. That is. 'However, in the method of the present invention which achieves the above object, after solution-treating an endless metal belt made of a precipitation-strengthened alloy, the belt is stretched between two tension rollers, and at least one of the tension rollers is rotated. The gist of this method is to provide an amount of plastic deformation of 0.2 to 1.9 inches by separating the belts from each other and elongating the circumferential length of the belt, and then subjecting the belts to an aging treatment.

First, as the raw material for the endless metal belt manufactured by the method of the present invention, a precipitation-strengthened alloy, for example, a high Ni steel having a mechanical composition shown in Table 1 is used. Of course, this is merely an example and does not limit the invention.

A precipitation-strengthened alloy as described above is used and subjected to processing such as rolling to produce an intermediate product of an endless metal belt. The circumferential length of the intermediate product is made slightly smaller than the circumferential length of the product in preparation for the stretching process described later. Then, the intermediate product is heated to 700 to 90
After being heated at 0°C and subjected to solution treatment, the resulting belt is stretched between two rollers, but when stretching the belt, a coil spring or the like is generally attached to the shaft that supports the rollers. In many cases, the belt is biased in a direction that increases the distance between the rollers and the belt is tightened to prevent the belt from coming off. Then, while rotating at least one of the rollers on which the belt is stretched, the distance between the rollers is increased to extend the belt section. This gives a Sibelt of 0.2 to 1.9
The belt is finished to a predetermined length while being given plastic working. Thereafter, the belt is heated at a temperature of, for example, 500° C. to undergo an aging treatment to obtain an endless metal belt.

The obtained endless metal belt had excellent fatigue strength as shown in the fatigue test results described below.

Note that if the amount of plastic working is less than 0.62%, a sufficient effect of improving fatigue resistance strength cannot be obtained, and -Yoshikawa deformation amount is 1.0%.
If it exceeds 9%, the fatigue life will actually decrease. The reason why the above-mentioned effects are obtained in the method of the present invention is not clear, but instead of applying residual stress to relieve stress as in the previous application (see Figure 2), We believe that the fatigue strength may have been improved by making the grains finer.

Furthermore, the method of the present invention can be applied not only to the production of single-layer belts but also to multi-layer belts. That is, in manufacturing a multilayer belt, an intermediate product of the multilayer belt is manufactured from a precipitation-strengthened alloy, and after solution treatment, it is stretched between a pair of rollers.

Then, without rotating at least one of the rollers, the distance between the rollers is increased to elongate the belt section. At this time, each belt of each layer constituting the multilayer belt must satisfy a plastic deformation amount of 0.2 to 1.9 inches. Thereafter, the multilayer belt may be heated and subjected to aging treatment.

Although the basic structure of the present invention is as described above, the process shown in FIG. 1, for example, is applied when producing an intermediate product of an endless metal belt using a precipitation-strengthened alloy material. That is, a belt material (hereinafter referred to as a ring roll) formed into an annular shape by rolling or the like is cut along the length direction of the selvage to adjust the shape, and a twill line groove (hereinafter referred to as a ring roll) is formed on the inner surface of the belt. After carving a crosshatch (called a crosshatch), the outer surface is mechanically polished. Next, hydrofluoric acid or H2O is used to remove 10 to 1
An intermediate product of an endless metal belt can be obtained by chemically polishing 5 μm to provide the process after solution treatment. In the case of obtaining a multilayer belt, a plurality of such intermediate products are laminated and then provided to a process subsequent to solution treatment. Note that the cross hatches carved on the inner surface of each layer of the belt have the effect of allowing lubricating oil to penetrate between each layer through the cross hatches when a multilayer belt is formed, thereby eliminating squeaks between the belts.

The present invention is configured as described above, and can provide an endless metal belt with excellent fatigue resistance.

Examples of the present invention will be described below.

EXPERIMENTAL EXAMPLE An endless metal belt was manufactured by ring-rolling or processing a precipitation-strengthened alloy according to the manufacturing process shown in FIG. When the residual stress at each process step was investigated, the results shown in FIG. 2 were obtained. From this result, it was found that the residual stress due to the final aging treatment was lower than that during roller elongation.

Example: After solution annealing intermediate products of endless metal belts made of precipitation-strengthened alloys having the composition shown in Table 2 below, the products were aged with various amounts of plastic deformation ranging from 0 to 2.0%. After processing and conducting a fatigue test, the third
The results shown in the figure were obtained. Is the tensile stress (σt) applied to the test product 30 kgf/mn? The bending stress (σB) was 135 kg f /mnF.

Table 2 (H) As shown in Fig. 3, when the amount of plastic deformation was zero, it broke after about 10 times of repeated bending. -The amount of useful deformation is 2
．． Even when the ratio was too large (0%), the number of repeated bending cycles until breakage was approximately 104 times.

For these, the amount of plastic deformation is 0.5%, 1.0%, 1.5
In the case of H, sufficient fatigue strength was obtained.

Reference Example When manufacturing a multilayer belt consisting of four layers according to the method of the present invention, the inner circumference length of each layer belt before elongation and the inner circumference length of each layer belt after elongation was measured, and the circumference difference was calculated. The results shown in Table 3 were obtained.

The amount of elongation<the amount of m-based deformation) was approximately 1.1 inches.

As shown in Table 3, the difference in circumferential length after elongation was reduced, and by implementing the present invention, the circumferential length of the layered belt could be adjusted with high accuracy.

[Brief explanation of the drawing]

Fig. 1 is a flow diagram showing the manufacturing process according to the present invention, Fig. 2 is a graph showing residual stress at each manufacturing process stage, and Fig. 3 is a flow diagram showing the manufacturing process according to the present invention.
The figure is a graph showing the relationship between the amount of plastic deformation and the number of times of repeated bending until breakage occurs. Applicant: Kobe Steel, Ltd. Toyota Motor Corporation

Claims (1)

[Claims] After solution treatment of the precipitation-strengthened alloy endless metal belt,
A plastic deformation amount of 0.2 to 1.9% was given by stretching the belt circumference by stretching the belt between two tension rollers and separating the tension rollers while rotating at least one of the tension rollers. A method for producing an endless metal belt, characterized by subjecting it to post-aging treatment.