JPS61180630A - Production of endless thin metallic band - Google Patents

Abstract

PURPOSE:To produce with good efficiency the endless thin metallic band having high accuracy, good quality and fatigue resistance by inserting to mandrel the hat shaped intermediate product which is formed by opposed hydraulic pressing a metallic plate and by slicing with spinning within the range of the specified rolling rate. CONSTITUTION:Hat shaped intermediate product 16 is made by press-forming a metallic plate 15 with opposed hydraulic press forming method. This intermediate product 16 is inserted to mandrel 20, made in the prescribed thickness with spinning within the range of 30-70% rolling rate by pressing member 22 and sliced in the prescribed width. This endless thin metallic band has high dimensional accuracy, unspoiled stiffness, no surface flaw and high fatigue resistance and is produced with high efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing an endless thin metal band used for, for example, a laminated power transmission belt.

[Conventional technology]

For example, laminated metal belts used in continuously variable transmissions for automobiles, such as endless metal belts for Pan-Donnel type transmissions (V
As conceptually shown in FIG. 4, the DT belt transmits power by stretching the laminated belt 1 between a pair of pulleys 2 and 3. As illustrated in FIG. 5, this type of laminated belt 1 consists of a plurality of (approximately 10 to 18) endless metal bands made of stainless steel or the like (a, ib, ic (only some of which are shown) in the thickness direction. At the same time, the metal band 1
a.

A large number of metal pieces 5 are held along 1b and Ic. Power is transmitted through the metal top 5.

The conventional method for manufacturing this type of seamless thin metal band is to deep-draw a metal plate using a well-known press die to obtain a hat-shaped intermediate product, and then - As seen in Publication No. 14430,
Ironing and spinning are performed to roll the material to a desired thickness (approximately 0.1 to 0.2 mm for VDT belts). Thereafter, the cylindrical portion of the intermediate product is cut into rings by slitting or the like to obtain a seamless thin metal band.

(Problem to be solved by the invention) However, in normal deep drawing, there is a large limit to the plate thickness due to its forming characteristics (in general, the minimum plate thickness that can be deep drawn is limited to about 0.5 μm). As a result, the rolling rate to achieve the desired plate thickness by ironing and spinning is:
For example, 0.5■→0. About 80% of In+a+ reaches everywhere.

When the rolling rate reaches 80% or more in this way, embrittlement becomes noticeable in steel, especially stainless steel. When a material that has become severely brittle is subjected to a tensile load up to its yield point, it exhibits almost no elongation and breaks near the yield point, which adversely affects the fatigue resistance of the metal band.

Another problem is that deep drawing involves the use of molds for both punches and dies, which causes surface scratches on the product material, which remain as defects even after subsequent spinning, and cause fatigue when made into metal bands. It has a negative impact on sexuality.

[Means for solving problems]

In the method for manufacturing an endless thin metal band according to the present invention, first, a metal plate is repress-molded by opposed hydraulic forming to obtain a hat-shaped intermediate product that conforms to the outer shape of a punch. Thereafter, this intermediate product is inserted into a mandrel, and the cylindrical portion of the intermediate product is rolled while being squeezed from the side with a pressing member such as a roller, thereby performing ironing and spinning.

This manufacturing method is characterized in that the cylindrical portion is then sliced into rings to obtain a metal band.

[Effect]

According to the above method, by using the opposed hydraulic forming method, a hat-shaped intermediate product with a thinner wall can be obtained than in the case of deep drawing. The rolling rate can be lowered. Therefore, compared to the conventional method in which spinning is performed after deep drawing, there is less deterioration in toughness, which has a positive effect on fatigue properties. In addition, by using the facing hydraulic forming method, the occurrence of surface scratches on the intermediate product can be extremely reduced and the dimensional accuracy can be increased, so by adding an ironing and spinning process after performing the facing hydraulic forming method, The product has no surface scratches and good results are obtained in terms of fatigue resistance, and the precision of the spinning process is also increased, making it easier to obtain a predetermined product thickness.

[Actually 7il! Example] Fig. 1 (A> to D) conceptually shows the steps of the opposed hydraulic molding method. In the figure, the punch 10 has a substantially cylindrical shape. In addition, in the hydraulic chamber 12 formed in the die 11,
A liquid such as oil or water is contained. A relief valve (not shown) is connected to the fluid path 13 communicating with the fluid pressure chamber 12 .

14 is a blank holder.

As shown in FIG. 1(A), first, a metal plate 15 to be used as a material for a metal band is set on the hydraulic pressure chamber 12.

The metal plate 15 is, for example, a stainless steel plate. However, it is of course possible to use a steel type other than stainless steel rR.

Next, as shown in the same figure (8), punch 10 and blank holder 1
4 descends at the same time and fixes the metal plate 15. Furthermore, the same figure (
When only the punch 10 continues to descend toward the hydraulic pressure chamber 12 as shown in C), a high opposing hydraulic pressure is generated and the metal plate 15 is pressed against the punch 10 and comes into close contact with it.

Then, in the process leading to the same figure (D), the metal plate 15 is
The shape is transferred along the outer shape, and as illustrated in FIG. 2, a hat-shaped intermediate product 16 consisting of a cylindrical portion 16a, a flange portion 16b and a bottom portion 16c is obtained.

According to the above-mentioned opposed hydraulic forming method, it is easy to suppress wrinkles, and the surface A smooth, high-quality intermediate product 16 is obtained. Furthermore, since the metal plate 15 is pressed against the punch 10 by high opposing hydraulic pressure immediately after the start of molding, molding can be performed with high precision. Furthermore, since the processing limit is improved compared to conventional deep drawing using a mold, the axial length L (FIG. 2) of the middle 1 split product 16 can be increased.

In addition, according to the conventional die pressing method, the minimum thickness that can be deep drawn is about 0.5 n+m, but with the opposed hydraulic forming method, it is possible to deep draw a thin sheet material up to 0.2IIIm.

After obtaining the above-mentioned hat-shaped intermediate product 16, the intermediate product 16 is inserted into a cylindrical (or cylindrical) mandrel 20 as shown in FIG. Rotate to perform ironing and spinning processing.

That is, the pressing member 2 presses the cylindrical portion 16a from its side.
2, rolling is performed between the mandrel 20 and the pressing member 22 by relatively moving the pressing member 22 in the axial direction while pressing in the circumferential direction. The pressing member 22 uses a spatula or a roller.

The plate thickness after rolling is, for example, up to about 0.1 mm. Therefore, in this example, the rolling processing rate is approximately 50% (0.2 mm→0
．． 1 film). The rolling rate is expressed as (plate thickness before processing - plate thickness after processing) ÷ plate thickness before processing x 100. In addition, the rolling processing rate to the specified product plate thickness is 30 to 70.
%, there will be no decrease in brittleness that would be a problem in practice, and a better effect on fatigue properties will be obtained compared to conventional methods.

After the spinning process, the cylindrical portion 16a is cut into rings by slitting or the like, thereby obtaining a plurality of endless metal bands. As mentioned above, since the length L in the axial direction of the hat-shaped intermediate product 16 is sufficiently longer than that obtained by conventional deep drawing, many metal bands can be obtained from one intermediate product 16, and the production Good sex.

Further, according to this embodiment, by combining the opposed hydroforming method and the ironing spinning process, it is possible to finish the belt with a sufficiently high dimensional accuracy and a smooth surface condition for practical use as a power transmission metal laminated belt.

〔Effect of the invention〕

According to the present invention, an endless thin metal band that exhibits excellent fatigue resistance without loss of toughness and surface flaws can be manufactured with high precision and efficiency.

[Brief explanation of drawings]

Figures 1 (A) to D) are schematic diagrams showing the opposed hydraulic forming method in the order of steps, Figure 2 is a perspective view of a hat-shaped intermediate product, and Figure 3 is a perspective view of a hat-shaped intermediate product.
The figure is a schematic diagram showing ironing spinning processing. FIG. 4 is a schematic diagram of a laminated belt, and FIG. 5 is a sectional view of a part of the laminated belt shown in FIG. 4. DESCRIPTION OF SYMBOLS 1... Laminated belt, 1a, 1b, 1c... Metal band, 15... Metal plate, 16... Intermediate product, 16a.
... Cylindrical portion, 20... Mandrel, 22... Pressing member. Applicant's agent Patent attorney Takehiko Suzue Figure 1 (A) CB) (C) (D) 16c

Claims (2)

[Claims] (1) A metal plate is repress-molded using the opposed hydraulic forming method to obtain a hat-shaped intermediate product that follows the outer shape of the punch, and then the intermediate product is inserted into a mandrel to form a cylindrical portion of the intermediate product. A method for producing an endless thin metal band, which comprises performing ironing spinning by rolling the metal band while pressing it from the side, and then cutting the cylindrical portion into rings to obtain a metal band. (2) The metal plate is a steel plate having a thickness such that the rolling rate from ironing and spinning to a predetermined product thickness is 30 to 70%. A method for manufacturing an endless thin metal band.