1. Field of the Invention
The present invention relates to a method of making the elements of a continuously variable transmission belt. The elements of a continuously variable transmission belt are metal pieces that constitute a Van Dome type belt used in a continuously variable transmission used on automobiles.
2. Description of the Related Art
The prior art in this field is exemplified in Unexamined Publication of Patent Application (A) 2001-246428. As shown in
The problems with this prior art are: firstly, plate 12 is expensive to manufacture; and secondly, it is difficult to obtain identical elements from tapered plate 12. In other words, it is difficult to control the accuracies of the dimensions (primarily the thickness) and the shape of the punched out elements. The first problem can be easily understood from the fact that it is more expensive to produce a tapered plate accurately than to produce a flat plate from the standpoint of facility requirements and complexity of the machining process. The second problem can also be easily understood from the fact that the punching of a tapered plate causes delicate changes in the thickness in various parts of the plate, so that plates with uniform dimensions and shapes cannot be obtained without determining the locations of those parts in high accuracy.
3. Problems to be Solved by the Invention
The present invention intends to provide a method of making the elements of a continuously variable transmission belt of high accuracy using a relatively inexpensive plate blank.
It is to obtain elements of desired shapes and dimensions using a flat plate blank by means of providing a coining process and notched areas to encourage better flows of material. More specifically, the invention of claim 1 is a method of making elements of a continuously variable transmission belt by coining plates and then punching, in particular, by providing notched areas on the outer periphery of said plates in the coining process, so that the material of said plates can flow more easily toward the periphery during the coining process. The invention of claim 2 is a method of making elements of a continuously variable transmission belt described in claim 1, wherein said plate has such a size and a shape that two elements are produced together from it arranged in such a way that their heads are facing with each other, said notched areas are constrictions located between said two elements provided along two abutting heads, while other notched areas are located toward the bottom center of each element's body.
a) is a front view of a plate after a punching process;
b) is a cross sectional view along line 3—3 of
a) is a front view of an intermediate product after a coining process;
b) is a cross sectional view along line 4—4 of
a) is a front view of a coined intermediate product after another punching process;
b) is a cross sectional view of scrap along line 5—5 of
c) is a cross sectional view of the element along line 5—5 of
a) and 3(b);
a) is a front view and
Let us describe here about the material flow in the aforementioned coining process. In
During the coining process, the material flows in the directions indicated by arrows a, b, c, d, e and f. When a plate is coined, the center of the plate normally increases its thickness by approximately 50 μm. In this embodiment, the thickness errors can be reduced to approximately 5 μm thanks to the provisions of notches 2a, 2b, 2c and 2d.
In other words, notches 2a, 2b, 2c and 2d help to encourage the flow of materials in the directions of a, b, c, d, e and f, thus eliminating said bulging effect in the middle. These notches are located to help the materials in the center of the plate to move outward. In other words, providing notches in the corner areas are not effective in encouraging the material flow.
Slanted area 1d in
The size of a notched area is determined based on the condition that the blank material eventually fills up the coining die. However, it is not required to maintain the thickness of the fringe areas as they are scrapped anyway after the coining process. Therefore, the size of the notches does not have to be controlled accurately. For the same reason, said fringe areas are pressed lightly only in limited areas during this coining process.
The notched areas are preferably shaped with smooth curved as much as possible so that the coining die will be sufficiently filled with material.
Number | Date | Country | Kind |
---|---|---|---|
2002-170906 | Jun 2002 | JP | national |
Number | Name | Date | Kind |
---|---|---|---|
4320647 | Kummeling et al. | Mar 1982 | A |
4894049 | Koppelaars | Jan 1990 | A |
6389865 | Easterbrook | May 2002 | B1 |
6427512 | Suzuki et al. | Aug 2002 | B2 |
6526798 | Suzuki | Mar 2003 | B2 |
6742373 | Wakui | Jun 2004 | B2 |
6748787 | Liu | Jun 2004 | B1 |
6863632 | Serkh | Mar 2005 | B2 |
Number | Date | Country |
---|---|---|
1 132 648 | Sep 2001 | EP |
1 158 203 | Nov 2001 | EP |
2001-246428 | Sep 2001 | JP |
Number | Date | Country | |
---|---|---|---|
20040029670 A1 | Feb 2004 | US |