Method for Manufacturing Spring Assemblies

The present invention relates to a method for manufacturing spring assemblies used in automotive automatic transmissions, etc. Spring assemblies in which plural springs are arranged on one side of an annular plate in spaced relation are used in automotive automatic transmissions. In conventional production, a projecting part is formed on one side of an annular plate by punching, etc., and one end of a spring is fayed to the projecting part. For example, forms and producing methods are disclosed in U.S. Pat. Nos. 3,782,708, 3,866,287 and 3,891,823. However, complicated processes are required for such spring assemblies because it is difficult to install a spring vertically, and fatigue of the projecting part of the obtained spring assemblies results from use and the danger of damage arises.

The present invention solves the above-mentioned problems, and spring assemblies having easy assembly and excellent durability are obtained.

It is an object of the present invention to provide spring assemblies using a method wherein holes for inserting one end of a helical spring to an annular plate are formed without requiring any projecting part, which is a cause of damage to annular plates, one end of a spring is inserted into the holes, and a compressing treatment is performed on side edges of the plate to collapse the holes.

A method for manufacturing spring assemblies involves forming a number of, for example, round or square holes for inserting a spring in a metal plate consisting of a linear or an annular narrow width bonded structure in spaced relation to each other, wherein the diameter of the holes for inserting a spring is slightly larger than the outside diameter of an inserting end of a spring, inserting one end of the spring into the holes, and then fixing the spring by compressing side edges of the plate to collapse the holes.

FIG. 1 is a perspective view illustrating a metal plate of the present invention;

FIGS. 2(A), 2(B), 2(C), 2(D) and 2(E) are detail views illustrating embodiments of the holes for inserting a spring into the metal plate;

FIG. 3 is a detail view of a portion of the metal plate illustrating a spring inserted into the metal plate; and

FIG. 4 is a perspective view of a manufactured spring assembly of the present invention.

Referring now in detail to the drawings, FIG. 1 shows an annular metal plate 1 which is a form of spring assembly used in automotive automatic transmissions. The form of the spring assembly is made in a straight form or a curved form in accordance with required use. An annular plate, as shown in FIG. 1, is obtained by a method in which an annular plate is obtained from a plain plate by press punching or a method in which a material having a different form is wound into an annular plate, and both ends of the annular plate are welded. Holes 2, such as round, oval, square or triangular holes 2 as shown in FIGS. 2(A) to 2(E) are arranged on metal plate 1. The size of the holes 2 for inserting a helical spring 3 has to be slightly larger than the size of an end part of spring 3 to be inserted therethrough. One side of spring 3 is inserted into the holes 2 as shown in FIG. 3, and spring 3 is fixed by compressing side edges of the plate to collapse the holes 2 from the side of metal plate 1. In this case, it is possible to use a spring 3 in which the size of an inserting end is the same as the other spring parts. It is also possible to use a spring in which the size of an inserting end is smaller than the other spring parts. When using a spring in which the size of an inserting end is smaller than the other spring parts, it is only necessary to enlarge the size of the holes 2 for inserting spring 3 enough to preserve the necessary spring force. Therefore, this embodiment is desirable when given the condition that it is hard to enlarge the width of metal plate 1. When spring 3 is inserted into the holes 2 for inserting spring 3 as shown in FIG. 3, spring 3 can be kept vertically aligned with fair accuracy if metal plate 1 is arranged on a horizontal plate, because spring 3 is inserted from above, spring 3 is fixed to metal plate 1 with sufficient vertical angle if compressing is performed from one side or both sides of metal plate 1 under the above-mentioned condition, it is not necessary to grind a pointed surface on the spring later on, and therefore, abbreviation of the process is achieved. However, a pointed surface of the spring has to be ground after the spring is fixed by compressing if further accuracy is needed.

In fixing spring 3 by compression of side edges of the plate to collapse the holes 2 in the present invention, the holes 2 for inserting a spring 3 are deformed to partially close, the inserting part of spring 3 is pressed at the same time, but the spring has a repulsion force, the inner circumference of the holes 2 for inserting a spring 3 are fayed to the spring 3, and they are tightly combined with each other because of such repulsion force.

Next, examples of the present invention are explained.

Round holes for inserting a spring having a 38 mm inside diameter are arranged at 20 points around an annular metal plate having a 167.4 mm outside diameter, which is formed by using a steel plate having a 6.6 mm width and a 2.0 mm thickness, at equal intervals by press-punching. Second, one end of a spring having a 22.5 mm total length and a 3.7 mm outside diameter, which is formed by using a wire having a 0.7 mm diameter, is fayed into the holes for inserting the spring, the core metal is devoted to an opening side in the inner circumference of the spring, and the spring is fixed to the metal plate by compression using a pressing tool from the outer circumference side.

A spring having an outside diameter of 3.7 mm for three turns of one end of a spring for fixing and an outside diameter of 5 mm for the remaining turns is fixed to a metal plate, which is similar to the metal plate mentioned in Example 1 and made by the same process as in Example 1. The diameter of the wire of the spring is also 0.7 mm.

In the springs obtained in Examples 1 and 2, the inner circumference of the holes for inserting the spring in the metal plate and the springs are tightly fayed, and their bond strength is great.

As mentioned above, the producing process according to the present invention is very simple. That is to say, only punching of the holes for inserting a spring through a metal plate and a compressing treatment after the spring is inserted are required in the present invention.

Also, the obtained spring assemblies are tightly combined because the repulsion force of the spring and deformation of walls of the holes for inserting the spring by compression work together. The assembly has excellent durability because there are not any members which are factors in fatigue failure from subsequent use, such as a metal plate projecting part for fixing a spring.