Metal deforming – By use of tool acting during relative rotation between tool... – During rotation of work
Reexamination Certificate
2000-05-16
2001-07-10
Larson, Lowell A. (Department: 3725)
Metal deforming
By use of tool acting during relative rotation between tool...
During rotation of work
Reexamination Certificate
active
06257036
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a metallurgical process apparatus, and more particularly to an apparatus of diametrically expanding a desired portion, such as a middle portion, of steel or any other metal shafts, so as to cut threads to form gears and cams in the expanded portion.
BACKGROUND ART
It is common practice to obtain a metal shaft having a partly increased diameter by machining a blank shaft of a relatively large diameter. However, this machining process takes time, and what is worse, wastes metal in the form of cutting chips.
In general, the mechanical power transmission shafts require components such as gears, cams, and sprockets whose diameter is larger than that of the shafts. In order to provide the metal shafts with these components, a mechanical method is not economical where the metal flesh of a shaft is machined to form gears as integral parts. An alternative way is to produce those component parts on a separate process, and then join them to the shafts by welding or bolting. This method is not efficient. Therefore, a metallurgical process was proposed for forcing a metal shaft to diametrically expand in a desired portion, and cutting gears or cams there. However, it has been considered to be impracticable to put the proposed metallurgical method in practice.
The inventor of the present application invented a method of expanding the diameter of a metal shaft in its middle portion through rotation, bending and compression, and has obtained Japanese Patent No. 1,993,956. This metallurgical method has overshadowed the conventional mechanical method, and made it possible to form gears or cams in the diametrically expanded portion of a metal shaft.
Nevertheless, the patented method is at the experimental stage, and is not fully developed for mass-production basis. The present invention has overcome the obstacles to practical use.
SUMMARY OF THE INVENTION
According to the present invention, there is an apparatus of expanding a diameter of a metal shaft in a desired portion, the apparatus including a driver section which is rotatively driven by an electric motor with a workpiece held in a first sleeve; a driven section having a second sleeve located opposite to the first sleeve of the driver section, the driven section being capable of relative movement to and from the driver section; a feeder unit for effecting the relative movement of the driven section to and from the driver section; a bias means for causing the second sleeve to decline with respect to the axis of the first sleeve of the driver section; and a press unit for pressing the driven section toward the driver section.
In performing the diametral expansion of a metal shaft, the driver section and the driven section are arranged such that the respective sleeves are axially aligned with a workpiece (blank shaft) held therebetween. Then, the driver section is driven to rotate the workpiece, and at the same time, the press unit is driven to compress it axially. At this stage, the bias means causes the portion of workpiece toward the driven section to decline with respect to the axis of the driver section. Preferably, the center of the bent is deviated outward from the center line of the blank shaft. Because of this deviation the bent portion is subjected to constant compression, and as a result, fracture due to fatigue is avoided; otherwise, fracture would be likely to occur the alternate application of compression and tension. In the course of rotation, bending and compression the workpiece is forced to diametrically expand in the portion between the holders of the driver section and the driven section. As the expansion proceeds, the driven section moves toward the driver section, during which compression is continued.
Upon completion of the expansion, the bias means is returned to its original position where the driver section and the driven section are axially aligned. Then the rotation and compression are stopped, and the finished shaft is released.
The press unit can be a fluid cylinder, a hydraulic jack, etc. The bias means can be an arrangement in which, for example, the sleeve of the driven section is pivoted rotatively around its own axis, and is declined by applying a force to it axially at right angle.
After the diameter of the shaft is partly expanded, it must be taken out. However, it often happens that it is difficult to release it from the sleeves because of the remainder of the force applied in the process. In order to overcome this difficulty, an extra remover can be employed, which is provided with a device engageable with the expanded portion of the workpiece.
REFERENCES:
patent: 57-22840 (1982-02-01), None
patent: 59-130641 (1984-07-01), None
patent: 59-206134 (1984-11-01), None
patent: 6-65423 (1994-08-01), None
Armstrong Westerman Hattori McLeland & Naughton LLP
Larson Lowell A.
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