Metal deforming – By use of closed-die and coacting work-forcer – Forcing work into or within closed die; e.g. – forging
Utility Patent
1998-11-12
2001-01-02
Larson, Lowell A. (Department: 3725)
Metal deforming
By use of closed-die and coacting work-forcer
Forcing work into or within closed die; e.g., forging
C072S466700, C413S069000
Utility Patent
active
06167743
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the field of metal container necking apparatus and methods used in the tapered reduction of the diameter of the top portion of beverage and other type metal containers. More specifically, the invention relates to a new and improved, simplified and less expensive necking apparatus and method providing enhanced functional results for necking metal containers such as beverage containers in which only one cam is employed for actuating and driving the tooling to effect the necking function.
A variety of prior art methods and devices have been employed for necking metal containers. The known prior art devices employ a cylindrical necking die which is reciprocated axially to engage the exterior of the upper end of a container workpiece and a coaxial die pilot also, known as a “knockout” or “pilot” which simultaneously moves axially in a mating manner into the open end of the container workpiece. The aforementioned prior art devices have employed a variety of complicated and expensive drive arrangement including a first cam for driving the necking die and a second cam for driving the pilot die.
While many of the prior devices have provided satisfactory results and have been capable of operating at progressively higher speeds during the recent years, such devices have been increasingly complex in construction and have been extremely expensive to manufacture and maintain.
For example, Lee at al. U.S. Pat. No. 5,249,449 discloses a can necking apparatus of complex construction in which a necking die 30 and a pilot 148 are reciprocated in unison into contact with a can body 12 that is pressured with air. The pilot 148 and the necking die 30 are capable of axial movement relative to each other and forward movement of the pilot is terminated by engagement of flange 88 with a bumper ring 92 as shown on the left end of FIG. 1 of the Lee et al. patent. However, the necking die 30 continues forward movement after forward movement of the pilot has been terminated. Thus, substantial vibration and noise as well as complexity of construction render the device of this patent to be expensive to construct and maintain. The device of the Lee patent is additionally deficient in that it is incapable of operating at high speeds comparable to other conventional necking devices.
Similarly, Miller et al. U.S. Pat. No. 4,457,158 is directed to a can necking apparatus employing a complex mechanically driven structure for effecting container necking by moving a die member 30 and a pilot 40 forwardly into the open end of a container workpiece. The pilot 40 has its forward travel terminated by engagement of its surfaces 46
a
and 47
a
with surfaces with 20
b
of the base 20 of the apparatus. Here again, noise and vibration are substantial problems which limit the speed of operation and reliability of the device.
Additionally, there are a wide variety of can necking machines employing two separate cams for respectively moving the pilot and the necking die members as exemplified by a number of U.S. and foreign patents.
Therefore, the primary object of the present invention to provide a new, improved, and reliable can necking apparatus which is less complex than prior known can necking devices.
A further object of the present invention is the provision of a new and improved can necking method and apparatus of simplified construction in which only a single cam is required for operating the necking tooling.
SUMMARY OF THE INVENTION
Obtainment of the foregoing objects of the present invention is enabled by two embodiments of the invention. In the first embodiment a conventional vacuum or conventional non-vacuum starwheel is provided on a driven main shaft for positioning and holding a cylindrical container workpiece, usually formed of aluminum but can be of other materials, in axial alignment with tooling comprising a coaxial pilot and necking die. Hereinafter the term starwheel can mean either vacuum or conventional starwheels. The necking die and pilot are mounted on a cam driven ram mounted for axial reciprocation on a continuously rotating turret which is fixedly attached to the driven main shaft. The pilot and necking die are coaxially positioned relative to the container workpiece and rotate in unison with the starwheel. The closed or bottom end of the container workpiece is engaged with a fixed radial stop forming part of the starwheel so that the container workpiece is held in proper axial position for working and cannot move axially away from the necking die.
The necking die assembly is mounted on a tool carrier member mounted on one end of a cam driven ram which is mounted for rotation on and with the turret. The ram, tool carrier member and necking die are moved forwardly from a home or retracted position toward the open end of the container workpiece so that the necking die engages the outer periphery of the open end of the container workpiece while the pilot enters the interior of the workpiece in well-known manner. Such movement of the necking die is effected by cam follower means on the ram which engages a fixedly positioned cam about which the cam follower means orbits due to rotation of the turret. As the necking die is being moved forwardly toward the container workpiece, air pressure in a cylindrical air chamber in the tool carrier urges a floating piston positioned in the air chamber forwardly toward the workpiece. The pilot is mounted on the forward end of the floating piston and a forwardly facing radial surface of the floating piston engages and remains in contact with a rear portion of the necking die assembly so that the pilot follows the necking die as the necking die moves forwardly from its home or retracted position toward and into contact with the outer surface of the open end of the container workpiece. Additionally, an axial bore provided internally of the floating piston provides compressed air to the interior of the container workpiece prior to and after the necking die engages the can so as to insure positioning of the base of the container workpiece against the fixed stop on the starwheel and to pressurize and consequently strengthen the container workpiece to aid in preventing distortion of the container workpiece during the necking operation.
Movement of the pilot forwardly toward the container workpiece is terminated by engagement of the open container workpiece end edge with a radial stop surface on the pilot to terminate further forward axial movement of that pilot inwardly of the container workpiece. However, the necking die continues its axial movement under the driving force of the cam follower means until the necking function is completed. Following completion of the forward movement of the necking die, the cam and cam follower reverse the direction of movement of the necking die so that it is moved rearwardly away from the can and engages the forwardly facing radical surface of the floating piston which, along with the pilot, is in its stopped position in contact with the open can. Continued movement of the necking die moves the floating piston and pilot rearwardly toward their original starting position. Meanwhile, the pressurized air in the container workpiece, aids in ejecting the container workpiece from the necking die and the pilot for subsequent removal by the starwheel to an outfeed conveyor.
In the second embodiment, the container workpiece is moved into contact with the necking die which is fixedly positioned on the turret with the sequence of working functions being the same as in the first embodiment.
Thus, the inventive structure is greatly simplified in that only a single drive cam is employed and the necking die and the pilot are not mechanically connected by springs or other means and are free for limited relative axial movement with respect to each other. The simplicity of the construction results in substantial cost savings in both fabrication and maintenance of the apparatus.
REFERENCES:
patent: 3524338 (1970-08-01), Bozek
patent: 3635069 (1972-01-01), Eichenhorst
patent: 4280383 (1981-07-01
Clem Ray M.
Marritt Clifford R.
Delaware Capital Formation Inc.
Foley & Lardner
Larson Lowell A.
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