Machine element or mechanism – Elements – Eccentric
Reexamination Certificate
1999-07-19
2001-06-26
Wright, Dirk (Department: 3681)
Machine element or mechanism
Elements
Eccentric
C074S571100
Reexamination Certificate
active
06250178
ABSTRACT:
FIELD OF THE INVENTION
The invention describes an eccentric mechanism with an eccentric shaft whose cylinder shaped eccentric with eccentric bush carries out a circular motion when the eccentric shaft rotates and with this motion being translated into a reciprocating motion via a connecting rod, slide, etc.
BACKGROUND OF THE INVENTION
Customary eccentric mechanisms, crank mechanisms or cam mechanisms are used to translate a motion of rotation into a translational reciprocating motion or vice versa. Such mechanisms usually have a fixed stroke that corresponds to the eccentricity of the eccentric of the eccentric shaft/secondary shaft or the dimension of the crank of the crankshaft.
There also are crank mechanisms with adjustable strokes (HüTTE Taschenbuch für Betriebsingenieure, Band II Fertigungsmaschinen, Verlag von Wilhelm Ernst & Sohn, 6
th
edition 1964, page 505). An adjustment bush with an eccentrically located bore is articulated on the eccentric, cylinder shaped crank pin of a so-called outside crankshaft and with the adjustment bush in turn being articulated on the connecting rod bearing of a connecting rod of a connecting rod press. By turning the adjustment bush on the crank pin, which can only be done when the press is at a standstill, the connecting rod stroke can be changed from a maximum size to a minimum size or vice versa.
However, there is a need especially for machines that work with an eccentric mechanism and a connecting rod stroke in which the stroke is adjustable during operation and in particular in a manner that ensures that the connecting rod stroke position after turning off the eccentric mechanism is identical to the one at the time of turning on the eccentric mechanism. A concrete example is the process of rotary friction welding of thermoplastic and elastic plastic materials. In these cases long profile belts with round or angular profiles, for example pentagonal profile sections, V-belt profile sections etc., made of such plastic material must be adjusted to finished size for the purpose of manufacturing such conveyor belts and then the ends of the profile belts must be welded by keeping one profile belt end in place while the other end of the belt is pressed against the stationary end of the belt and simultaneously is melted onto it via a translational reciprocating motion accompanied by the development of frictional heat. The same is true for the repair of such profile belts when they are torn. It is important that the ends of the belts are exactly aligned during the final welding process of the ends of the profile belts. Customary eccentric mechanisms whose connecting rods would provide the translational reciprocating motion of the end of one of the profile belts for the purpose of rotary friction welding cannot guarantee this because when such an eccentric mechanism or crank mechanism runs out, it arrives at its fixed eccentricity when at a standstill, which would not be desirable for the use of a friction welding device, for example.
SUMMARY OF THE INVENTION
The object of the invention is to provide an eccentric mechanism which guarantees that the eccentricity or the connecting rod stroke position is adjustable and that its position at the time when the eccentric mechanism is turned off is identical to its position at the time when the eccentric mechanism is turned on without requiring any elaborate measuring or automatic control engineering.
The object of the invention is attained with the features of the described in the appended claims.
The fact that in the eccentric mechanism in accordance with the invention the cylinder shaped eccentric of the eccentric shaft is pivoted in the cylinder bore of the eccentric bush in a manner that ensures that when the eccentric mechanism is at a standstill concentricity is obtained due to the fact that the eccentricities of eccentrics of the eccentric shaft and cylinder bore of the eccentric bush cancel each other out while during rotation of the eccentric shaft the centrifugal force on at least one actuator automatically causes a counter-torsion movement that is controlled by the centrifugal force between eccentric shaft and eccentric bush while canceling out the concentricity and the eccentricity acts on the main drive pinion of the eccentric mechanism, results in the fact that the eccentric system can be rotated automatically from a first position (neutral or start position) into a second position (working or operating position) in which the eccentric system has a pre-determined eccentricity and therefore a pre-determined connecting rod stroke at the main drive pinion which can be used for the side-head of a machine (tool), for example.
The stroke of the eccentric mechanism is automatically adjustable in that at least one actuator that rotates together with the eccentric mechanism moves due to the centrifugal force and acts on the eccentric shaft as well as on the eccentric bush and in that it causes components to counter-rotate with regard to each other by a certain angle and thus automatically changes or adjusts the eccentricities whereby once the eccentric mechanism is turned off and the centrifugal force on the actuator no longer exists, the change in eccentricity is cancelled by at least one readjusting spring. This ensures that when the eccentric mechanism in accordance with the invention is turned off, the position of the connecting rod stroke automatically always is identical to the one when the eccentric mechanism is turned on.
In accordance with another characteristic of the invention the eccentric shaft, in its peripheral area as well as the eccentric bush in its peripheral area, can have at least one tappet each in axial direction whereby the at least one actuator expands between the tappets due to the effects of the centrifugal force, spreads the tappets against the force of the readjusting spring and thus counter-rotates the eccentric shaft and eccentric bush with regard to each other.
The actuator that is controlled automatically by the centrifugal force can be a mass body in the form of a globe, for example, that moves freely in the annulus between the eccentric shaft and the tappets of the eccentric shaft and eccentric bush. The actuator that is controlled automatically by the centrifugal force also can be at least an arm of a lever, one end of which can be linked to a tappet of the eccentric shaft or eccentric bush and the other end of which swings out due to the centrifugal force, acts on the adjacent tappet of the eccentric bush or eccentric shaft, pushes the tappets apart and rotates the eccentric shaft and eccentric bush against the force of the readjusting springs.
The invention and its additional characteristics and advantages will be explained in more detail with the help of the schematically represented exemplary embodiment in the figures.
REFERENCES:
patent: 3180178 (1965-04-01), Brown et al.
patent: 3554846 (1971-01-01), Billett
patent: 3441213 C1 (1986-02-01), None
patent: 4226361 A1 (1994-04-01), None
Berkowitz Marvin C.
Ch. Beha GmhB Technische Neuentwicklungen
Nath Gary M.
Nath & Associates PLLC
Wright Dirk
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