192 clutches and power-stop control – Clutch and brake – Sliding operation
Reexamination Certificate
2001-06-08
2003-11-18
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Clutch and brake
Sliding operation
C188S170000, C192S200000, C464S098000
Reexamination Certificate
active
06648114
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to clutch-brake combinations for use in press machine environments, and, more particularly, to a brake system employing a flex disk brake.
2. Description of the Related Art
Mechanical presses of the type performing stamping and drawing operations have a conventional construction comprising a crown and a bed portion configured within a frame structure. A slide supported within the frame is adapted for reciprocating movement toward and away from the bed. The slide is driven by a crankshaft having a connecting arm coupled to the slide. These mechanical presses are widely used for a variety of workpiece operations employing a diverse array of die sets, with the press machine varying substantially in size and available tonnage depending upon its intended use.
The drive apparatus of a press machine typically includes a drive motor directly engaged to rotate a massive flywheel. The flywheel serves as the source of rotational energy that is appropriately distributed throughout the machine. A clutch assembly selectively connects the flywheel to the crankshaft during a press working cycle. Energy is removed from the flywheel and transferred to the rotating parts of the press, namely, the crankshaft. The crankshaft rotation controls the reciprocating motion of the slide. The linear driving force produced by motion of the slide is used to process a workpiece disposed between respective die shoes attached to the slide and bolster assembly. During operation, then, the rotational energy of the flywheel is used to drive the rotating parts of the machine and produce the stamped part.
The clutch typically forms part of a clutch-brake combination that coordinates the braking function and clutch function. During operation, when a press cycle is initiated, the clutch-brake combination is adapted to disengage the brake at the same time that the clutch is engaged. Following completion of the working cycle, the press operation is terminated by activating the brake, which concurrently disengages the clutch to disconnect the flywheel from the crankshaft. The brake and clutch mechanisms cooperate in an interdependent fashion such that activation of one component necessarily causes a concurrent deactivation of the other component.
In one form, the brake assembly acts to apply a braking action to the working components of the machine by stopping all of the rotating parts except the flywheel. For this purpose, the brake is adapted for selective connection to the crankshaft. In one configuration, a brake component such as a brake disk rotates in unison with a clutch component such as a clutch plate mounted to the crankshaft. A stationary brake plate is disposed between the brake disk and clutch plate.
When the brake is activated, the clutch is released from the flywheel. At the same time, the brake activation causes both the rotating clutch plate and the rotating brake disk to be brought into frictional contacting engagement with the stationary brake plate at opposite sides thereof. The frictional coupling employs brake lining material mounted on the rotating parts. In effect, the stationary brake plate becomes pinched between the brake disk and clutch plate.
Although the brake plate is designed for stationary movement in the rotational direction, the brake plate is adapted for axial movement between the adjacent rotary parts to enable the clutch plate and brake disk to center the stationary brake plate and create a full surface-to-surface abutting engagement. Otherwise, less than full contact may occur between the stationary brake plate and the rotary parts. This axial movement is typically along a dimension parallel to the longitudinal axis of the crankshaft.
The stationary brake plate is mounted on keys, pins, splines, studs or other such mechanisms to restrain rotational movement of the brake plate while allowing linear movement between the rotary parts of the clutch-brake combination. However, as the die repetitively impacts the workpiece during the stamping process, the resulting vibrational activity will pound out these spline devices and create unwanted clearances between the stationary brake plate and the splines or keys. These free and undamped clearances will allow the brake plate to move in the rotary direction during braking, thus causing impact loadings on the keys or spline devices. These impact loading forces increase with the amount of clearance. Also, this free and undamped clearance will allow the brake to move up and down due to the vibrations from the die when stamping out the parts at a high rate of speed. This action will pound out the clearance between the brake plate and key.
SUMMARY OF THE INVENTION
A flex disk brake is provided in the form of a disk structure annularly disposed about the press crankshaft and having a ring-shaped central body portion. The flex disk includes a plurality of flange-type arm portions each extending from a peripheral edge of the central ring portion in a spiral configuration which preferably forms a circumferential slot with the central ring portion. The arm portions are fixedly mounted to the press crown at respective ends thereof to establish a stationary anchor point.
The flex disk brake is fixedly mounted at its central ring portion to a brake component of the clutch-brake combination. Additionally, the arm portions are arranged to extend in a direction opposite to the typical direction of rotation of the crankshaft to allow the arm portions to offer maximum braking resistance. In a preferred form, the individual arm portions extend sufficiently in the circumferential direction to form a slot with the outer circumferential edge of the ring portion such that the preferred direction of crankshaft rotation is directed towards the closed end of the slot, although opposite rotation is also provided for.
The flex disk brake is rotationally stationary and axially flexible. Accordingly, the flex disk brake eliminates free and undamped clearances of the brake disk in the rotational direction, while simultaneously accommodating axial sliding of the brake disk due to an axially-directed flexing feature characteristic of the arm extensions.
During operation, when the brake is activated following release of the clutch, the brake component of the clutch-brake combination is axially moved into contact-type engagement with a pair of brake lining elements disposed on opposite sides of the brake component. This axial displacement or sliding is accommodated by a corresponding axial deflection of the attached flex disk brake. The braking action is applied by the brake component due to its connection to the stationary crown via the flex disk brake. In particular, the motional rigidity of the flex disk brake in the rotary direction has the effect of applying a braking torque that opposes the crankshaft rotation and eventually stops the press working members. This rotational strength of the flex disk brake substantially prevents any rotary displacement of the brake component, thereby eliminating the free and undamped rotary clearances occurring in conventional machines.
The rigid coupling of the brake component to the flex disk also ensures that the brake component will be positively located in a non-interfering, spaced-apart relationship to adjacent brake lining elements during clutch engagement (i.e., brake release). In particular, when the clutch is engaged and the brake is released, the rigid connection of the flex disk brake to the brake component serves to accurately locate the brake component between the brake lining elements, thereby ensuring the maintenance of suitable axial clearances therebetween while the brake is idle.
Moreover, following completion of the braking activity, the axial elasticity of the flex disk brake is effective in returning the brake component to its idle position concurrent with the release of the brake actuating force.
In one form, the flex disk brake has a multi-layered construction formed of several thin laminated steel plates. This arrangement of stack
Bornhorst John B.
Evers Kevin J.
Bonck Rodney H.
Knuth Randall J.
The Minster Machine Company
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