Emergency brake for presses

A safety brake for use on presses that provides a positive stop which is positioned so that its braking surfaces will be engaged if the press overtravels its normal home position due to failure of the standard clutch and brake system of the press. The braking surfaces of the emergency brake are moved to a released position when the press is energized to begin a cycle of its operation. Once the released braking surfaces have passed by each other during the normal cycle of press operation, they are returned to their braking positions so as to preclude overtravel of the press past its home position to any substantial degree if the conventional brake of the press should fail.

BACKGROUND OF THE INVENTION 
This invention relates to an emergency brake for presses or the like and 
more particularly to an improved press emergency brake. 
As is well known, most mechanical presses employ a clutch and brake 
arrangement which permits the press ram to move through a cycle of 
operation from a home position through a striking or operative position 
and back to the home position. Normally, the brake and clutch mechanism is 
operated so that the brake is released when the drive clutch is engaged 
and the brake is re-engaged and the clutch disengaged when the ram returns 
back to its home position. In order to provide additional safety, it has 
been proposed to incorporate an emergency brake for the ram which has the 
purpose of preventing accidental movement of the ram in the event of 
failure of the conventional press clutch and braking mechanism. For the 
most part, these emergency brakes incorporate positive detent elements 
which are engaged with each other when the press ram is in its home 
position. The disadvantage of this type of locking mechanism is that it 
depends upon the detent element being accurately aligned at the time the 
emergency brake is actuated. If this accurate alignment is not insured, 
the emergency brake will be inoperative. Another disadvantage of this type 
of system is that it does not truly provide an independent emergency brake 
that is only operative to stop the ram movement in the event of 
malfunction. 
It is, therefore, a principle object of this invention to provide an 
improved emergency brake for presses or the like. 
It is another object of this invention to provide an emergency brake for 
presses that does not depend upon accurate location of the braking 
elements to become effective and further one in which the braking elements 
may be moved to their braking position and retained in that position 
during a substantial part of the press operation cycle so as to insure 
safety braking in the event of failure. 
SUMMARY OF THE INVENTION 
This invention is adapted to be embodied in an emergency brake for a press 
or the like which has a ram and a driving element operatively connected to 
the ram for operating the ram through a cycle of operation from a home 
position to a working position and back to a home position. The emergency 
brake comprises a first brake element that is fixed for rotation upon 
operation of the driving element and a second brake element that is fixed 
against rotation relative to the first brake element, the first brake 
element has a braking surface that extends outwardly from one of its 
surfaces and the second brake element has a braking surface that is 
complementary to the braking surface of the first brake element. Means are 
provided for actuating the second brake element from a released position 
wherein the braking surfaces will not interfere with each other upon 
relative rotation of the braking elements and a safety position wherein 
the braking surfaces will engage each other to prevent further rotation of 
the first braking element. The braking surfaces of the first and second 
brake elements are spaced from each other when the ram is in its home 
position and the second braking element is in its safety position. The 
distance between the braking surfaces in this position is relatively small 
so that any overtravel of the driving element from its home position will 
be arrested by contact of the braking surfaces of the first and second 
braking elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring first to FIG. 1 of the drawings, a press embodying an emergency 
brake constructed in accordance with this invention is identified 
generally by the reference numeral 11. The press may be of any known type 
and is depicted as including a flywheel 12 which is driven in any known 
manner and which is specifically connected to the ram 13 for movement of 
the ram between its home position, as shown in FIG. 1, a striking or work 
position, and back to its home position. As is common with mechanical 
presses of the type shown, a clutch and brake mechanism is associated with 
the flywheel 12 and ram 13 for effecting operation of the ram 13 through a 
single cycle. As is well known, the clutch and brake mechanism is actuated 
to hold the flywheel 12 and ram 13 in its home position unitl a cycle of 
operation is commenced. During this inoperative period the brake is 
maintained engaged and the clutch disengaged. When the press is actuated 
the brake is released and the clutch is engaged so as to connect the 
flywheel 12 and ram 13 with the continuously driven motor of the press. 
This motor is not shown in detail but is indicated schematically at 14. As 
illustrated, the motor 14 with its clutch and brake are positioned on the 
side of the ram 13 opposite the flywheel 12. It is to be understood, 
however, that the motor, clutch and flywheel may all be positioned on the 
same side of the same or, alternatively, flywheels may be positioned on 
both side of the ram 13. The construction of the press per se forms no 
part of this invention and is merely described so as to illustrate the 
environment in which the invention is found. 
After the ram 13 has completed its work cycle and is returning to its home 
position, the clutch is disengaged and the brake re-engaged. The 
construction and operation of the clutch and brake mechanism which are 
employed for this purpose are believed to be well known and form no part 
of this invention. Therefore, these elements have not been illustrated in 
any detail. 
In accordance with this invention, an emergency brake is incorporated which 
is effective to provide a positive stop for rotation of the flywheel 12 
and operation of the ram 13 past their home positions in any substantial 
distance. Thus, in the event the clutch and brake mechanism fails, an 
operator who places his hands beneath the ram 13 will not be injured. 
The emergency brake mechanism in the illustrated embodiment includes a ramp 
15 which extends from one radially extending surface 16 of the flywheel 12 
and extends axially therefrom. The ramp 15 includes a tapered or inclined 
portion 17 that terminates in an axially extending braking surface 18 
which is generally radially disposed, as may be best seen from an 
inspection of FIG. 3. The normal direction of rotation of the flywheel 12 
is indicated by the arrow 19 in FIGS. 2 and 4 wherein it may be seen that 
the incline surface 17 tapers outwardly from the flywheel surface 16 
toward the braking surface 18 in the direction of rotation 19. 
An axially moveable braking element, indicated generally by the reference 
numeral 21, is juxtaposed to the flywheel surface 16. The braking element 
21 may be of a cylindrical shape and has a radially extending surface 22 
which is complimentary to the flywheel surface 16. A braking ramp 
indicated generally by the reference numeral 23 extends axially outwardly 
from the surface 22 and includes an inclined portion 24 and an axially 
extending braking surface 25. The braking surface 25 is complimentary to 
the braking surface 18 of the flywheel ramp 15. The angle of inclination 
of the ramp surface 24 is the same as that of the surface 17 but in the 
opposite direction, as may be readily seen from an inspection of FIG. 4. 
The braking element 21 is actuated in any suitable manner from a released 
position as shown in FIG. 4 wherein the braking surfaces 18 and 25 are 
axially spaced from each other so that the flywheel 12 may rotate freely 
without encumbrance by the braking element 21 to an engaged or operative 
position. As has been previously noted, this movement is axial and may be 
accomplished by means of hydraulic or pneumatic motors and appropriately 
located springs, alternately, the axial movement may be effected 
electrically in any known manner. Because such actuating devices are 
believed to be well known to those skilled in this art, a detailed 
description of them is not believed to be necessary. However, the 
actuating and release device has been identified graphically by the box in 
FIG. 4. 
When the braking element 21 is in its engaged or operative position, its 
surface 22 will be justaposed to the flywheel surface 16 with the spacing 
therebetween equal to the height of the braking surface 18 or 25 and the 
respective ramp braking surfaces 18 and 25 will be positioned in an 
interference location. 
The braking surfaces 18 and 25 are located relative to the flywheel 12 and 
braking element 21 so that when the flywheel 12 is in its home position 
and the braking element 21, which is fixed against rotation, is in its 
operative or engaged position, the braking element braking surface 25 will 
be spaced slightly from the flywheel braking surface 18 in the direction 
of rotation of the flywheel 19. The amount of this spacing will depend 
upon the particular application involved, but should be something less 
than the order of 30.degree. rotation of the flywheel 12 and before any 
substantial downward movement of the ram 13 from its home position will 
occur. 
When the flywheel 12 is in its home position, the braking element 21 will 
have been positioned in its operative or braking position for a 
substantial period of time, as will become apparent. When a cycle of 
operation is initiated by the operator, the braking element 21 is actuated 
through appropriate electrical, hydraulic and/or pneumatic circuitry so 
that it will move to its disengaged position as shown in FIG. 4. The 
clutch and braking mechanism is then operated so that the flywheel 12 will 
commence rotation in the direction of the arrow 19 and the ram 12 may 
commence its downward movement. 
As soon as the flywheel has rotated sufficiently so that the flywheel 
braking surface 18 has passed, in a radial direction, the braking element 
braking surface 25, the braking element 21 is actuated so as to again 
return it to its operative, braking, position. If this actuation is 
initiated before the ramp surfaces 17 and 24 are free of each other, which 
may be permitted and even desirable, the inclination of these surfaces 
will merely retard the movement of the braking element 21 to its 
appropriate braking position. The braking element 21 is then retained in 
this position until a new cycle of operation of the press 11 is initiated 
by the operator. 
The flywheel 12 will continue to rotate to bring the ram 13 to its 
operative position and then back toward its home position. When the home 
position is reached or approached, the clutch and brake mechanism should 
be actuated so as to disengage the flywheel 12 from the driving motor 14 
and so as to engage the brake to stop the flywheel 12 in its home 
position. In the event, however, of any malfunction of the clutch and 
brake mechanism, the braking element braking surface 25 will contact the 
flywheel braking surface 18 upon slight overtravel of the flywheel 12 and 
ram 13 from their home positions and prevent any injury to the operator 
who might have placed his hands back beneath the ram 13 under the 
assumption that the press was fully operative. 
The circuitry and actuating device for controlling the movement of the 
brake element 21 has not been described or illustrated as aforenoted 
because it is believed it is well within the scope of the art to provide 
appropriate mechanism for achieving the aforedescribed operation. 
Furthermore, the emergency brake described may be used with other types of 
presses than the flywheel type by providing appropriate braking surfaces 
on elements which move in conjunction with movement of the ram of the 
press. An important feature of this invention is the positioning of the 
braking surfaces so that they are normally slightly spaced apart when the 
ram is in its home position even though the braking surfaces are disposed 
in their braking position. The braking surfaces are moved to their 
released position immediately upon actuation of the press and are returned 
to their braking position after the ram has undergone sufficient movement 
so as to move the braking surface past their contact point. In this way, 
it is unnecessary for the emergency brake to rely upon accurate 
positioning of the moving elements in a predetermined location so as to 
insure actuation of the emergency brake, as was true with prior art detent 
mechanisms which were held in their locked or braking position when the 
ram was in its home position. 
In the illustrated embodiment, one braking element 21 has been provided and 
the braking surfaces 18 and 25 extended axially from radially extending 
surfaces of the respective brake components. Of course, an additional 
braking element could be provided for co-action with a braking surface 
formed on the surface of the flywheel 12 opposite to the surface 16. Such 
braking elements would be actuated axially in unison so that they would in 
effect move toward and away from the flywheel 12 together. Alternately, 
the braking surfaces could extend radially outwardly beyond the outer 
periphery of the flywheel 12. The configuration of such an embodiment is 
shown in FIG. 5 wherein such a braking device associated with the flywheel 
12 is identified by the reference numeral 31. Of course, both axial and 
radial braking surfaces could be incorporated. Various other changes and 
modifications from the illustrated embodiment are possible without 
departing from the spirit and scope of the invention as defined by the 
appended claims.