Friction shock assembly for a forging hammer

A friction shock absorber comprised of a plurality of mating friction surfaces in constant contact together is incorporated on an oscillating member of the valve shifting mechanism of a forging hammer for preventing the valve from bouncing away from its intended position after it has been shifted by the motion of the forging hammer ram.

BACKGROUND OF THE INVENTION 
It is well known in the art that a forging hammer having a pneumatic 
cylinder for powering the ram to accelerate the ram to high velocities 
before the object to be forged is struck and engaged by the ram. It is 
also common practice in the art to mechanically link a valve shifting 
mechanism, which reverses the direction of the ram or hammer to the motion 
of the ram itself. Furthermore, in addition to having the direction of its 
motion reversed, it is common for the ram to rapidly bounce back. To 
maintain the valve mechanism in its intended position, hydraulic shock 
absorbers of the automotive type have been employed in the valve shifting 
mechanism. Unfortunately, the heat and abrasive particles in a forging 
atmosphere have a deleterious effect to such hydraulic shock absorbers. As 
a result, they have an exceedingly variable life, sometimes only a matter 
of days or weeks. 
SUMMARY OF THE INVENTION 
The primary object of the present invention is to provide a rugged friction 
type shock absorber which can withstand the heat and abrasive particles 
associated with a forging atmosphere and maintain the shifting valve in 
its intended position once it has been moved as the result of the motion 
of the ram of the forging hammer. 
The present invention incorporates a friction type shock absorber assembly 
on an oscillating member of the valve shifting mechanism and includes 
friction elements on the surfaces which are constantly in contact with 
each other thus minimizing the inclusion of foreign particles which could 
rapidly deteriorate the assembly. 
The present invention further incorporates spring means which bias and hold 
the surfaces of the friction elements together under the desired pressure. 
Adjustment screws or means are provided to maintain the desired pressure 
as the friction surfaces eventually wear to the point where adjustment is 
required.

DETAILED DESCRIPTION OF THE INVENTION 
FIG. 1 shows the slide portion 11 of the frame 12 of a forging hammer 10. 
As it is known in the art, a ram 13 is guided by the slide portion 11 as 
it is moved up and down by a cylinder 14. 
Also shown in FIG. 1 is a valve shifting mechanism 15 comprised of a rocker 
arm 16 which pivots about stud 17 and has on the lower end a projection 
member 18 which contacts ram 13 at the lower end of its path of travel. 
The upper end of rocker arm 16 is pivotally connected to linkage 19 as 
shown in FIG. 2. The opposite end of linkage 19 is pivotally attached to 
an arm element 20 which is affixed to an oscillating shaft 21 is a second 
arm member 22 which is linked to a shifting valve assembly 23 by linkage 
element. 
Referring now to FIG. 3, the friction shock assembly 25 is shown 
sectionally on the oscillating shaft 21. The assembly includes a hub 
member 26 keyed to the shaft 21 by key 27 and held against a shaft 
shoulder 28 by a washer 29 and shaft nut 30. Washer 29 is large enough in 
diameter to retain adjusting ring 31 on the hub member 26. Adjusting means 
or screws 32 press against a first splined disc means 33 which is free to 
slide axially on hub member 26 but is retained rotationally by key 34 to 
hub member 26. A pair of friction discs 35 are on either side of center 
plate member 36 and, all elements are free axially and rotationally on hub 
member 26. Center plate 36 has wing extensions (not shown) which extend 
radially outward and contact hammer frame 12 thereby preventing any 
rotational movement of center plate 36 with respect to frame 12. A second 
splined disc 37 is provided and is free to slide axially on hub 26 but 
which is retained rotationally by key 38 to hub 26. Lastly, a spring 39 on 
one end abuts second splined disc 37 and on the other end abuts shoulder 
40 of hub 26. The spring 39 biases the assembly together to prevent 
abrasive particles from penetrating the assembly. 
As can be seen in FIG. 3, rotation of oscillating shaft 21 is dampened by 
friction shock assembly 25 and in turn shifting valve 23 is prevented from 
bouncing away from its intended position once it is forced there by valve 
shifting mechanism 15. The materials of the friction shock assembly 25 are 
such that they readily withstand the heat of the forging hammer and, 
because splined discs 33, 37, friction discs 35 and center plate 36 are 
constantly in contact with one another by spring 39, foreign abrasive 
particles do not penetrate the assembly 25. Additionally, after months of 
use it is only necessary to move in adjusting means or screws 32 slightly 
to adjust for wear, if necessary. 
It is readily apparent that the present invention provides a rugged 
friction type shock absorber assembly which can withstand the heat and 
particles associated with a forging atmosphere and effectively maintains 
the shifting valve assembly in its intended position. Further, the present 
invention is not subject to sudden catastrophic failure as are the 
hydraulic shock absorbers used previously for this purpose. The useful 
life of the friction type shock absorber assembly is many times that of 
the hydraulic type in this application, with excellent performance as well 
.