Apparatus for a pelletizer having hydraulically adjustable pressing rolls

Apparatus is described for a pelletizer having hydraulically adjustable pressing rolls. Specifically, each pressing roll is mounted in two bearing journals and is eccentrically located with respect thereto. The pelletizer includes a hydraulically actuated device for adjusting the position of the outer surface of the pressing rolls relative to the inner surface of the mold, wherein this device utilizes at least one hydraulic cylinder having an end that is connected to a bearing journal which is, in turn, attached to a shaft of a pressing roll. In addition, the pelletizer also includes a hydraulically actuated device for clamping the rolls into a desired position. Oil supply and discharge pipes for each hydraulic cylinder extend through a main shaft of the pelletizer. Through this apparatus, the position of the pressing rolls can be controllably adjusted while the pelletizer is operating, i.e. while the annular press mold is rotating.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a pelletizer that has a driven annular driveable 
press mold mounted on a stationary main shaft within a frame and 
eccentrically mounted hydraulically adjustable pressing rolls located 
within the mold. 
2. Description of the Prior Art 
A similar pelletizer is known e.g. from Dutch patent No. 139,111. As 
disclosed in this patent, the position of each pressing roll is manually 
adjusted in the direction of the inner surface of the press mold. To that 
end, a hexagonal shoulder is disposed on a bearing journal of each 
pressing roll. A nut spanner can be placed on this shoulder. 
Another drawback of the manual adjustment of the pressing roll is that this 
adjustment can take place only with an inoperative pelletizer. A further 
drawback is that the correct setting of the pressing roll relative to the 
mold can only be obtained through a trial and error method, since the 
correct setting of the pressing roll can only be determined experimentally 
with the pressed product. In fact, the correct placement of the pressing 
roll depends upon the material to be processed by the pelletizer. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to remove these drawbacks and to 
provide a pelletizer in which the pressing rolls can be adjusted while the 
pelletizer is in operation and, moreover, in such a manner that for a 
given material to be processed the correct position of the pressing rolls 
is immediately adjustable. The pelletizer according to the present 
invention is characterized, to that end, in that the adjustment device 
includes at least one hydraulic adjustment cylinder having an end 
connected to a bearing journal of the pressing roll shaft, while the oil 
supply and discharge pipes of each hydraulic adjustment cylinder extend 
through the main shaft of the pelletizer. 
Preferably, each pressing roll is adjustable by means of an associated 
adjustment cylinder whose piston rod engages with the adjustment crank of 
the pressing roll and the other end is fixedly connected to a stationary 
spacer plate provided within the press mold. 
Hydraulic adjustment of the pressing rolls has the advantage that 
adjustment of the pressing rolls can take place when the pelletizer is in 
operation. Moreover, the pressure supplied to an adjustment cylinder is 
indicative of the force with which the outer surface of the pressing roll 
presses against the inner surface of the annular mold. When the material 
to be processed by the pelletizer is changed, only an experimentally 
established oil pressure needs to be supplied to the hydraulic adjustment 
cylinders in order to obtain for that material the optimum position of the 
pressing rolls relative to the annular mold. By having the oil supply and 
discharge pipes of each hydraulic cylinder extend through the main shaft 
of the pelletizer, sealing problems that would occur, if pipes should 
extend through the cover closing one side of the annular press mold, are 
avoided. Moreover, one side of the pelletizer is kept entirely free, 
thereby allowing easy access to the filling end of the mold for operation 
and maintenance purposes. 
Inasmuch as the hydraulic adjustment cylinders can be kept under pressure, 
the pressing rolls remain in their proper position during compaction of 
the material. Preferably, each pressing roll is provided with an hydraulic 
clamping device for fixing the roll in a given position after its 
adjustment. Such a hydraulic clamping device consists of a tie rod that 
extends coaxially with the bearing journals through the pressing roll. The 
tie rod is provided on the main shaft end with a cup-shaped nut whose edge 
can be pressed against wedge-shaped bearing brasses mounted about the 
bearing journal of a pressing roll. At the other side of the pressing 
roll, a hydraulically operated servo piston is provided on the tie rod 
through which the tie rod can be subjected to a tensile load. 
By applying wedge-shaped bearing brasses, a proper fixation of the pressing 
roll in a given position can be obtained, while the clamping effect can be 
easily operated by means of a small servo piston. 
Because the stroke of the hydraulic cylinder is usually smaller than the 
admissible wear of the surfaces of the pressing rolls and the annular 
mold, it is desirable to have the possibility of adapting the adjustment 
range to the extent of wear that occurs over time. Preferably and to that 
end, the bearing journal of the pressing roll shaft which is located 
remote from the main shaft, is provided with a polygonal shoulder. The 
adjustment crank is provided internally with a correspondingly formed 
cut-out. The mounting arrangement is such that the adjustment crank can be 
placed in different positions on the polygonal shoulder. 
In this manner, the entire adjustment range of the pressing roll can be 
traversed in the event of a small stroke of the adjustment cylinder. The 
magnitude of the adjustment range of the pressing roll is determined by 
the extent of eccentricity of the pressing roll shaft.

DETAILED DESCRIPTION 
FIGS. 1 and 2 collectively show the main components of the pelletizer, 
consisting of frame 1 wherein main shaft 2 is mounted in a stationary 
relationship thereto. Annular mold 5 is attached to mold holder 3 which, 
in turn, is mounted on main shaft 2. Mold holder 3 is connected to drive 
wheel 4 which is driven by a motor, not shown, through means of vee ropes. 
Within annular mold 5 are provided two pressing rolls 6 mounted on the one 
hand in main shaft 2 and on the other hand in spacer plate 7 which, in 
turn, is connected to main shaft 2 by means of two rods. Two hydraulic 
adjustment cylinders 8, one for each pressing roll 6, are mounted in 
spacer plate 7. The construction and operation thereof will be further 
explained hereinafter in conjunction with FIG. 4. Each pressing roll 6 is 
provided with hydraulic clamping device 10 to be explained hereinafter in 
conjunction with FIG. 3. Material supply device 11 is mounted above 
annular mold 5 and rests on frame 1 of the pelletizer. The material supply 
device includes a diagrammatically shown transport/mixing mechanism 
supplying the material to be processed to feed hopper 12 which is, in 
turn, connected to the annular mold 5. The grains compacted by the annular 
mold are discharged via a chute located at the bottom of mold 5. 
A. The hydraulic clamping device 
FIG. 3 shows pressing roll 6 abutting against annular press mold 5. This 
mold is mounted, via partially shown mold holder 3, in the frame of the 
pelletizer and specifically on main shaft 2 which is also partially shown. 
Pressing roll 6 is mounted on pressing roll shaft 13 by means of roller 
bearings 14 with the axis of shaft 13 indicated by label "X". Shaft 13 is 
eccentrically located relative to two bearing journals 16 and 22. Journal 
16 is placed in a cut-out located in stationary main shaft 2. Journal 22 
rests in a cut-out provided in spacer plate 7. Tie rod 18 extends through 
journals 16 and 22 and projects from spacer plate 7. Cup-shaped nut 17 is 
secured to an end of tie rod 18 that faces main shaft 2. An edge of this 
nut whose faces pressing roll 6 abuts against two wedge-shaped ring 
clamping segments 20 which are shown in cross-section in FIG. 3. A second 
set of wedge-shaped clamping segments 20 is mounted at a left end of 
journal 16. Intermediate ring 21 is placed axially between the 
wedge-shaped clamping segments. The leftmost wedge-shaped ring in the 
leftmost wedge-shaped camping segments abuts against a shoulder provided 
on pressing roll shaft 13. 
Polygonal shoulder 23, the function of which will be explained hereinafter, 
is mounted on journal 22. Cap 24 is screwed onto the left end of tie rod 
18. Chamber 26 which is formed from a recess in cap 24 accommodates servo 
piston 25. Cap 24 is held down by means of nut 27 which is provided on the 
left end of tie rod 18. 
To prevent bearings 14 of pressing roll 6 from contacting the material to 
be pelletized, the side walls of pressing roll 6 are provided with sealing 
plates 15. 
The hydraulic clamping device, i.e. hydraulic clamping device 10 shown in 
FIG. 1, operates as follows: When pressing roll 6 is to be adjusted, the 
oil pressure between cap 24 and servo piston 25 is relieved, allowing the 
servo piston to move in the direction of cap 24 (in FIG. 3 to the left), 
thereby creating room for tie rod 18 to move to the right. In this manner 
the edge of cup-shaped nut 17 is released from wedge-shaped clamping 
segments 20, so that these segments are no longer clamped onto each other. 
As such, bearing journal 16 is no longer clamped within main shaft 2. 
In the manner to be described hereinafter, polygonal shoulder 23, connected 
to journal 22, is then rotated so that eccentric pressing roll shaft 13 
occupies a different position whereby the circumferential surface of roll 
6 is moved towards or away from the inner wall of mold 5. After this 
adjustment of roll 6 is made, pressure is supplied to chamber 26 situated 
between cap 24 and servo piston 25. Servo piston 25 is thereby pressed to 
the right until it abuts against polygonal shoulder 23. As such, cap 24 is 
pressed to the left in FIG. 3, thereby exerting a tensile force onto tie 
rod 18. As a result, wedge-shaped clamping segments 20 of cup-shaped nut 
17 are pressed onto each other, thus ensuring a clamping of journal 16 in 
stationary main shaft 2. Consequently, pressing roll 6 is thus clamped in 
its newly adjusted position. 
B. The adjustment device for the pressing roll 
FIG. 4 shows a front view of spacer plate 7 on which only one adjustment 
cylinder 8 is mounted. For the sake of clarity, the other cylinder has 
been omitted from this figure. As shown, one end of adjustment cylinder 8 
is pivotally mounted on attachment journal 32 which, in turn, is fixedly 
connected to spacer plate 7. Piston rod 33 exists within the cylinder. The 
free end of this rod is connected to crank 39. This crank has a polygonal 
internal shape so as to matingly fit on polygonal shoulder 23 connected to 
journal 22 of pressing roll shaft 13 (see also FIG. 3). Piston rod 33 is 
shown in FIG. 4 in its most retracted position in adjustment cylinder 8. 
The position that is shown for crank 39 corresponds to the most extended 
position of piston rod 33. Adjustment cylinder 8 is provided with two oil 
inlets 34 and 35 for moving the piston of adjustment cylinder 8 in the 
desired direction. Shown at the underside of spacer plate 7 are three oil 
pipes 36, 37 and 38, two of which are connected (though not specifically 
shown to simplify the drawing) to inlets 34 and 35 of adjustment cylinder 
8. Oil pipe 38 is connected (again not specifically shown to simplify the 
drawing) to chamber 26 of servo piston 25 shown in FIG. 3 for operating 
the clamping device. As shown in FIG. 4, spacer plate 7 is connected with 
two attaching rods 30 and 31 to the front face of main shaft 2 (also see 
FIG. 1). As shown in FIG. 4, piston rod 33 of adjustment cylinder 8 is 
pivotally connected to adjustment crank 39 by means of connecting pin 40 
suitably secured in the crank by means of split pin 41. 
Adjustment cylinder 8 is adapted to swivel adjustment crank 39 through an 
angle of about 70.degree.. The circumference of pressing roll 6 can thus 
be displaced along a distance of X mm in the direction of the inner 
circumference of the press mold. Because, during pelletizing material, 
pressing rolls 6 may be subjected to more wear than X mm at their outer 
surface and at the inner surface of mold 5, the position of adjustment 
crank 39 relative to the polygonal shoulder 23 should be variable. 
In the embodiment shown, polygonal shoulder 23 has an external dodecagonal 
shape, which also applies to an internal shape of adjustment crank 39. 
Consequently, crank 39 can be placed in twelve positions on the polygonal 
shoulder 23 so that there is an ample choice for the desired adjustment 
range of the pressing rolls. 
As shown in FIG. 2, the second pressing roll is adjusted identically by use 
of an identical adjustment cylinder 8 mounted on spacer plate 7 in an 
inverse symmetrical relationship to the adjustment cylinder shown in FIG. 
4. 
C. Hydraulic pipes 
FIG. 1 shows in dotted lines, at the right end of the pelletizer, oil pipes 
which subsequently extend horizontally through main shaft 2. The 
connection of the oil pipes to the pelletizer is shown in detail in FIG. 
5. 
Main shaft 2 is stationary. However, in the event that the case of the 
pelletizer seizes, mold 5 may be entrained. Consequently, the different 
oil pipes have to be connected to main shaft 2 by means of slip rings. If 
this was not the case, then all the hydraulic pipes would be fractured in 
the event the pelletizer seizes and the main shaft rotates. 
As specifically shown in FIG. 5a, extension piece 2' has a smaller diameter 
than main shaft 2 and is screwed onto the end of the main shaft. The 
extension piece accommodates a central oil channel and eight oil pipes 
uniformly distributed over a circle, wherein two of these pipes are 
illustratively indicated in FIG. 5b as pipes 45 and 46. Except for the 
central oil pipe, the eight other oil pipes are plugged at the end of 
extension piece 2'. Pipe 45 terminates in an annular channel of slip ring 
42 and is sealed on both ends of the slip ring by seals 44. Channel 46 
terminates in an annular oil channel of slip ring 43 which is sealed in an 
identical fashion. All other oil channels provided in extension piece 2' 
are connected in an identical fashion to the remaining slip rings which 
are indicated diagrammatically. 
Because the oil pipes in main shaft 2 are situated at a larger interspace 
from the axis of the shaft than in extension piece 2' each oil pipe, such 
as illustratively oil pipes 45 and 46, is connected through by-pass 47 to 
a corresponding oil channel, such as illustratively channel 45', that is 
provided in the main shaft. FIG. 5a shows the course of the oil pipes in 
extension piece 2', as well as the course of the associated pipes in main 
shaft 2. Three oil pipes serve in lubricating the main bearing and the 
bearings of pressing rolls 6. Two oil pipes extend towards adjustment 
cylinder 8, while for each clamping device 10 (see FIG. 1) an oil pipe 
also passes from the connection point on extension piece 2, through main 
shaft 2 to spacer plate 7.