Device for shelling nuts

A process for shelling nuts, particularly pistachio nuts, includes the step of slowly and continuously compressing the nuts in the longitudinal direction and not increasing the compression at the moment when the shells break. This compression can preferably be effected in the longitudinal direction with the aid of two rotating disks arranged to be slightly inclined relative to each other.

This invention relates to a process and device for shelling nuts, 
particularly pistachio nuts, wherein the unshelled nuts are subjected to a 
force acting substantially in the longitudinal direction. 
Pistachio nuts have a very strong shell of irregular shape. In contrast to 
walnuts, for example, they do not have a definite seam and their shells 
are irregular in shape. At the present time it is customary in the 
countries where they grow for pistachio nuts to be struck with stones or a 
hammer. An impulse is thus transmitted to the shell and leads to a 
deforming force. If this impulse is too slight, the shell remains closed. 
If on the other hand it is too great, the resistance decreases immediately 
after the shell bursts open, so that the hammerhead continues to move 
forward because of its great mass and destroys the pistachio nut itself. 
Since the force required to open pistachio nuts varies considerably, it is 
scarcely possible to achieve an economically reasonable result in this 
manner. 
A process is also known by which pistachio nuts are opened with the aid of 
steam. Although the kernels then remain intact, nevertheless their quality 
suffers because of the heat. Other types of nut can be opened and shelled 
more easily, but here again difficulties continually occur, because nuts 
are natural products whose growth varies. 
The problem underlying the invention is that of providing a process and a 
device for shelling nuts which can be applied economically, in which the 
quality of the shelled nuts is not impaired, which operates with a low 
rejection rate, and which can be applied in particular also to pistachio 
nuts. 
According to the invention this problem is solved in that the nuts are 
gripped in the region of their ends, compressed to a continuously 
increasing extent in the longitudinal direction, and immediately released 
when the shell breaks. In comparison with hammer blows, the compression 
occurs relatively slowly, and the geometrical compression ensures that on 
the fracture of the shell no further force will act on the kernel. By this 
method it is therefore possible to obtain intact shelled pistachio nuts 
with a low rejection rate. 
As a further development, provision may be made for the nuts to be moved 
preferably transversely of their longitudinal direction during the 
compression. This type of movement makes continuous operation particularly 
simple. 
Since the irregular shape of the shells may have the consequence that the 
nuts will evade the compression while they are being gradually gripped, 
the invention further proposes that at least during the gripping and at 
the commencement of the compression the nuts can be guided laterally of 
their path of movement. Through this lateral guidance it is made 
impossible for the nuts to escape, so that the yield of the process is 
increased. 
According to another feature of the invention, the nuts can be moved over a 
path dependent on their size during the compression. Since the nuts are of 
different sizes, and since these different sizes occur in a statistical 
distribution, it is thus ensured that two nuts will have the least 
possible influence on one another during the process proposed by the 
invention. It may be particularly advantageous for the nuts to be moved 
over a circular path. 
Provision is made according to the invention for the nuts to be able to be 
presorted in accordance with their size before they are gripped. This can 
likewise increase the yield of the process. 
In order to enable the nuts to be gripped and effectively compressed with 
the greatest possible certainty, provision may be made for the nuts to be 
aligned before they are gripped. 
After the shell has been broken, provision may be made according to the 
invention for the opened nuts, together with their shells, to be subjected 
to air separation. This air separation serves to separate the larger 
shells from the smaller kernels. In this case it may be particularly 
advantageous for the opened nuts together with their shells or residues of 
shells to be passed into an upwardly directed suction current. This 
suction current then draws the shells upwards, while the shelled nuts fall 
downwards and can there be collected. 
According to the invention provision may be made for a plurality of nuts to 
be compressed substantially simultaneously or overlappingly in respect of 
time. It is thus possible to increase the amount of nuts shelled per unit 
of time. 
The invention also proposes a device for shelling nuts which according to 
the invention comprises at least one cyclically operated pressing member 
which is adapted to be driven by a drive and whose distance from a 
coacting member gradually decreases, as well as a feed device for bringing 
the unshelled nuts into the region between the pressing member and the 
coacting member. The feed device can for example bring nuts successively 
into the region of the coacting member, while from the other side the nut 
is compressed with the aid of a cam or the like. 
It is however particularly advantageous for the device to comprise two 
rotating pressing members which are adapted to be driven by a drive and 
the distance between which gradually decreases in the direction of 
rotation, while the feed device brings the nuts into the region between 
the pressing members. The two pressing members may for example be chains 
or similar devices the distance between which decreases in the direction 
of their movement, and which compress the nuts between them. As soon as 
the shell has yielded, it can be discharged together with the nut. 
As a further development provision may be made for a collector device 
receiving the shelled nuts and the shells or parts of shells to be 
disposed in the release region of the device, for example in the release 
region of the pressing members, and to be connected to a wind separation 
device. This collector device collects the nuts and the shells and guides 
them to the air separator device, which separates the shells from the 
nuts. The air separator device may for example be a horizontally acting 
blower. It is however particularly advantageous for the air separator 
device to have a vertically extending air separator tub which contains an 
upwardly directed current of air and to which the collector device, which 
is provided with a collector funnel, is connected via a tube provided with 
a constriction. It is thus possible to adjust the flow and speed of the 
air current in such a manner that the smaller kernels fall downwards while 
the larger shells are blown or sucked away in the upward direction. 
It is particularly advantageous for an exhaust fan to be connected to the 
air separator tube to produce in the latter the upwardly directed current 
of air. It has been found that with a suction fan it is possible to 
produce a more constant current of air, which will thus lead to more 
uniform results. In addition, the use of a suction fan provides the 
advantage that air is also drawn in through the collector funnel, so that 
the power of the latter can be further increased. Air separation of this 
kind is also suitable for separating other mixtures. 
The shelled nuts fall downwards through the air separator tube. According 
to the invention provision can now be made for the bottom end of the air 
separator tube to lie above a resorting device. With the aid of this 
resorting device the shelled nuts can be graded according to size. 
Furthermore, any nuts which have not been opened can then be fed back to 
the device. 
Sorting devices of the kind used in accordance with the invention are known 
per se. They may for example consist of two contrarotating smooth 
cylindrical rollers, which can for example advantageously be disposed to 
be slightly divergent. Because of the contrarotation of the rollers and 
their inclination in relation to the horizontal, the nuts slide in the 
longitudinal direction on the rollers, while because of the slight 
divergence sorting according to size can be effected. 
It is particularly advantageous for the pressing members to consist of two 
disks which rotate at the same speed and are slightly inclined relative to 
one another, and whose mutually facing surfaces are preferably slightly 
irregularly profiled. The slight irregular profiling serves to grip the 
nuts at their ends. Because of the slight inclination of the two disks, 
the nuts are then subjected to compression acting in the axial direction 
of the disks. The inclination of the two discs can be slightly varied in 
accordance with requirements, the size of the disks, the speed of 
rotation, and so on. It has been found particularly advantageous for the 
axes of rotation of the two disks to enclose with a horizontal plane an 
angle of a few degrees and, with a vertical plane, an angle about twice as 
large. 
According to the invention provision may be made for the position of the 
shortest distance between the two disks to lie, viewed in the direction of 
rotation, downstream of the highest point and upstream of the horizontal 
diameter of the disks, preferably approximately in the region of about 45 
to 60 degrees downstream of the apex. 
According to the invention the feed device may have a rotating belt 
provided with prism-shaped humps extending transversely of its 
longitudinal direction and forming between them compartments, each of 
which will receive a nut lying transversely of the longitudinal direction 
of the belt. Cogged belts of this kind are relatively simple to make and 
result in a good feed device with the aid of which the nuts are aligned 
and delivered at regular intervals of time to the pressing members. When 
rotating pressing disks are used, the nuts are lifted out of the 
compartments by these disks. 
Provision may advantageously be made for the belt to be guided over a 
pulley disposed approximately concentrically to the pressing disks and 
preferably driven conjointly with them. In this way the drive can be made 
particularly simple. It is naturally also possible for the belt to be 
moved at a different speed or also non-concentrically to the pressing 
disks. 
In order to improve the alignment of the nuts, provision may be made for 
the belt to have a vibrating device in the region of the charging end 
remote from the pressing disks. The belt is thus vibrated to improve the 
alignment of the nuts. 
According to the invention provision may be made for the feed device to be 
disposed between a charging point of a presorting device and the pressing 
members. This presorting device can be provided in order to presort the 
nuts according to size. Residues of shells or the like can also be 
separated there. According to the invention a transfer tube, through which 
the nuts slide, may then extend from the charging point of the presorting 
device to the charging point of the feed device. 
In order to make the construction of the belt as simple as possible, 
provision may be made for guide plates to be disposed on both sides of the 
belt. These plates obviously need not be made of metal. 
Provision may be made for stripper members to be disposed in the region of 
the charging point of the belt, in order to ensure uniform distribution of 
the nuts. 
In the transition region between the feed member and the pressing disks 
resiliently mounted guide members may be provided to guide the nuts 
laterally and to hold them particularly in the compartments of the belt 
feed device. The guide members may in particular consist of a plurality of 
vertically movable springloaded slides, which are adapted to move 
independently, but only by a limited distance, in relation to the 
respective neighbouring slide. 
The invention is suitable for opening or shelling various kinds of nuts, 
such as hazelnuts, walnuts, almonds, and the like. It is particularly 
valuable for shelling pistachio nuts, since hitherto these could be 
shelled industrially only with inadequate results.

FIG. 1 first shows a general view in perspective of the device proposed in 
accordance with the invention. The device contains a presorting device 11, 
from which a feed device 12 leads to the two pressing members 13. The 
pressing members 13 and the feed device 12 are driven by a drive means 15 
in the form of an electric motor 14. In the region of the pressing members 
13, or more precisely at their underside, is disposed a collecting funnel 
16, shown in simplified manner, which is connected via a tube 17 to the 
air separator tube 18, shown broken away. The air separator tube 18 
extends vertically and contains, above the pressing members 13, a suction 
fan 19 which draws in air in the direction of the arrow 20. The air is 
then carried off through an outlet pipe 21, the outgoing air also 
containing pistachio nut shells. 
The bottom end 22 of the air separator tube 18 has its mouth directly above 
a resorting device 23, and the pistachio nuts leaving the resorting device 
23 pass onto a conveyor belt 24. Resorting can be effected on this 
conveyor belt. 
The mode of operation of the apparatus according to the invention, which is 
shown in FIG. 1, is as follows. The pistachio nuts are loaded into a 
hopper 25. From the latter they pass via a shaking chute 26 onto the 
presorting device, which is composed of two contrarotating rollers 27. 
With the aid of the presorting device 11 residues of shells or the like 
are removed. It is also possible to provide a plurality of presorting 
devices 11, so that for each device only pistachio nuts of a determined 
size are used. The pistachio nuts slide on the rotating rollers 27 from 
the charging point beneath the shaking chute 26 to their discharge point 
28, from which they pass through a curved tube 29 onto the belt 30 of the 
feed device 12. The belt 30 is driven in the direction of the arrow 31 
(FIG. 2). The pistachio nuts pass through the action of the upwardly 
moving belt 30 between the two pressing members 13, where they are 
compressed and thereby opened. The pistachio nuts together with their 
shells drop into the collector funnel 16 and pass via the tube 17 into the 
air separator tube 18. An upwardly directed current of air acts in the 
tube 18 and carries the shells away in the upward direction, while the 
pistachio nuts fall downwards through the air separator tube 18 onto the 
resorting device 23. The latter likewise consists of two contrarotating 
sorting rollers 27, which are likewise arranged to drop towards front 
right, but are not quite parallel. As soon as the pistachio nut has 
reached a point where the distance between the two sorting rollers 27 of 
the resorting device 23 is greater than the size of the pistachio nut, it 
falls downwards and then passes via a chute 32 or directly onto the 
conveyor belt 24. If an occasional unopened pistachio nut falls out of the 
tube 18, it will leave the resorting device 23 at its free end 33, where 
it can pass into a special vessel and then can be returned to the hopper 
25. 
In FIG. 2, which shows the device of FIG. 1 viewed from front right, it can 
be seen that the sorting rollers 27 of the resorting device 23 extend with 
a slight drop and slight divergence. They rotate in the direction of the 
arrows 34. The pistachio nuts therefore slide from the free end 22 of the 
air separator 18 in the direction of the free end 33 of the resorting 
device 23. 
The air separator tube 18 extends vertically. The suction fan 19 disposed 
above the pressing members 13 is driven by a motor 35. The tube 17 between 
the collector funnel 16 and the air separator tube 18 has a diameter 
considerably smaller than that of the air separator tube 18, and its last 
portion extends obliquely downwards in a straight line. The collector 
funnel 16 is constructed in such a manner that it reaches as close as 
possible to the pressing members 13, so that the air current provided by 
the fan 19 also produces suction through the funnel 16 and the tube 17. 
The upper portion of the belt 30, approaching the pressing elements 13, 
extends in the upward direction at an angle of about 24 degrees to the 
horizontal. 
The presorting device 11, which likewise comprises two contrarotating 
sorting rollers 27, extends downwards from its charging end to its 
discharge point 28, so that the pistachio nuts slide along the rollers 27. 
The two rollers 27 are driven in opposite directions with the aid of a 
motor 36. 
The shaking chute 26 disposed under the funnel 25 is vibrated with the aid 
of a drive 37. 
FIG. 3 shows once again the resorting device 23, which is disposed under 
the air separator tube 18. The chute 32 is disposed beneath the sorting 
rollers 27, its outlet 38 lying in the region of the left-hand half of the 
conveyor belt 24. This results in a certain coarse sorting of the 
pistachio nuts into large and small nuts, the larger ones arriving in the 
region of the right-hand half of the conveyor belt 24. Any unopened 
pistachio nuts pass into a vessel 40 via a short chute 39. 
Details of the pressing members 13 can be seen in FIGS. 4 and 5. From FIG. 
5 it can be seen that the two pressing members are in the form of pressing 
disks 41, which extend slightly obliquely in relation to one another. A 
pulley 42 is mounted concentrically to the pressing disks 41 and is 
likewise driven by the motor 14. It turns at the same speed as the 
pressing disks 41. The pulley has a smaller diameter than the two pressing 
disks 41, its diameter amounting to about 55% of that of the pressing 
disks 41. The belt 30 extends around the pulley 42 and is guided over a 
second ond, freewheeling pulley 43. The charging point of the feed device 
constituted by the belt 30 lies approximately on the upper side of the 
second, undriven pulley 43. The mouth of the transfer tube 29 coming from 
the presorting device lies at that point. Immediately downstream of the 
undriven pulley 43, referring to the direction of movement, is disposed a 
vibration device 45, which vibrates the belt 30. A guide plate 46 is 
disposed on each side of the belt 30 in its portion 30a which serves to 
convey the pistachio nuts. The guide plates 46 prevent the pistachio nuts 
from slipping off the sides of the belt 30, so that a simpler belt can be 
used. The humps 47 which are provided on the outer side of the belt, and 
which are approximately trapeziform in shape, bound between them 
compartments 48, which are likewise approximately trapeziform and in which 
the pistachio nuts lie. 
In the region above the driven pulley 42 a total of six guide members 49 
are disposed between the pressing disks 41, with their lower faces lying 
approximately above the upper face of the humps 47 in the unloaded state. 
The guide members are disposed substantially to the right of a vertical 
line extending through the axis 50 of the pulley 42. They are slidable in 
the vertical direction, for example by means of plates disposed in front 
of and behind the plane of the drawing. Each of them is guided with the 
aid of a pin 51 fastened on the guide member 49 and extending through a 
crossbar 52. Above the crossbar 52 each pin has a widened portion, for 
example a nut 53. Beneath the crossbar 52 a spring 54 is disposed around 
each pin 51 and is supported on the upper face of the guide members 49. 
The guide members 49 serve to hold the pistachio nuts in the respective 
compartments 48 on the belt 30 until they are gripped sufficiently firmly 
by the converging pressing disks 41 to prevent any possibility of the nuts 
being released. 
In FIG. 5 it can be seen that the two pressing disks 41 converge slightly 
in the upward direction, and in FIG. 6 it can be seen that they also 
converge slightly in the forward direction. The two disks are mounted in 
bearings 55 fastened on a common baseplate 56. The electric motor 14, 
whose output shaft 57 turns in the direction of the arrow 58, is also 
fastened on the baseplate 56. A slightly flexible coupling of an ordinary 
commercially available type is interposed between the output shaft 57 and 
the pressing disk 41. A flexible coupling of this type is also disposed 
between the pressing disk on the right in FIG. 5 and the pulley 42, and 
also between the pulley 42 and the pressing disk 41 on the left in FIG. 5. 
A rotatably mounted rubber roller 81 acts on the outer periphery of the two 
pressing disks 41. The the axis of rotation of the rubber roller 81 
extends approximately parallel to the axis of rotation of the two pressing 
disks. The rubber roller 81 is disposed in such a manner that it acts with 
a certain force on the outer periphery of the pressing disks 41. The play 
of the two disks in the direction of rotation, resulting from the flexible 
coupling, can be reduced or in certain circumstances even completely 
eliminated by the rubber roller 81. This arrangement is particularly 
expedient when a plurality of such pressing units 13 are disposed side by 
side and driven by the same motor 14. In this case the rotational play is 
cumulative. The arrangement of a plurality of pressing units driven by a 
common motor is nevertheless particularly expedient. 
FIG. 6 shows on the right a plan view of the outlet end of the presorting 
device 11. The two rollers 27, which turn in the direction of the arrows 
59, are mounted in bearings 60. One of the two rollers 27 has an end 61 of 
smaller diameter, so that a gap is formed there. The pistachio nuts fall 
through this gap into the upper end of the transfer tube 29, from where 
they pass onto the upper face of the belt 30. 
Between the belt and each of the guide plates 46 is disposed a respective 
guide rail 62, these guide rails extending in the longitudinal direction 
of the belt 30 and being riveted to the guide plates 46. At their front 
end, directed towards the pressing disks 41, they are extended in the form 
of parts 63 of plastic material, which lie between the disks 41 and the 
belt 30, being pressed against the latter. The vibration of the belt 30 is 
thus reduced in this region. 
As can be seen from FIG. 4, the guide rails 62 are inclined upwards to a 
slightly greater extent than the belt 30, so that just in front of the 
pressing disks 41 they lie at a higher level than the floor of the 
compartments 48, on both sides of the belt 30. 
FIG. 7 shows on a larger scale details of the belt 30, guide plates 46 and 
guide rails 62. The belt 30 is provided on its upper face with the humps 
47, which are approximately trapeziform in cross-section. The shorter side 
69 of the trapezium is in each case directed upwards. Compartments 48, 
which are likewise trapeziform, are thus formed between the humps 47. The 
guide rails 62 are disposed on both sides of the belt 30, with their top 
edges 83 approximately flush with the bottom surfaces 64 of the 
compartments 48 in this region. The guide rails 62 are interrupted in the 
region of the charging point 44 and replaced with a channel 65, which 
embraces the belt in its region free from humps and which is connected to 
the vibration device 45. At this point the belt 30 is set in vibration. On 
the right-hand side, referring to the direction of movement of the belt 
30, a stripper member 66 is disposed; this member has a slowly rising ramp 
67 followed by a region 68 extending parallel to the belt 30. The parallel 
region 68 is at the same height as the upper face 69 of the humps 47. 
A second stripper member 70 of asymmetrical construction in relation to the 
first stripper member 66 is disposed opposite the latter. It has a rising 
ramp 71 followed by a descending ramp 72. The apex 73 formed between the 
ramps 71 and 72 is at a higher level than the upper face 69 of the humps 
47. The cooperation of the two stripper members ensures that only one 
pistachio nut will lie in the compartments between each two humps 47. If 
more than one pistachio nut should lie in one compartment, they will be 
raised on one side and the upper nut will be forced off to the rear, that 
is to say to the right in FIG. 7. 
FIG. 8 now shows on a larger scale the guide members 49 which have already 
been seen in FIG. 4. The belt 30 moves in the direction of the arrow 74. 
Each guide member 49 can be lifted against the action of the springs 54. 
With the exception of the guide member in the extreme left-hand position 
in FIG. 8, each guide member 49 is provided with a pin 75 which engages in 
a longitudinal slot 76 in the respective guide member 49 in the 
neighbouring position on the left. If therefore a guide member 49 should 
be raised by an incorrectly disposed pistachio nut, or one that is too 
large, after it has been raised a determined distance the next guide 
member on its left, that is to say lying next to it in the direction of 
movement of the belt 30, will also be raised. Each pistachio nut is guided 
by these guide members until it is sufficiently firmly clamped between the 
two pressing plates 41 to prevent it from escaping to one side as the 
compression proceeds. 
The mode of operation of the device is as follows. The pistachio nuts lying 
in the compartments between the humps 47 are aligned transversely of the 
longitudinal direction of the belt 30, that is to say the longitudinal 
direction of the pistachio nuts extends across the belt 30. The nuts now 
come between the two pressing disks 41. The farther they move on the belt 
30 between the two pressing disks 41, the shorter the distance between the 
pressing disks will become, since the narrowest space between them lies 
approximately at the mark 77 in the form of a broken line in FIG. 4. As 
soon as the pistachio nuts have reached a position where the distance 
between the two pressing disks is somewhat shorter than their longitudinal 
dimension, they are gripped by the pressing disks and lifted obliquely out 
of the compartments 48 on the belt 30. They then move on the path of a 
circular arc, along which path the two regions of the pressing disks 
holding the ends of the pistachio nuts become increasingly close to one 
another. At some point the compression is then sufficient to burst the 
shell open. No further conmpression then occurs, because the pressing 
disks approach one another purely geometrically and without momentum. 
After the shell has been broken the pistachio nut is thus free of any 
action of a force, and under its own weight it can fall into the collector 
funnel 16. If the shell is broken in a region in which it will still fall 
onto the belt 30, this is not detrimental because shells and shelled nuts 
can also be conveyed by the belt. 
FIG. 10 shows, in a section through the belt 30, a pistachio nut 78 drawn 
in broken lines. This nut lies in a compartment 48 between two humps 47, 
and is guided on the right and the left by the two guide plates 46 and at 
the top by the guide member 49. Consequently, it cannot escape and in this 
way is conveyed, correctly aligned, between the pressing disks 41. 
FIG. 9 shows a slightly modified form of construction of the pressing disks 
41. Whereas the pressing disks 41 shown in FIGS. 5 and 6 have plane 
surfaces 79 facing one another, the pressing surfaces 80 of the pressing 
disks 41 are here slightly conical. It is therefore possible for the 
minimum distance between the pressing surfaces 80 lying opposite one 
another to be identical at all points in the narrowest part, irrespective 
of the radius. It is naturally also possible to ensure that the minimum 
distance between the pressing surfaces of the pressing disks 41 will be 
greater at the outer edge than in the direction of the centre of the 
disks. With the arrangement of the feed device shown in FIG. 4, it is 
obviously sufficient for the pressing surfaces 80 to be made conical. 
In one example of embodiment the pressing disks 41 have a diameter of 18 
centimeters, the pulley 42 has a diameter of 10 centimeters, the width of 
the belt is 13 millimeters, and the pressing disks rotate at a speed 
between 17 and 85 revolutions per minute. If it is assumed that the 
operation of compressing the pistachio nut extends over an angular region 
of about one fourth of a revolution before the shell of the nut yields, 
this would mean, at the maximum speed of rotation indicated, a compression 
time of about one sixth of a second. The compression process accordingly 
takes place substantially more slowly than in the case of shelling by 
means of a blow.