Process and apparatus for producing filled wafer blocks

In a process in which cover sheets and/or coated wafer sheets are joined to form filled wafer blocks, each coated wafer sheet and, if desired, each cover sheet is moved in a stacking location from a lower position to an overlying upper position, the coated upper surface of each coated wafer sheet is joined to the underside of the cover sheet which is in the upper position and which, if desired, has previously been raised to the upper position, or to the underside of the coated wafer sheet which has previously been raised to the upper position, and each complete wafer block consisting of at least two sheets is moved from said upper position out of said stacking location. To increase the production rate, it is proposed that the successive coated wafer sheets for each wafer block or successive coated wafer sheets and cover sheets disposed between successive coated wafer sheets are successively and continuously fed one by one to the lower position in the stacking location, and at least part of the movement of each of said sheets to said lower position is performed while the next preceding sheet is being raised. It is also proposed to carry out the process by means of two helical conveyors, which have parallel axes of rotation, which are inclined from a normal on the plane of conveyance of the wafer sheet feeder and each of which has a lower convolution, an upper convolution, and an inclined step joining said upper and lower convolutions.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to the production of filled wafer blocks in a 
process in which cover sheets, such as uncoated wafer sheets, and/or wafer 
sheets coated on their upper surface with a spreadable composition, such 
as a cream, are joined, wherein the top of each coated wafer sheet is 
contacted with the underside of the cover sheet or of another coated wafer 
sheet. 
2. Description of the Prior Art 
In the industrial production of filled wafer sheets it is known to insert 
successive coated wafer blocks in a lower position into two non-moving 
helical conveyors, which are rotatable in opposite senses about parallel 
axes, then to move said helical conveyors so that they raise the coated 
wafer sheet until it has been joined to the underside of a cover sheet or 
a coated wafer sheet which is in an upper position, whereafter the helical 
conveyors are arrested and the next coated wafer sheet is inserted in the 
lower position into the helical conveyors while they are not moving. When 
the helical conveyors are then started again, the wafer sheet in the lower 
position is raised and joined to the underside of the preceding coated 
wafer sheet, and the helical conveyors are then arrested again. 
During the rotation of the helical conveyors, each coated wafer sheet which 
is being raised from the lower position to the upper position and the 
partial wafer block which is in the upper position are urged by the 
helical conveyors against a stop. When coated wafer sheets in the number 
required for the desired wafer block have been joined to the cover sheet, 
the stop is lowered and the rotation of the helical conveyors is resumed 
so that the complete wafer block is removed from the upper position. The 
stop is subsequently raised to its initial position. The formation of the 
next wafer block is not initiated until the stop has returned to its 
initial position and the helical conveyors have been arrested after the 
wafer block has been removed. 
That known process of producing wafer blocks restricts the production rate. 
SUMMARY OF THE INVENTION 
It is an object of the invention to permit the production of wafer blocks 
at a higher rate. 
For this purpose, the invention proposes a process of producing wafer 
blocks in which cover sheets, such as uncoated wafer sheets, and/or wafer 
sheets coated on their upper surface with a spreadable composition, such 
as a cream, are joined, wherein each coated wafer sheet and, if desired, 
each cover sheet is moved in a stacking location from a lower position to 
an overlying upper position, the coated upper surface of each coated wafer 
sheet is joined to the underside of the cover sheet which is in the upper 
position and which, if desired, has previously been raised to the upper 
position, or to the underside of the coated wafer sheet which has 
previously been raised to the upper position, and each complete wafer 
block consisting of at least two sheets is moved from the upper position 
out of the stacking location. Successive coated wafer sheets for each 
wafer block or successive coated wafer sheets and cover sheets disposed 
between successive coated wafer sheets are successively and continuously 
fed one by one to the lower position in the stacking location, and at 
least part of the movement of each sheet to said lower position is 
performed while the next preceding sheet is being raised. Because the 
individual sheets are no longer fed intermittently, the process permits a 
much higher production rate. 
In a process in which the cover sheets are directly fed one by one to the 
upper position independently of the coated wafer sheets, it is proposed in 
accordance with the invention to feed the cover sheet for each wafer block 
to the upper position while the coated wafer sheet which is to be joined 
to the underside of said cover sheet is being fed to the lower position 
and/or is being raised. That practice permits an overlap in time between 
the feeding of the cover sheet and of the feeding of the coated wafer 
sheet to the lower position and permits also a feeding of the cover sheet 
as the coated wafer sheet is raised so that the production rate can be 
further increased. 
The process in accordance with the invention may also be carried out in 
such a manner that each complete wafer block in the upper position is 
discharged from the stacking location while the coated wafer sheet which 
is to be joined to the underside of the cover sheet of the next succeeding 
wafer block is being fed to the lower position and/or raised. That 
practice will eliminate the need for discharging the wafer block in a 
separate step in the known process. In accordance with the invention, the 
process steps comprising the discharge of the wafer block, the feeding of 
the cover sheet for the next succeeding wafer block and the feeding and/or 
raising of the wafer sheet which is to be joined to the underside of the 
cover sheet of the next succeeding wafer block may overlap each other in 
time in such a manner that these process steps can be performed in the 
time which is required to feed and raise one coated wafer sheet. As a 
result, the formation of the next succeeding wafer block can begin before 
the next preceding wafer block has been removed. 
In a process in which the cover sheets and the coated wafer sheets are one 
by one fed to the lower position, it is proposed in accordance with the 
invention to discharge each complete wafer block from the upper position 
out of the stacking location while the cover sheet for the next succeeding 
wafer block is being fed to the lower position and/or raised. In that 
practice, all sheets for a wafer block can be continuously fed one by one 
to the lower position and the formation of the next succeeding wafer block 
can begin before the next preceding wafer block has been removed from the 
upper position. 
For carrying out the process in accordance with the invention in such a 
manner that the cover sheets are directly fed to the upper position 
separately from the coated wafer sheets, an apparatus is proposed which 
comprises a cover sheet feeder and a wafer sheet feeder, which is operable 
to feed coated wafer sheets one by one to the lower position in the 
stacking location in a predetermined feeding direction on a predetermined 
plane of conveyance, two helical conveyors, which are spaced apart 
transversely to the feeding direction and adapted to rotate in mutually 
opposite senses about parallel axes of rotation, the cover sheet feeder 
and the wafer sheet feeder having delivery ends disposed adjacent to both 
the helical conveyors on one side thereof, a wafer block discharge 
conveyor having a receiving end disposed adjacent to both helical 
conveyors on the opposite side thereof, and a stop, which is adapted to be 
raised and lowered into and out of the path of wafer blocks moving from 
the upper position on the helical conveyors to the receiving end. Each 
helical conveyor has a lower convolution, which is preferably adapted to 
receive coated wafer sheets from the plane of conveyance, and which is 
joined by an inclined step to an upper convolution, which is preferably 
adapted to receive cover sheets from the cover sheet feeder and to deliver 
wafer blocks to the wafer block discharge conveyor. 
For carrying out the process in accordance with the invention in such a 
manner that the cover sheets and the coated wafer sheets are fed to the 
lower position, an apparatus is proposed which comprises a sheet feeder, 
which is operable to feed sheets for the wafer blocks one by one to the 
lower position in the stacking location in a predetermined feeding 
direction on a predetermined plane of conveyance, two helical conveyors, 
which are spaced apart and adapted to rotate in mutually opposite senses 
about parallel axes of rotation, the sheet feeder having a delivery end 
disposed adjacent to both helical conveyors on one side thereof, a wafer 
block discharge conveyor having a receiving end disposed adjacent to both 
helical conveyors on the opposite side thereof, and a stop, which is 
adapted to be raised and lowered into and out of the path of wafer blocks 
moving from the upper position on the helical conveyors to the receiving 
end. Each helical conveyor has a lower convolution, which is preferably 
adapted to receive sheets from the plane of conveyance and which is joined 
by an inclined step to an upper convolution, which is preferably adapted 
to deliver wafer blocks to the wafer block discharge conveyor. By means of 
the inclined steps the helical conveyors can pull each sheet entirely to 
the lower position and can raise each sheet out of the lower position at 
such an early time that the next succeeding sheet cannot be inserted too 
soon into the lower position and cannot impinge on a convolution of a 
helical conveyor. The step will prevent an insertion of two successive 
sheets onto the same convolution. 
If each helical conveyor comprises only two convolutions, these two 
convolutions are separated by the step. If each helical conveyor comprises 
more than two convolutions, the step is provided between the lowermost 
convolution and the next upper convolution. 
For carrying out the process in accordance with the invention, the 
invention proposes also apparatus comprising a sheet feeder, which is 
operable to feed sheets for the wafer blocks one by one to the lower 
position in the stacking location in a predetermined feeding direction on 
a predetermined plane of conveyance, two helical conveyors, which are 
spaced apart transversely to the feeding direction and adapted to rotate 
in mutually opposite senses about parallel axes of rotation, the sheet 
feeder having a delivery end disposed adjacent to both helical conveyors 
on one side thereof, a wafer block discharge conveyor having a receiving 
end disposed adjacent to both helical conveyors on the opposite side 
thereof, and a stop, which is adapted to be raised and lowered into and 
out of the path of wafer blocks moving from the upper position on the 
helical conveyors to the receiving end. The axes of rotation of the 
helical conveyors define a plane which is inclined in the feeding 
direction from a normal on the plane of conveyance, and each helical 
conveyor has a lower convolution, which is preferably adapted to receive 
sheets from the plane of conveyance and which is joined by an inclined 
step to an upper convolution, which is preferably adapted to deliver wafer 
blocks to the wafer block discharge conveyor. 
Within the scope of the invention the plane defined by the axes of rotation 
of the helical conveyors has an inclination of 3 to 45 degrees, preferably 
of 5 to 15 degrees, from the normal on the plane of conveyance of the 
sheet feeder. 
In accordance with a further feature of the invention the plane of 
conveyance of the wafer block discharge conveyor is downwardly offset from 
the plane of conveyance of the sheet feeder. 
According to a further feature of the invention, each helical conveyor 
comprises helical wire flights, which have two consecutive convolutions, 
offset from each other in the direction of the axis of rotation of the 
helical conveyor and joined by the inclined step.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The invention will now be described more in detail with reference to the 
drawings, which show illustrative embodiments of apparatus in accordance 
with the invention. 
With reference to FIG. 1, a frame 1 incorporates a wafer sheet feeder 2, 
which preferably consists of a belt conveyor and has a delivery end 
disposed adjacent to two helical conveyors 3, 3' on one side thereof. 
Helical conveyors 3, 3' are spaced apart transversely to the feeding 
direction of the wafer sheet feeder 2. A cover sheet feeder 4 is disposed 
above the wafer sheet feeder 2 and has a delivery end disposed adjacent to 
both helical conveyors 3', 3 on the same side thereof as wafer sheet 
feeder 2. The two helical conveyors 3, 3' rotate in mutually opposite 
senses. Each helical conveyor 3, 3' has helical wire flights, which rise 
opposite to the sense of rotation of the helical conveyor. The helical 
wire flights of each helical conveyor are secured by a crosspiece 5 or 5' 
to one end of a drive shaft 6, which protrudes from an angle drive 7, 
mounted on the frame 1 and to which a drive motor 8 is flanged. Each angle 
gear is secured to a mounting plate 10, which is inclined from the plane 
of conveyance of the wafer sheet feeder 2 and is connected to the frame 1 
by posts 9. 
Each of the helical flights of the helical conveyors 3, 3' comprises a 
lower convolution 11 or 11', which is joined by an inclined step 12, 12' 
to an upper convolution 13 or 13', which has a free end 14, 14' that is 
disposed above the step 12 or 12' and before the same. The two lower 
convolutions 11, 11' of the two helical conveyors 3, 3' are adapted to 
receive coated wafer sheets from the plane of conveyance of the wafer 
sheet feeder 2. The two upper convolutions 13, 13' of the two helical 
conveyors 3, 3' are adapted to receive cover sheets from the cover sheet 
feeder 4. A stop 15, which is adapted to be lowered and extends 
transversely to the feeding direction, is disposed close to the two 
helical conveyors 3, 3' on that side thereof which is opposite to the 
wafer sheet feeder 2 and the cover sheet feeder 4. That stop 15 is 
succeeded by a wafer block discharge conveyor 16, preferably a belt 
conveyor, which has a plane of conveyance below the plane of conveyance of 
the wafer sheet feeder 2 and is adapted to receive wafer blocks from the 
upper convolutions 13, 13' of the two helical conveyors 3, 3'. The stop 15 
is disposed in the path of the wafer blocks moving from the upper 
convolutions 13, 13' to the wafer block discharge conveyor 16. 
FIG. 1 shows only one of the helical conveyors 3, 3', the axes of rotation 
of which extend in a plane which is inclined in the feeding direction of 
the wafer sheet feeder 2 from a normal on the plane of conveyance of wafer 
sheet feeder 2. 
FIG. 2 shows the helical flights of two helical conveyors 3, 3' which have 
axes of rotation which are at right angles to the plane of conveyance of 
the wafer sheet feeder, which is not shown. The upper convolutions 13, 13' 
of the two helical conveyors 3, 3' are provided on their upper side with 
bosses 17, 17' in order to increase the friction. 
In order to produce wafer blocks, wafer sheets which are coated on their 
upper side, preferably with cream, are continuously fed one by one by the 
wafer sheet feeder 2 to the helical conveyors 3, 3', which are provided at 
the stacking location. Each wafer sheet is inserted between the two 
helical conveyors 3, 3' and received by the lower convolutions 11, 11' 
thereof and is raised by the rotating conveyors 3, 3' as the two steps 12, 
12' move under the wafer sheet and pull it into the helical conveyors so 
that the next succeeding wafer sheet is received on the lower convolutions 
11, 11' behind the two steps while the next preceding wafer sheet is 
raised until it lies on the upper convolutions 13, 13'. As that wafer 
sheet is raised, its coated upper surface is joined to the underside of a 
cover sheet or coated wafer sheet which lies already on the upper 
convolutions 13, 13'. That process step is terminated when the two helical 
conveyors 3, 3' have been rotated through 180 degrees (from the positions 
shown). If the thus joined coated wafer sheet was the last (lowermost) 
sheet of a wafer block, the stop 15 is lowered and the complete wafer 
block is transferred to the wafer block discharge conveyor 16 as the two 
helical conveyors 3, 3' rotate through additional 180 degrees. The stop 15 
is then raised and thereafter a cover sheet is fed by the cover sheet 
feeder 4 directly onto the upper convolutions 13, 13' of the two helical 
conveyors. During the next rotation of the two helical conveyors 3, 3' 
through 180 degrees, the first (uppermost) coated wafer sheet for the next 
wafer block is raised by the steps 12, 12' and is joined to the cover 
sheet from below while the second coated wafer sheet for that wafer block 
is being received by the lower convolutions 11, 11' in the lower position. 
If the wafer sheets fed by the wafer sheet feeder 2 abut at their adjacent 
end edges, a reliable separation of successive wafer sheets can be ensured 
if each wafer sheet is pulled in by the two helical conveyors 3, 3' 
somewhat faster than it is fed by the wafer sheet feeder 2. If the cover 
sheets are also fed by the wafer sheet feeder rather than by the cover 
sheet feeder 4, the cover sheet for the next wafer block is supplied to 
the lower convolutions of the helical conveyors 3, 3' while the last 
(lowermost) coated wafer sheet of the preceding wafer block is raised to 
the upper position on the upper convolutions. 
The invention permits the operations of the helical conveyors 3, 3' and of 
the wafer sheet feeder 2 to be synchronized so that the helical conveyors 
3, 3' can rotate continuously and can produce more wafer blocks per unit 
of time.