Baling press with bale binding device and operation thereof

A baling press of the kind comprising a pressing channel containing a reciprocating pressing plunger has a bale binding device which binds the bales with bands each consisting of two separate lengths of wire from different rolls twisted together. The binding device includes a twisting mechanism for twisting the wires together and this twisting device comprises a disc which is rotatable about an axis situated in the plane of the binding and this disc has a single finger which projects outwards from the axis of rotation of the disc and is forwardly curved in the direction of rotation of the disc in order to seize the two wires and twist them together. The inner edge of the finger leads into a slit which extends through the disc up to the center of rotation of the disc and this slit tapers in a region adjacent the center of rotation of the disc to a width which only just exceeds the thickness of one wire. The binding device is operated in such a way that during the last turn of the disc at the end of a twisting operation, a needle which draws a loop from one of the wires is moved towards the disc so that the subsequent rotation of the disc at the end of its last turn swings the loop out of the path of the needle before the disc is brought to a standstill.

This invention relates to baling presses comprising a pressing channel, 
means for feeding material to be baled to the channel, a pressing plunger 
which is reciprocable in the channel to form a succession of pressed bales 
in the channel and a device for binding the bales formed in the channel. 
It is particularly concerned with such presses in which the binding device 
comprises holders for holding two separate rolls of binding wire, a 
twisting mechanism for connecting the wires to each other, a binding 
needle, means for moving the needle across the channel to form a loop of 
one wire in a position in which, in use, the first wire, together with the 
second wire, forms a band surrounding a bale in the pressing channel, and 
a cutting device which, in use, cuts the wires in between two positions in 
which they are connected together by the twisting mechanism. The invention 
also relates to methods of operating the binding devices of such presses. 
The above-described form of binding device, which is disclosed in German 
Offenlegungsschrift No. 2,253,160 comprises, for twisting the wires, a 
disc, which operates with two fingers projecting from the disc 
approximately radially for the purpose of pulling in the wires to be 
twisted together. The wires are held under tension adjacent to the disc at 
a specific distance from each other and from the disc. The fingers are of 
different lengths and the shorter finger, which is in front of the other 
finger in the direction of rotation of the disc, has the function of 
seizing the wire nearest to the disc, and the longer finger has the 
function of seizing the wire furthest from the disc and of conducting both 
the wires into associated slits in the disc. Of the two wires to be 
twisted together, the wire associated with the shorter finger comes 
directly from a storage roll situated on the side of the channel adjacent 
the twisting device, whereas the wire which is seized by the longer finger 
is brought as a loop by the binding needle from a storage roll situated on 
the opposite side of the channel. 
During the forming of the loop by means of the binding needle, it is 
absolutely essential for the disc carrying the fingers to be stationary in 
the position shown in FIG. 3 of the drawings of the Offenlegungsschrift. 
This is necessary to prevent a collision with the binding needle and/or 
the wires to be twisted. Therefore, the disc must, after the previous 
twisting operation has been completed, be stopped in a position which must 
be maintained very accurately. This can only be achieved if an electric 
motor driving the disc is stopped by cam discs and/or by limit switches in 
dependence upon the number of revolutions executed by the disc, or by a 
timing relay. This is, however, technically very difficult, since braking 
devices are subjected to wear and then operate inaccurately and timing 
relays also have too large a switching tolerance for the present case, so 
that the range of stopping positions of the disc is too great. In practice 
in operating of this known form of binding device, therefore, it 
frequently occurs that, after a twisting operation has been completed, one 
of the fingers, usually the shorter finger, stops in the critical 
collision region, so that the length of wire associated with this finger 
is then drawn by means of the binding needle along the back of this finger 
which has already rotated too far. The consequence of this is that the 
wire associated with the shorter finger is subsequently seized not by this 
finger, but is seized together with the other wire by the longer finger. 
From FIG. 3 of the drawings of Offenlegungsschrift No. 2,253,160 it can be 
seen that the slits in the disc which receive the wires are considerably 
wider than the thickness of the wires. Indeed this is to be expected in 
view of the manner in which the device operates. As a result, it can occur 
in the above-described, undesired operating condition, that the two wires 
which have both entered the same slit in the disc are not twisted together 
because they cannot be held firmly in the slit, but simply turn in the 
slit as the disc rotates without appreciably changing their relative 
positions. Since the discs of a number of binding devices for forming a 
number of bindings side by side round the bale are driven synchronously, 
this disadvantage arises equally in all the planes of all the bindings, so 
that an effectively unbound and thus useless bale is produced. This must 
be removed from the press with considerable loss of time and output. The 
above-described disadvantage can also occur with the known binding device 
if the wires to be seized by the fingers, due to distortions in the wires 
produced by residual strains in the wires do not adopt exactly the 
positions required by the construction of the baling press and binding 
device. 
Further disadvantages of the known device arise from the fact that the 
twisting together of the two wires cannot take place at the centre of the 
disc, since the wires are held apart from one another in the two different 
slits in the disc and only converge on both sides of the disc. This has 
the disadvantage that the twisting commences, not simultaneously along the 
entire length of the wires to be twisted together, but initially at the 
positions furthest from the disc. Starting from these positions, a very 
flat, loose twist is initially produced. The twist then becomes steeper 
and tighter towards the disc, because the angles which the wires make with 
the surface of the disc become more acute the closer the twist approaches 
the disc. During the last third of the twisting operation, the twist as it 
approaches the disc thus changes into a torsional movement of the wires 
which does not move along the length of the wires. Such a torsional 
loading frequently exceeds the strength limits of the wire, so that wire 
breakages near to the disc are not infrequent either during the twisting 
operation or during the subsequent transporting of the bale. 
The prising apart of the wires in the region of the disc also has an 
undesirable aspect in that it causes the wire ends to project from the 
twist positions on the finished, bound bales, and this leads to an 
increased risk of injury of persons handling the bales. 
In presses in which the known device operates with a binding needle which 
draws the wire loop upwards from below, the mode of operation according to 
which the wire loop is held in the binding needle until after twisting and 
cutting of the wire between the twist positions and is only then removed 
from the binding needle, is moreover complicated and not reliable. This is 
mainly because the binding needle, after the twisting together and cutting 
of the wire between the twist positions, is lowered until the wire loop is 
situated above the barb or hook of the needle and is then removed from the 
binding needle by the forward movement of the next bale being formed in 
the channel so that the binding needle cannot be withdrawn until after the 
next bale has been partly formed by a few strokes of the pressing plunger. 
Here again it can happen that the wire loop is not released from the hook 
of the binding needle due to distortion of the wire, with the result that 
as the pressing operation of the next bale proceeds bending of the needle 
can occur. 
The aim of the present invention is to provide a binding device in a baling 
press as described above and also to provide a method of operating the 
device, which do not suffer from the aforementioned disadvantages and are 
distinguished by a considerably simpler construction and more reliable 
mode of operation than the device disclosed in the above-mentioned 
Offenlegungsschrift. 
To this end, according to this invention, in such a baling press provided 
with a binding device as described above, the twisting device comprises a 
disc which is rotatable about an axis situated in the plane of the 
binding, the disc being arranged to seize and twist the wires together as 
the disc rotates and, for seizing the wires, having a single finger which 
projects outwards from the axis of rotation of the disc and is forwardly 
curved in the direction of rotation of the disc, the inner edge of the 
finger leading to a slit which extends through the disc up to the centre 
of rotation thereof, the slit tapering in a region adjacent the centre of 
rotation to a width which only just exceeds the thickness of one wire. 
Owing to the provision of only a single finger on the disc, the range of 
angular positions in which the disc may be stopped at the end of a 
twisting operation is increased from about 30.degree. in the known device 
to about 180.degree. in the device in accordance with the invention, so 
that the disadvantages previously explained in connection with the 
stopping position for the known device are reliably avoided. A precisely 
defined distance between the two wires to be twisted together is also no 
longer necessary, so that this cause of trouble is also removed. Owing to 
the wires being held close together during the twisting operation at the 
centre of the disc, a twisted connection is produced having a largely 
uniform pitch and thus a constant strength throughout the length of the 
connection. Moreover, the wires lie closely together at the position of 
subsequent cutting, thus considerably reducing the risk of injury to 
persons handling the bound bales. 
The invention also consists, according to another of its aspects in a 
method of operating the binding device of a baling press in accordance 
with the invention in order to move the loop of the one wire out of the 
needle, wherein the needle during the last turn of the disc at the end of 
a twisting operation is moved towards the disc and the subsequent rotation 
of the disc swings the loop out of the path of the needle, after which the 
disc is brought to a standstill.

The baling press comprises a pressing plunger 2, which is operated by a 
drive not shown, and reciprocates in a pressing channel 1 of rectangular 
cross-section. When the pressing plunger is retracted, material to be 
pressed into bales is supplied to the channel 1 through a filler shaft 3 
which leads from above. Several working strokes of the plunger are 
necessary for producing each bale. In the pressing channel 1 as shown in 
FIG. 1, there are already three pressed bales 4 of waste paper, of which 
the central and right-hand bales have already been bound with wire, while 
the left-hand bale is just about to be bound. From a lower storage reel 5, 
a first wire 6 passes beneath the pressing channel 1 via a guide roller 7 
and around a forward end face 8 of the bale just about to be bound and is 
connected at the upper face of this bale, at a twist connection 9a, the 
formation of which will be described in more detail below, to a second 
wire 10, which is drawn from an upper storage reel 11. A binding needle 
12, which is reciprocable up and down along its longitudinal axis and has 
a hook 13 (FIG. 7), is moved at the desired instant transversely through 
the pressing channel 1 and through a groove 2a formed in the front face of 
the pressing plunger 2, and lifts from the lower wire 6 a wire loop 6a, 6b 
above the top of the pressing channel, so that the length of wire 6a which 
forms a closure length of the bale binding is situated closely adjacent 
the upper wire 10, which is held taut vertically between two guide rollers 
14, 15. A twisting and cutting device 16 is mounted on the top of the 
channel 1. In the twisting and cutting device, a disc 17 which serves to 
seize and twist together the wires 6a and 10, is mounted so that it is 
rotatable about a vertical axis on a housing 18 and is driven by means of 
a motor 19 through gearing in the housing 18. 
As shown in FIG. 2, the disc 17 has a single finger 20, which projects 
laterally beyond the disc circumference which is of a diameter D and is 
curved in the direction of rotation L of the disc in order to seize the 
stretched wires 6a and 10. An inner edge 21 of the finger 20 leads into a 
slit 22, which continues as far as the centre of rotation Z of the disc 
17. The slit 22 has adjacent the centre of the disc 17, a width b, which 
is only slightly larger than the thickness d of either one of the wires to 
be twisted together, so that the wires 6a and 10 are held firmly against 
rotation in the slit 22 of the disc 17 during the twisting operation. The 
shape of the operative edge 21 of the finger 20 and of a guide surface 23 
of a stationary plate 24 associated with the finger are such that these 
two edges form an angle of approximately 90.degree. as they pass over one 
another. As a result, jamming of the wires between the relatively moving 
surfaces during the pulling in of the wire is prevented. 
The above-described device operates as follows: 
When, as shown in FIG. 3, the left-hand bale 4 has just been pressed, the 
pressing plunger 2 is in the right-hand limiting position, so that the 
groove 2a formed in the front face of the pressing plunger is in alignment 
with the binding needle 12. In the stage of operation shown in FIG. 4, the 
binding needle 12 has meantime executed a downward and upward movement and 
the hook 13 has seized the lower wire 6 and formed a wire loop, consisting 
of the lengths of wire 6a, 6b. The disc 17 has already rotated so far that 
the wires to be twisted together have just come into contact with the 
inner edge 21 of the finger 20. 
In FIG. 5, the twisting operation has already proceeded to some extent but 
is not yet quite complete. In this stage of operation, the binding needle 
12 is lowered during the last rotation of the disc 17 into the position 
shown in FIG. 6, so that the wire loop is released from the hook 13. As a 
result, the wire follows the remaining position of the disc 17 and is 
swung out of the plane of the drawing (FIG. 5), so that it reaches a 
position shown in FIGS. 6 and 7 out of the upward path of the binding 
needle 12. The twisting operation is thus completed. Above the disc 17, a 
twist connection 9a has been formed, and this maintains the connection 
between the upper wire 10 and lower wire 6. A twist connection 9b formed 
below the disc closes the band of wire around the left-hand waste paper 
bale 4. 
In the stage of operation shown in FIG. 8, the binding needle 12, which is 
freed of the wire loop, has returned into its starting position. A cutting 
device 25 has severed the wires between the twist connections 9a, 9b above 
the disc 17 and the pressing plunger 2 has already executed one subsequent 
working stroke and has pressed a first slab of material 4a against the 
wire 6 which is held across the pressing channel, in order to form a new 
bale. The disc 17, during the forming of the bale, is held in a position 
in which the finger 20 is located as seen in FIG. 2, in an "inactive" 
range between the position shown in chain-dotted lines and that shown in 
full lines.