Web splicing apparatus

A bobbin changer includes a storage arrangement for storing a number of reels, a reel unwinding station arranged to receive successive reels from the storage arrangement, means for initially rotating each new reel at the unwinding station in a reverse direction (i.e. opposite to the direction of rotation during unwinding), a suction head which is mounted adjacent to the reel and is arranged to pull the leading end portion of the web away from the reel as it approaches the suction head, and means responsive to the movement of the leading end portion of the web and arranged to discontinue the reverse drive on the reel and to initiate a splicing operation.

This invention is primarily concerned with devices commonly known as 
"bobbin changers," especially for machinery of the cigarette industry; 
that is to say, apparatus for automatically splicing (i.e. joining) webs 
drawn from successive reels. However, it includes subsidiary features 
which can be used in other forms of apparatus. The term "bobbin changer" 
in this specification applies to a device whereby the trailing end of the 
web drawn from one reel (i.e. when the reel is about to expire) is spliced 
to the leading end of the web on the next reel to be used, so as to 
maintain a continuous supply of the web. 
This invention is particularly concerned with an automatic bobbin changer 
for uniting the web used in a filter attachment machine for joining 
filters to cigarettes. 
A bobbin changer according to one aspect of the present invention includes 
a storage arrangement for storing a number of reels, a reel unwinding 
station arranged to receive successive reels from the storage arrangement, 
means for initially rotating each new reel at the unwinding station in a 
reverse direction (i.e. opposite to the direction of rotation during 
unwinding), a suction head which is mounted adjacent to the reel and is 
arranged to pull the leading end portion of the web away from the reel as 
it approaches the suction head, and means responsive to the movement of 
the leading end portion of the web and arranged to discontinue the reverse 
drive on the reel and to initiate a splicing operation. 
This invention enables the bobbin changer to "find" the end of each new 
reel. Therefore the reels do not need to be placed in the storage 
arrangement in any particular angular orientation and there is no need, 
while each reel is being transferred from the storage arrangement to the 
unwinding station, to maintain the orientation of the reels; i.e. the 
reels can be transferred from the storage arrangement to the unwinding 
station in any convenient way, e.g. by rolling into position. The end of 
each reel is "found" and is then joined to the expiring end of the 
previous reel with the minimum wastage of web material. 
In a preferred arrangement, there is an end detecting device which is 
mounted near the suction head and is engaged by the leading end portion of 
the web when that portion of the web is pulled away from the reel by the 
suction head. The end detecting device detects when the actual end of the 
web reaches a predetermined position whereupon the reverse drive is 
discontinued and splicing commences. In preparation for splicing, the 
suction head is moved automatically so as to carry the end of the web to a 
splicing device, and the end detecting device is automatically moved away 
from the web so as to allow the web to project freely from the suction 
head, thus facilitating the application to the end of the web of an 
adhesive patch or other means for joining the end to the trailing end of 
the previous reel. 
A subsidiary feature of this invention, which may be used in different 
bobbin changers, concerns a device for applying adhesive patches during 
splicing. The device comprises means for feeding around a sharp-edged 
guide a carrier web carrying adhesive patches which separate from the 
carrier web on passing around the guide, and including a splicing member 
having a suction port by which each successive adhesive patch is drawn 
against the splicing member, which is then arranged to press the adhesive 
patch against the webs to be joined. 
According to another subsidiary feature of this invention, the web drawn 
from the in-use reel is arranged to pass through a reservoir having means 
for weighing the web, and the speed at which the web is fed into the 
reservoir is controlled so as to maintain a substantially constant weight 
of web in the reservoir. The length of web thus maintained in the 
reservoir is sufficient to allow web to continue to be drawn from the 
reservoir while a splicing operation is being carried out, during which 
period the web feed into the reservoir is stopped to allow splicing to 
take place with the web stationary.

As shown in FIGS. 1 and 4, the bobbin changer includes a storage 
arrangement 10 for reels 11, the reels being carried as a coaxial row on a 
conveyor 12. This conveyor is tilted slightly to the left (FIG. 1) so that 
the front reel rolls sideways off the conveyor 12 to the unwinding station 
(occupied by the reel 13 in FIG. 1) when the front reel is driven by the 
conveyor 12 beyond the end of a retaining bar 14. 
On reaching the unwinding station, each new reel is engaged by a conical 
boss 15 mounted on a shaft 16 which is driven forward by an air cylinder 
17. The narrow end of the boss 15 engages in a central aperture in the 
reel (regardless of small variations in the diameter of the reel), and 
moves the reel against a second conical boss 18 mounted on a shaft 19. The 
axes of the shafts 16 and 19 are at a height such that, when the bosses 
engage in the reel, the reel is lifted slightly clear of a slightly 
sloping platform 20 which previously supported it. 
For the purpose of "finding" the end of the web, the reel 13 is 
automatically rotated slowly in the reverse direction by a motor 21 which 
drives the shaft 19 via a belt 22 and a magnetic clutch 23. 
Adjacent to the reel 13 at the unwinding station there is a suction head 24 
including suction passages 25 and 26 extending from a suction manifold 27. 
As the end of the web on the reel 13 approaches the suction head during 
reverse rotation of the reel, the suction head pulls the web away from the 
reel; it in effect straightens out the web so that the end portion of the 
web then lies substantially vertical, adjacent to an end detecting device 
28 (see FIG. 2). This device includes a suction passage 29 which is 
connected to a source of suction (not shown) via a pipe 30. The end of the 
passage is at first closed by the web and then, as the end 13A of the web 
moves past the passage 29, it is exposed to atmosphere. A pressure 
transducer 31 connected to the pipe 30 detects the drop in suction which 
indicates that the end of the web has just passed the passage 29, and a 
signal from the transducer first de-energises the magnetic clutch 23 and 
then initiates the further operations necessary for splicing, as described 
below. 
The imminent expiry of a reel at the unwinding station is detected by an 
arm 32 resting on the reel and pivoted on a spindle 33. As the web is 
unwound from the reel, the arm 32 moves downwards and, on reaching a 
predetermined position, it operates a switch 34 which initiates the entire 
splicing operation. Firstly, the expired reel is released by the air 
cylinder 17, which withdraws the boss 15, whereupon the expired reel rolls 
away down a ramp 35. At the same time, a drive is transmitted to the 
conveyor 12 so as to move the front reel in the storage arrangement to the 
position from which it can roll down to the unwinding station as already 
described. 
Operation of the switch 34 by the arm 32 also stops a motor (not shown) 
driving a pulley 36 which is arranged to draw web from the reel at the 
unwinding station and to feed the web into a reservoir 37. A roller 38 
cooperates with the pulley 36 to grip the web. 
As soon as the web feed is stopped, an actuator 39 (FIG. 3) is extended so 
as to move to the right a splicing member 40 carrying a blade 41 with a 
serrated edge which enters a gap between two fixed web guides 42 and 43 
and thus cuts the web. The portion of the web below the cut line (i.e. the 
trailing end portion of the web of the expiring reel) is pulled away as 
the reel rolls down the ramp 35. 
When the end detecting device 28 detects that the end of the new reel is in 
the correct position, an actuator 44 is extended so as to move the suction 
head 24 upwards to the position shown in FIG. 3, the reel 13 being free to 
rotate so as to enable this to happen. During this upward movement of the 
suction head 24, a roller 45 on the suction head engages the end detecting 
device 28 and swings it in a counter-clockwise direction about a pivot pin 
46 to the position shown in FIG. 3, in which it engages a stop 80. 
Therefore, as the suction head 24 moves upwards, it carries the end of the 
web of the new reel upwards to a position in which it overlaps with the 
trailing end of the web 47 of the previous reel. The position of the end 
13A of the new web at this stage is shown in FIG. 3, the trailing end of 
the web 47 being adjacent to the gap between the guide blocks 42 and 43. 
Thus the ends of the webs are ready to be joined by an adhesive patch. 
After splicing has occurred, the actuator 44 is automatically retracted. A 
projection 81 on the member 28 passes through a groove 82 in the suction 
head 24 and is finally engaged by the roller 45, which rotates the member 
back to the position shown in FIG. 2, in which position the member 28 
rests on top of flange 60 on the suction head. 
Adhesive patches used for joining the webs are obtained from a reel 50 
which is a bought-out item comprising a smooth web carrying, at spaced 
intervals, pieces of paper coated with a pressure-sensitive adhesive. This 
adhesive holds the paper patches with adequate security on the web 50A 
until the web is passed around a sharp bend which tends to peel the 
patches off the web. A sharp bend is formed around an edge 51A of guide 51 
around which the web is drawn by a pulley 52 against which the web is 
pressed by a spring-loaded roller 53. 
The adhesive patches may be of reflective material to facilitate detection 
and ejection of finished cigarettes including the adhesive patches. 
An actuator 54 advances the web 50A through a predetermined distance for 
each splicing operation in the following manner. A rod 55 extending from 
the actuator carries a finger 56 engaging a chain 57 which passes partly 
around a sprocket 58 and has one end secured to the sprocket. Thus linear 
movement of the actuator rod 55 caused by expansion of the actuator 54 is 
translated into predetermined angular movement of the pulley 58, this 
movement being resisted by a spring 59 which then returns the chain 57 and 
the sprocket 58 to its original position; the sprocket 58 is connected to 
the pulley 52 by a unidirectional clutch which allows this return movement 
of the sprocket without rotating the pulley. 
As the web 50A passes around the sharp edge 51A of the guide 51, an 
adhesive patch (lying on the outside of the web) is peeled off the web and 
is then suctionally gripped by the member 40 at position 50B, suction 
being applied through a passage 40A. The actuator 39 is then extended so 
that the paper patch 50B is pressed against the ends of the webs by the 
member 40 and thus secures the web ends to one another. During this 
movement of the member 40, the blade 41 is held back (i.e. prevented from 
cutting the web) by the flange 60 on the suction head 24; for this 
purpose, the blade 41 is resiliently mounted on the member 40. 
While these splicing operations are being carried out, web continues to be 
drawn from the reservoir 37 so that the filter attachment machine can 
operate continuously. The quantity of web stored in the reservoir is 
sufficient for this purpose. During normal running of the machine, the 
weight of web in the reservoir is kept substantially constant by varying 
the speed of rotation of the pulley 36 in response to a weight signal 
emitted by a circuit 70 connected to a strain gauge 71 on a flexible bar 
72 which carries the reservoir in cantilever fashion; alternatively, other 
weighing methods may be used. This ensures that there is always sufficient 
web in the reservoir to allow a splicing operation to take place at any 
time. 
The speed of rotation of the pulley 36 may be steplessly variable. 
Alternatively, the pulley 36 may be driven selectively at, for example, 
two speeds one of which over-feeds the web and the other of which 
underfeeds the web, so that the average feed rate of the web into the 
reservoir depends upon the proportion of time during which the pulley 36 
runs at the higher speed. 
In place of the bar 72 and strain gauge 71, the reservoir may be 
resiliently suspended by "Flexures" of the type made by Darenth Weighing 
Limited, and one or more microswitches may be used to detect when vertical 
movement of the reservoir has occurred to an extent indicative that 
sufficient web has been accumulated in the reservoir. 
The operative face of the suction head 24 may be slightly curved in 
horizontal cross-section (preferably concave) so as to give the upstanding 
web a slightly curved cross-section, thus increasing its rigidity.