Printing device for packaging machines

In a packaging machine for packing in packages formed in a material web a printing means having type bars for printing on the material web reciprocally movable between a rest position having a distance from the material web and an operating position, and an inking wheel and drive means for moving the inking means in a direction transversely to the type bars and for applying ink onto the type bars. In order to eliminate the frequent exchange of an ink ribbon the inking wheel is designed such that ink is applied to the type bars only in case the inking wheel is heated to a temperature being above room temperature, and the inking wheel is disposed in a casing which at least partly surrounds the inking wheel and which is designed to be heated and to be moved reciprocally together with the inking wheel.

BACKGROUND OF THE INVENTION 
The invention relates to an improved printing device for a packaging 
machine and in particular to a packaging machine for packing in packages 
formed in a material web or sheet material. 
In a known packaging machine of this kind an ink ribbon is provided between 
the type bars and the film to be printed. In the same manner as in a 
typewriter the ink ribbon is drawn from a supply roll and moved along the 
type bars. In particular in cases where several type bars are provided 
which correspond to each other and which are associated to packages 
arranged side by side it cannot be avoided that a considerably unused 
portion of the ink ribbon must be pulled through. As a result the ink 
ribbons have to be exchanged a couple of times a day with the consequence 
of an interruption of the machine operation each time. 
OBJECTS OF THE INVENTION 
It is an object of the invention to provide an improved printing device for 
a packaging machine. It is a further object to design a printing device 
such that the frequent exchange of the ink ribbon is eliminated. 
SUMMARY OF THE INVENTION 
In order to achieve the above mentioned objects the invention provides in 
combination with a packaging machine for packing in packages formed in a 
material web, printing means having type bars for printing on the material 
web and being reciprocally movable between a rest position having a 
distance to the material web and an operating position, an inking wheel 
and drive means for moving the inking wheel in a direction transverse to 
the type bars and for applying ink on the type bars, the inking wheel 
being designed such that ink is applied to the type bars only if the 
inking wheel is heated to a temperature above room temperature, the inking 
wheel being disposed in a casing which at least partly surrounds the 
inking wheel and which is designed to be heated and to be reciprocally 
moved together with the inking wheel.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The packaging machine 1 comprises a machine frame 2, a forming station 3 
and sealing station 4 supported by the machine frame. A bottom film 5 is 
drawn from a supply roll 6 and intermittently advanced between the 
operating cycles of the stations 3 and 4. Containers 7 are formed in the 
forming station 3 and supplied to the sealing station 4 after being 
filled. A cover film 9 is drawn from a second supply roll 8 and carried on 
top of the containers 7 via a deflection roller 10 and thereafter into the 
selaing station 4 for sealing the containers. In accordance with the 
invention, printing means 11 are provided for the aforesaid printing 
machine disposed in a position on the way of the cover film from the 
supply roll 8 to the deflection roller 10 and hence in front of the 
transport of the cover film into the sealing station 4. 
The printing means 11 comprises a frame 12 which is connected with the 
machine frame 2. The frame 12 carries two guide bars 13, 14 which are 
disposed in a distance from each other and which extend in a direction 
perpendicular to the cover film 9 to be passed through the printing means. 
A cross-beam 15 is disposed parallel to the cover film and movably 
arranged on the guide bars 13, 14. On the sides thereof facing the cover 
film the cross-beam supports heating means 16 with type bars 17, 18, 19 
attached thereto. The type bars are formed as blocks. They are arranged on 
the side facing the cover film 9 and aligned parallel to the surface of 
the cover film and further connected with the heating means 16 in such a 
manner that they may be heating to a predetermined temperature of 
preferably between around 130.degree. and 150.degree. C. The lateral 
distance of the type bars 17, 18, 19 is selected as a function of the size 
and number of the packages arranged side by side in direction transverse 
to the feed direction of the machine such that a printing is performed for 
each row of packages. As may be seen from FIG. 2 the type bars have a 
distance from each other. 
Moreover, an abutment plate 20 is provided in a position parallel to the 
cover film 9 carried through the printing means on the side which is 
turned away from the type bars, and parallel to the cover foil 9. During 
the printing process the cover film contacts the abutment plate by action 
of the type bars 17, 18, 19. 
A drive means 21 is provided which is formed as a piston-cylinder-means. 
The cylinder of this drive means is rigidly connected with the frame 12. 
The piston rod is rigidly connected with the cross-beam 15. The drive 
means is adjusted such that it moves the type bars into the retracted 
position shown in FIG. 2 and into the printing position, respectively, in 
which the type bars press the cover film against the abutment 20, above 
the cross-beam 15 is a reciprocating manner controlled by a control means. 
Two further guide bars 22, 23 are disposed in a right angle to the guide 
bars 13, 14 and parallel to the plane of the cover film 9. The guide bars 
22, 23 are laterally supported by the frame 12 and have a casing 24 
reciprocally movable arranged thereupon. The casing comprises a base 25 
having two horizontal bores provided therein through which the two guide 
bars 22, 23 extend. The diameter of these bores is selected such that the 
base slides freely on the guide bars. The base further comprises a 
vertical central bore with ball bearings 26, 27 at each end of the bore. 
Moreover, the ends of the chain 36 passing parallel to the direction of 
the guide bars 22, 23 are rigidly connected with the base 25. 
The base has a casing formed as a heating chamber 29 on the top side 
thereof. The casing has a vertically extending opening 30 on the side 
facing the type bars only. 
The interior of the heating chamber 29 is substantially cylidnrical and has 
a size such that an inking wheel 31 just fits therein. The inking wheel 31 
is supported on a mandrel 32 and consists of foamed material which is 
saturated with printing ink. The printing ink is designed such that it is 
solid and not colouring at ambient temperature. The ink softenes when 
heated to a temperature above the ambient temperature and preferably in 
the order of 130.degree. to 150.degree. C. and is transferred to the type 
bars when contacting the same. 
The inking wheel is inserted into the vertical bore of the base 25 through 
an axle extension 34 connected with the mandrel 32 and is supported in the 
ball bearing 26, 27. A sprocket wheel 35 is fixedly attached to the axle 
extension on the side thereof opposite to the inking wheel. 
The heating chamber 29 is heated to a preselected temperature of preferably 
about 130.degree. to 150.degree. C. by means of a control unit. 
An endless-loop drive chain 36 is provided parallel to the guide bars 22, 
23 and carried around two sprocket wheels 37, 38 disposed at opposite 
sides of the frame 12. The sprocket wheel 38 may be driven by a motor 39. 
The drive chain is connected with the base in such a manner that during a 
movement of the drive chain the casing 24 and hence the inking roller 31 
is carried along and is reciprocally moved between both side walls of the 
frame in direction of the arrow 40. 
Furthermore a second drive chain 41 is provided and carried by four 
deflection gear wheels 42-45 which extend parallel to the axis of the 
inking wheel 31. The second drive chain is aligned such that it engages 
the gear wheel 35. The second drive chain may be driven by a motor 46. 
In operation, at first the cover film is passed between the type bars and 
the abutment plate which is preferably made of elastomer, in the manner 
shown in FIG. 2. 
With the heating switched on the inking wheel is continuously rotated by 
the motor 46 and the drive chain 41 such that permanently a uniform 
heating is obtained. For applying the ink to the type bars the motor 46 is 
switched off and at the same time the motor 38 is switched on. Thus the 
inking roller is moved along the blocks whereby the inking wheel is 
permanently rotated by means of the drive chain 41 now acting as rack. The 
inking wheel rolls over the type bars or type blocks, respectively, and 
applies the ink thereto. As soon as the inking wheel arrives at the second 
end position and hence the type bars are coloured, the motor 39 is 
switched off and the motor 46 is switched on. At the same time the type 
bars are pressed in direction of the arrow 47 agaisnt the cover film by 
means of the drive means 21 whereby the ink is transferred to the cover 
film. Since the cover film is not heated the ink transferred thereto is at 
one smudge-proof. This is followed by the next cycle. 
While the invention has been described in preferred form it is not limited 
to the precise nature shown as various modifications may be made without 
departing from the scope of the appended claims.