Transfer cylinder with electromotive drive unit

Transfer cylinder with an electromotive drive unit includes a common bearing for a rotor of the electromotive drive unit and for the transfer cylinder, the bearing being disposed in a unit of a printing press supporting the drive unit and the transfer cylinder.

BACKGROUND OF THE INVENTION 
FIELD OF THE INVENTION 
The invention relates to a transfer cylinder for printing presses and an 
electromotive drive unit therefor. 
It has become known heretofore for a transfer cylinder of a printing press, 
for example, an impression cylinder, to be driven by a motor installed at 
some other point in the printing press and connected to the transfer 
cylinder via force transmitting elements, such as a gear transmission. In 
such an arrangement, the transfer cylinder, the motor and, if necessary or 
desirable, the gear transmission, respectively, have their own bearings in 
one or more units of the printing press which support them, such as the 
side walls, for example. 
SUMMARY OF THE INVENTION 
It is accordingly an object of the invention to provide a transfer cylinder 
with an electromotive drive unit which is particularly simple mechanically 
and largely play-free. 
With the foregoing and other objects in view, there is provided, in 
accordance with the invention, a transfer cylinder with an electromotive 
drive unit, comprising a common bearing for a rotor of the electromotive 
drive unit and for the transfer cylinder, the bearing being disposed in a 
unit of a printing press supporting the drive unit and the transfer 
cylinder. 
In accordance with another feature of the invention, the transfer cylinder 
has a shaft, and the electromotive drive unit is an internal rotor 
armature, the rotor being disposed on an axial end of the transfer 
cylinder and on the shaft of the transfer cylinder. 
In accordance with a further feature of the invention, the transfer 
cylinder has an elongated journal pin, the rotor is formed by the 
elongated journal pin, and a plurality of magnets are secured on the 
outside of the elongated journal pin. 
In accordance with an added feature of the invention, the electromotive 
drive unit is an external rotor armature, the rotor is formed by a hollow 
part of the transfer cylinder, and a plurality of magnets are secured on 
the inside of the hollow part of the transfer cylinder. 
In accordance with an additional feature of the invention, the 
electromotive drive unit is a synchronized motor having a rotor, the rotor 
being provided with permanent magnets. 
In accordance with yet another feature of the invention, the electromotive 
drive unit is formed of the rotor and a part firmly joinable to a printing 
press, and a stator and a sensor are included for scanning the position of 
the transfer cylinder, the stator and the sensor being integrated in the 
part. 
In accordance with yet a further feature of the invention, the transfer 
cylinder includes at least one of an open and closed-loop control 
electronics system and a power electronics system for the electromotive 
drive unit also integrated in the part firmly joinable to the printing 
press. 
In accordance with yet an added feature of the invention, the transfer 
cylinder is formed with a work surface, and a respective bearing surface 
is formed at each of the axial ends thereof, the transfer cylinder being 
formed as an open tube at least at an end thereof at which the 
electromotive unit is located, the open tube having an outside forming 
both the work surface of the transfer cylinder and also one of the bearing 
surfaces, the work surface and the one bearing surface being of continuous 
construction and having the same diameter. 
In accordance with a concomitant feature of the invention, the outer 
surface of the transfer cylinder is formed so as to accommodate one of a 
direct bearing between roller bodies of a roller bearing, and a slide 
bearing. 
Because the rotor of the electromotive drive unit is supported together 
with the transfer cylinder in a common bearing, and the appertaining 
stator is joinable firmly to the printing press, a separate support for 
the drive unit is unnecessary. Moreover, at no point are there any force 
transmitting elements which are subjected to play. The elimination of 
bearings, force transmitting elements and the corresponding retaining 
devices makes for especially economical production. 
Direct drives are indeed known per se, for example, for record players. 
However, driving the cylinders of printing presses in a similar way has 
never been considered heretofore, because not only must the synchronized 
travel of a single cylinder be assured, but all the cylinders must always 
be synchronized exactly with one another, and this must be done in the 
presence of considerable driving and load-varying forces. As has been 
demonstrated, these demands can be met, in the realization of the 
invention, by a suitable choice of motor type and by using a suitable 
electronic open and closed-loop control device. 
A first motor type suitable for the invention is an internal rotor armature 
having a rotor which is disposed at an axial end of the transfer cylinder 
and on the shaft of the transfer cylinder; for example, the journal of the 
transfer cylinder is elongated or lengthened past the appertaining 
cylinder bearing and is provided on the outside thereof with an 
arrangement of magnets. A cup-shaped stator which is secured to the 
printing press radially surrounds the rotor. 
As mentioned hereinbefore, an additional bearing of the rotor can be 
dispensed with or omitted. The prerequisite for this, however, is 
adequately high resistance to deflection on the part of the journal or 
journal pin, to avoid collisions of the rotor and stator caused by shaft 
impact. 
A second suitable type of motor is an external rotor armature type having a 
rotor formed by a part of the transfer cylinder and having magnets secured 
on the inside thereof. As a result, such rigidity exists from the very 
outset that no collision between the rotor and stator is possible. 
The stringent demands for synchronized operation of the drive are met best 
by a slow-speed, permanently excited synchronized motor having 
concentricity properties which are optimized, for example, by inclined 
slotting, sinusoidal magnetization in the air gap, and an adequately high 
number of poles. 
For controlling synchronization, the angular position of the transfer 
cylinder must be detected continually. A sensor scanning suitable markings 
on the rotor or on the transfer cylinder is preferably integrated with the 
stator at a fixed installation position. Because the position transducer 
formed by the markings and the sensor is located at the same end of the 
transfer cylinder as the rotor, practically no errors in measuring the 
rotary angle occur. Due to the great stiffness or rigidity of the 
structure-, excellent closed-loop control properties are attained. 
The structural unit having the stator is mountable as a whole on the 
printing press and removable again therefrom without adjustment effort. 
This structural unit may additionally contain closed and open-loop control 
electronics and/or power electronics for the electromotive drive unit, so 
that it forms an autonomous drive unit with local intelligence. 
The transfer cylinder of the essential drive components thus include only 
two structural units, first an integral unit formed of the transfer 
cylinder and the rotor, and second a stator unit with integrated 
electronics, which makes the printing press relatively easy to repair and 
maintain. 
The drive according to the invention is very sturdy and, in comparison with 
heretofore known transfer cylinder drives, has a lower weight and a 
smaller structural volume. 
In the case wherein the motor is of the external rotor armature type, a 
conventional cylinder bearing with journals or journal pins flanged to the 
transfer cylinder cannot be used at the side of the motor. For such a 
case, the invention provides that the transfer cylinder, at least at the 
end with the motor, takes the form of an open tube, the outside of which 
forms not only the work surface of the transfer cylinder but also a 
bearing surface; the work surface and the bearing surface are of 
continuous construction and have the same diameter. 
The rotor magnets are secured on the inside of the open end of the transfer 
cylinder. In addition, any additional devices necessary for printing 
technology can be accommodated inside the transfer cylinder. 
Such a transfer cylinder can also be removed from the printing press 
laterally, without having the remove the bearings or the side walls. 
When both ends of the transfer cylinder are formed as an open tube, the 
transfer cylinder can then also be made from a tubular semifinished 
product, without expensive welding and without extensive metal-cutting or 
machining. No sagging of the journal or deformation of flanges occurs as 
in conventional transfer cylinders, and the transfer cylinder has the 
greatest possible stiffness or rigidity for a given weight. 
Such a construction is particularly suitable for transfer cylinders with a 
continuous work surface, which lack any longitudinal groove, slot or gap. 
Such transfer cylinders may be provided with a hard, wear-resistant, 
high-precision surface, in order to lend the work surface of the transfer 
cylinder certain properties which are significant from the standpoint of 
printing technology, primarily. If the entire outer surface of a transfer 
cylinder of the invention is constructed in this manner, the 
aforementioned properties are then also advantageous for the bearing of 
the transfer cylinder. In particular, it becomes possible to use the hard 
surface simultaneously as a bearing surface, and to support the printing 
roller directly on the roller bodies of a roller bearing or in a slide 
bearing. 
A tubular embodiment of the transfer cylinder can be considered not only 
for an external rotor armature but also for an internal rotor armature. In 
the latter case, the rotor is preferably embodied as a substantially 
cylindrical component which protrudes laterally from the transfer cylinder 
and is radially encompassed by a cup-shaped stator. 
Other features which are considered as characteristic for the invention are 
set forth in the appended claims. 
Although the invention is illustrated and described herein as embodied in a 
transfer cylinder with an electromotive drive unit, it is nevertheless not 
intended to be limited to the details shown, since various modifications 
and structural changes may be made therein without departing from the 
spirit of the invention and within the scope and range of equivalents of 
the claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings and, first, particularly to FIG. 1 thereof, 
there is shown therein a transfer cylinder 1 having a respective journal 
or journal pin 2, 3 at each end thereof, the journal pins 2 and 3, 
respectively, being supported via ball bearings 4, 5 in side walls 6, 7 of 
a printing press. 
The journal pin 3 is elongated outwardly past the ball bearing 5. A 
cylindrical sleeve 9, on the outside of which premounted permanent magnets 
10 are disposed, is pressed force-lockingly onto the elongated part 8 of 
the journal pin 3. In this regard, it is noted that a force-locking 
connection is one which connects two elements together by force external 
to the elements, as opposed to a form-locking connection which is provided 
by the shapes of the elements themselves. 
The rotor formed in this way is surrounded concentrically by a stator 
formed by electromagnets 11 which are secured on the cylindrical inside of 
a cup-shaped stator housing 12, which is secured at an open side thereof 
to the side wall 7 of the printing press. 
In FIG. 2 wherein elements largely matching those of the exemplary 
embodiment of FIG. 1 are identified by the same reference numerals, a 
transfer cylinder 20 is formed at one end, as in FIG. 1. At the other end 
thereof, the transfer cylinder 20 has no journal pin but instead is 
constructed as an open tube supported in a ball bearing 21 having a 
diameter matching the diameter of the tube, the ball bearing 21 being 
supported in the side wall 7 of the printing press. A cylindrical sleeve 
22, on the inside of which premounted permanent magnets 23 are disposed, 
is pressed force-lockingly into the open end of the transfer cylinder 20. 
The transfer cylinder 20 to be driven serves, in this embodiment, in 
combination with the sleeve 22 and the permanent magnets 23, as the rotor. 
The appertaining stator is formed by electromagnets 24, which are secured 
to the outside of a journal-like part of a stator housing 25. The stator 
housing 25 is secured to the side wall 7 of the printing press in a way 
that the journal-like part having the electromagnets 24 dips 
concentrically into the arrangement of permanent magnets 23. 
FIG. 3 shows a transfer cylinder 30 in the form of a continuous straight 
tube, which extends along an axis 32. The outer surface of the transfer 
cylinder 30 is an extremely hard, wear-resistant and high-precision 
ceramic surface which, with the same diameter throughout, forms both an 
axially middle cylindrical work surface 33 as well as bearing surfaces 34 
on the axial ends of the transfer cylinder 30. In other words, the work 
surface 33 and the bearing surfaces 34 and 35 together form one continuous 
surface with the same diameter throughout. 
The bearing surfaces 34 and 35 are supported, for axial rotatability of the 
transfer cylinder 30, in radial bearings 36 and 37, which are secured to 
side walls 38 and 39 of the printing press. The bearing surfaces 34 and 35 
run directly on roller bodies 40 and 41, respectively, of the radial 
bearings 36, 37. 
Adjacent to the bearing surface 35 and entirely at one axial end, the 
transfer cylinder 30 has an annular axial bearing surface 42 with a 
somewhat smaller diameter than the bearing surface 35. Between a shoulder 
43 on the transfer cylinder 30, formed by a reduction in diameter, and an 
annular cup spring 44 screwed onto the end thereof, an axial bearing 45 is 
seated on the axial bearing surface 42. The axial bearing 45 contains 
roller bodies 46, which axially guide the transfer cylinder 30 and, like 
the radial -bearing 37, is secured to the side wall 39. 
The transfer cylinder 30 shown in FIG. 3 can be removed very simply by 
being pulled laterally out of the printing press after the axial bearing 
45 has been loosened. While the transfer cylinder 30 can be removed to 
both sides, in the exemplary embodiment shown, because the work surface 33 
and the bearing surfaces 34 and 35 have the same diameter, embodiments are 
also possible wherein, for example, the diameter of the bearing surface 34 
is somewhat greater or the diameter of the bearing surface 35 somewhat 
smaller than the diameter of the work surface 33, so that the transfer 
cylinder 30 can be removed to at least one side. On the other hand, a tube 
with an essentially uniform surface, as shown in FIG. 1, is naturally the 
easiest to make. 
A cylindrical rotor 47 is press-fitted concentrically into one end of the 
transfer cylinder 30; it contains permanent magnets, not shown in detail, 
and protrudes past the end of the transfer cylinder 30. The protruding 
part of the rotor 47 is radially surrounded by electromagnets 48, which 
are permanently mounted in a stator housing 49. The stator housing 49 is 
secured to the side wall 38 of the printing press, for example, by means 
of a non-illustrated clamping device pressing the stator housing 49 
against the side wall 38, with the stator housing 49 being axially fixed 
with pins 50. This makes for easy mounting and removal of the stator 
housing 49. 
A marking disk 51 is secured to the outer axial end of the rotor 47. The 
stator housing 49 contains one or more sensors 52, which are disposed 
adjacent to the marking disk 51, with an air gap therebetween. The marking 
disk 51 and the sensor or sensors 52 form a position transducer for the 
angular position of the rotor 47 or of the transfer cylinder 30. The 
position transducer has a resolution of 1000 periods per revolution or 
more, depending upon the particular demands for synchronization. 
Also accommodated in the stator housing 49, as shown diagrammatically, are 
open and closed-loop control electronics 53 and power electronics 54. The 
power electronics 54 are connected, via non-illustrated power supply 
lines, to a power supply at the printing press, and supplies current to 
the electromagnets 48 as a function of control signals of the open and 
closed-loop control electronics 53. The open and closed-loop control 
electronics 53, together with the power electronics 54, the motor, and the 
position transducer with the sensor or sensors 52 to which they are 
connected, form a closed control loop for controlling the synchronization 
of the transfer cylinder 30. For synchronization with additional transfer 
cylinders or for controlling and monitoring the rotation of the cylinders, 
the open and closed-loop control electronics 53 are connected to a 
printing-press computer. 
FIG. 4 is an exemplary embodiment of a tubular transfer cylinder with an 
integrated external rotor armature. Elements which match those of the 
exemplary embodiment of FIG. 3 are identified by the same reference 
numerals. 
In FIG. 4, in a transfer cylinder 60 which otherwise matches the transfer 
cylinder 30 of FIG. 1, a number of magnets 61 are machined or otherwise 
embedded into the inside thereof at one axial end. Located in the interior 
of the transfer cylinder 60 is a stator shaft 62 carrying magnet coils 63 
which are located opposite the magnets 61. The stator shaft 62 extends 
through the entire transfer cylinder 60 and is secured to the printing 
press at both ends, as diagrammatically shown. The result is an especially 
high rigidity of the stator. 
As in the exemplary embodiment of FIG. 3, a position transducer, open and 
closed-loop control electronics and power electronics can be integrated 
with the stator in the exemplary embodiments of FIGS. 1, 2 and 4, as well. 
It is also possible to drive a transfer cylinder from both sides, by 
providing both ends of the transfer cylinder with drives of the type shown 
and described. 
FIGS. 5a to 5d show several alternatives for supporting a tubular transfer 
cylinder 70 in a side wall 71. The use of a roller bearing 72 with an 
inner and outer race, as shown in FIG. 5a, is advantageous if the bearing 
face of the transfer cylinder cannot or should not be stressed directly. 
Instead of the needle bearing shown in FIG. 3 or FIG. 4, ball bearings can 
be used as the roller bearings, as shown in FIGS. 5a and 5b. The balls of 
a ball bearing can also roll directly along the bearing surface of the 
transfer cylinder 70, as shown in FIG. 5b for a roller bearing 73 without 
an inner race. 
As suggested in FIG. 5c without details, roller bodies can also roll 
directly, without the interposition of bearing races, along both the 
transfer cylinder 70 and a bearing surface 74 formed in the side wall 71. 
Finally, the roller bodies may also be omitted, if a slide bearing of the 
transfer cylinder 70 in a bearing bushing 75 is used, as shown in FIG. 5d.