Transport device in a packaging machine

A transport device in a packaging machine includes a plurality of circulating transport chains which each travel over at least one chain wheel. In order to be able to adjust the transport device to differing formats for the bulk product and/or the packaging, the chain wheels can be adjusted with respect to each other in a peripheral direction upon a support shaft. In order to effect as simple and compact a construction as possible, a hydraulic fastening device is provided for fixing the chain wheels relative to each other, wherein the fastening device can be deactivated by means of a releasing device to effect adjustment. The chain wheels can be radially fixed to the shaft by the hydraulic fastening device. It is however also possible for the chain wheels to be disposed on coaxial shaft members which can be adjusted with respect to each other in the peripheral direction and which can be fixed to each other by the hydraulic fastening device.

This application claims Paris Convention Priority of German patent
 application number 197 44 416.4 filed Oct. 8, 1997 the complete disclosure
 of which is hereby incorporated by reference.
 BACKGROUND OF THE INVENTION
 The invention concerns a transport device in a packaging machine having a
 plurality of circulating endless transport members which each travel via
 at least one drive wheel, wherein the drive wheels can be adjusted
 relative to each other in the peripheral direction upon a supporting
 shaft.
 In a packaging machine, in particular in a cartoning machine for folded
 containers, differing transport members, e.g. in the form of transport
 chains, are provided for in order to transport the bulk product, i.e. the
 product to be packaged, the folded containers and, if appropriate, the
 brochures accompanying the packaging through the machine. Towards this end
 it is important for the function and the efficiency of the packaging
 machine that the relative motion of the chains with respect to each other
 be precisely tuned. This is generally achieved through the precise
 alignment of chain wheels of the respective chains on a common shaft.
 Transport means can also be utilized comprising toothed belts instead of
 chains and having associated drive wheels in the form of pulleys. These
 transport means are explicitly included within the purview of the
 invention.
 When the packaging machine is reconfigured to adapt to a different type and
 amount of bulk product and associated folded container, the drive wheels
 must be newly aligned with respect to each other on the common shaft.
 Towards this end one has, in the past, held at least one drive wheel on
 the shaft in a detachable fashion using a screw clamp arrangement so that,
 after loosening of the clamping screw, a manual adjustment of the drive
 wheel in the peripheral direction, i.e. a rotation of the drive wheel is
 possible. After the drive wheel has been adjusted to the desired
 rotational position, it is once more fixed to the shaft by tightening the
 clamping screw. This procedure is time consuming and relatively imprecise.
 In a conventional arrangement disclosed in DE 43 14 632 C2, each adjustable
 chain wheel (disposed on a central shaft in a freely rotating fashion) has
 its own coaxial toothed wheel in engagement with a drive toothed wheel
 seating on a secondary shaft disposed parallel to the central shaft,
 wherein the central shaft and the secondary shaft can be synchronously
 driven by means of a linkage. The linkage driving both shafts comprises a
 drive wheel seating in a rotationally secure fashion on the central shaft
 as well as a drive wheel seated for rotation on the secondary shaft and
 having a pneumatic clutch. When the clutch is activated, a coupling
 bushing is also activated which fixes the secondary shaft with the drive
 wheel borne thereon in a rotationally secure fashion. In order to adjust
 the chain wheels, the secondary shaft can be decoupled from the drive
 using the clutch, to permit relative motion of the chain wheels via the
 drive. The amount of constructive effort required by this device is
 however quite extensive. In particular, the secondary shaft and additional
 drive require a substantial amount of space within the packaging machine.
 It is the underlying purpose of the invention to create a transport device
 in a packaging machine of the above mentioned kind with which the relative
 adjustment of the drive wheels is facilitated in a simple and precise
 fashion and requiring only a small amount of space.
 SUMMARY OF THE INVENTION
 This purpose is achieved in accordance with the invention by a transport
 device of this kind via a hydraulic fastening device to fix the drive
 wheels relative to each other and with a releasing device to deactivate
 the fastening device.
 The drive wheels can either be chain wheels or pulleys, wherein the
 transport means are formed accordingly from chains or toothed belts.
 In a preferred embodiment, the drive wheels are disposed on a common
 continuous shaft, wherein at least one of the drive wheels can be fixed
 radially on the shaft by means of a hydraulic fastening device. In order
 to adjust the drive wheels relative to each other it is thereby only
 necessary to decrease the hydraulic pressure of the fastening device to a
 sufficient extent that the connection or pressure between the drive wheel
 and the shaft is relieved. The relative adjustment of the drive wheels can
 then be effected by means of the central drive of the packaging machine to
 rotate the shaft. The released drive wheel thereby remains stationary to
 effect relative motion. In this manner, no additional drive device is
 required for the adjustment so that the constructive effort is accordingly
 simplified.
 Instead of radially fixing the adjustable drive wheel to the shaft by means
 of the hydraulic fixing device, an alternative embodiment provides that
 the drive wheels are disposed on coaxially disposed shaft members which
 can be fixed relative to each other by means of the hydraulic fixing
 device and, after release of the fixing mechanism, can be adjusted in the
 peripheral direction relative to each other. The adjustment of the coaxial
 shaft members is associated with the relative adjustment of the drive
 wheels located respectively thereon as result of which a format adjustment
 is achieved. Also in this case the central drive of the machine can be
 utilized for the adjustment having, if appropriate, manual or motor drive
 forces acting thereon.
 In a preferred embodiment of the invention, the hydraulic fixing device
 comprises a pressure loaded piston and a hydraulic channel feeding into a
 pressure chamber, wherein the pressure chamber has an associated fixing
 element which can be pressed against the shaft via the pressure reigning
 in the pressure chamber. Displacement of the piston leads to changes in
 the hydraulic pressure in the hydraulic channel in a conventional manner.
 A particularly simple constructive configuration results when the piston
 is loaded by a spring determining the hydraulic pressure and thereby the
 required fixing force.
 If the adjustable drive wheel is directly fixed radially to the shaft, the
 pressure chamber should be fashioned in the drive wheel. When two
 coaxially disposed shaft members are to be fixed by the hydraulic fixing
 device it is possible, in a preferred embodiment of the invention, for an
 adapter sleeve to be mounted to one of the shaft members into which the
 other shaft member is inserted for rotation. The pressure chamber is
 formed in the adapter sleeve so that the adapter sleeve can be firmly
 connected to the inserted shaft member at appropriate hydraulic pressures.
 An improvement of the invention provides that the adapter sleeve
 simultaneously supports the drive wheel to keep constructive effort low.
 The fixing forces can be introduced onto the shaft or the shaft member in a
 point-like fashion, wherein a plurality of fixing points are then
 preferentially provided about the periphery of the shaft. It has turned
 out to be particularly advantageous if the pressure chamber is a ring
 chamber surrounding the shaft to effect an even radially inwardly directed
 pressure about the girth of the shaft. A seating over a wide area and an
 even introduction of the fixing forces can thereby be effected if a
 membrane is disposed between the pressure chamber and the surface of the
 shaft which seats on the outer surface of the shaft at high hydraulic
 pressures.
 In principle, the hydraulic channel can extend in an arbitrary fashion
 between the piston determining the hydraulic pressure and the pressure
 chamber. In particular, conduits leading to the pressure chamber can e.g.
 also be provided. This is a particularly compact solution insensitive to
 external influences having, however, the hydraulic channel traveling
 axially within the shaft, wherein the spring can then also be disposed in
 a spring chamber formed in the shaft.
 When the adjustable drive wheel or the adjustable shaft member is released
 from the shaft through deactivation of the hydraulic fixing device and the
 adjustment is carried out through activation of the central drive of the
 packaging machine, an unintentional adjustment of the released drive wheel
 in consequence of vibrations, friction or the like can be avoided. This is
 achieved in an embodiment of the invention by locking the adjustable drive
 wheel in the position released from the shaft using a holding device.
 Brake shoes engaging the drive wheel or locking pins can be used for this
 purpose.
 An embodiment is described in more detail below with reference to the
 drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENT
 FIG. 1 shows a shaft 11 of a transport device 10 of a packaging machine,
 wherein the shaft 11 is borne for rotation via a bearing 12 in a housing
 wall 14. Additional bearings for the shaft 11 are not shown in FIG. 1. Two
 drive wheels in the form of chain wheels 13 and 15 of a bulk product chain
 or folded container chain are borne on the shaft 11. The chain wheel 13 is
 firmly connected to the shaft 11, whereas the chain wheel 15 is fixed in
 the axial direction to the shaft 11, but rotates with respect thereto.
 A pulley 22 is fixed at the outer side of the housing wall 14 on a widened
 section 11a of the shaft 11 over which a belt (not shown) travels. A
 spring chamber 25 is formed in the widened section 11a of the shaft 11
 into which a hydraulic channel 23, traveling in the axial direction of the
 shaft 11, feeds. A piston 17 extends through the spring chamber 25 from
 the outer side of the axial end of the shaft 11 and into the hydraulic
 channel 23, and a seal 24 is disposed on the front end of the piston 17
 engaging into the hydraulic channel 23. A spring 19 is supported at one
 end by a collar 18 formed on the piston 17 within the spring chamber 25
 and seats at its opposite end on the axial wall of the spring chamber. The
 spring 19 exercises a biasing force on the piston 17 towards the hydraulic
 chamber 23, i.e. in accordance with FIG. 1, to the left. The piston is
 connected via a bracket 21 to the hydraulic unit 20 at its outer free end
 the operation of which allows the piston 17 to be displaced, in accordance
 with FIG. 1, towards the right in opposition to the force of the spring
 19.
 The hydraulic channel 23 extends axially through the shaft 11 into the
 region of the adjustable chain wheel 15. It feeds at this location via a
 radial bore 23a into a ring channel 27 formed in the chain wheel 15 which
 is axially sealed on both sides by a ring seal 26 mounted on the shaft.
 The ring channel 27 is connected to a ring chamber 29 via a connection
 channel 28 which is likewise formed in the chain wheel 15. A membrane 30
 extends between the surface of the shaft 11 and the ring chamber 29 and is
 pushed against the surface of the shaft 11 when an increased pressure is
 introduced into the ring chamber 29.
 In order to be able to block the chain wheel 15 against rotation, a bore
 hole 15a is formed therein into which a locking pin 16 can be introduced.
 In the normal operating state of the packaging machine, the spring 19
 exercises a force on the piston 17 via the collar 18 as result of which
 same subjects the hydraulic oil present in the hydraulic channel 23 to
 pressure. This pressure is also present, via the radial bore 23a, the ring
 channel 27 and the connection channel 28, in the ring chamber 29, as
 result of which the membrane 30 is pressed against the shaft 11 so that
 the chain wheel 15 is held to the shaft and rotates along therewith. In
 order to be able to change the relative position between the chain wheels
 13 and 15, the locking pin 16 is initially introduced into the bore hole
 15a of the chain wheel 15 to hold same stationary. The hydraulic unit is
 then activated to displace the piston 17, in opposition to the force of
 the spring 19, towards the right in accordance with FIG. 1 so that the
 pressure in the hydraulic channel 23 and thereby in the ring chamber 29 is
 reduced to release the pressure between the membrane 30 and the outer
 surface of the shaft 11. Activation of the central drive of the packaging
 machine can thereby rotate the shaft 11 together with the chain wheel 13
 mounted rigidly thereto, whereas the releasable chain wheel 15 remains
 stationary due to engagement of the locking pin 16 in the bore hole 15a.
 In this manner, there is a change in the relative piston between the chain
 wheels 13 and 15 such that they can be adjusted to a new format of the
 bulk product and/or the packaging.
 After the adjustment motion has ended, the hydraulic unit 20 is deactivated
 and the piston 17 returns back into its normal position due to the force
 of the spring 19. The hydraulic pressure in the hydraulic channel 23 and
 the ring chamber 29 is increased to a sufficient extent that the membrane
 30 pushes against the shaft 11 to fix the chain wheel 15 thereon. After
 the locking pin 16 has been pulled out of the bore hole 15a, the
 adjustment procedure is ended.
 The embodiment shown in FIG. 2 has the same basic design as the embodiment
 in accordance with FIG. 1, wherein identical or similar components are
 given reference symbols corresponding to those of FIG. 1. In the
 configuration in accordance with FIG. 2, an adjustable pulley 15 has a
 construction which has already been described in connection with FIG. 1
 with regard to the similar chain wheel 15. Two additional pulleys 13 and
 22 are fixed to the shaft 11. These could e.g. be the drive wheel for the
 brochure folding apparatus and the drive wheel for the brochure clasp
 chain. Since both these pulleys 13 and 22 are firmly connected to the
 shaft 11, they maintain their relative positions even when the shaft 11 is
 adjusted relative to the pulley 15 so that a synchronous drive of the
 units coupled to the pulleys 13 and 22 is guaranteed after format
 adjustment.
 Whereas in the embodiments in accordance with FIGS. 1 and 2 a chain wheel
 and a pulley respectively are directly fixed to the shaft, in accordance
 with FIG. 3, an alternative embodiment provides for two coaxial shaft
 members 11 and 31 which can be adjusted with respect to each other. Also
 in FIG. 3, components which have already been described in connection with
 FIG. 1 are designated with corresponding reference symbols.
 The first shaft member 11 accepts the piston 17 with the associated spring
 19 at its, in accordance with FIG. 3, right end in a manner already
 described and supports an adapter sleeve 32 at its opposite, in accordance
 with FIG. 3, left end which is fixed to the shaft member 11 and has an
 additional chain wheel 13 disposed thereon. The adapter sleeve 32 is borne
 for rotation in a housing member 33 together with the shaft member 11 via
 bearing 12.
 One end of an additional shaft member 31 can be introduced into an opening
 32a of the adapter sleeve 32 in such a fashion that both shaft members 11
 and 31 are disposed coaxially with respect to each other, wherein the
 shaft member 31 can rotate in the adapter sleeve 32. The axial hydraulic
 channel 23 fashioned in the shaft member 11 is connected to a ring chamber
 29 of the adapter sleeve 32 in the manner described above and has an
 associated peripheral membrane 30. When the hydraulic pressure in the ring
 chamber 29 is increased, the membrane 30 can be pressed against the
 outside of the additional shaft member 31 as result of which both shaft
 members 11 and 31 are firmly connected to each other and turn as a unit
 during normal operation of the packaging machine.
 For format adjustment, the fixing force introduced by the membrane 30 is
 reduced so that the shaft member 11 can be rotated relative to shaft
 member 31. After the desired adjusting position as been reached, the two
 shaft members 11 and 31 are once more firmly connected by increasing the
 pressure in the ring chamber 29.