ACCUMULATOR ROLLER CONVEYOR AND DRIVING ROLLER THEREFORE

Abstract: For starting and stopping rollers in view of stopping goods provided thereon, while a driving chain (21) for the rollers (5) is continuously moving, each roller has a membrane housing (16), operated by pressurized air, which contacts or releases a friction disc (22) connected to the roller. The invention provides said membrane housing (16) coaxial with the roller shaft (13) and operating through an intermediate disc (24), which is moved by the pressurized air into contact with the friction disc (22) for starting the roller. For stopping the roller said intermediate disc contacts a stationary surface, whereby the roller is immediately stopped. Therewith the stopping distance for the goods and thereby the conveyor length are reduced.

Description: The invention relates to a roller conveyor of the accumulator conveyor type, adapted to be driven by an endless belt or chain drive, comprising rollers which are axially fixed in place and mounted for rotation about a stationary shaft having its ends fixedly mounted in a supporting frame, a drive wheel mating with said belt or chain drive and being mounted for rotation coaxially to the respective roller, a friction disc being provided, which is in permanent driving connection with said roller and adapted to be also drivingly connected with said drive wheel, an axially expandable actuation member (membrane) being supported by a house portion on the supporting frame at one roller end, said member being adapted to be pressure-activated so as to cause the friction disc and the drive wheel to axially engage one another. Such a roller conveyor is disclosed in DE-A-3.222.177. Accumulator conveyors are used for carrying goods from one location to another location, where the goods are taken from the conveyor for further treatment, e.g. in a processing or packaging machine. In case of a stagnation of the goods at the delivery end of the conveyor, e.g. when the fully loaded processing or packaging machine is temporarily prevented from taking goods from the conveyor, the goods are permitted to remain (i.c. accumulate) on the delivery end section of the conveyor due to the rollers in that conveyor section being stopped. The driving motor for the conveyor, however, may be kept going, so that the supply of goods may continue along the upstream conveyor sections. Even when the conveyor is completely loaded with goods and as a consequence of this all of the rollers have been brought to a standstill, the drive motor may keep rotating. As soon as goods are taken from the conveyor again the rotation of the rollers in the delivery end section of the conveyor is restored. The activation and deactivation respectively of the drive of the rollers in any section is effected by means of a switching roller in such section, which normally projects above the level of the conveyor rollers but is mounted to be depressed by an article resting on it so as to produce a signal in the rollers in the respective conveyor section to be disengaged from the conveyor drive. More specifically the signal produced results in the actuation of a pneumatic control valve which causes a release of pressure and thereby a collapse of the axially expandable member, due to which the drive wheel(s) is (are) disengaged from the respective conveyor roller(s). In the roller conveyor according to DE-A-3.222.177 the friction disc is fixedly connected to an end face of the respective roller, whereas the expandable member is acting upon the driving wheel so a to displace the latter axially into and out of engagement with said friction disc. A similar friction disc is provided on the opposite end face of the roller for cooperation with a braking disc, which is mounted non-rotationally, but may be axially displaced by a second expandable member into engagement with said second friction fisc so as to brake the roller, after the latter has become disengaged from the drive wheel. The roller conveyor proposed by the present invention distinguishes from this well-known roller conveyor in that said friction disc is slidably mounted relative to said roller for movement between a first axial position ― corresponding to the inactivated state of the expandable member ― in which it is spring-urged with an axial face in friction contact with a fixed wall portion of said housing, and a second axial position, in which it is urged by the pressure-expanded member into driving engagement with an axial surface of said drive wheel. Consequently, in the roller conveyor of the present invention a single friction disc is mounted to function both as a drive-coupling disc and as a braking disc, while a single axially expandable member is needed for both the drive and break function. It is to be noted that US-A-4.108.303 discloses an accumulator roller conveyor of the same general type, in which a plurality of rollers is driven by a driving chain through a friction disc which is controlled by a gas pressure-operated expandable member (membrane). In this well-known construction, however, the movement of the rollers into and out of engagement with the drive means is rather jerky due to the type of engagement between sprocket-drive wheel and chain, which may result in rapid wear of the conveyor and damage to shock-sensitive goods. It is further to be noted that a roller conveyor is known from the EP-A-0034131 in which an inflatable ring is mounted coaxially around the roller shaft and is shiftable with respect thereto. A sprocket is provided around the roller with the interposition of self releasing wedges. A thrust member is provided around the roller shaft and axially shiftable relative thereto and is adapted to press the wedges into fixed engagement with the sprocket, through the inflatable ring, whereby the roller drive may be switched on. A disadvantage is the continuous slipping occuring between one of the wedges, secured to the roller, and the sprocket, whereby wear occurs and further that the roller is not positively braked as according to the invention, when the roller drive is switched off. Further BE-870.482 discloses a roller conveyor having a friction clutch between a roller and a driving sprocket. An inflatable tube, provided locally adjacent to the roller, engages the clutch through a rocker arm. Disengagement of the clutch is obtained with the help of a compression spring. Also here the roller is not positively braked and quickly stopped when the drive is switched off. In a preferred embodiment of the invention the said house portion is formed to enclose the drive wheel with its friction surface, the chain or belt, the friction disc and the expandable-member (membrane), said house portion being provided with a hinged bottom part which may be swung away from the return run of the chain. Preferably also at least the lower part of the housing portion is formed from a resilient synthetic material, permitting the swinging movement of the bottom part. The invention also relates to a roller assembly adapted to be used in the roller conveyor according to the invention. Fig. 1 shows a very schematic side view of an accumulator roller conveyor. Fig. 2 shows an elevation of a conveyor roller with driving unit in section. In fig. 1 a schematic example is shown of an accumulator conveyor having four zones or conveyor parts 1, 2, 4 which are situated one behind the other as seen in the conveying direction. It will be clear that the conveyor may comprise more parts. The parts are mutually equal. Each part comprises a plurality of conveyor rollers 5, situated one behind the other in the conveying direction and mounted in a frame (not shown). The number may differ from the number as shown in fig. 1. The said switching roller 6 is pivotably mounted on a lever 7 to the frame forward of the last roller or last rollers of a conveying zone. A pneumatic circuit is connected somewhere (not shown) to a pressurized air source, e.g. a mains having an above atmospheric pressure of about 4 bar. This circuit comprises a conduit 8 extending along the conveyor, a circuit 9 being branched therefrom to each conveyor part 1, 2, 3, 4, each said branch conduit conducting in series to the conveyor rollers 5 situated one behind the other, particularly to the membrane housings thereof, which will be described below. Likewise for each conveyor part a conduit 10 is branched from the conduit 10 connecting with a pneumatic switch 11. Fig. 2 shows at an enlarged scale a conveyor roller 5, mounted in the frame 12 of the conveyor on a shaft 13. A bearing housing 15 secured to the roller 5 is mounted on the right hand end of the shaft 13 as shown in figure 2, freely rotatable through a ball bearing 14. An axially expandable member in the form of a membrane housing 16 with membrane 17 is secured to this right hand shaft end through a slidable sleeve 28. Therewith the conduit 9 is connected at 18. A sprocket 20 is mounted freely rotatable through a ball bearing 19 on the bearing housing 15, said sprocket being in engagement with the pulling run of the driving chain 21 of the conveyor. Said sprocket has a flange or friction disc 22 facing the membrane housing and is provided non-shiftable in the axial direction of the bearing housing 15. The complete driving unit for the roller is received in a housing 23 which is secured to the frame 12. An intermediate disc 24 is provided between the sprocket flange 22 and the membrane housing 16, freely rotatable on the slidable sleeve 28 through a ball bearing 25. Said intermediate disc 24 is also axially slidable relative to the shaft 13 in that a hub sleeve of the disc 24 is provided on the bearing housing 15 of the conveyor roller through a key connection 26. A compression spring 27 is received around the shaft 13 in a chamber of the bearing housing 15 and acts on the intermediate disc 24 through the slidable sleeve 28. In the inoperative condition, i.e. when pressurized air is not admitted to the membrane housing, the intermediate disc 24 engages, as shown, through the spring 27 a surface of the housing 23 through its right hand surface. The operation is as follows that when pressurized air is admitted to the membrane housing 16, 17, this housing moves to the left, overcomes the force of the spring 27 and pushes the intermediate disc 24 to the left whereby its left hand surface engages with the right hand surface of the flange 22 on the sprocket 20. Since the chain 21 is continuously driven, its driving force drives the roller 5 through the flange 22, the intermediate disc 24 and the key connection 26 with the bearing housing 15. It will be clear that the intermediate disc constitutes a friction clutch with the part 22 and the housing 23 situated at both sides thereof. The start of the roller drive occurs gradually because of said friction clutch, but also stopping takes place without shocks and yet quickly. For stopping the drive, e.g. when a carton engages the switching roller 6, the pneumatic switch 11 is actuated. If in the pneumatic circuit the occupied signal of the previous sone is given, the membrane housings of the relative zone are depressurized. Thereafter the spring 27 is allowed to push the intermediate disc 24 against the housing 24, so that this disc and therefore the conveyor roller 5 is quickly braked. Thereby only a short stopping length is required at the end of a conveyor part, since the carton quickly stops after switching off the drive. Preferably the housing 23 is manufactured from a resilient synthetic material whereby the bottom 29, after releasing snap elements (not shown), can be pivoted downwardly, as is shown with broken lines in figure 2. Thereafter the complete roller with its driving housing may be released from the chain for repairs or maintenance. Apart from pneumatic, the drive may also be mechanical, hydraulic or electrical. The pneumatic drive, however, is usually the most simple and most inexpensive.

Claims: 1. A roller conveyor of the accumulator conveyor type, adapted to be driven by an endless belt or chain drive (21), comprising rollers (5) which are axially fixed in place and mounted for rotation about a stationary shaft (13) having its ends fixedly mounted in a supporting frame (12), a drive wheel (20) mating with said belt or chain drive (21) and being mounted for rotation coaxially to the respective roller (5), a friction disc (24) being provided, which is in permanent driving connected with said roller (5) and adapted to be also drivingly connected with said drive wheel (20), an axially expandable actuation member (membrane) (16, 17) being supported by a house portion (23) on the supporting frame (12) at one roller end, said member (16, 17) being adapted to be pressure-activated so as to cause the friction disc (24) and the drive wheel (20) to axially engage one another characterized in that said friction disc (24) is slidably mounted relative to said roller (5) for movement between a first axial position ― corresponding to the inactivated state of the expandable member (16) ― in which it is spring-urged with an axial face in friction contact with a fixed wall portion of said housing (23), and a second axial position, in which it is urged by the pressure-expanded member (16) into driving engagement with an axial surface (22) of said drive wheel (20). 2. A roller conveyor according to claim 1, characterized in that the house portion (23) is formed to enclose the drive wheel (20) with its friction surface (22), the chain or belt (21), the friction disc (24) and the expandable member (16), said house portion (23) having a hinged bottom (29) which may be swung away from the return run of the chain (21). 3. A roller conveyor according to claim 2, characterized in that at least the lower part of the house portion (23) is formed from a resilient synthetic material permitting the swinging movement of the bottom (29). 4. A roller assembly for use in a roller conveyor according to claim 1, comprising a roller (5) which is axially fixed in place and mounted for rotation about a stationary shaft (13) having its ends fixedly mounted in a supporting frame (12), a drive wheel (20) adapted to mate with the belt or chain drive (21) of the conveyor and mounted for rotation coaxially to the roller (5), a friction disc (24) being provided, which is in permanent driving connection with said roller (5) and adapted to be also drivingly connected with said drive wheel (20), an axially expandable actuation member (membrane) (16, 17) being supported by a house portion (23) on the supporting frame (12) at one roller end, said member (16, 17) being adapted to be pressure-activated so as to cause the friction disc (24) and the drive wheel (20) to axially engage one another, and which is characterized in that said friction disc (24) is slidably mounted relative to said roller (5) for movement between a first axial position ― corresponding to the inactivated state of the expandable member (16) ― in which it is spring-urged with an axial face in friction contact with a fixed wall portion of said housing (23), and a second axial position, in which it is urged by the pressure-expanded member (16) into driving engagement with an axial surface (22) of said drive wheel (20).

Inventors: SCHIEDON, JOHANNES
Applicants: STORK CONVEYOR SYSTEMS B.V.
Application year: 1988
Main classification: B65G47
IPC codes: B65G47, B65G13