WO2020055310A1

WO2020055310A1 - Stop device for a conveyor system, conveyor system, and method of controlling a flow of objects by using the stop device

Info

Publication number: WO2020055310A1
Application number: PCT/SE2019/050844
Authority: WO
Inventors: Marko Salmi; Magnus Lindblad
Original assignee: Flexlink Ab
Priority date: 2018-09-11
Filing date: 2019-09-09
Publication date: 2020-03-19
Also published as: DE212019000373U1

Abstract

Stop device (1) for a conveyor system (40) comprising a body (2), a drive unit (3) attached to the body (2), a shaft member (4) rotationally arranged in the body (2) and a wheel (5) arranged to be driven by the drive unit (3), where a freewheeling slip clutch (6) is arranged between the wheel (5) and the drive unit (3). A conveyor system (40) comprising said stop device (1) and a method of controlling a flow of objects (42) on a conveyor track (41) by using said stop device (1) are also provided. The advantage of the invention is that a reliable, cost-effective and safe stop device for a conveyor system is provided.

Description

STOP DEVICE FOR A CONVEYOR SYSTEM, CONVEYOR SYSTEM, AND METHOD OF CONTROLLING A FLOW OF OBJECTS BY USING THE STOP DEVICE

TECHNICAL FIELD

The present invention relates to a stop device for a conveyor system, which can also be used to group products and to provide a spacing between products.

BACKGROUND ART

Conveying devices, such as those that are used for moving objects between different stations in a factory, usually comprise a conveying track in the form of a belt or a chain. The conveying tracks can be recessed in a trench with vertical side surfaces. Alternatively, they can be located on the horizontal upper surfaces of the trench or arranged in some other way.

The objects to be conveyed are arranged slidably in relation to the conveying tracks, either directly or via carrying means, which are also known as pallets. A specific type of pallet is a puck, which is a circular pallet adapted for smaller and more lightweight objects.

An object is conveyed along the conveying device, which comprises different workstations. Along the conveyor track, the object may be stopped by a stop member or the like such that an operation may be performed on the object. In some cases, the object may pass a specific work station without an operation being performed on the object. The stop member may for this reason be arranged to either stop the object or to let the object pass the workstation. A stop member may also be arranged along the conveyor track in between workstations in order to stop several objects in a queue. This will provide a buffer which is of advantage e.g. where different workstations have different operating times.

If the conveying device is of a conventional type, in which all workstations are positioned after each other and the operations on the objects are performed synchronous, every object will stop at each workstation. If no operation is to be performed on an object at a specific workstation, the object will have to wait until the operation on the previous object at that workstation is ready, until the object can continue. All objects are in this case released at the same time and moves at the same time. One advantage of such a system is that it is easy to predict the performance of the system. One disadvantage of such a system is that it is not very flexible. If the operating time at a specific workstation is long, all objects will have to wait for that time, even if there is no operation performed on all objects. Thus, such systems are mostly used for a single product or when the differences in the products are small.

In other systems, the operations on the objects are performed asynchronous, i.e. the object stops at a workstation where an operation is to be performed, and is released when the operation is ready. In such systems, a queue comprising a number of objects may thus be required at at least a few of the workstations in order to compensate for the different through-flow times of the objects and for the different operating times at a workstation.

In a normal queue, comprising either objects that stand directly on the conveyor track or objects conveyed by a pallet or a puck, the objects, pallets or pucks are allowed to bump into each other when they reach the end of the queue. This will create an impact on the stop member, especially if the queue is long or if the object is heavy. A pallet or puck may be provided with a damper or resilient member in order to minimize the impact force acting on the stop member, but this technology is only used on pallets or pucks that convey heavy objects. For freestanding objects or light pucks, no additional damping is normally used. Instead, the stop member is designed for the worst-case scenario. At the same time, there may be a desire to release objects from a stop member in a controlled manner, e.g. in order to provide a predefined spacing between the objects, or to group the objects in groups having a predefined number of objects. For this purpose, stop cylinders and/or screw feeders may be used. One problem with these is the safety aspect. In order to prevent a user to reach a stop cylinder or a screw feeder with e.g. a finger, protective safety covers must be used. Safety covers must be relatively large and long in order to provide the required safety.

There is thus room for improvements. DISCLOSURE OF INVENTION

An object of the invention is therefore to provide an inventive stop device for a conveyor system. Another object of the invention is to provide a conveyor system comprising at least one stop device. A further object of the invention is to provide a method for stopping, grouping and spacing objects.

The solution to the problem according to the invention is described in the characterizing part of claim 1. Claim 11 contains an advantageous conveyor system and claim 13 an advantageous method. The other claims contain advantageous embodiments and further developments of the stop device, the system and the method.

In a stop device for a conveyor system, comprising a body, a drive unit attached to the body, a shaft member rotationally arranged in the body, and a wheel arranged to be driven by the drive unit, the object of the invention is achieved in that a freewheeling slip clutch is arranged between the wheel and the drive unit.

By this first embodiment of the stop device according to the invention, a stop device that can stop an object completely, that can reduce the speed of an object, that can release objects with a predefined spacing and that can group objects in a group having a predefined size is provided. At the same time, the stop device will disengage its driving power if e.g. a finger is caught in the stop device, which will increase the safety of the stop device and which will provide the required safety without the need of protective covers. With such a stop device, a compact stop device with a spacing function is obtained. The stop device can be positioned at almost any position of a conveyor track, and can easily be adjusted in a longitudinal direction along the conveyor track or can be repositioned to a new position if the requirements changes.

The conveyor may be any type of conveyor in which an object of some kind moves from one position to another position. The most common type of conveyor is a conveyor in which objects or pallets are conveyed on an endless belt or chain driven by a motor. The conveyor track is in this case often arranged in a horizontal direction. A conveyor may also be a conveyor in which the objects slide or roll down a slope or a chute of some kind by gravity. The stop device according to the invention is suitable for all kinds of such conveyors.

The function of the stop device is controlled by the wheel driven by an electric motor of the drive unit, which in turn is controlled by the control system of the conveyor system. If the motor is stopped completely from running, the stop device will function as a regular stop device and an object will be stopped by the wheel. If the motor is driving the wheel with the same speed or a higher speed than the conveyor track, the objects will pass the stop device without being influenced by the stop device. The speed of the wheel is here to be understood as the circumferential speed of the wheel, i.e. when the circumference of the wheel moves with the same speed as the conveyor track, the speed of the wheel is said to equal the speed of the conveyor track. If the motor drives the wheel with a speed that is lower than the conveyor track, the objects will pass the stop device with the speed of the wheel, i.e. with a speed that is slower than the speed of the conveyor track. In this way, a spacing between each object is created. If the motor e.g. drives the wheel with a speed that is half of the speed of the conveyor track, each object will be spaced apart with a distance corresponding to the length of an object.

The stop device will further reduce the risk of an object being damaged by the stop device. When a screw feeder is used to space or group objects, each object must enter the screw feeder in a correct way with a proper orientation. If an object is misaligned, the object may be squeezed by the feed cylinder of the screw feeder. If pallets are used, the screw feeder itself may also be damaged by a misaligned pallet.

The stop device is suitable to be used with freestanding objects or with pallets that can carry an object. In one example, the object or the pallet is circular. In this case, the wheel is preferably a star wheel having a predefined number of tips and part-circular recesses arranged between the tips conforming to the shape of the object. It is also possible to use a belt, a rubber wheel or the like having a relatively high friction if rectangular objects or pallets are used. The stop device is provided with a freewheeling slip clutch that allows the wheel to be driven by the drive unit in one direction, and that will allow the wheel to disengage from the drive unit when the wheel is stopped and the drive unit continues to rotate, or when the wheel is pushed in the opposite rotational direction. This will be the case e.g. when the object flow of the conveyor is blocked completely. In this case, the stop device will not be able to push objects forwards, but the wheel will disengage from the drive unit and stop rotating while the drive unit continues to rotate. This will also be the case if a user inserts e.g. a finger at the wheel. The drive unit will not be able to catch the finger and to push it towards e.g. an edge of the conveyor, since the wheel will disengage from the drive unit. By a normal star wheel installation, where the wheel is fixedly attached to the drive unit, the finger would be forced towards e.g. an edge that could function as a scissors. The drive unit is adapted to rotate the wheel. The drive unit comprises an electric motor that is connected to a reduction gear, to which the shaft member is attached. The reduction gear may be a straight transmission or may be a worm gear. Preferably, a self-locking worm gear is used. The reduction gear is attached to a body of the stop device in which the shaft member is arranged. Preferably, the shaft member is supported by a roller bearing in the body. The wheel is arranged at the upper end of the shaft member. In one example, the slip clutch is integrated in a roller bearing, which is referred to as a freewheel bearing. The freewheel bearing is mounted on the upper end of the shaft member and the wheel is mounted on the freewheel bearing. This gives a compact and reliable solution. It is also possible to mount a slip clutch, e.g. a freewheel bearing, between the reduction gear and the shaft member. One advantage of using a freewheel bearing between the shaft member and the wheel is that the rotating mass is reduced and the friction of the roller bearing supporting the shaft member must not be considered.

For circular objects or pucks, the used wheel is preferably a star wheel having recesses conforming to the object or puck. In this way, an object or a puck can be completely stopped and held in a reliable manner, and can hold a train of objects or pucks pushing on the held object or puck. For elongated objects, such as rectangular objects or rectangular pallets, the wheel may be circular and is preferably provided with a friction surface that allows the wheel to stop and hold an object or pallet. The stop member may also be provided with a belt running on the wheel and a pulley. The friction surface of the circular wheel or the belt may be somewhat resilient such that the surface can adapt to the surface of the object or pallet. With a relatively long belt, a sufficient holding force can be provided.

BRIEF DESCRIPTION OF DRAWINGS The invention will be described in greater detail in the following, with reference to the embodiments that are shown in the attached drawings, in which

Fig. 1 shows a stop device according to the invention arranged on a conveyor beam, Fig. 2 shows a stop device according to the invention spacing objects,

Fig. 3 shows a stop device according to the invention grouping objects,

Fig. 4 shows a stop device according to the invention comprising a circular wheel, and

Fig. 5 shows a stop device according to the invention comprising a belt.

MODES FOR CARRYING OUT THE INVENTION

The embodiments of the invention with further developments described in the following are to be regarded only as examples and are in no way to limit the scope of the protection provided by the patent claims. References such as longitudinal, horizontal, vertical, right, left etc. refer to directions of a conveyor in normal use.

Figs. 1 to 3 show a view of a conveyor with a stop device according to the invention comprising a star wheel, Fig 4 shows a stop device comprising a circular wheel and Fig. 5 shows a stop device comprising a belt. The stop device is primarily intended to be used in conveyor systems adapted for lighter objects, where an object or a loaded pallet may weigh up to a few kg or less, but may with a proper design be suitable for much heavier objects or pallets.

The stop device 1 comprises a body 2, in the shown example provided with a mounting flange 7 such that the stop device can easily be mounted to a conveyor beam by the use of a T-slot of the conveyor beam. The body 2 is further provided with a lower flange 8 to which a drive unit 3 is attached. The drive unit 3 may be a standardized drive unit and comprises in the shown example an electric motor 9 and a reduction gear 10. The electric motor may be e.g. a DC-motor or a stepper motor and may comprise a rotational sensor that will detect the rotation of the electric motor and that will enable feedback for the motor driver. The reduction gear 10 is used to decrease the rotational speed of the electric motor to a rotational speed suitable for the wheel and that is adapted to the speed of the conveyor track. The reduction gear may be a straight transmission or may be a worm gear. In the shown example, a self-locking worm gear is used. The reduction gear is attached to the lower flange 8 of the body 2 and may be fixedly attached to the shaft member 4. The shaft member is arranged in the body with a rotational axis 11. The shaft member is supported by a roller bearing 12 arranged at the upper part of the body 2.

The wheel 5 is arranged at the upper end of the shaft member 4. In the shown example, the freewheeling slip clutch 6 is integrated in a roller bearing mounted on the upper end of the shaft member 4. The wheel 5 is mounted on the roller bearing. Such a combined freewheeling slip clutch and roller bearing is referred to as a freewheel bearing. This gives a compact and reliable solution. One advantage of using a freewheel bearing between the shaft member and the wheel is that the rotating mass is reduced and the friction of the roller bearing supporting the axle member must not be considered. It is also possible to mount a freewheeling slip clutch, e.g. a freewheel bearing, between the reduction gear 10 and the shaft member 4 at the lower end of the shaft member 4.

The wheel 5 is in a first example a star wheel 16 having a number of tips 14 and part-circular recesses 15 arranged between the tips. The part- circular recesses are adapted to the size of the object or puck that is to be handled by the stop device. In the shown example, the star wheel is provided with five tips and five part-circular recesses. The size of the wheel and the number of tips are dependent e.g. on the distance between the conveyor track and the rotational axis 11. The wheel may also be a circular wheel 17, e.g. a rubber wheel or the like, having an outer circumferential surface 18 with a relatively high friction. In this way, also rectangular objects or pallets may be handled by the stop device in a secure way without having to use specific protection covers. The stop device may also comprise a belt 19 and an additionally pulley 20 in order to be able to handle elongated objects.

The wheel may also be provided with a rotational sensor that will provide feedback information to a control system of the conveyor system. The control system will in this way be able to control the throughput of objects by controlling the speed and runtime of the wheel.

The stop device 1 is adapted to function as a stop member in a conveyor system 40, where the stop device 1 can stop objects 42 conveyed on a conveyor track 41. Other conveyor systems in which an object is conveyed by gravity may also be used. In the described example, a conveyor system comprising an endless conveyor chain will be used as a conveyor system. An object is in a first example a circular object and may be a freestanding object such as a can, jar or bottle, or may be a circular pallet, referred to as a puck, which can carry a product of some kind. In the described example, a puck will be used as an object. In this case, the stop device comprises a star wheel. A stop function can be performed in different ways. When there is a steady flow of pucks, the star wheel is allowed to rotate with the puck flow. This is done by letting the motor drive the star wheel with the same speed or a higher speed than the speed of the puck flow of the conveyor track. If the star wheel is rotated with a speed higher than the conveyor track, the slip clutch will allow the star wheel to adapt to the speed of the pucks. In a conventional system using a star wheel fixedly attached to the drive unit, it is important that the motor rotates the star wheel with exactly the same speed as the conveyor track in order to allow for the pucks to pass the stop device.

When the puck flow is to be stopped, the motor is stopped and the puck flow will consequently be stopped and the first puck in the remaining puck train will be held by the star wheel. By using a self-locking reduction gear, there is no need to provide a hold current to the motor. This situation is shown in Fig. 1. Here, a recess is aligned with a puck and the recess can be seen as parallel with the conveyor track. When the puck flow should continue, the star wheel is driven by the motor with the same speed as before, such that the stop device does not restrict the puck flow. The pucks will be driven by the conveyor track and the star wheel will let the pucks pass the stop device.

The speed of the wheel is here to be understood as the circumferential speed of the wheel, i.e. when the circumference of the wheel moves with the same speed as the conveyor track, the speed of the wheel is said to equal the speed of the conveyor track.

The stop device 1 can also stop one or more pucks that arrives at the stop device individually. Here, the star wheel may be oriented in any position and does not have to be oriented in a specific orientation to be able to stop a puck. When the puck arrives at the star wheel, one of the tips will stop the puck. The puck will be caught by a tip of the star wheel and the puck will be held in this position. When a second puck arrives, it will bear against the first puck. When one or more pucks are to be released, the star wheel is driven by the motor such that the star wheel rotates and releases one or more pucks. If only one puck is to be released, the motor will only drive the star wheel part of a revolution.

The stop device 1 is also adapted to space pucks with a predefined distance or to group pucks in groups having a predefined number of pucks. Fig. 2 shows an example where the stop device releases pucks with a predefined spacing. This is done by driving the star wheel with a speed slower than the speed of the conveyor track. If the star wheel is driven by the motor with half the speed of the conveyor track, the spacing between two pucks will correspond to the length of a puck. By adapting the speed of the motor, the spacing between the pucks can be selected freely.

The stop device 1 is further adapted to group pucks in groups having a number of pucks. The size of a group can be predefined or may be adapted to actual requirements of the conveyor system. Fig. 3 shows an example where the stop device groups pucks in groups of two. This is done by rotating the star wheel such that two pucks are released, and then by stopping the star wheel for a period of time before the star wheel is rotated again to release two new pucks. The size of a group and the spacing between two groups can be selected freely. In this way, groups comprising two, three, four or more pucks can be obtained, and the spacing between the groups can vary. It is also possible to create groups having a varying number of pucks, and to vary the distance between two groups. Since the stop device 1 is provided with a freewheeling slip clutch, a safe stop device is provided. The star wheel will for this reason not be able to push a puck forwards on the conveyor track, but can only let pucks pass with the speed of the conveyor track or can restrict the speed of pucks passing the stop device. If the flow of pucks is blocked downstream of the stop device, the star wheel will disengage from the shaft member and will not be able to push any pucks forwards, while the motor continues to spin with the same speed as before. A conventional star wheel arrangement would continue to drive pucks forwards, which could damage both the star wheel and the pucks.

If a user puts e.g. a finger in the star wheel, the star wheel will also disengage from the shaft member. There is thus no risk for injuries with the inventive stop member. A user may remove or add pucks to the puck flow without the risk of being caught by the star wheel. In this way, there is no need to use protective covers over and around the stop member. Since a protective cover may have to extend up to 80 cm or more from the stop member in each direction, space can be saved. At the same time, it is easy to move a stop member to a new position or to add a stop member to a conveyor track. In another example, shown in Fig. 4, the stop device is adapted to handle rectangular or elongated objects, here an elongated pallet. In this example, the wheel 5 is a circular wheel 17 having an outer friction surface 18 that may be somewhat resilient in order to be able to stop and hold the pallet. By rotating the circular wheel with the same or a higher speed than the speed of the conveyor track, the wheel will allow the pallets to pass without restricting the pallet flow. By rotating the wheel with a lower speed, the speed of the pallet is decreased, and each pallet will be released with a spacing. The distance between two pallets is determined by the speed of the wheel. By stopping the wheel, a pallet is stopped and is held by the wheel. A group of pallets is obtained by rotating the wheel with the same speed as the conveyor track until the desired number of pallets has passed, and then by stopping the wheel for a desired time period, until the next group is released. The spacing between two groups depends on the waiting time. Also in this example, a safe stop device is provided, where a user may insert a finger without the risk of injury. Additional protective covers are thus not necessary.

It is also possible to provide the stop device with a circular wheel 17 and an additional pulley 20, where a belt 19 is arranged on the circular wheel 17 and the pulley 20. The circular wheel 17 is provided with a freewheeling slip clutch 6 and the pulley 20 is provided with a roller bearing. The belt 19 will provide a longer contact surface that may be advantageous when elongated objects are to be handled, as is shown in Fig. 5.

The invention is not to be regarded as being limited to the embodiments described above, a number of additional variants and modifications being possible within the scope of the subsequent patent claims. The stop device may have any size and may be made from any suitable material.

REFERENCE SIGNS

1 : Stop device

2: Body

3: Drive unit

4: Shaft member

5: Wheel

6: Freewheeling slip clutch 7: Mounting flange 8: Lower flange

9: Electric motor

10: Reduction gear

1 1 : Rotational axis

12: Roller bearing

14: Tip

15: Part-circular recess

16: Star wheel

17: Circular wheel

18: Outer surface

19: Belt

20: Pulley

40: Conveyor system

41 : Conveyor track

42: Pallet

Claims

1. Stop device (1) for a conveyor system (40), comprising a body (2), a drive unit (3) attached to the body (2), a shaft member (4) rotationally arranged in the body (2) and a wheel (5) arranged to be driven by the drive unit (3), characterized in that a freewheeling slip clutch (6) is arranged between the wheel (5) and the drive unit (3).

2. Stop device according to claim 1, characterized in that the freewheeling slip clutch (6) is arranged between the wheel (5) and the shaft member (4).

3. Stop device according to claim 1, characterized in that the freewheeling slip clutch (6) is arranged between the shaft member (4) and the drive unit (3).

4. Stop device according to any of claims 1 to 3, characterized in that the freewheeling slip clutch (6) is integrated in a roller bearing.

5. Stop device according to any of claims 1 to 4, characterized in that the wheel (5) is a star wheel (16) having a number of tips (14) and part-circular recesses (15) arranged between the tips (14).

6. Stop device according to any of claims 1 to 4, characterized in that the wheel (5) is a circular wheel

7. Stop device according to claim 6, characterized in that the outer surface (18) of the circular wheel (17) is provided with a rubber material.

8. Stop device according to any of claims 6 or 7, characterized in that the outer surface (18) of the circular wheel (17) is resilient.

9. Stop device according to any of claims 6 to 8, characterized in that the stop device is additionally provided with a belt (19) and a pulley (20).

10. Stop device according to any of claims 1 to 9, characterized in that the body (2) is provided with a mounting flange (7).

11. Conveyor system (40) adapted to convey objects (42), characterized in that the conveyor system (40) comprises at least one stop device (1 ) according to any of claims 1 to 10.

12. Conveyor system according to claim 11, characterized in that the conveyor system (40) is adapted to convey objects (42) on a conveyor track (41 ).

13. Method of controlling a flow of objects on a conveyor track by using a stop device according to claim 1 , comprising the steps of:

- driving the wheel with a speed higher than or equal to the speed of the conveyor track when the objects are to pass the stop device uninterrupted,

- driving the wheel with a speed lower than the speed of the conveyor track when the objects are to be spaced apart from each other, - disengaging the wheel from the shaft member when the object is stopped by an external force, and

- stopping the wheel when an object is to be stopped by the stop device.

14. Method according to claim 13, further comprising the steps of grouping objects:

- driving the wheel with a speed higher than or equal to the speed of the conveyor track until a predefined number of objects has passed the stop device in order to obtain a group of objects,

- stopping the wheel for a predefined time period in order to create a desired spacing between the groups of objects, repeating the steps of grouping objects.