WO2009035390A1

WO2009035390A1 - A pallet, a pallet system and a locating module

Info

Publication number: WO2009035390A1
Application number: PCT/SE2007/050654
Authority: WO
Inventors: Göran Abbestam
Original assignee: Flexlink Components Ab
Priority date: 2007-09-14
Filing date: 2007-09-14
Publication date: 2009-03-19

Abstract

Pallet (1) for a conveyer system, comprising a body (2) having at least one central locating aperture (10a, 10b), a first guide disc (3) with a first slide plate (9) and a second guide disc (4) with a second slide plate (10), where the pallet (1) further comprises an index plate (7; 107) having a first locating aperture (15a; 115a) and a second locating aperture (16a, 116a), where the first locating aperture (15a; 115a) and the second locating aperture (16a, 116a) are adapted to define a first and a second rest position for the pallet when interacting with a positioning pin (21, 22) in a locating module (20).

Description

A PALLET, A PALLET SYSTEM AND A LOCATING MODULE

TECHNICAL FIELD

The present invention relates to a pallet with a plurality of index positions for a conveyor system.

BACKGROUND ART

Conveying devices, such as those which 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 supporting means, which are also known as pallets.

A pallet is conveyed along the conveying device comprising different work stations. In some cases, every work station will perform one operation on the transported object. In those cases, the work flow is designed such that every pallet will stop at every work station. In other cases, for example when different products or different versions of the same product are produced in the same product flow, all pallets do not have to stop at all the work stations.

When the pallet is stopped at a work station, it is often important that the position at which the pallet stops is well defined and repeatable. The accuracy of the stop position is determined by the goods produced or handled by the system. In some cases, a low accuracy is enough, and a simple stop mechanism acting on the front guide disc, also referred to as a puck, can be used. In more demanding applications, a higher accuracy is required. In those cases, a locating module is used. A locating module comprises a locating pin that is adapted to interact with a bushing in the pallet. When a pallet is stopped at a work station, the locating pin is raised from below into the locating bushing. The top of the locating pin and/or the entrance of the locating bushing is provided with a bevel so that the locating pin can enter the bushing in an easy way, allowing a slight misalignment before the locating pin is raised. The bushing and the locating pin are precision machined, giving a high accuracy and repeatability to the positioning of the pallet.

When the pallet is positioned at the predefined position, the work operation can be performed on the object carried by the pallet. In some work stations, one operation is performed on an object. The object is then moved to the next work station, where the same or a similar operation at a different position on the object is performed. It may be impossible or at least difficult and expensive to move the head of the work station to another position. Instead, the work station is duplicated and the pallet is stopped at a different position at that work station, allowing an operation at the new position. In some cases, it may simpler and cheaper to have two different work stations performing the same operation on different position, than to move the head of the work station and/or the pallet.

In other work stations, more operations may be performed. Depending on the type of work station and the type of operation performed, the head of the work station can be moved in order to perform more operations. In other work stations, the goods, and thus the pallet, must be moved in order to perform more operations. One way of moving the pallet is to use a linear actuator that moves the complete locating module, or to integrate a linear actuator that moves the pallet in the locating module. If the pallet only has to be moved to a few different positions, this is an expensive and complicated solution. There is thus room for improvements. Replacement sheet PCT/SE2007/050654 DISCLOSURE OF INVENTION

An object of the invention is therefore to provide a pallet adapted for a plurality of rest positions in a conveyor system.

A further object of the invention is to provide a pallet system comprising interchangeable index plates. Another object of the invention is to provide a locating module enabling a plurality of rest positions.

The solution to the problem according to the invention is described in the characterizing part of claim 1. Claim 8 contain an advantageous pallet system. Claim 10 contain an advantageous locating module. The other claims contain advantageous embodiments and further developments of the pallet.

In a pallet for a conveyer system, comprising a body having at least one central locating aperture, a first guide disc with a first slide plate and a second guide disc with a second slide plate, the object of the invention is achieved in that the pallet further comprises an index plate having a first locating aperture and a second locating aperture, where the first locating aperture and the second locating aperture are adapted to define a first and a second rest position for the pallet when interacting with a locating pin in a locating module.

By this first embodiment of the pallet according to the invention, a pallet with more than one rest position is obtained. This is advantageous in that a pallet can be held at different positions at a work station. This allows the work station to be used in a more efficient way.

In an advantageous development of the invention, the index plate comprises an elongated recess adapted to define a stop position for the pallet, corresponding to the second rest position, when interacting with a positioning pin in the locating module. The advantage of this is that the stop position can be changed by exchanging the index plate. In this way, complete system must not be changed. In another advantageous development of the invention, the index plate comprises a further elongated recess.

In another advantageous development of the invention, the pallet further comprises a positioning plate having a first locating aperture and a second locating aperture. This gives a higher accuracy and stability to the system, since two locating pins can be used.

In another advantageous development of the invention, the positioning plate comprises an elongated aperture adapted to actuate a sensor in the locating module. This gives the system a signal of when to raise the positioning pin. In another advantageous development of the invention, the positioning plate comprises a further elongated aperture.

In a pallet system, comprising an inventive pallet, the system further comprises a second index plate being of a different type. This is advantageous in that the same pallet can be used for different conveyor system, e.g. being set up for different work stations using different rest positions.

In a locating module for the inventive pallet, the locating module comprises a locating pin and a positioning pin adapted to interact with an elongated recess in the index plate. This is advantageous in that a pallet can be held in different rest positions by the locating module. This allows a work station to be used in a more efficient way, e.g. by allowing the same operation at different positions.

In an advantageous further development of the inventive system, the locating module further comprises a sensor adapted to interact with an elongated aperture in the positioning plate. This is advantageous in that a signal is obtained from the pallet of when to raise the positioning pin of the locating module. 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 first embodiment of a pallet according to the invention from below,

Fig. 2 shows a second embodiment of the pallet according to the invention from below, and

Fig. 3 shows a first embodiment of a locating module according to the invention.

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.

Fig. 1 shows a first embodiment of a pallet for a conveyor system according to the invention from below. The pallet 1 comprises a body 2, a first guide disc 3 and a second guide disc 4. The guide discs 3, 4 are located at the underside of the body, i.e. underneath the body. The body is preferably made from a light but stiff material, such as an aluminium alloy or a plastic composite. The body may be produced using injection moulding. The guide discs are fitted to the body.

The pallet further comprises a central locating aperture 10a located at the outer periphery of the body. In order to obtain an increased accuracy, the pallet may be provided with a second central locating aperture 10b, positioned at the opposite periphery of the pallet. The locating apertures are precision machined in order to obtain a high accuracy, e.g. by milling or grinding. The locating apertures are used when a pallet is stopped at a work station in order to obtain a high accuracy. The pallet is stopped at a work station using a simple stop mechanism acting on the front guide disc. This position is referred to as a normal stop position. If a higher accuracy is required, a locating module is used, holding the pallet in a high accuracy position referred to as a rest position. A locating module comprises in this example two locating pins positioned at each side of the conveyor track, that are adapted to interact with the locating apertures 10a, 10b in the pallet.

When a pallet is stopped at a work station, the locating pins are raised from below, into the locating apertures. The locating pins are also precision machined, e.g. by turning or grinding. The top of a locating pin and/or the entrance of a locating aperture is provided with a bevel so that the locating pin can enter the locating aperture in an easy way, allowing a slight misalignment before the locating pin is raised. With the locating pins raised, the pallet is held firmly in a rest position, allowing a high accuracy operation to be performed on the goods carried by the pallet. Such a pallet is well-known to the skilled person and is commonly used in present conveyor systems.

The first embodiment of the inventive pallet 1 further comprises an index plate 7 and a locating plate 8 fixedly attached to the body 2. The index plate and the locating plate are preferably attached to the body in a way that allows them to be removed or replaced, e.g. using screws. It is also possible to integrate the index plate and the locating plate in the housing, if there is no need to remove, replace or exchange them. The index plate 7 comprises a first locating aperture 15a, a second locating aperture 16a and an elongated recess 9 having a positioning edge 12. The locating plate 8 comprises a first locating aperture 15b and a second locating aperture 16b. The elongated recess 9 is adapted to interact with a positioning pin in the locating module. Fig. 3 shows an inventive locating module 20 having a first locating pin 21 , a second locating pin 22, a positioning pin 23 and a sensor 24. The first locating pin 21 is adapted to interact with locating apertures 15a and 16a in the first embodiment. The second locating pin 22 is adapted to interact with locating apertures 15b and 16b in the first embodiment. The shape of the positioning pins is selected such that the pins will not jam in the pallet. The positioning pin 23 is adapted to interact with the elongated recess 9. The locating module also comprises a conventional stop mechanism 25.

The index plate 7 and the locating plate 8 provide the pallet with the possibility to be held in two different rest positions at a work station. By doing this, the work station can be used in a more efficient way in some cases, and an extra work station can in some cases be omitted from the system.

When an inventive pallet with indexing possibilities is stopped in a first position at a work station using the locating module 20, the locating pins 21 and 22 are raised into the first locating apertures 15a and 15b, holding the pallet in a first rest position. When the work operation at the first rest position is finished, the locating pins are lowered, allowing the pallet to continue travelling on the conveyor track. This is detected by the system, using e.g. suitable detectors. When the pallet has travelled somewhat, the positioning pin 23 is raised into the elongated recess 9. With the positioning pin 23 raised into the recess 9, the pallet can only move until the positioning edge 12 of the recess hits the positioning pin. The pallet is now in a second position and the locating pins 21 , 22 are raised into the second locating apertures 16a and 16b, giving a second high precision rest position, in which a new operation can be performed on the goods carried by the pallet. When the work operation at the second rest position is finished, the locating pins are lowered, allowing the pallet to continue travelling to the next work station. When the pallet leaves the first position in the direction to the second position, the positioning pin must be raised before the positioning edge passes the positioning pin. The moment at which the positioning pin should be raised can be determined in different ways. One possibility is to simply measure the time from the release of the pallet from the first position. Since the speed of the conveyor track is known, an appropriate time delay for the positioning pin can be determined.

In a further embodiment of the inventive pallet, the locating plate 8 comprises an elongated aperture 11. The elongated aperture 11 is used, together with a sensor 24, to determine a time delay for the raising of the positioning pin 23. The sensor 24 is positioned at the conveyor track in a position close to a locating pin, at an axle aligning the locating pins 21 , 22, and is in this example laid out to detect the elongated aperture 11. When the pallet is released from the first position, i.e. when the locating pins 21 , 22 are lowered, the signal from the sensor is measured at the same time. In this example, the sensor gives a high output when the aperture 11 is in front of the sensor. In this position, the aperture 11 is present and thus, the signal from the sensor is high. When the pallet moves, the edge 17 of the elongated aperture 11 will pass the sensor. When the edge has passed the sensor, the output of the sensor will change to low. By using a flank trigged input in the control system, the end of the elongated aperture 11 can be detected. This signal in turn is used to raise the positioning pin 23.

In a second embodiment of the invention, the index plate 107 comprises a first elongated recess 109 having a first positioning edge 112 and a second elongated recess 113 having a second positioning edge 114. The second elongated recess 113 is positioned on the same longitudinal axis as the first elongated recess 109. The first and second elongated recesses are adapted to interact with the positioning pin 23 in the locating module. The index plate 107 and the locating plate 108 provide the pallet with the possibility to be held in three different rest positions at a work station. When a pallet with an index plate 107 is stopped in a first position at a work station using the locating module 20, the locating pins 21 and 22 are raised into the first locating apertures 115a and 115b, holding the pallet in a first rest position. When the work operation at the first rest position is finished, the locating pins are lowered, allowing the pallet to continue travelling on the conveyor track. This is detected by the system, using e.g. suitable detectors. When the pallet has travelled somewhat, the positioning pin 23 is raised into the elongated recess 109. With the positioning pin 23 raised into the recess 109, the pallet can only move until the positioning edge 112 of the recess hits the positioning pin. The pallet is now in a second position and the locating pins 21 , 22 are raised into the central locating apertures 110a and 110b, giving a second high precision rest position, in which a new operation can be performed on the goods carried by the pallet. When the work operation at the second rest position is finished, the locating pins are lowered, allowing the pallet to continue travelling on the conveyor track.

When the pallet has again travelled somewhat, the positioning pin 23 is raised into the elongated recess 113. With the positioning pin 23 raised into the recess 113, the pallet can only move until the positioning edge 114 of the recess hits the positioning pin. The pallet is now in a third position and the locating pins 21 , 22 are raised into the second locating apertures 116a and 116b, giving a third high precision rest position, in which a new operation can be performed on the goods carried by the pallet. When the work operation at the third rest position is finished, the locating pins are lowered, allowing the pallet to continue travelling to the next work station.

When the pallet leaves the first position in the direction to the second position, or when the pallet leaves the second position in the direction to the third position, the positioning pin must be raised before the positioning edge passes the positioning pin. The moment at which the positioning pin should be raised can be determined in different ways as described above.

In a further embodiment of the inventive pallet, the locating plate 108 comprises a first elongated aperture 111 and a second elongated aperture 118. The elongated apertures are used, together with a sensor 24, to determine a time delay for the raising of the positioning pin 23. The determination of when to raise the positioning pin 23 into the first elongated aperture 111 and the second elongated aperture 118 is done in the same way as described above, i.e. for the pallet with the locating plate 8.

When the pallet is released from the first rest position, i.e. when the locating pins 21 , 22 are lowered, the output signal from the sensor 24 is high. When the pallet moves, the edge 117 of the first elongated aperture 111 will pass the sensor. When the edge has passed the sensor, the output of the sensor will change to low. By using a flank trigged input in the control system, the end of the first elongated aperture 111 can be detected. This signal in turn is used to raise the positioning pin 23 into the elongated recess 109. When the positioning pin 23 bears on the edge 112, the locating pins 21 , 22 are raised into the central locating apertures 10a, 10b. The pallet is now in the second rest position.

When the operation at the second rest position is finished, the locating pins are lowered, and the output signal from the sensor 24 is again high. When the pallet moves, the edge 119 of the second elongated aperture 118 will pass the sensor. When the edge has passed the sensor, the output of the sensor will change to low. By using a flank trigged input in the control system, the end of the second elongated aperture 118 can be detected. This signal in turn is used to raise the positioning pin 23 into the second elongated recess 113. When the positioning pin 23 bears on the edge 114, the locating pins 21 , 22 are raised into the second locating apertures 116a, 116b. The pallet is now in the third rest position. In a pallet system according to the invention, a pallet and a plurality of index plates are comprised. By using this pallet system, a pallet can easily be adapted to suit different requirements. In this way, the same pallet can be used for objects that are to be held in one, two or more rest positions at the same work station. By using index plates having elongated recesses with different lengths, different rest positions can also be obtained. Thus, both the number of rest positions and the absolute position for theses rest positions can be altered with the inventive pallet system.

In the inventive locating module 20, a locating pin 23 is comprised. The locating pin is, as described above, used with pallets comprising index plates in order to position the pallet in two or three different rest positions at the same work station. Apart from the locating pin, the locating module is well known to the skilled person. Therefore, the locating module is not described further. In an embodiment of the inventive locating module, a sensor 24 adapted to detect an elongated aperture is also comprised.

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. For example, other index plates and other locating plates that are adapted for more or other positions are also possible. The position and design of the locating pins, the positioning pin, the elongated recesses, the elongated apertures, the locating apertures and the sensor can be selected depending on the system in which the pallet is used.

REFERENCE SIGNS

1 : Pallet

2: Body

3: First guide disc

4: Second guide disc

5: First slide plate

6: Second slide plate

7: Index plate

8: Positioning plate

9: Elongated recess

10a, b: Central locating aperture

11 : Elongated aperture

12: Positioning edge

15a, b: First locating aperture

16a, b: Second locating aperture

17: Sensor edge

20: Locating module

21 : Locating pin

22: Locating pin

23: Positioning pin

24: Sensor

25: Stop

107: Index plate

108: Positioning plate

109: First elongated recess

111 : First elongated aperture

112: First positioning edge

113: Second elongated recess

114: Second positioning edge

115a, b: First locating aperture

116a, b: Second locating aperture

117: First sensor edge

118: Second elongated aperture

119: Second sensor edge

Claims

Replacement sheet PCT/SE2007/050654CLAIMS

1. Pallet (1) for a conveyer system, comprising a body (2) having at least one central locating aperture (10a, 10b), a first guide disc (3) with a first slide plate (9) and a second guide disc (4) with a second slide plate (10), characterized in that the pallet (1) further comprises an index plate (7; 107) having a first locating aperture (15a; 115a) and a second locating aperture (16a, 116a), where the first locating aperture (15a; 115a) and the second locating aperture (16a, 116a) are adapted to define a first and a second rest position for the pallet when interacting with a locating pin (21, 22) in a locating module (20).

2. Pallet according to claim 1, characterized i n that the index plate (7, 107) comprises an elongated recess (9; 109) adapted to define a stop position for the pallet, corresponding to the second rest position, when interacting with a positioning pin (23) in the locating module (20).

3. Pallet according to claim 2, cha racterized in that the index plate (107) comprises a further elongated recess (113) adapted to define a stop position for the pallet, corresponding to a third rest position, when interacting with the positioning pin (23) in the locating module (20).

4. Pallet according to one of the preceding claims, characterized in that the pallet further comprises a positioning plate (8, 108) having a first locating aperture (15b; 115b) and a second locating aperture (16b, 116b).

RECT^IFIED SHF^T mi M E 91)

5. Pallet according to claim 4, ch a racterized i n that the positioning plate (8, 108) comprises an elongated aperture (11; 111) adapted to actuate a sensor (24) in the locating module (20).

6. Pallet according to claim 5, ch a racterized i n that the positioning plate (108) comprises a further elongated aperture (118) adapted to actuate the sensor (24) in the locating module (20).

7. Pallet according to claim 5 or 6, cha racterized i n that the actuation of the sensor (24) gives information to the control system about when to raise the positioning pin (23).

8. Pallet system, comprising a pallet according to any of claims 1 to 7, ch a racterized i n that the system further comprises a second index plate (7, 107) being of a different type.

9. Pallet system according to claim 8, ch a racterized i n that the index plates (7, 107) determines the number of rest positions for the pallet in a locating module.

10. Locating module for a pallet according to any of claims 1 to 7, ch a racterized i n that locating module (20) comprises a locating pin (21, 22) and a positioning pin (23) adapted to interact with an elongated recess (9, 109, 113) in the index plate (7; 107).

11. Locating module for a pallet according to claim 10, ch a racterized i n that locating module (20) further comprises a sensor (24) adapted to interact with an elongated aperture (11, 111, 118) in the positioning plate (8; 108).