WO2006010368A1

WO2006010368A1 - Accumulating conveyor system

Info

Publication number: WO2006010368A1
Application number: PCT/DK2005/000511
Authority: WO
Inventors: Ole D. Jensen; Kristian Grøn Thaagaard ANDREASEN
Original assignee: Jensen Ole D; Andreasen Kristian Groen Thaag
Priority date: 2004-07-30
Filing date: 2005-07-27
Publication date: 2006-02-02
Also published as: EP1778569A1

Abstract

The present invention relates to an accumulating conveyor system (1) comprising a conveyor surface (2), a number of carriers (3), one or more conveying members (4), a number of drive wheels (5), a number of drives (6), a control system, where the carri ers (3) are attached to the conveying members (4), where each of the conveying members (4) are arranged as endless members around the drive wheels (5), where a movement of the conveying members (4) are caused by the drives (6) and controlled by the control system, and where the carriers (3) comprise a :frame (7) which is provided with at least two sets of wheels (8, 9), wherein the frame (7) encloses the sets of wheels (8, 9), which are vertically and horizontally displaced in the frame (7), and where a first set of wheels (8) comprises at least two juxtaposed wheels (14), which are adapted to move along the conveyor surface (2), and a second set of wheels (9) comprising at least two juxtaposed wheels (15), which are adapted to support a part placed entirely or partly on the carrier (3).

Description

Accumulating conveyor system

Field of the invention

The present invention relates to an accumulating conveyor system comprising a con¬ veyor surface, a number of carriers, one or more conveying members, a number of drive wheels, a number of drives, a control system, where the carriers are attached to the conveying members, where each of the conveying members are arranged as end¬ less members around the drive wheels, where a movement of the conveying members is caused by the drives and controlled by the control system, and where the carriers comprise a frame which is provided with at least two sets of wheels.

Background of the invention

In a production company where products are produced continuously, it is important that the separate parts are ready and available at the right place and at the right time, as it is costly to stop the production due to a supply failure, both as regards employees and machinery.

Two different methods of production exist:

The first method is the just-in-time method (JIT method) where every part arrives at the correct production destination right on time. The disadvantages and the advantages of the JIT method are that:

+ The need for large storage areas is reduced.

+ The number of waste/excessive parts during or after production is reduced. ÷ A very strict control is required concerning the logistical procedures regarding every single part and assembly of the parts. This control is costly, as it requires a comprehensive computer system. ÷ The risk of interrupting the production due to either supply failures or damage of the production parts is not reduced significantly.

A second method is the storage flow production method (SFP method), where every part is kept in stock, and new parts are ordered before the stock is run down. The advantages and disadvantages of the SFP method are that:

+ In principle it is very simple to control the stock and to order new parts. Fur- thermore, the method only requires a limited computer system.

+ The risk of interrupting the production due to either supply failures or damage of production parts is reduced significantly, as every part is kept in stock.

÷ Storage areas are needed to store the separate parts.

÷ The method results in a number of waste/excessive parts during or after produc- tion.

All over the world these different methods of production are used at random according to different company policies, product production or the storage area on the production site.

When opting for a storage flow production method, an efficient storage system is vital. Typically, the storage systems are either manually operated by a couple of persons or operated semi-automatically e.g. operated by persons and conveyors/elevators or oper¬ ated fully automatically e.g. by robots.

One type of storage system relies on accumulating conveyors, where the parts are loaded onto an accumulating conveyor and brought to the other end of the accumulat¬ ing conveyor continuously or in step. The parts are stacked/piled on a line and brought forward, when the part lying first in line is removed. Hence the parts are removed from the exact same position every time, while other parts are stored on the accumu¬ lating conveyor.

At present several types of accumulating conveyors are applied e.g. accumulating con¬ veyors provided with motorized rollers, belt conveyors provided with carriers, chain conveyors and the like.

US 5,746,304 describes an accumulating chain conveyor, where a chain is provided with a number of rollers, upon which the parts can be placed and conveyed. The dis- advantages of this kind of accumulating conveyor are that only a limited contact sur¬ face between the parts and the rollers exist, hence it is necessary either to apply a num¬ ber of accumulating chains side by side in order to support small parts or to use a large support pallet upon which the small parts can be placed.

Many accumulating conveyors working side by side is a very costly solution. Further¬ more, if the parts moving across one or several accumulating chain conveyors, the chain conveyors must be exactly positioned, otherwise it is difficult to determine where the parts end.

US 5,873,452 and US 5,735,384 disclose an accumulating conveyor provided with carriers which span across two chains and which are attached to both chains. The dis¬ advantages of this kind of accumulating chain conveyor are that it is time-consuming to assemble the carriers on the chains and that the chains must be adjusted to allow the carriers to move along the accumulating conveyor in an orderly manner.

Furthermore, the surface of these carriers is flat or provided with a number of pins allowing very good conveying of the parts placed on the carriers. When the parts reach the end of the accumulating conveyor they stop moving or are pushed over the surface of the underlying moving carriers which may cause the parts to become damaged.

If the accumulated conveyor stops, when the first part reaches the end of the accumu¬ lated conveyor, there is likely to be gaps between the parts conveyed, meaning that the storage capacity of the accumulated conveyor is not exploited to the outmost.

US 3,967,721 discloses an accumulating conveyor which is provided with an endless rope, having a number of carriers attached to it. Once more the problem is that when the parts reach the end, they stop moving or are pushed over the surface of the under¬ lying moving carriers.

US 6,315,104 discloses a type of accumulating conveyor which is provided with a number of rollers each roller being motorized. The accumulating conveyor is very costly as the motorized roller is very expensive and a large control system is needed to control the rollers efficiently. Furthermore, the parts are handled in a very uncaring way as the parts move from one roller to another on the accumulating conveyor.

Where all the rollers are unmotorized, it is necessary to handle each part manually, meaning that it is very time-consuming and often hard work to ensure that a part is stopped at the end of the accumulating conveyor at all times.

Lastly, conveyor belts provided with protruding wheels are known, the parts being supported by the wheels. However, the disadvantage of these conveyor belts is that they need extra power to drag the conveyor belt, as opposed to a chain conveyor. Fur¬ thermore, a durable conveyor belt is costly and the risk of damage or failure is high.

US 5,096,050 discloses a type of accumulating conveyor belt, which on the upper side of the conveyor belt is provided with a number of rows of wheels. The disadvantage of this accumulating conveyor belt is that the accumulating conveyor belt is provided by interlinking a number of individual links, hence it is necessary to use many wheels, and the underside of the conveyor belt will be dragged alongside the underlying sup¬ port causing wear of the support and the conveyor belt.

Object of the invention

An object of the present invention is to provide an automatically accumulating con¬ veyor system, allowing optimum accumulation of parts and at the same time protects the conveyed parts. A second object of the present invention is to provide an accumu¬ lating conveyor system, which is manufactured at low costs and which is easily oper- ated. A third object of the present invention is to provide an accumulating conveyor system, which requires low maintenance.

This is achieved with an accumulated conveyor system according to the preamble of claim 1 , wherein the frame encloses the sets of wheels, which are vertically and hori- zontally displaced in the frame, and where a first set of wheels comprises at least two juxtaposed wheels, which are adapted to move along the conveyor surface, and a sec¬ ond set of wheels comprising at least two juxtaposed wheels, which are adapted to support a part placed entirely or partly on the carrier. Description of the invention

The accumulating conveyor system according to the present invention comprises a conveyor surface, a number of carriers, one or more conveying members, a number of drive wheels, a number of drives, a control system, where the carriers are attached to the conveying members, where each of the conveying members are arranged as end¬ less members around the drive wheels, and where movement of the conveying mem¬ bers are caused by the drives and controlled by the control system, and where the car¬ riers comprise a frame, which is provided with at least two sets of wheels, whereby it is possible to optimize accumulation of parts and which at the same time protects the conveyed parts

To ensure optimum accumulation of the parts conveyed, the carriers comprise a frame which encloses the sets of wheels, which are vertically and horizontally displaced in the frame, and where a first set of wheels comprises at least two juxtaposed wheels, which are adapted to move along the conveyor surface, and a second set of wheels comprising at least two juxtaposed wheels, which are adapted to support a part placed entirely or partly on the carrier.

The vertically displaced configuration of the two wheel sets in the frame makes it pos¬ sible to move a first part to the end of the accumulating conveyor and consequently move the following parts in the line reducing the space between the parts on the accu¬ mulating conveyor.

Due to the fact that the parts in line simply roll on the moving carrier's second set of wheels, they maintain their position while the following parts are being moved by the carrier until they reach the other parts in line.

This kind of accumulation is possible because of the second set of wheels, and it is very gentle towards the parts as the surface of the moving carrier is not in contact with the parts, thus it cannot damage or wear out the parts. The juxtaposed wheel configuration of the two wheel sets makes it possible to use narrower wheels while at the same time securing sufficient contact surface for the transport of the parts on the carrier. Using narrower wheels allows manufacturing of the accumulating conveyor system at low costs.

It is important that the carriers move steadily along the conveyor surface. Hence the wheel sets must be arranged in the frame such as to obtain stability of the carrier.

According to a preferred embodiment of the present invention the first set of wheels comprises at least two sets of juxtaposed wheels, where the juxtaposed wheels are arranged at the front of the frame, and the juxtaposed wheels are arranged at the rear end of the frame, and the second set of wheels comprises the juxtaposed wheels which are arranged between the front and rear wheels of the first set of wheels in the frame..

The second set of wheels comprises one or more wheels which are arranged between the front and the rear wheels of the first set of wheels in the frame. The wheels of the first set of wheels are arranged at the front and at the rear end of the frame, while one wheel is arranged in each corner of the frame ensuring stability, meaning that it is vir¬ tually impossible to turn or tip over the carrier, thus allowing the parts to move safely along the accumulating conveyor.

The second set of wheels is arranged between the wheels of the first set of wheels and is arranged in a scattered pattern as to provide the best support surface for the parts conveyed. Other configurations of the wheel sets are possible. However, the stability of the frame must be maintained regardless of the configuration.

To prevent scrapping of the carrier in case one of the carrier wheels is damaged, the wheels of the at least two sets of wheels are exchangeably attached to the frame, which makes it possible to replace the first set of wheels with wheels of a larger diameter raising the carrier's support surface of the second set of wheels allowing e.g. parts with protruding parts to be conveyed. Alternatively, it is possible to replace the second set of wheels with wheels of a large width and thereby enlarge the contact surface which results in gentle conveying of the parts or sufficient support of heavy parts. When the first wheel set is running on the conveyor surface, the parts move smoothly and straightly.

However, as the carriers are attached to the underlying conveying member, it is impor¬ tant that the conveyor surface is provided with a number of recesses, which are adapted to receive the conveying members. Hence the conveying member is hidden in the recess, and the risk of the parts bumping into or being jammed between the con- veying members is reduced significantly.

Furthermore, the recesses are used as guides for the conveying member, allowing the carriers to move along a predetermined route from the accumulating conveyor loading area to the removal area. The route does not have to follow a straight line but can de- viate allowing the accumulating conveyor to change direction around corners. The angel of the possible bends is determined by the flexibility of the conveying member and the turning ability of the wheels of the first set of wheels on the carriers.

Typically, one accumulating conveyor system consists of a conveyor surface with one or several recesses, preferably two or three recesses. However, it is possible to manu¬ facture an accumulating conveyor which is provided with a very wide conveyor sur¬ face. For instance a part of the storage area is provided with an elevated floor, where a number of recesses are parallel to each other.

Due to the fact that the accumulating conveyor system, according to the present inven¬ tion, is fully automatically, there is no need for work space next to the accumulating conveyor, hence the accumulating conveyor can be placed close to the wall or on ele¬ vated floors whereby the storage capacity is increased significantly.

In order to easily replace the carriers when the accumulating conveyor has been used for certain parts, the frame of the carrier is exchangeably attached to the conveying members. Hence it is possible to replace the carrier with carriers of different sizes and/or different wheel size, which is advantageous when the parts e.g. differ in length, width or weight.

For instance a carrier with a wheel set of which the wheels are wider than usual, pro- vides a large contact surface between the product and the carrier which is advantageous, if the parts are large or heavy.

According to one embodiment of the present invention the exchangeable attachment is a snap lock, which makes it easy to replace the entire carrier on the conveying mem- ber. The snap lock is a two part unit, where e.g. a male part is attached to the convey¬ ing member and a female part is attached to the carrier. The female part should be similar to female parts of every carrier regardless of the shape of different carriers.

In stead of replacing the carrier it is possible to replace the entire conveying member with another conveying member, which is provided with a different set of carriers. Thus the advantage is that the time for replacement is very short, and it is possible to prepare a conveying member in the workshop prior to replacement reducing the down¬ time of the accumulating conveyor.

According to the present invention the conveying members are preferably one of the following: a chain, a serrated belt, and/or a rope upon which the carriers are attached. The aforementioned types of conveying members are ideally suited for providing end¬ less conveying members, as it is very easy to connect the end parts of the conveying member.

To ensure that the conveying member is moved satisfactorily, the drive wheels are positioned at each end of the accumulating conveyor system. The drive wheels are one of the following: a sprocket wheel, a grooved wheel which is also toothed, and/or a grooved wheel which is also sheaved, where a sprocket wheel is used if the conveying member is a chain, and a grooved and toothed wheel is used if the conveying member is a serrated belt, and a grooved and sheaved wheel is used if the conveying member is a rope. To obtain optimum use of the storage areas, it is important that there are not any significant openings between the parts, as this would be a waste of storage capacity. Therefore the control system comprises a number of movement sensors, which detect if/when the parts are being moved, which ensures that the parts are positioned as close as possible to each other on the accumulating conveyor.

This means that the moving sensors are positioned at the loading part of the accumu¬ lating conveyor detecting when a part is positioned on the carriers and subsequently ensuring that the part is moved at least a distance away from the loading area allowing another part to be positioned at a later stage.

Similarly a moving sensor is positioned near the end of the accumulating conveyor, detecting when a part is positioned at the desired removal position, or if a part can be moved into the desired removal position.

Hence, the control system can move the conveying member at the right time in order to obtain optimum accumulation on the accumulating conveyor. In storage areas where the accumulating conveyor has a substantial length, it can be necessary to position a number of movement sensors along the accumulating conveyor in order to ensure op- timum accumulation of the parts. Furthermore, the last moving sensor can be con¬ nected to the operation of an end stop.

To ensure that the parts on the accumulating conveyor is positioned correctly and to prevent the parts from rolling off the accumulating conveyor, the accumulating con- veyor system, furthermore, comprises at least one end stop.

This end stop can be integrated into the control system and can be activated, when a movement sensor detects movement near the end of the accumulating conveyor. Likewise the end stop can be automatically reactivated, when the first part is re- moved.

Alternatively the end stops are manually operated and deactivated when the first part is removed and then repositioned in a lock position right after removal. According to one embodiment of the present invention, an end stop is an oblong plate spanning across the width of one or more conveying members, hence providing an obstruction barrier to the accumulating conveyor.

Alternatively, the end stops comprise one or more plates which are activated to¬ gether or separately.

Preferably, the accumulating conveyor system described above is used in connection with the production of furniture, where many wood parts are kept in stock. However, the accumulating conveyor system can easily be applied in the production of other things, where parts are kept in stock and there is a need of optimum use of the stor¬ age areas.

Short description of the drawings The invention is described in more detail below with reference to the accompanying drawings in which:

Fig. 1 shows a perspective view of an accumulating conveyor system according to the present invention,

Fig. 2 shows an end view of the accumulating conveyor system in fig. 1,

Fig. 3 shows a perspective view of a carrier according to the present invention, and

Fig. 4 shows a side view of the carrier in fig. 3.

Detailed description of the invention

Fig. 1 shows a perspective view of an accumulating conveyor system 1 comprising a conveyor surface 2, a number of carriers 3, two conveying members 4, two drive wheels 5, a drive 6, a control system (not shown), where the carriers 3 are attached to the conveying members 4, where each of the conveying members 4 are arranged as endless members around the drive wheels 5, where a movement of the conveying members 4 are caused by the drives 6 and controlled by the control system (not shown), and where the frame 7 encloses the sets of wheels 8, 9, which are vertically and horizontally displaced in the frame 7, and where the first set of wheels 8 com¬ prises at least two juxtaposed wheels 14, which are adapted to move along the con¬ veyor surface 2, and the second set of wheels 9 comprising at least two juxtaposed wheels 15, which are adapted to support a part placed entirely or partly on the carrier 3.

The accumulating conveyor system 1 shown, furthermore, comprises one end stop 10, which is used to prevent the product (not shown) from rolling off the carriers 3, when it reaches the end of the conveyor surface 2. The end stop 10 can be automati¬ cally/manually moved/lowered, when it is necessary to take a first part (not shown) off the accumulating conveyor system 1 and subsequently it can be repositioned/raised to stop the next part (not shown) in line at the end of the conveyor surface 2.

The control system (not shown) comprises a number of movement sensors 11, which provides the control system (not shown) with a signal, if there are parts (not shown) on the accumulating conveyor system 1 and/or if the parts (not shown) are moving.

The conveyor surface 2 is shown raised with the help of a number of legs 12, which allows the conveying member 4 to be arranged as endless members around the drive wheels 5, hence the carriers 3 follow the conveying member 4 along the conveyor sur¬ face 2 in one direction and beneath the conveyor surface 2 in the opposite direction.

Furthermore, the conveyor surface 2 is provided with a number of recesses 17 which are adapted to receive the conveying members 4, and subsequently allowing the first wheel set 8 to be in contact with the conveyor surface 2.

The support wheel 18 supports the parts (not shown), when the parts are lying on the surface 2 of the accumulating conveyor, as the end of the accumulating conveyor sur- face 2 bends downward to allow the drive wheels of the carriers 3 to turn around the accumulating conveyor and leave the parts (not shown) at the end of the accumulating conveyor surface 2. Fig. 2 shows an accumulating conveyor system 1, where it is possible to see that the carriers 3 are attached to conveying members 4, which are arranged as endless mem¬ bers around the drive wheels 5. The carriers 3 comprise a frame 7 which is provided with a first wheel set 8 and a second wheel set 9 which is vertically displaced in the frame 7.

The first set of wheels 8 are in contact with the conveyor surface 2, and the second set of wheels 9 are in contact with the part (not shown) which is placed on the carriers 3.

Fig. 3 shows a perspective view of a carrier 3 which is attached to a conveying mem¬ ber 4 in the shape of a chain. The attachment is conducted with a nut/bolt arrangement 16. The first wheel set 8 and the second wheel set 9 are shown both vertically dis¬ placed and horizontally displaced in the frame 7, causing the two wheel sets 8, 9 to be able to rotate independently of each other and to allow a compact carrier 3.

The wheels 13 of the first wheel set 8 are arranged in front of the frame 7, and the wheels 14 of the first wheel set 8 are arranged rear of the frame 7, meanwhile the wheels 15 of the second wheel set 9 are arranged between the wheels 13, 14 of the first wheel set 8.

Fig. 4 shows a side view of the carrier 3, where it is possible to see the vertical dis¬ placement of the two wheel sets 8, 9 in the frame 7. Furthermore, it is possible to see that the carrier 3 is attached to the conveying member 4 with a nut/bolt arrangement 16.

Claims

1. Accumulating conveyor system (1) comprising a conveyor surface (2), a number of carriers (3), one or more conveying members (4), a number of drive wheels (5), a number of drives (6), a control system, where the carriers (3) are attached to the con¬ veying members (4), where each of the conveying members (4) are arranged as endless members around the drive wheels (5), where a movement of the conveying members (4) are caused by the drives (6) and controlled by the control system, and where the carriers (3) comprise a frame (7) which is provided with at least two sets of wheels (8, 9), characterized in that the frame (7) encloses the sets of wheels (8, 9), which are vertically and horizontally displaced in the frame (7), and where a first set of wheels (8) comprises at least two juxtaposed wheels (14), which are adapted to move along the conveyor surface (2), and a second set of wheels (9) comprising at least two juxtaposed wheels (15), which are adapted to support a part placed entirely or partly on the carrier (3).

2. Accumulating conveyor system (1) according to claim 1, characterized in that the first set of wheels (8) comprises at least two set of juxtaposed wheels (13, 14), where the juxtaposed wheels (13) are arranged at the front of the frame (7) and the juxtaposed wheels (14) are arranged at the rear end of the frame (7), and the second set of wheels (9) comprises the juxtaposed wheels (15) arranged between the front and rear wheels (13, 14) of the first set of wheels (8) in the frame (7).

3. Accumulating conveyor system (1) according to any of the preceding claims, characterized in that the wheels (13, 14, 15) are exchangeably attached to the frame (7).

4. Accumulating conveyor system (1) according to any of the preceding claims, characterized in that the conveyor surface (2) is provided with a number of recesses (17) which are adapted to receive the conveying members (4).

5. Accumulating conveyor system (1) according to any of the preceding claims, characterized in that the frame (7) of the carrier (3) is exchangeably attached to the conveying members (4).

6. Accumulating conveyor system (1) according to claim 5, characterized in that the exchangeable attachment is a snap lock.

7. Accumulating conveyor system (1) according to any of the preceding claims, characterized in that the conveying members (4) are one of the following: - a chain,

- a serrated belt, and/or

- a rope.

8. Accumulating conveyor system (1) according to any of the preceding claims, characterized in that the drive wheels (5) are positioned at each end of the accumulating conveyor system (1) and are one of the following:

- a sprocket wheel,

- a grooved wheel which is also toothed, and/or

- a grooved wheel which is also sheaved.

9. Accumulating conveyor system (1) according to any of the preceding claims, characterized in that the control system comprises a number of movement sensors (11).

10. Accumulating conveyor system (1) according to any of the preceding claims, characterized in that the accumulating conveyor system (1), furthermore, comprises at least one end stop (10).