GB2145685A - Chain conveyor - Google Patents

Abstract

A phase-adjustable chain conveyor provided with dogs includes two pairs of parallel endless chains. The pair of first chains is entrained between a pair of first sprockets (12,12') rotatably supported on a driving shaft (4) and a pair of third sprockets (15,15') rotatably supported on a follower shaft (5) with the other chains being entrained between a pair of second sprockets (13,13') fixedly supported on the driving shaft (4) and a pair of fourth sprockets (16,16') fixedly supported on the follower shaft (5). The driving and follower shafts are rotatably supported by a frame and a first clutches (14) is provided to enable the first and second sprockets (12,13,12',13') coupled or decoupled. The driving shaft (4) is adapted to be driven by a driving motor and the follower shaft (5) is connected to a servomotor (22) through a second clutch (21). Also provided is a mechanism (17,18,19,20) for detecting the phase difference between the first and second chains. The servomotor (22) is selectively operated under the control of the phase difference-detecting mechanism to set the phase between the first and second chains at a desired value. <IMAGE>

Description

SPECIFICATION Chain conveyor This invention relates to a chain conveyor for transporting an article as carried thereon, and, in particularly, to a phase-adjustable chain conveyor including at least two parallel chains, the phase between which is to be adjusted.

Achain conveyorfortransporting an article as carried thereon along a predetermined path is well known. The two chains of such a conveyor are typically provided respectively with front and rear dogs between which an article to be transported is maintained and the distance between the two dogs is adjustable according to the size of the article to be transported. For example, two parallel endless chains are provided, each entrained between a pair of sprockets. One of the two sprockets arranged side-by-side is provided with an elongate slot with the other sprocket being rotatable with respect to the one having the elongate slot. A bolt received in the said other sprocket extends through the elongate slot and a nut is tightly screwed onto the bolt to secure the two sprockets together.With such a structure, when phase adjustment, ie., adjustment in the distance between the front and rear articleengaging dogs, is desired, the nut is first untightened and, after rotating one of the two sprockets with respect to the other over a desired angle, the nut is retightened to re-connect the two sprockets.

However, such a prior art structure requires manual operation in implementing phase adjustment so that it cannot be carried out accurately as well as rapidly as desired.

It is an object of the present invention to obviate the disadvantages of the prior art as described above and to provide an improved phase-adjustable chain conveyor.

Another object of the present invention is to provide an automatic phase-adjustable chain conveyor capable of implementing phase adjustment rapidly as well as accurately without requiring manual operation.

A further object of the present invention is to provide an automatic phase-adjustable chain conveyor capable of transporting articles of different sizes with ease.

The invention resides in a chain conveyor comprising first and second shafts which are rotatably supported on a frame, said first shaft being adapted to be driven so as to be rotated by a driving source; a first sprocket rotatably mounted on said first shaft; a second sprocket fixedly mounted on said first shaft; first clutch means for coupling said first sprocket to or decoupling said first sprocket from said second sprocket; a third sprocket rotatably mounted on said second shaft; a fourth sprocket fixedly mounted on said second shaft; a first chain entrained around said first and third sprockets; a second chain parallel to said first chain and entrained around said second and fourth sprockets; rotating means connected to said second shaft through a second clutch means for rotating said second shaft when said second clutch means is in a coupled condition; detecting means for detecting a phase difference between said first and second chains; and control means for controlling the operation of said first and second clutch means and said rotating means in response to signals supplied from said detecting means, thereby adjusting the phase between said first and second chains.

The invention is further described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic front view showing the overall structure of a phase-adjustable chain conveyor constructed in accordance with one embodiment of the present invention, when applied to a cartoning apparatus; Figure 2 is a plan view showing two parallel chains of the conveyor and each provided with a dog; Figure 3 is a front view of the chains with the dogs shown in Figure 2; Figure 4 is a cross-sectional view taken along line IV-IV shown in Figure 1; and Figure 5 is a cross-sectional view taken along line V-V shown in Figure 1.

Referring now to Figure 1,a phase-adjustable chain conveyor 3, constructed in accordance with one embodiment of the present invention, is applied to a system for forming a carton from a flat folded carton blank and filling the thus formed carton with desired items, such as bottles and cans. As shown, flat folded carton blanks are stored as stacked in a carton blank magazine or holder 1 provided at the right hand end of the system in Figure 1, and the carton blanks are taken out of the holder 1 by means of a picker 2 one by one. The carton blank taken out of the holder is then placed on the endless chain conveyor 3 to be transported from right to left in Figure 1 as indicated by the arrow A, during which the carton blank is formed into a carton through engagement with a carton forming mechanism disposed along the chain conveyor 3.As will be made clear later, the endless chain conveyor 3 includes a plurality of chains entrained around sprockets mounted on shafts, such as a driving shaft 4, a follower shaft 5 and intermediate shafts 6 and 7, which are rotatably supported on the stationary frame. The driving shaft 4 is driven so as to be rotated by a driving motor during the normal operating condition. The carton carried on the conveyor 3 is filled with desired items and then transported to the next process line after having seen sealed.

As shown in Figures 2 and 3, in the illustrated embodiment, the conveyor 3 includes a first chain 8 and a second chain 9 which are arranged parallel and side-by-side and are spaced apart by a predetermined distance. The first chain 8 is provided with a front article-engaging dog or pawl 10 and the second chain 9 is provided with a rear article-engaging dog or pawl 11 which is positioned spaced apart downstream of the front dog 10 with respect to the advancing direction of the chains 8 and 9. A carton is carried on the chains 8 and 9 and is interposed between the front and rear dogs 10 and 11.The spacing between these front and rear dogs 10 and 11 may be adjusted for handling cartons having differing sizes.As will be made clear later, in the conveyor 3 of the illustrated embodiment, the first and second chains 8 and 9 are respectively provided in a pair with the pair of first chains 8,8 being arranged parallel to one another and between the pair of second chains 9,9.

Figure 4 shows the structure around the driving shaft 4 which is located at the downstream side of the conveyor 3. On the driving shaft 4 are mounted a pair of first sprockets 12, 12' and a pair of second sprockets 13, 13' which are located on opposite sides of the pair of first sprockets 12, 12'. Thus, the pair of first chains 8,8 is passed around the pair of first sprockets 12, 12' and the pair of second chains 9, 9 is passed around the pair of second sprockets 13,13'.

The second or outer sprockets 13, 13' are fixedly mounted on the driving shaft 4, thereby rotating in unison; on the other hand, the first or inner sprockets 12, 12' are mounted on the driving shaft 4 through respective clutches 14, so that the first sprockets 12, 12' may be set rotatable together with the driving shaft 4 or freely rotatably around the driving shaft 4 depending on whether the clutches 14,14 are coupled or decoupled.

Figure 5 shows the structure around the follower shaft 5. As shown, similarly with the structure around the driving shaft 4, on the follower shaft 5 are mounted a pair of third sprockets 15, 15' and a pair of fourth sprockets 16, 16' disposed on opposite sides of the third sprockets 15,15' with the pair of first chains 8, 8 being passed around the third or inner sprockets 15, 15' and the pair of second chains 9,9' being passed around the fourth or outer sprockets 16, 16'. The third sprockets 15, 15' are fixedly mounted on the follower shaft 5, thereby rotating in unison with the follower shaft 5; on the other hand, the fourth sprockets 16,16' are freely rotatable around the shaft 5.

Therefore, when the driving shaft 4 is driven to be rotated with the clutches 14, 14 in the coupled condition, the sprockets 12,12', 13 and 13' mounted on the driving shaft 5 are set in rotation in unison, and, thus, the rotation of the first sprockets 12,12' on the driving shaft 4 is transmitted to the third sprockets 15, 15' on the follower shaft 5 through the first chains 8,8 and the rotation of the second sprockets 13, 13' on the driving shaft 4 is transmitted to the fourth sprockets 16,16' on the follower 5 via the second chains 9,9. As a result, the inner and outer sprockets 15, 15', 16 and 16' mounted on the follower shaft 5 are set in rotation in unison.Under this condition, the distance between the front and rear dogs 10 and 11 fixedly attached to the first and second chains 8 and 9, respectively, is maintained always constant, and the normal operation takes place.

On the other hand, if the follower shaft 5 is driven to be rotated with the clutches 14, 14 decoupled, the third sprockets 15, 15' fixedly mounted on the follower shaft 5 are set in rotation and this rotation is transmitted to the first sprockets 12,12' mounted on the driving shaft4through the first chains 8, 8; however, since the fourth sprockets 16,16' are mounted freely rotatably on the follower shaft 5, the second chains 9, 9 remain stationary. In this manner, by moving one of first and second pairs of chains whilst keeping the other stationary, the distance between the front and rear dogs 10 and 11 may be suitably adjusted.

It is to be noted that, by changing the mounting positions of the respective sprockets 12,12', 13, 13', 15,15',16 and 16' on the shafts 4 and 5, the distances between the respective chains may be suitably adjusted.

As also shown in Figure 5, a first reference or index disk plate 17 is provided integrally with the fourth sprocket 16. The first reference disk plate 17 is provided with a through-hole (not shown) which is detected by a first photosensor 18 for detecting the rotational position of the disk plate 17 and thus of the fourth sprocket 16. Furthermore, a second reference or index disk plate 19 is fixedly mounted on the follower shaft 5, and the second disk plate 19 is also provided with a through-hole (not shown) which is detected by a second photosensor 20 for detecting the rotational position of the third sprockets 15,15' which are set in rotation in unison with the second disk plate 19 and the follower shaft 5.

With such a structure, by detecting a rotational phase difference between the first and second disk plates 17 and 19 by means of the first and second photosensors 18 and 20 and counting the number of pulses generated by a pulse generator 23, which is driven from the shaft 5, a phase difference between the first and second chains 8 and 9 can be determined. As also shown in Figure 5, the follower shaft 5 is connected to a servomotor 22 through a clutch 21, and, thus, when the servomotor 22 is activated with the clutch 21 in the coupled condition, the follower shaft 5 is driven to be rotated, thereby causing the third sprockets 15, 15' and the second reference disk plate lSto be set in rotation in unison.

The operation of the servomotor 22 is controlled by another pulse generator 24.

With the above-described structure, under the normal operating condition, the clutches 14,14 supported on the driving shaft 4 are in the coupled condition and the clutch 21 between the servomotor 22 and the follower shaft 5 is in the decoupled condition. Thus, when the driving shaft 4 is set in rotation, the first and second sprockets 12,12', 13 and 13' are all set in rotation in unison so that the first and second chains 8 and 8 advance at the same speed thereby causing the third and fourth sprockets 15,15', 16 and 16' to be set in rotation in unison. As a result, the front and rear dogs 10 and 11 travel at the same speed maintaining the space therebetween unchanged, and thus, a carton held between opposed surfaces 10a and 1 1a of the respective dogs 10 and 11 is transported along a predetermind path as carried on the chains 8 and 9.

In the case where a carton having a differing size is to be transported using the above-described structure, the spacing between the front and rear dogs 10 and 11 must be suitably adjusted. In this case, the present system is first set in the normal operating mode as described above, during which in response to a first detection signal supplied from the first photosensor 18 by detecting the through-hole provided in the first reference disk plate 17, the pulse generator 23 starts to count the number of pulses until a second detection signal is supplied from the second photosensor 20 by detecting the throughhole provided in the second reference disk plate 19, and, then, the system stops its operation. The number of pulses thus counted correspond to the distance between the front and rear dogs 10 and 11.

Then, after setting the clutches 14, 14 supported on the driving shaft 4 to be in the decoupled condition and the clutch 21 between the follower shaft 5 and the servomotor 22 to be in the coupled condition, the servomotor 22 is actuated until it comes to be aligned with the initial position of the pulse generator 24.

Then, with the clutches 14, 14 on the driving shaft 4 decoupled and the clutch 21 between the follower shaft 5 and the servomotor 22 coupled, the servomotor 22 is actuated, thereby causing the third sprockets 15, 15' fixedly mounted on the follower shaft 5 to be set in rotation. As a result, the first chains 8 extended between the sprockets 15, 15' and the first sprockets 12, 12' mounted on the driving shaft 4 as being freely rotatable are set in motion so that the front dogs 10 move over a predetermined distance.

In this instance, the fourth sprockets 16, 16' on the follower 5, second sprockets 13, 13' on the driving shaft 4 and the second chains 9 extended between these sprockets all remain motionless, so that the rear dogs 11 also stay fixed in position. Therefore, the distance between the front and rear dogs 10 and 11 can be set to another desired value or pitch corresponding to the size of carton to be transported as interposed between the front and rear dogs 10 and 11.

Once the new pitch is set as described above, the normal operating condition is established, and in response to a first detection signal from the first photosensor 18, which is generated by detecting the through-hole provided in the first reference disk plate 17, the pulse generator 23 starts its count until the second photosensor 20 detects the through-hole provided in the second reference disk plate 19, followed by the step of stopping the normal operating condition. This is a checking procedure to examine a difference between an intended pitch and an actual pitch.

As described above, by the application of a numerical control using a digital servomotor, a phase adjustment of two conveyor chains can be carried out automatically as well as accurately.

Although not shown specifically, such an adjustment operation may be carried out automatically by providing a central processing unit (CPU) to control the sequence of steps in the adjustment operation.

While the above provides a full and complete disclosure of the preferred embodiments of the present invention, various modifications, alternative constructions and equivalents may be employed without departing from the scope of the invention.

Therefore, the above description and illustration should not be construed as limiting the scope of the invention, which is defined by the claims.

Claims (8)

1. A chain conveyor comprising first and second shafts which are rotatably supported on a frame, said first shaft being adapted to be driven so as be rotated by a driving source; a first sprocket rotatably mounted on said first shaft; a second sprocket fixedly mounted on said first shaft; first clutch means for coupling said first sprocket to or decoupling said first sprocket from said second sprocket; a third sprocket rotatably mount on said second shaft; a fourth sprocket fixedly mounted on said second shaft; a first chain entrained around said first and third sprockets; a second chain parallel to said first chain and entrained said second and fourth sprockets; rotating means connected to said second shaft through a second clutch means for rotating said second shaft when said second clutch means is in a coupled condition; detecting means for detecting a phase difference between said first and second chains; and control means for controlling the operation of said first and second clutch means and said rotating means in response to signals supplied from said detecting means, thereby adjusting the phase between said first and second chains.

2. A conveyor as claimed in Claim 1, wherein said rotating means includes a servomotor.

3. A conveyor as claimed in Claim 1 or 2, wherein said detecting means includes a first disk plate having a first reference mask and provided integrally with said fourth sprocket, a first detector for detecting said first reference mark, a second disk plate having a second reference mark and fixedly mounted on said second shaft, and a second detector for detecting said second reference mark, whereby said first and second detectors supply first and second detector signals, respectively, upon detection of the corresponding marks to said control means.

4. A conveyor as claimed in Claim 3, wherein said control means includes a pulse generator which starts counting of pulses upon receipt of said first detection signal and ceases counting upon receipt of said second detection signal from said detecting means.

5. A conveyor as claimed in any of Claims 1 to 4, wherein said first and second chains are provided with first and second article-engaging means, respectively, whereby the distance between said first and second article-engaging means is varied by adjusting the phase between said first and second chains.

6. A conveyor as claimed in any Claims 1 to 5, wherein said first and second chains are both in an endless form.

7. A conveyor as claimed in any of Claims 1 to 6, wherein said first to fourth sprockets and said first and second chains are provided in pairs.

8. A chain conveyor, constructed and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.