Information
-
Patent Grant
-
6497320
-
Patent Number
6,497,320
-
Date Filed
Wednesday, February 28, 200123 years ago
-
Date Issued
Tuesday, December 24, 200221 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Armstrong, Westerman & Hattori, LLP
-
CPC
-
US Classifications
Field of Search
US
- 198 34101
- 198 5023
- 198 81001
- 198 81003
- 198 718
- 198 726
- 198 6261
- 198 6265
- 198 6266
- 198 5024
- 053 3713
- 053 564
- 053 565
- 141 177
-
International Classifications
-
Abstract
A conveyor has a rotary encoder for measuring the amount of rotation of a driven sprocket having an intermittently drivable chain reeved therearound, and a processor for processing the measurement obtained by the encoder as operation support operating data corresponding to the amount of rotation of the driven sprocket. The processor determines a reference position of the chain in time series when the chain is moved a distance at a time by intermitting driving, computes the actual position of the chain corresponding to the reference position based on the measurement obtained by the encoder, and computes the deviation of the actual position of the chain from the reference position.
Description
BACKGROUND OF THE INVENTION
The present invention relates to container conveyors, for example, for use in packaging machines.
Conveyors of the type mentioned are already known which comprise a drive sprocket, a driven sprocket, a chain reeved around the sprockets and drivable intermittently, and a plurality of container holders attached to the chain at a spacing corresponding to the distance the chain is moved at a time by intermittent driving. The chain has a container transport path extending successively via a group of devices including a filling device and a sealing device.
With the conveyor described, the container holders need to be brought to a halt accurately at specified operating positions such as the locations of the filling device and the sealing device. Otherwise, the required packaging operation will not be performed on the containers. However, the chain becomes inevitably stretched with time, and if exceeding a certain limit, the stretch starts to cause trouble in the packaging operation. Although maintenance is provided on the conveyor in the event of trouble arising, the procedure performed is not efficient.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a conveyor wherein operation support operating data, for example, as to the halted position and movement of the chain is readily available to ensure facilitated and efficient maintenance of the chain.
The present invention provides a conveyor comprising a drive sprocket, a driven sprocket and an intermittently drivable chain reeved around the sprockets, the conveyor being characterized in that the conveyor comprises an instrument for measuring the amount of rotation of the driven sprocket, and a processor for processing the measurement obtained by the instrument as operation support operating data corresponding to the amount of rotation of the driven sprocket.
With the conveyor of the invention, the amount of rotation of the driven sprocket is measured to obtain operation support operating data based on the measurement. This assures the chain of facilitated and efficient maintenance.
The processor comprises setting means for determining a reference position of the chain in time series when the chain is moved a distance at a time by intermitting driving, means for computing the actual position of the chain corresponding to the reference position based on the measurement obtained by the instrument, and means for computing the deviation of the actual position of the chain from the reference position. This enables the operator to observe the dynamic variations involved in the movement of the chain when it is moved a specified distance at a time by intermittent driving.
The processor may comprise setting means for determining a reference halted position of the chain every time the chain is moved a distance by intermitting driving during one turn of movement, means for computing the actual halted position of the chain corresponding to the reference halted position based on the measurement obtained by the instrument, and means for computing the deviation of the actual halted position of the chain from the reference halted position. This enables the operator to observe the static variations involved in one turn of movement of the chain.
The present invention provides another conveyor comprising a pair of drive sprockets, a pair of driven sprockets and a pair of intermittently drivable chains each reeved around the drive sprocket and the driven sprocket corresponding to the chain, the conveyor being characterized in that the conveyor comprises a first instrument for measuring the amount of rotation of one of the driven sprockets, a second instrument for measuring the amount of rotation of the other driven sprocket, and a processor for processing the measurements obtained by the two instruments as operation support operating data.
The invention is useful also for the maintenance of the pair of chains included in this conveyor.
The processor of the conveyor comprises setting means for determining reference halted positions of the respective chains every time the chains are moved a distance by intermitting driving during one turn of movement, means for computing the actual halted position of each of the chains corresponding to the reference halted position of the chain based on the measurement obtained by the corresponding instrument, and means for computing the deviation of the actual halted position from the reference halted position. This enables the operator to observe the static variations involved in one turn of movement of the pair of chains.
When a plurality of container holders are attached to the chain at a spacing corresponding to the distance the chain is moved at a time by intermittent driving, and further when the chain has a container transport path extending successively via a group of devices including a filling device and a sealing device, each container holder can be brought to a halt at a desired operating position of the group of devices.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is an overall side elevation showing a packaging machine including a conveyor embodying the invention;
FIG. 2
is a perspective view of the conveyor of the invention;
FIG. 3
is a diagram showing the construction of a data processor for the conveyor;
FIG. 4
is a graph showing the operation waveform of driven sprockets;
FIG. 5
is a graph showing part of
FIG. 4
on an enlarged scale;
FIG. 6
is a graph showing variations in the amount of movement of a left driven sprocket; and
FIG. 7
is a graph showing variations in the amount of movement of a right driven sprocket.
DESCRIPTION OF THE PREFERRED EMBODIMENT
An embodiment of the present invention will be described below with reference to the drawings.
As shown schematically in its entirety in
FIG. 1
, a packaging machine comprises a container bottom forming rotor
12
provided with radial mandrels
11
each having fitted therearound a container C of square to rectangular cross section and intermittently drivable counterclockwise, and a container conveyor
13
having a transport path forwardly extending from below the rotor
12
.
Arranged one after another around the rotor
12
toward the direction of rotation of the rotor are a feeder
21
, bottom heater
22
, bottom breaker
23
, folding rail
24
, bottom press
25
and unloader
26
. Successively arranged along the path of transport of the conveyor
13
are a primary top breaker
31
, filling device
32
, secondary top breaker
33
, top heater
34
and top sealing device
35
.
With reference to
FIG. 2
, the conveyor
13
comprises a pair of left and right vertical drive shafts
41
A,
41
B, a pair of left and right vertical support rods
42
A,
42
B arranged in the rear of and spaced apart from these drive shafts
41
A,
41
B, upper and lower two left drive sprockets
43
A fixed to the left drive shaft
41
A and vertically spaced apart, upper and lower two right drive sprockets
43
B fixed to the right drive shaft
41
B and vertically spaced apart, upper and lower two left driven sprockets
44
A mounted on the left support rod
42
A and vertically spaced apart, upper and lower two right driven sprockets
44
B mounted on the right support rod
42
B and vertically spaced apart, upper and lower two left chains
45
A reeved around the left drive sprockets
43
A and the left driven sprockets
44
A at upper and lower levels, respectively, upper and lower two right chains
45
B reeved around the right drive sprockets
43
B and the right driven sprockets
44
B at upper and lower levels, respectively, and a horizontal guide rail
46
extending forward below the space between the left and right chains
45
A,
45
B.
A pair of left and right rotary encoders
49
A,
49
B are connected to the respective drive shafts
41
A,
41
B. Among the two left and two right driven sprockets
44
A,
44
B at the upper and lower levels, the left and right driven sprockets
44
A,
44
B at the upper level have a pair of left and right rotary encoders
55
A,
55
B, respectively.
The support rods
42
A,
42
B are supported upright on free ends of a pair of left and right horizontal pivotal arms
52
A,
52
B, respectively. A pair of fluid pressure cylinders
53
A,
53
B are directed rearward and have piston rods, which are connected to the respective support rods
42
A,
42
B. The fluid pressure cylinders
53
A,
53
B are horizontally pivotably supported at their cylinder side, and the piston rods can releasably be locked at a desired advanced or retracted position by the respective lock mechanisms
54
A,
54
B. The cylinders
53
A,
53
B each have incorporated therein a distance (displacement) sensor for measuring the amount of advance or retraction of the piston rod.
A plurality of L-shaped vertical pieces
56
A extend between and are attached to the two left chains
45
A, and a plurality of L-shaped vertical pieces
56
B corresponding to the pieces
56
A extend between and are attached to the two right chains
45
B.
With reference to
FIG. 2
, a servomotor
51
intermittently drives the left drive shaft
41
A counterclockwise when seen from above, and the right drive shaft
41
B clockwise as timed with the shaft
41
A, whereby the opposed portions of the left and right chains
45
A,
45
B are moved forward, providing a path of movement for feeding. Each pair of L-shaped pieces
56
A and each pair of L-shaped pieces
56
B on the respective left and right chains
45
A,
45
B form a holder. The holder traveling the feeding path fits to the four corners of the container C, which is transported with its bottom supported by the guide rail
46
.
The servomotor
51
is controlled by an unillustrated controller, and the chains
45
A,
45
B can be brought to a halt at desired positions, for example, with pulses provided by the controller.
When the chains
45
A,
45
B become stretched owing to the operation of the conveyor over a prolonged period of time, the piston rods of the fluid pressure cylinders
53
A,
53
B are advanced as unlocked from the lock mechanisms
54
A,
54
B, causing the cylinders
53
A,
53
B to apply pressures to the chains
45
A,
45
B to make the chains
45
A,
45
B taut. The piston rods are then locked by the lock mechanisms
54
A,
54
B again. This procedure is advantageous from the viewpoint of the stretch of the chains
45
A,
45
B since the pressures of the cylinders
53
A,
53
B will not act on the chains
45
A,
45
B at all times. However, the chains
45
A,
45
B may be subjected to the pressures at all times as the case may be. The chains
45
A,
45
B are then used always as tensioned.
The pressures to be applied to the chains
45
A,
45
B by the fluid pressure cylinders
53
A,
53
B respectively may be the same in magnitude, or one pressure may be made greater than the other in accordance with the difference between the two chains
45
A,
45
B in stretch.
The angles of rotation of the left and right drive sprockets
43
A,
43
B are measured individually by the drive-side rotary encoders
49
A,
49
B, while the angles of rotation of the left and right driven sprockets
44
A,
44
B are measured individually by the driven-side rotary encoders
55
A,
55
B.
Procedures will be described below for effectively utilizing the values measured by the drive-side and driven-side rotary encoders
49
A,
49
B,
55
A,
55
B, by processing the measurements as operation support operating data.
FIG. 3
is a diagram showing the construction of a processor
61
for a system for maintaining and supporting the operation of the conveyor. The processor
61
has a computing unit
62
, which receives the measurements from the drive-side and driven-side rotary encoders
49
A,
49
B,
55
A,
55
B. The unit
62
performs the required computation based on the measurements, and the result of computation is sent to a recorder
64
via a D/A conversion unit
63
and also to a display
65
. The recorder
64
records the result of computation, while the display
65
shows the result. If the result of computation is abnormal on the other hand, the computation unit
62
delivers a stop signal and an alarm signal. The conveyor is brought out of operation in response to the stop signal, while an alarm
66
gives a warning.
The drive-side rotary encoders
49
A,
49
B are driven by the servomotor
51
, therefore operate ideally at all times and can accordingly be dispensed with. These encoders
49
A,
49
B are used in the present embodiment in view of the mechanical loss involved in the path from the servomotor
51
to the drive shafts
41
A,
41
B, and the pulse signals produced by the encoders
49
A,
49
B are used for providing reference values. The driven-side rotary encoders
55
A,
55
B produce pulse signals corresponding to the actual angles of rotation of the driven sprockets
44
A,
44
B and to be used as actual values. The pulse signals are converted into the angles of the rotation of the drive and driven sprockets
43
A,
43
B,
44
A,
44
B in proportion thereto and into the amounts of movements of the chains (as reeved around the sprockets) in proportion to the signals.
FIG. 4
shows operation waveforms of the drive and driven sprockets
43
A,
43
B,
44
A,
44
B every time the conveyor is moved a distance by being driven intermittently (each conveyor cycle). Plotted as abscissa is time vs. the angle (dimensionless) of rotation of the drive and driven sprockets as ordinate. Each wave of the operation waveform indicated at A represents the operations of the drive and driven sprockets
43
A,
43
B,
44
A,
44
B corresponding to one conveyor cycle. The waveform A is reset every cycle and returns to the origin. Since there is no difference that is discernible in the waveform A between the operations of the drive and driven sprockets
43
A,
43
B,
44
A,
44
B, the operations appear to be represented by a single common line. Accordingly, the difference in operation waveform between the drive and driven sprockets
43
A,
43
B,
44
A,
44
B is represented as enlarged 20 times by a waveform B.
FIG. 5
shows one cycle of the operation waveform of
FIG. 4
as enlarged with respect to time. It is seen that the operation of the driven sprockets
44
A,
44
B lags behind the operation of the drive sprockets
43
A,
43
B by a maximum deviation G immediately after the start of travel of the chains, thereafter gradually recovers and overtakes the operation of the drive sprockets
43
A,
43
B immediately before halting and comes to a halt after going on ahead of the operation of the drive sprockets.
FIGS. 4 and 5
indicate dynamic variations in the operation of the chains during one cycle of conveyor operation.
The lag of the operation of the driven sprockets
44
A,
44
B, namely, the deviation G of the operation of the driven sprockets
44
A,
44
B from the operation of the drive sprockets
43
A,
43
B, indicates the degree to which the driven sprockets
44
A,
44
B follow the drive sprockets
43
A,
43
B and which corresponds mainly to the slackening of the chains
45
A,
45
B due to a stretch. The greater the deviation, the greater the tendency for the chains
45
A,
45
B to operate abruptly inadvertently, consequently greatly rocking the liquid filled in the container C as held by the holder. If the liquid is rocked to spill, a faulty seal will result. If the deviation exceeds a predetermined value, the computing unit
62
outputs a stop signal and an alarm signal, and required maintenance is provided. The predetermined value of deviation is, for example, 7 degrees.
Local faults in the chains
45
A,
45
B, biting of containers, application of an abnormal load or like trouble can be detected by monitoring the waveforms shown in
FIGS. 4 and 5
at all times to halt the conveyor in an emergency.
FIGS. 6 and 7
show variations in the deviation of halted positions of the drive and driven sprockets
43
A,
43
B,
44
A,
44
B during each cycle of conveyor operation while the chains
45
A,
45
B make one turn,
FIG. 6
showing the data for the left chain
45
A, and
FIG. 7
the data for the right chain
45
B.
The period T
1
, T
2
for one turn of the chains
45
A,
45
B is plotted as abscissa, and successively plotted as ordinate is the variation in the halted position on completion of each cycle of conveyor operation during the period T
1
, T
2
. The origin
0
is always taken as the halted positions of the drive sprockets
43
A,
43
B, providing reference halted positions for the chains every time the chains are moved a specified distance by intermittent driving during one turn of movement of the chains. The waveforms CA and CB represent the actual deviations of the driven sprockets
44
A,
44
B from the origin
0
, in terms of variations in the halted position as converted in mm from the angle of rotation of each driven sprocket
44
A or
44
B. The waveforms CA and CB represent the data in the initial state, and the waveforms DA and DB represent the data available a specified period of time thereafter.
Noteworthy is the following fact. The pattern representing the variations in the deviation during each period T
1
or T
2
for one turn of movement of the chain has regularity, and the same pattern is available in each period T
1
or T
2
.
The chains
45
A,
45
B stretch with time, and the resulting variations are manifest in the transition from the waveforms CA and CB to waveforms DA and DB, and are static variations. The time taken for the deviation in the pattern reaches a limit necessitating maintenance can be estimated by measuring the static variations with the lapse of time. Based on the estimated result, the computing unit
62
produces a stop signal and alarm signal. The limit of deviation is, for example, 2.0 mm at the location of the driven sprockets
44
A,
44
B, 2.0 mm at the location of the filling device, or 1.5 mm at the location of the sealing device.
If the pattern deviates toward the positive direction to reach the limit, adjustment is so made as to halt the chain
45
A or
45
B at a position shifted toward the negative direction. Containers C can then be halted at a desired operating position such as the location of the filling device, sealing device, or the like.
In the case where the pattern deviates toward the positive direction as the chain
45
A or
45
B stretches as described above, it is possible to lengthen the time taken for the deviation of the pattern to reach a limit necessitating maintenance, by causing the chain
45
A or
45
B to halt, for example, at a specific position in the pattern where the variation of the halted position is minimum, and adjusting the halted position of the chain
45
A or
45
B so that this position is close to the limit value at the negative side. Conversely, in the case where the pattern deviates toward the negative direction as the chain
45
A or
45
B stretches as described above, it is possible to lengthen the time taken for the deviation of the pattern to reach a limit necessitating maintenance, by causing the chain
45
A or
45
B to halt, for example, at a specific position in the pattern where the variation of the halted position is maximum, and adjusting the halted position of the chain
45
A or
45
B so that this position is close to the limit value at the positive side.
Although the embodiment described is adapted to measure the angles of rotation of the left and right drive and driven sprockets, the present invention can be practiced merely by measuring the angle of rotation of at least one driven sprocket. Furthermore, other device such as a laser sensor is usable in place of the rotary encoder for measuring the angle of rotation of the driven sprocket.
When the measuring instrument is provided for each of the left and right driven sprockets, the deviation patterns of the respective left and right chains are available. The deviation, in the transport direction, of the container holders (vertical L-shaped pieces) provided on the respective chains can be diminished by making such adjustment as to ensure synchronism between the two patterns.
The left and right drive sprockets may be driven by a single servomotor, whereas if these sprockets are driven individually by separate servomotors, the above adjustment can be effected automatically.
The driven sprockets and the vicinity thereof (the portion where containers are fed to the conveyor in the case of the present embodiment) which are liable to malfunction due to a stretch of the chain can be reliably monitored by providing the instrument for measuring the amount of rotation of the driven sprocket, whereby the trouble is avoidable.
The upstream side of the conveyor with respect to the container transport direction may serve as the drive portion, with the downstream side serving as the driven portion.
Claims
- 1. A conveyor comprising a drive sprocket, a driven sprocket and an intermittently drivable chain reeved around the sprockets, the conveyor being characterized in that the conveyor comprises an instrument for measuring the amount of rotation of the driven sprocket, and a processor for processing the measurement obtained by the instrument as operation support operating data corresponding to the amount of rotation of the driven sprocket, wherein the processor comprises:setting means for determining a reference halted position of the chain every time the chain is moved a distance by intermitting driving during one turn of movement, means for computing the actual halted position of the chain corresponding to the reference halted position based on the measurement obtained by the instrument, and means for computing the deviation of the actual halted position of the chain from the reference halted position.
- 2. A conveyor according to claim 1 wherein the processor comprises setting means for determining a reference position of the chain in time series when the chain is moved a distance at a time by intermitting driving, means for computing the actual position of the chain corresponding to the reference position based on the measurement obtained by the instrument, and means for computing the deviation of the actual position of the chain from the reference position.
- 3. A conveyor comprising a pair of drive sprockets, a pair of driven sprockets and a pair of intermittently drivable chains each reeved around the drive sprocket and the driven sprocket corresponding to the chain, the conveyor being characterized in that the conveyor comprises a first instrument for measuring the amount of rotation of one of the driven sprockets, a second instrument for measuring the amount of rotation of the other driven sprocket, and a processor for processing the measurements obtained by the two instruments as operation support operating data, wherein the processor comprises:setting means for determining a reference halted positions of the respective chains every time the chains are moved a distance by intermitting driving during one turn of movement, means for computing the actual halted position of each of the chains corresponding to the reference halted position based on the measurement obtained by the instrument, and means for computing the deviation of the actual halted position of the chain from the reference halted position.
- 4. A conveyor according to any of claims 1, 2 and 3 wherein a plurality of container holders are attached to the chain at a spacing corresponding to the distance the chain is moved at a time by intermittent driving.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2000-055219 |
Mar 2000 |
JP |
|
US Referenced Citations (5)
Number |
Name |
Date |
Kind |
2794536 |
Roza et al. |
Jun 1957 |
A |
4172347 |
Nitz |
Oct 1979 |
A |
4641742 |
Igarashi et al. |
Feb 1987 |
A |
4818540 |
Chien et al. |
Apr 1989 |
A |
5337885 |
Mills et al. |
Aug 1994 |
A |
Foreign Referenced Citations (3)
Number |
Date |
Country |
0 574 087 |
Dec 1993 |
EP |
0 945 372 |
Mar 1999 |
EP |
WO 9641760 |
Dec 1996 |
WO |