U.S. patent application number 10/067861 was filed with the patent office on 2002-07-11 for apparatus and method for temporarily retaining articles midway a transport system.
This patent application is currently assigned to MURATA KIKAI KABUSIKI KAISHA. Invention is credited to Ikegami, Iwao.
Application Number | 20020088686 10/067861 |
Document ID | / |
Family ID | 18425624 |
Filed Date | 2002-07-11 |
United States Patent
Application |
20020088686 |
Kind Code |
A1 |
Ikegami, Iwao |
July 11, 2002 |
Apparatus and method for temporarily retaining articles midway a
transport system
Abstract
An article retention apparatus includes a roller conveyor unit
with a plurality of rollers arranged in a horizontal plane and a
plurality of ladder-shaped rack units on which articles rest. The
roller conveyor unit and rack units are configured such that the
rack units may be moved above and below the plane of the conveyor
unit rollers without interference between the conveyor unit rollers
and the rack units. By lifting the rack units one by one from below
the roller plane to emerge above the roller plane, the article is
transferred from the roller conveyor unit to the rack unit. The
articles are taken aside of a transport system and temporarily
retained by the apparatus. A belt conveyor unit can be used instead
of the roller conveyor unit.
Inventors: |
Ikegami, Iwao;
(Shizuoka-ken, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. Box 19928
Alexandria
VA
22320
US
|
Assignee: |
MURATA KIKAI KABUSIKI
KAISHA
|
Family ID: |
18425624 |
Appl. No.: |
10/067861 |
Filed: |
February 8, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10067861 |
Feb 8, 2002 |
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09874244 |
Jun 6, 2001 |
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09874244 |
Jun 6, 2001 |
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08950749 |
Oct 15, 1997 |
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08950749 |
Oct 15, 1997 |
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08703931 |
Aug 28, 1996 |
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08703931 |
Aug 28, 1996 |
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08525243 |
Sep 8, 1995 |
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08525243 |
Sep 8, 1995 |
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08365162 |
Dec 28, 1994 |
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08365162 |
Dec 28, 1994 |
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08161802 |
Dec 6, 1993 |
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Current U.S.
Class: |
198/418.4 |
Current CPC
Class: |
B65G 47/5181 20130101;
B65G 2207/46 20130101 |
Class at
Publication: |
198/418.4 |
International
Class: |
B65G 047/30 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 10, 1992 |
JP |
4-352668 |
Claims
1. An article retention apparatus for use in a transport system,
comprising a conveyor unit including a conveying surface for
supporting and conveying an article horizontally, a plurality of
rack units each having support means on which the article rests
horizontally, suspension means for suspending the plurality of rack
units in a vertically spaced apart relationship while keeping the
rack units horizontal, and drive means for moving up and down the
suspension means, wherein said conveyor unit and said plurality of
rack units are configured such that the rack units may be moved
above and below the conveying surface of said conveyor unit without
interference between the conveying surface of said conveyor unit
and the support means of said rack units.
2. The article retention apparatus of claim 1 wherein said
suspension means includes generally flexible strips and said
plurality of rack units are attached to the strips at predetermined
intervals.
3. The article retention apparatus of claim 1 wherein said conveyor
unit comprises a roller conveyor unit having a plurality of rollers
arranged in a horizontal plane, the rollers at their top defining
the conveying surface.
4. The article retention apparatus of claim 1 wherein said conveyor
unit comprises at least one belt conveyor unit having an endless
belt, the belt presenting a horizontal upper surface defining the
conveying surface.
5. A method for retaining articles midway a transport system using
the article retention apparatus of claim 1, placing said plurality
of rack units on standby in a stack at a position below the
conveying surface of the conveyor unit, feeding an article from the
transport system to the conveyor unit so that the article rests on
the conveying surface, lifting upward the suspension means for
moving upward the rack unit of the uppermost stage to emerge above
the conveying surface, thereby transferring the article from the
conveying surface to the support means of the rack unit,
sequentially lifting upward the suspension means each time when a
new article is fed and rested on the conveying surface, for moving
upward the rack unit of the next lower stage to emerge above the
conveying surface, thereby transferring the article from the
conveying surface of the conveyor unit to the support means of the
rack unit, permitting the respective rack units to retain the
articles at spaced apart positions above the conveying surface,
thereafter, sequentially moving downward the suspension means until
each of the rack units descends below the conveying surface of the
conveyor unit, thereby transferring the article from the support
means of the rack unit back to the conveying surface, and
discharging the article from the conveyor unit to the transport
system.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a transport system for feeding
articles from station to station in a continuous manufacturing line
and warehouse. More particularly, it relates to an apparatus and
method for temporarily retaining articles midway the transport
system.
[0003] 2. Prior Art
[0004] A continuous manufacturing system includes a transport line
in the form of a roller conveyor for feeding stock items or
intermediate articles from station to station for processing and
finally feeding finished articles to a packaging station or a
shipping outlet. Midway the transport line, there sometimes arises
a need to temporarily retain the stock items, intermediate articles
or finished articles for a relatively short time. For example, in a
process for manufacturing edible items including bread, cakes,
noodles, and paste items, stock powder and suitable agents are
mixed. It is often desired to retain such a mixture for some time
at room temperature for aging for allowing the material to gain
some drape, texture or body. When the material is heated as by
baking, it is also desired to allow the material to cool down at
room temperature. In such a situation, if one attempts to perform
aging or cooling while the articles are being fed along the
transport line, the line must be extremely extended. If the
articles are removed off the line for aging or cooling purpose,
then the process becomes discontinuous, resulting in less efficient
operation. It is, therefore, desirable to temporarily retain the
articles midway the transport line for aging or cooling. In another
situation where there is a difference in processing speed between
upstream and downstream stations, it is also desirable to
temporarily retain articles midway the transport line between these
stations. In a still further situation where articles are
continuously fed along a transport line from within a warehouse to
a shipping exit, if shipping is intermittent, it is desirable to
temporarily retain articles midway the transport line.
[0005] Exemplary apparatus for temporarily retaining and storing
articles midway a transport line are disclosed in Japanese Patent
Application Kokai No. 225210/1990 and Japanese Utility Model
Application Kokai No. 132008/1990 as comprising two multi-stage
racks arranged in a transport line in a conveyance direction
whereby articles being conveyed are sequentially loaded in the
multi-stage racks and fed back to the transport line.
[0006] These apparatus have a satisfactory function of temporarily
retaining and storing articles midway the transport line, but
require a relatively complex and expensive mechanism for loading
articles in the multi-stage racks. Because of the complex
mechanism, maintenance is rather difficult.
SUMMARY OF THE INVENTION
[0007] Therefore, an object of the present invention is to provide
an apparatus of simple, inexpensive construction for temporarily
retaining articles midway a transport line and a retaining method
using the apparatus.
[0008] An article retention apparatus for use in a transport system
according to the present invention includes a conveyor unit having
a conveying surface for supporting and conveying an article
horizontally. A plurality of rack units each have support means on
which an article rests horizontally. Suspension means is provided
for suspending the plurality of rack units in a vertically spaced
apart relationship while keeping the rack units horizontal. Drive
means is provided for moving up and down the suspension means. The
conveyor unit and the plurality of rack units are configured such
that the rack units may be moved above and below the conveying
surface of the conveyor unit without interference between the
conveying surface of the conveyor unit and the support means of the
rack units.
[0009] Preferably the suspension means includes generally flexible
strips or chains land the plurality of rack units are attached to
the strips or chains at predetermined intervals.
[0010] In one preferred embodiment, the conveyor unit comprises a
roller conveyor unit having a plurality of rollers arranged in a
horizontal plane. The rollers at their top define the conveying
surface. More preferably, each rack unit is a ladder-shaped rack
and the conveyor unit has a plurality of spaced apart rollers, the
crosspieces of the ladder-shaped rack and the rollers are
alternately arranged in a non-contact interdigitating
relationship.
[0011] In another preferred embodiment, the conveyor unit comprises
at least one belt conveyor unit having an endless belt. The belt
presents a horizontal upper surface defining the conveying
surface.
[0012] Using the article retention apparatus, articles are retained
midway a transport system by placing the plurality of rack units on
standby in a stack at a position below the conveying surface of the
conveyor unit. An article is fed from the transport system to the
conveyor unit so that the article rests on the conveying surface.
The suspension means is lifted upward for moving upward the rack
unit of the uppermost stage to emerge above the conveying surface,
thereby transferring the article from the conveying surface to the
support means of the rack unit. The suspension means is lifted in
increment each time when a new article is fed and rested on the
conveying surface, for moving upward the rack unit of the next
lower stage to emerge above the conveying surface, thereby
transferring the article from the conveying surface to the support
means of the rack unit. The respective rack units retain the
articles at spaced apart positions above the conveying surface for
a desired time. Thereafter, the suspension means is moved downward
in increment until each of the rack units is moved below the
conveying surface of the conveyor unit, thereby transferring the
article from the support means of the rack unit to the conveying
surface. The articles are then discharged from the conveyor unit to
the transport system.
[0013] In the article retaining apparatus of the invention, a
plurality of rack units each having support means on which an
article rests horizontally can be suspended by suspension members
in a vertically spaced apart relationship while the rack units
remain horizontal. The conveyor unit and the plurality of rack
units are configured such that the rack units may be moved to
positions above and below the conveying surface of the conveyor
unit (which is the roller plane in the case of a roller conveyor
and the belt surface in the case of a belt conveyor) without
interference between the conveying surface of the conveyor unit and
the support means of the rack units. Therefore, in retaining an
article which has been fed to the conveying surface of the conveyor
unit from the transport system, the rack unit of the uppermost
stage among a plurality of rack units which have been placed on
standby at a position below the conveying surface is lifted upward
by the suspension members to emerge above the conveying surface
whereby the article on the conveying surface is transferred to the
support means of the rack unit. That is, the article rests on the
rack unit independent of the conveyor unit. Rack units of
subsequent lower stages are then sequentially lifted from the
standby position to emerge above the conveying surface to thereby
sequentially transfer the articles from the conveying surface to
the support means of the rack units. The articles are stored on the
respective rack units which are lifted above the conveyor unit.
[0014] Transport of the articles which have been stored as
mentioned above is restarted by moving down the suspension members
to cause the rack units to descend from above to below the
conveying surface of the roller conveyor unit. On passage of each
rack unit across the conveying surface, the article on the rack
unit is left on the conveying surface and then horizontally fed by
the conveyor unit along its the conveying surface. By sequentially
moving the rack units below the conveying surface, the articles are
fed from the rack units back to the conveying surface of the
conveyor unit and then horizontally fed until they are fed back to
the transport system.
[0015] In the preferred embodiment wherein the suspension members
are chains or strips which are flexible as a whole, the chains can
flex between the rack units, which allows the rack units, when they
are on standby below the conveying surface, to be closely stacked
on a stationary surface below the conveying surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a perspective view showing an overall transport
system having incorporated therein a temporary retention apparatus
according to one embodiment of the present invention.
[0017] FIG. 2 is a perspective view showing a roller conveyor unit
and rack units included in the exemplary retention tower shown in
FIG. 1.
[0018] FIG. 3 is a perspective view showing a drive unit,
suspension chains and rack units included in the exemplary
retention tower shown in FIG. 1.
[0019] FIG. 4 is a side elevation of rack units in a standby state
for illustrating the operation of the retention tower of FIG.
1.
[0020] FIG. 5 is a side elevation similar to FIG. 4, showing the
state that articles are being transferred from the roller conveyor
to the rack unit of the uppermost stage.
[0021] FIG. 6 is a side elevation similar to FIG. 4, showing the
state immediately after the articles have been transferred from the
roller conveyor to the rack unit of the uppermost stage.
[0022] FIG. 7 is a side elevation similar to FIG. 4, showing the
state that all the rack units of one retention tower are loaded
with articles.
[0023] FIG. 8 is a perspective view showing a roller conveyor unit
and rack units according to another embodiment.
[0024] FIG. 9 is a plan view of another arrangement of retention
towers relative to the main transport line, which is adapted for a
first come, first go system.
[0025] FIG. 10 is a schematic elevation of the arrangement of FIG.
9 showing the initial stage at the start of loading articles.
[0026] FIG. 11 is a schematic elevation similar to FIG. 10, showing
an intermediate stage.
[0027] FIG. 12 is a schematic elevation similar to FIG. 10, showing
an final stage when the retention towers are fully loaded with
articles.
[0028] FIG. 13 is a schematic elevation similar to FIG. 10, showing
a next stage at the start of unloading articles.
[0029] FIG. 14 is a perspective view showing a belt conveyor unit
and rack units according to a further embodiment of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0030] FIG. 1 illustrates an overall transport system having
incorporated therein a temporary retention apparatus according to
one embodiment of the present invention. FIGS. 2 and 3 illustrate
major components of the retention apparatus. In this embodiment, a
roller conveyor is used as a conveyor unit of the retention
apparatus.
[0031] In FIG. 1, the transport system includes a main transport
line 1 in the form of a conventional roller conveyor la for feeding
articles 4 in an arrow direction. Disposed perpendicular to the
main transport line 1 at a suitable position are a pair of parallel
arranged temporary retention towers 2A and 2B. A pair of junction
conveyors 3A and 3B each in the form of a conventional roller
conveyor are disposed between the main transport line 1 and the
retention towers 2A and 2B. A pair of ball conveyors 1b and 1c are
disposed in the sections of the main transport line 1 connected to
the junction conveyors 3A and 3B for permitting the article 4 on
the main transport line 1 to be fed in both a main feed direction
along the main transport line 1 and a transverse direction toward
the retention towers 2A and 2B.
[0032] The retention towers 2A and 2B are described in detail.
Since these two retention towers 2A and 2B are identical, only one
of them is described. Each of retention towers 2A and 2B includes a
roller conveyor unit 6, a plurality of (six in the illustrated
embodiment) rack units 7A to 7F, four suspension members 8A to 8D,
a drive unit 8, and a pair of upper and lower stage frame units 10A
and 10B for supporting these components.
[0033] Each of the frame units 10A and 10B is constructed from
channel bars into a generally rectangular shape. The upper frame
unit 10A is stacked on the lower frame unit 10B, and they are
removably joined by means of bolts (not shown) into an assembly.
Although a-two stage stack is illustrated herein, a vertical stack
of more than two stages is also possible as will be described later
and, of course, a single stage frame unit is acceptable.
[0034] Referring to FIG. 2, the roller conveyor unit 6 includes a
plurality of drive rollers 11 adapted to be driven in both forward
and backward directions, a plurality of free rollers 12 adapted to
freely rotate, the drive and free rollers 11 and 12 being
alternately arranged at predetermined intervals in a parallel
array, and plural pairs of vertical stands 13 anchored to a
rectangular base 14. Each of the drive and free rollers 11 and 12
at its ends is mounted between a pair of stands 13 for rotation.
The rollers including drive and free rollers are arranged at a
pitch P2 and has an outer diameter R. The rollers are parallel
arranged in a horizontal plane which is referred to as a roller
plane, hereinafter (exactly speaking, the roller plane is defined
as a plane SR passing the top of the respective rollers as shown in
FIG. 4). The roller conveyor unit 6 is accommodated within the
lower stage frame unit 10B of the frame unit assembly, with the
base 14 being removably secured to the bottom of the frame unit 10B
by means of bolts (not shown). The drive rollers 11 each have a
drive motor built therein in the illustrated embodiment although an
external drive motor may be coupled to the drive rollers 11 through
a suitable transmission mechanism.
[0035] Each of the rack units 7A to 7F is of a generally ladder
shape including a pair of parallel long side bars 15a, 15b and a
plurality of spaced apart short crosspieces 16 spanning between the
bars 15a, 15b as shown in FIGS. 2 and 3. The plurality of
crosspieces 16 cooperatively form a comb-shaped support means or
surface 17 on which an article rests. The plurality of crosspieces
16 are arranged at a pitch P.sub.1 which is equal to the pitch
P.sub.2 between the conveyor rollers 11, 12. The spacing S.sub.1
between the adjacent crosspieces 16 is greater than the outer
diameter R of the conveyor rollers 11, 12. The spacing S.sub.2
between the side bars 15a and 15b is greater than the width W.sub.1
of the roller conveyor unit 6 (more exactly, the distance between
the outer ends of the stands 13 supporting the rollers). When the
rack units 7A to 7F are vertically moved above and below the roller
plane (a plane passing the top of the respective rollers, also
referred to as a conveying surface) with their attitude kept
horizontal, the crosspieces 16 of the rack units 7A to 7F (defining
the support means 17) pass between the rollers 11, 12 of the roller
conveyor unit 6 and the side bars 15a, 15b of the rack units 7A to
7F move outside the stands 13 of the roller conveyor unit 6 so that
no interference occurs between the rack unit crosspieces 16 and the
conveyor rollers 11, 12 and between the rack unit side bars 15a,
15b and the conveyor stands 13.
[0036] The plurality of rack units 7a to 7F are suspended by a
drive unit 9 through suspension means including four flexible
chains 8A to 8D as shown in FIG. 3. More particularly, the rack
unit side bars 15a, 15b at the outside are provided with fixtures
18a, 18b in the form of claws or pins at a longitudinally
equidistance from the center of each side bar. The spacing S.sub.3
between the fixtures 18a and 18b is reduced from the upper stage to
the lower stage rack unit. The chains 8A to 8D are suspended from
the four corners of the drive unit 9 so that they may be moved up
and down. The chains 8A to 8D are removably engaged to the fixtures
18a, 18b of the rack units 7A to 7F. The positions of engagement of
the fixtures 18a, 18b of the rack units 7A to 7F with the chains 8A
to 8D are at a predetermined spacing along the length of each chain
8A to 8D. The spacing S.sub.3 between the left and right fixtures
18a and 18b of the rack units 7A to 7D is reduced as one goes to
the lower stage rack unit so that when all the rack units 7A to 7f
are suspended, the chains 8A to 8D are obliquely extended. It is
seen from FIG. 1 that a pair of chains 8A and 8B define a
frusto-triangle shape.
[0037] The drive unit 9 is removably secured to the top of the
upper frame unit 10A of the frame unit assembly by means of bolts
(not shown). As shown in FIG. 3, the drive unit 9 includes a
rectangular base frame 20, pillow blocks 21A to 21D disposed near
the four corners of the frame 20, rotating shafts 22aand 22b
extending between the pillow blocks 21A and 21C and 21B and 21D,
respectively, and rotatably supported thereby, and sprockets 23a to
23d mounted on the shafts 22aand 22b and adapted to be in meshing
engagement with the chains 8A to 8D for suspending the chains 8A to
8D from the drive unit 9. Relay sprockets 24a, 24b are mounted on
the shaft 22b and adapted to be in meshing engagement with the
chains 8A, 8C. The distal ends of the chains 8A to 8D are extended
from the sprockets 24a, 23b, 24b, 23d and secured to a weight 25.
The shaft 22b is adapted to be driven for rotation by a rotational
drive source 27 capable of forward and backward rotation in the
form of a geared motor fixedly secured to the base frame 20, via a
rotation transmission mechanism 28 such as a belt.
[0038] Referring to FIGS. 1 and 4 to 7, the operation of the
temporary retention towers 2A, 2B shown in FIGS. 1 to 3 is
described.
[0039] The article 4 to be fed and retained is horizontally fed by
the main transport line 1 consisting mainly of the roller conveyor
1a from the left upper position toward the right lower position in
FIG. 1. The article 4 is a generally rectangular container or
pallet in the illustrated embodiment and actually, stock items,
intermediate products or final products are placed in the
container, but are omitted for the sake of convenience in the
figures. Depending on their shape, the stock items or products can
be directly placed on the roller conveyor without using the
container.
[0040] When each article 4 is fed to the ball conveyor 1b by the
main transport line 1, a pusher (not shown) pushes the article 4 to
turn its feed direction at a right angle. The articles 4 are then
fed to the retention tower 2A through the junction conveyor 3A and
placed on the rollers 11, 12 of the roller conveyor unit 6, that
is, on the roller plane SR. The articles 4 resting on the roller
plane (or conveying surface) SR are shown in FIG. 4. The initial
state shown in FIG. 4 is a standby state wherein the chains 8A to
8D are extended to the maximum length and the rack units 7A to 7F
are vertically closely overlaid in a stack below the conveyor
rollers 11, 12. The respective slack sections of the chains 8A to
8D each between two adjacent ones of the rack units 7A to 7F sag
under gravity in a J bent shape.
[0041] Once the articles 4 rest on the roller plane SR, the
rotational drive source 27 such as a geared motor of the drive unit
9 is actuated. The rotational drive force is transmitted to the
shaft 22b through the transmission mechanism 28 whereby the
sprockets 24a, 24b, 23a to 23d are rotated to pull up the chains 8A
to 8D. The rack unit 7A of the uppermost stage is then lifted
upward with its attitude kept horizontal as shown in FIG. 5. When
the rack unit 7A moves upward past the roller plane SR, the
articles 4 resting on the roller plane SR are picked up by the
plurality of crosspieces 16 of the rack unit 7A serving as the
support means 17. That is, the articles 4 are transferred from the
rollers 11, 12 of the roller conveyor unit 6 to the rack unit 7A.
This state is shown in FIG. 6.
[0042] Then the lifting of the chains 8A to 8D or the drive source
27 is interrupted. During this quiescent period, a next set of
articles 4 are fed from the main transport line 1 to the roller
conveyor unit 6 in the same manner as described above. Once the
articles 4 have rested on the roller plane SR, the rotational drive
source 27 of the drive unit 9 is actuated again to pull up the
chains 8A to 8D whereby the rack unit 7B of the second upper stage
is lifted from below to above the roller plane SR. Then the
articles 4 on the roller plane SR are transferred to the rack unit
7B.
[0043] Thereafter, the rack units 7C to 7F of subsequent stages are
sequentially lifted in the same manner as described above whereby
the articles 4 are transferred to the rack units 7C to 7F. When the
articles 4 have been transferred to the rack unit 7F of the
lowermost stage, all the rack units 7A to 7F are above the roller
plane SR as shown in FIG. 7. Although lifting of the rack units 7A
to 7F by the chains 8A to 8D is intermittent in this embodiment,
the rack units 7A to 7F can be continuously lifted if the roller
conveyor unit 6 can be loaded with a set of articles 4 in
appropriate timing or in a synchronous manner.
[0044] When one retention tower 2A is fully loaded with articles in
this way, subsequent articles 4 are fed from the main transport
line 1 to the other retention tower 2B via ball conveyor 1c and
junction conveyor 3B whereupon the rack units 7A to 7F of the other
retention tower 2B are sequentially loaded with articles in the
same manner as described above.
[0045] After the articles are retained and stored for a
predetermined time, the articles are fed back to the main transport
line from the retention towers 2A and 2B by repeating the
above-mentioned operation in a reverse manner. More particularly,
the rotational drive source 27 of one retention tower 2A is
actuated in the reverse direction to extend downward the chains 8A
to 8D a predetermined distance. The rack unit 7F of the lowermost
stage is moved from above to below the roller plane SR of the
roller conveyor unit 6 whereby the articles 4 on the support means
17 (crosspieces 16) of the rack unit 7F are left on the roller
plane SR. Then the drive rollers 11 of the roller conveyor unit 6
are driven in the reverse direction to feed the articles 4 toward
the junction conveyor 3A along the roller plane SR. The articles 4
are discharged from the retention tower 2A to the junction conveyor
3A by which they are fed to the ball conveyor 1b in the main
transport line 1. A pusher (not shown) pushes each of the articles
to turn its feed direction from the ball conveyor 1b toward the
main transport line 1. The articles are fed forward by the roller
conveyor 1a along the main transport line 1. Next, the rack unit 7E
of the second lower stage is moved from above to below the conveyor
roller plane SR whereby the articles 4 are transferred from the
rack unit 7E to the roller plane SR and thereafter fed back to the
main transport line 1 in the same manner as described above.
Thereafter, the articles 4 on the rack units 7D to 7A are
sequentially fed back to the main transport line 1 in a similar
manner.
[0046] Since the spacing S.sub.3 between the fixtures 18aand 18b in
the rack units 7A to 7F is reduced from the upper stage to the
lower stage rack unit, the chains 8A to 8D are obliquely extended
when the rack units 7A to 7F are lifted as shown in FIGS. 1 and 7.
As compared with parallel or vertical extension, the oblique
extension of chains 8A to 8D is effective for restraining the rack
units 7A to 7F from swing motion in a longitudinal direction
(parallel to the loading and unloading direction of the articles 4
to and from the retention towers 2A, 2B), thus holding the rack
units relatively stable. When the rack units 7A to 7F are stacked
below the roller plane SR, the fixtures 18a, 18b are horizontally
offset between the vertically adjacent ones of the rack units 7A to
7F, permitting the slack chain sections between the adjacent ones
of the fixtures 18a (or 18b) to sag in J shape. This is effective
for preventing the slack chain sections between the vertically
adjacent ones of the rack units 7A to 7F from tangling with the
fixtures 18a, 18b or other parts or with each other. Then on
lifting, the rack units 7a to 7F can be moved up smoothly without
any twining of the chains 8A to 8D with the fixtures 18a, 18b and
any mutual entangling of the chains 8A to 8D.
[0047] If it is desired to increase the capacity of each retention
towers 2A, 2B to accommodate articles in the illustrated
embodiment, the number of rack units 7A to 7F suspended from the
chains 8A to 8D is increased and the number of the vertically
stacked frame units 10A, 10B is optionally increased. Since the
chains 8A to 8D are removably engaged with the fixtures 18a, 18b
and the upper and lower frame units 10A and 10B are removably
connected, it is quite easy to install an additional rack unit or
units and an additional frame unit. The entire tower is an assembly
of unit structures in the illustrated embodiment. This is
advantageous when the entire tower is to be installed in a
containment with a narrow inlet because the respective units can be
carried into the containment and assembled at an installation site
therein.
[0048] FIG. 8 illustrates another example of the roller conveyor
unit 6 and rack units 7A to 7F of the retention tower according to
the present invention.
[0049] In FIG. 8, each of the drive and free rollers 11 and 12 of
the roller conveyor unit 6 consists of two or more roller segments.
The roller conveyor unit 6 of FIG. 8 includes two rows of drive and
free roller segments. One row is a series of drive roller segments
11A and free roller segments 12A alternately arranged parallel at a
predetermined spacing and the other row is a series of drive roller
segments 11B and free roller segments 12B alternately arranged
parallel at a predetermined spacing. The roller segments 11A, 12A
of one row are supported for rotation by stands 13a, 13b and the
roller segments 11B, 12B of the other row are supported for
rotation by stands 13c, 13d. The one row is laterally spaced from
the other row, that is, a spacing is left between the stands 13b
and 13c.
[0050] Each of the rack units 7A to 7F includes a rectangular frame
32 having longitudinal and transverse sides. A center support rod
33A longitudinally straddles between the transverse sides at the
center. Side support rods 33B, 33C longitudinally extend between
the transverse sides at a distance S.sub.4 from the center. The
spacing S.sub.4 between the center support rod 33A and side support
rods 33B, 33C of each rack unit 7A to 7F is greater than the width
W.sub.2 of each roller conveyor unit row (more exactly, the
distance between the outer ends of the stands 13c, 13d supporting
the roller segments). The longitudinal sides of the rack unit frame
at the outside are provided with fixtures 18a, 18b at a
longitudinally equidistance from the center of each side for
removable engagement with the chains 8A to 8D.
[0051] Also in the example shown in FIG. 8, the rack units 7A to 7F
can be moved up and down by the chains 8A to 8D. The rack units 7A
to 7F can be moved below and above the roller plane of the roller
conveyor unit 6 without any interference therebetween, that is,
without any interference between the support rods 33A to 33C of the
rack units 7A to 7F and the roller segments 11A, 11B, 12A, 12B and
stands 13a to 13d of the roller conveyor unit 6. Then articles can
be transferred between the roller plane of the roller conveyor unit
6 and the rack units 7A to 7F.
[0052] FIG. 9 shows in plan view another arrangement including a
multiplicity of retention towers, for example, five retention
towers 2A to 2E. Each of the retention towers 2A to 2E is of the
same structure as the previously mentioned retention tower 2A of
FIG. 1.
[0053] In FIG. 9, the main transport line 1 consists mainly of a
roller conveyor 1a and includes ball conveyors 1b to 1f at
positions corresponding to the retention towers 2A to 2E. Each of
the ball conveyors 1b to 1f is of the same construction as that in
the FIG. 1 embodiment capable of turning the feed direction of an
article at right angles. Junction conveyors 3A to 3E are disposed
between the ball conveyors 1b to 1f and the retention towers 2A to
2E, respectively.
[0054] The arrangement shown in FIG. 9 permits for a first
come-first go system. After temporary retention of the articles in
the retention towers 2A to 2E, those articles which are earlier
loaded in the retention towers 2A to 2E can be unloaded earlier
than the later loaded ones. Exemplary operation is described at
several stages shown in FIGS. 10 to 13.
[0055] First referring to FIG. 10, the first retention tower 2A at
the farthest side in the feed direction of the main transport line
1 is left empty. The second retention tower 2B is sequentially
loaded with articles 4-11 to 4-16 coming from the main transport
line 1. The first come article 4-11 is placed on the uppermost
stage rack unit and subsequent articles 4-12 to 4-16 are placed on
the lower stage rack units in accordance with their order of
arrival.
[0056] When the second retention tower 2B is fully loaded, the
third retention tower 2C is sequentially loaded with articles 4-21
to 4-24 as shown in FIG. 11. Thereafter, the fourth and fifth
retention towers 2D and 2E are sequentially loaded with articles in
a similar manner. On the other hand, after the second retention
tower 2B has been fully loaded, as also shown in FIG. 11, the
articles 4-11 to 4-16 in the second retention tower 2B are once
discharged to the main transport line 1 and fed back along a
U-shaped route via a part of the main transport line 1, but to the
first retention tower 2A, which are loaded with the articles 4-11
to 4-16. At this point, the order of stacking the articles in the
first retention tower 2A is reverse to the order of stacking of the
articles 4-11 to 4-16 in the second retention tower 2B. That is,
the articles are loaded in the first retention tower 2A in the
order of from 4-16 (top) to 4-11 (bottom). Differently stated, the
article 4-11 which was first loaded in the second retention tower
2B is located at the lowermost stage in the first retention tower
2A and the articles which were later loaded in the second retention
tower 2B are located at higher stages in the first retention tower
2A.
[0057] After all the articles 4-11 to 4-16 are relocated from the
second retention tower 2B to the first retention tower 2A in this
way, the articles in the third retention tower 2C are once
discharged and relocated to the second retention tower 2B in a
similar manner. Thereafter the same procedure is repeated. FIG. 12
shows the final state when the articles 4-41 to 4-46 have been
relocated from the fifth retention tower 2E to the fourth retention
tower 2D. It will be understood that in each of the retention
towers 2A to 2D, articles of earlier arrival are located at lower
stages. At this point, the fifth retention tower 2E is empty.
[0058] At the point of time when a predetermined time has passed
since the start of loading of articles, that is, when at least the
first come article has finished aging or heat release, the articles
4-11 to 4-16 are unloaded from the first retention tower 2A to the
main transport line 1 as shown in FIG. 13. At this point, the
article 4-11 at the lowermost stage of the first retention tower 2A
is first unloaded and thereafter articles 4-12 to 4-16 are
sequentially unloaded in the order of from lower to upper stages.
This means that from the retention tower 2A, the first come article
is first discharged and the second and later come articles are
discharged in the order of their arrival. Thereafter, the articles
are similarly discharged sequentially from each of the second to
fourth retention towers 2B to 2E to the main transport line 1.
[0059] In this way, articles are sequentially discharged from the
retention towers 2A to 2E to the main transport line 1 in the order
of their arrival or loading. That is, the first come article goes
out first. Then all the articles reside in the tower for an equal
duration. This arrangement is best suited where an exact residence
time is strictly required.
[0060] It will be understood that even when a plurality of articles
rest on each of rack units 7A to 7F (see FIG. 1) within each of the
retention towers 2A to 2E, the configuration of FIGS. 10 to 13
permits the first come, first go system to be also applied to the
plurality of articles in the single rack unit.
[0061] Referring to FIG. 14, there is illustrated a further
embodiment of the retention apparatus according to the present
invention in which a belt conveyor unit 51 is used as the conveyor
unit in combination with rack units 7A to 7F. The belt conveyor
unit 51 includes a pair of belt conveyors 51A and 51B arranged
parallel such that their upper surfaces are horizontal. The upper
belt surfaces cooperatively define a conveying surface. Each of the
belt conveyors 51A and 51B includes an endless belt 53A, 53B
extended between a drive roller 55 and a drive roller 57. The
rollers 55 and 57 are supported by upright support arms 59. The
drive roller 55 is coupled to rotational drive means (not shown).
Disposed between the rollers 55 and 57 and immediately below the
upper section of the belt 53A, 53B is a bed 61 for supporting the
belt upper section horizontally between the rollers 55 and 57 while
the belt travels. The bed 61 is supported by upright support arms
63.
[0062] Since the rack units 7A to 7F are of the same construction
as shown in FIG. 8, they need not be described in detail. The
spacing S.sub.4 between the center support rod 33A and side support
rods 33B, 33C of each rack unit 7A to 7F is greater than the width
W.sub.3 of each belt conveyor 51A or 51B.
[0063] Also in the embodiment shown in FIG. 14, the rack units 7A
to 7F can be moved up and down by the chains 8A to 8D. The rack
units 7A to 7F can be moved below and above the conveying surface
(upper belt surface) of the belt conveyor unit 51 without any
interference therebetween, that is, without any interference
between the support rods 33A to 33C of the rack units 7A to 7F and
the belts 53A and 53B and support arms 59, 63 of the belt conveyors
51A and 51B of the belt conveyor unit 51. Then articles can be
transferred between the conveying surface of the belt conveyor unit
51 and the rack units 7A to 7F.
[0064] There has been described an article retention apparatus
combined with a transport system according to the present
invention. By lifting the rack units from below to above the
conveying surface (roller plane or belt surface) of the roller or
belt conveyor unit, articles are transferred from the conveying
surface to the rack units. Simply by holding the rack units
suspended above the conveying surface, the articles are retained
and stored in the retention apparatus. By lowering the rack units
from above to below the conveying surface of the conveyor unit,
articles are transferred from the rack units to the conveyor unit
and fed back to the main transport line. The apparatus has many
benefits including simple construction, low cost, a smaller number
of drives, and ease of maintenance.
[0065] The preferred embodiment wherein the suspension means are
comprised of flexible strips or chains is advantageous in that when
a plurality of rack units are in a standby position below the
conveying surface of the conveyor unit, the rack units can be
closely stacked with the suspension chains made loose. When it is
desired to use a larger number of rack units in order to increase
the accommodation capacity, it is unnecessary to substantially
elevate the conveying surface. This allows not only the overall
apparatus to be compact, but also the height of the conveying
surface to match with the height of the existing roller or belt
conveyor line. Then the retention apparatus can be easily applied
to the existing conveyor line.
[0066] Although some preferred embodiments have been described,
many modifications and variations may be made thereto in the light
of the above teachings. It is therefore to be understood that
within the scope of the appended claims, the invention may be
practiced otherwise than as specifically described.
* * * * *