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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a treatment apparatus for workpieces in which a
plurality of treatment stations are provided disposed side by side along
the apparatus, and transporter means are provided to transport workpieces
from one treatment station to the next along the apparatus. Such treatment
apparatus may be used for cleaning, pickling, plating and similar
treatments applied to workpieces. Usually, each treatment station will
comprise a tank of a liquid into which the workpieces are immersed for
treatment but there may be treatment stations where articles are sprayed
with a liquid or treated with a gas, for example warm air for drying
purposes. The particular details of the process being carried out are not
relevant to the present invention.
Many different types of workpiece may need to be treated and the workpieces
are commonly supported either on jigs or in open topped baskets or in
fully enclosed barrels made of a perforated material to allow access of
the treatment medium to the articles. The present invention was devised
for a treatment machine in which at least some of the articles to be
treated are enclosed in barrels.
2. Description of the Prior Art
It is essential, when workpieces are enclosed in a barrel, to ensure that
the treatment medium penetrates fully through the perforated barrel and
flows freely around the workpieces. Treatment apparatus has been proposed
in which each barrel is provided with an external toothed gear wheel which
can engage a drive gear at each of the stations, the individual drive
gears being driven by respective electric motors. The barrel is rotated by
the motor so that the workpieces inside are tumbled through the treatment
medium which percolates into the barrel.
However, this rotation arrangement is of limited applicability since the
axis of the barrel needs to be stationary so as to engage the drive gear.
The barrel can only be rotated at the treatment station when it is in the
treatment medium. Where cup-shaped articles are being treated or the
barrel contains a large number of very small articles, quite large
quantities of the treatment medium may be lifted out of the tank at the
treatment station when the articles are removed from the treatment medium.
It would be desirable to be able to rotate the barrel just above the
surface of the treatment medium for drainage purposes but this has not
been possible with the fixed drive motor and spur-gear arrangement
referred to.
There are various different types of treatment apparatus and the invention
was devised especially for use with a walking beam type of treatment
apparatus, as described in our prior British Pat. No. 1,409,784, for
example.
When a walking beam type transporter is used, it has hitherto not proved
possible to arrange for rotation of the barrel either in or above the
treatment medium.
The type of apparatus referred to as a "walking beam" type of treatment
apparatus has a long rigid horizontal beam which can be raised and lowered
and also moved longitudinally of the apparatus, for example by means of a
suitable arrangement of chains and pulleys with hydraulically or
pneumatically operated drive means. The barrels (or jigs or baskets) are
suspended from the beam by means of parts which rest on supporting ledges
of the beam. This enables the beam to pick up the workpieces, move them
longitudinally from one station to another, lower them at the treatment
stations into the relevant medium and then disengage from the barrel by
slight further downward movement so that the beam can be returned to its
original longitudinal position to pick up the next adjacent set of
workpieces.
In addition to this movement, the beam can be arranged to perform a
reciprocating up and down movement whilst supporting the workpieces at the
treatment stations so as to "dunk" the workpieces in the treatment medium
to ensure good coverage of the workpieces by the medium. This dunking may
be especially useful where the workpieces are provided in an open topped
basket. The articles may be packed together and prevent access of the
treatment medium but the basket can only satisfactorily be agitated in an
up and down "dunking" movement without the risk of losing some of the
workpieces.
However, if a walking beam type of machine is to be capable of use to treat
articles in barrels as well as in baskets or jigs, it would be desirable
to be able to rotate the barrels without interfering with the normal
functioning of the machine and in particular to do so independently of the
position of the beam so that rotation is independent of dunking and can be
carried out whether the barrel is immersed at, or disposed above the
treatment station.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide a walking beam type
treatment apparatus wherein a barrel containing workpieces can be rotated
at least at one treatment station.
Some or all of the problems and disadvantages referred to above may be
overcome by embodiments of the invention.
According to the invention there is provided a walking beam type treatment
apparatus comprising a plurality of side by side treatment stations, one
or more barrels adapted to contain workpieces, a transporter beam adapted
to support the barrel or barrels and capable of movement longitudinally of
the apparatus to transport workpieces from one station to another, and of
up and down movement to raise and lower the workpieces at the treatment
station, the or each barrel being rotatably mounted and being provided
with an indexing mechanism including a pivoted lever linkage, and the beam
having a longitudinally reciprocable barrel drive means adapted to bear on
said lever linkage to operate the indexing mechanism when the barrel is
supported by the beam.
The barrel may be released from the beam by providing supports at the
treatment station on to which it may be lowered, the beam being arranged
to then move downwardly by a short distance to free itself from the barrel
to enable a return movement of the beam to take place to its original
position.
The reciprocable barrel drive means may comprise a rod supported for
movement along the beam and provided, at one or more treatment stations,
with at least one outwardly extending lug adapted to bear on the lever
linkage when the barrel is supported on the beam. Preferably, two such
lugs are provided, spaced apart from each other sufficiently to receive
the lever linkage between the lugs, whereby the lugs alternately engage
the lever linkage during reciprocating movement in alternate directions of
the rod.
The indexing mechanism may comprise a ratchet wheel secured rigidly to the
barrel and capable of being indexed in one direction of rotation by the
lever linkage, pawl means being provided to hold the ratchet wheel against
rearward movement after each forward indexing movement of the ratchet
wheel.
The reciprocable barrel drive means may be reciprocated by a piston and
cylinder assembly. Preferably, where the barrel drive means comprises a
reciprocable rod of substantial length, the piston and cylinder assembly
is mounted on the beam at a position where it will not be fouled by the
movement of the beam or the barrels during use and is operatively
connection to the rod by a linkage comprising a swinging arm caused to
undergo arcuate movement by reciprocating movement of the piston, the arm
being linked to the rod by coupling means capable of transmitting only a
linear component of the swinging movement of the arm. These means may
comprise a bush mounted for horizontal sliding movement parallel with the
rod and having a portion of the swinging arm slidably received therein,
the slidable movement of the swinging arm relative to the block being in a
direction perpendicular to the direction in which the block itself
reciprocates.
The invention will now be described in more detail by way of example only
with reference to the accompanying drawings in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation, partly broken away, of a barrel, shown to a
small scale,
FIG. 2 is a detail side elevational view of a reciprocable barrel drive
means,
FIG. 3 is an axial sectional view of the barrel of FIG. 1 in use in a
walking beam type of treatment apparatus
FIG. 4 is a side elevational view of an operating means for reciprocable
barrel drive means of FIG. 2,
FIG. 5 is a sectional view on the line 5--5 of FIG. 4,
FIG. 6 is a perspective view of the treatment apparatus.
DETAILED DESCRIPTION
Referring firstly to FIG. 1 of the drawings, a barrel is generally
indicated at 10 and is of constant hexagonal cross-section, having one
wall provided with a closure 11 through which articles for treatment are
inserted and from which they are withdrawn at the end of the treatment
cycle. The barrel is mounted for rotation about an axis 12, the ends of
which are journalled in a frame 13 which is shown partly broken away for
clarity. The frame comprises a pair of limbs 14 which receive the opposed
ends of the axis. Each limb has, at its lower end, a rigid transverse foot
15. The upper ends of the limbs are provided with means for resting on a
flange of a main transporter beam of the apparatus, this arrangement being
seen more clearly in FIG. 3 of the drawings and also being illustrated
somewhat diagrammatically in FIG. 2. A flange 16 of the main transporter
beam generally indicated at 17 supports a pair of pegs 18 welded to
respective angle bracket 19 which in turn is welded to the top of each
limb 14. Two pegs are provided at opposed ends of the angle bracket at
each end of the barrel and a pair of stops 20 are welded to the flange 16
of the main beam at each treatment station. The barrel is therefore
supported by four pegs 18, located by four stops 20, two at each end of
the barrel.
The treatment apparatus overall is of generally conventional design as
shown in FIG. 6. It comprises a row of treatment stations 9 disposed side
by side, together with a main transporter beam 17 mounted for up and down
movement and also for longitudinal movement relative to the stations. Each
treatment station is provided with suitable guides and also with a support
bracket 21 which can support a load to be treated. The main transporter
walking beam 17 picks up a load at a first loading station, raises it,
moves longitudinally of the apparatus until the load is directly above the
first treatment station, lowers the load until it reaches and is supported
by the support brackets 21 at the treatment station and then continues
moving downwardly to release the load temporariliy. The beam then moves
longitudinally in the reverse direction so as to return towards the
loading station. It will be appreciated that repeated movements of the
beam will tend to work the load along the apparatus to the discharge end,
generally indicated at 7 and that a series of loads can therefore be
treated simultaneously, each load occupying an adjacent treatment station.
The loads can be on jigs, in open-topped baskets, one of which is shown at
6 in FIG. 6, or in barrels of the type shown in FIGS. 1 and 3 of the
drawings. The present invention enables the barrels to be rotated, without
in any way hindering the use of the apparatus for treatment of loads
supported other than in barrels.
This is achieved by providing a reciprocating barrel drive mechanism
generally indicated at 22 in FIG. 2 of the drawings, and extending along
one side wall of the main transporter beam 17. The reciprocating barrel
drive operates an indexing mechanism generally indicated at 23 on the side
of the barrel so that the barrel can be indexed rotationally about the
axis 12.
The indexing mechanism is operated by a lever linkage generally indicated
at 24 which is mounted on a bracket 25 fixed to the limb 14 of the barrel
frame. The lever linkage 24 comprises a bell crank lever pivotally mounted
about an axis 26 on the bracket and comprising a first arm 27 and a
second, perpendicular arm 28. The arm is biased upwardly by means of a
strong spring 29 which is housed within the hollow limb 14. The outer end
of the second arm 28, remote from the pivotal axis 26, is attached by a
link 30,31 to a bush 32 which also carries a lug 33. The lug 33 has a
pivoted pawl 34 which engages a ratchet 35 fixed with respect to the
barrel 10.
Also mounted on the barrel 10 is a support pawl 36 which acts in generally
known manner to support the ratchet 35 against reverse movement when the
pawl 34 is not in driving engagement with a tooth of the ratchet 35.
The way in which this ratchet device operates is that the upper end of the
first arm 27 is rocked from side to side relative to its pivotal axis 26,
thereby causing the second arm 28 of the bell crank lever to operate the
links 30 and 31 and hence to rotate the ratchet 35 via the pawl 34. When
the ratchet has rotated by a certain fraction of its circumference,
determined by the placing of the ratchet teeth, the support pawl 36 slips
over one of the teeth and prevents the ratchet from return movement when
the swinging movement of the first arm 27 is reversed.
The first arm 27 is rocked by the reciprocable barrel drive 22 shown in
FIG. 2. At the upper end of the first arm 27, there is provided a roller
37. For clarity in FIG. 2, the first arm is not shown.
The roller 37 is disposed between a pair of flanges 38, 39, when the
reciprocable barrel drive is operating. The flanges 38 and 39 are mounted
on a plate 40 which is fixed on a rod 41 extending along the entire length
of the apparatus. The rod 41 is mounted on the main transporter beam 17
for reciprocation relative to the beam. The beam is provided with a low
friction cushion 42 disposed at the rear of the rod, together with pairs
of freely rotatable low friction support bushes 43 which guide the rod 41
for smooth longitudinal movement relative to the main beam 17.
The rod 41 is reciprocated by operating means to be described subsequently
and hence it moves the flanges 38,39 back and forth from right to left as
shown in FIG. 2 of the drawings. The roller 37 is therefore positively
pushed back and forth from right to left, swinging the arm 27 of the bell
crank lever between the limit positions shown in chain dotted lines in
FIG. 2.
In a typical treatment apparatus having a plurality of stations side by
side, the rod 41 may be ten or fifteen meters long and may be required to
reciprocate the lever linkages of perhaps eight or ten barrels, each of
which may have a substantial weight and may be loaded with even greater
quantity of articles to be treated.
An operating means for the reciprocating barrel drive rod 41 therefore
needs to be robust in nature. However, it also requires to be so
positioned as not to obstruct the movement of barrels along the apparatus,
the movement of the main transporter beam 17, or the support arrangements
for articles to be treated on jigs or in open-topped baskets for example.
To satisfy these requirements in the apparatus under consideration, the
operating means for the reciprocable barrel drive are disposed within the
hollow main transporter beam and can be seen in FIGS. 4 and 5 of the
drawings. The main transporter beam 17 is of hollow box-section, the
flange 16 being visible along one lower side edge. A powerful piston and
cylinder assembly 44 is disposed within the transporter beam 17, being
mounted on support brackets 45 which are sufficient to take the reaction
load of the piston and cylinder in use.
Since the linear movement of the piston rod 46 of the piston and cylinder
cannot be transmitted directly to the rod 41 which is housed outside the
transporter beam 17, a linkage, capable of withstanding a substantial
turning moment, needs to be interposed between the piston rod 46 and the
rod 41. The turning moment is due to the necessary lateral separation of
the two rods.
The arrangement is shown in FIGS. 4 and 5 and comprises a pendulum link 47
which is pivotally mounted at 48 to rigid supports mounted on the beam 17.
The pendulum link 47 is a composite structure having a pair of spaced
apart limbs 48 joined by bracing 49 and by a rigid link bar 50. The link
bar extends outwardly through a longitudinal window 51 in the beam 17 and
is mounted in a block 52. The arrangement is such that the link bar 50 can
move upwardly and downwardly relative to the block 52, which is provided
with a vertical slot to receive it, but is in driving engagement
considered from side to side of the block. The block is constrained for
sliding movement in the window 51 which is defined in a support 53 secured
to the outer face of the beam 17.
In operation, the piston and cylinder assembly is extended and contracted
by regulating the supply of fluid and this causes the piston rod 46 to
push or pull the pendulum link 47. The component of motion of the pendulum
link which is longitudinal of the beam is transferred to the block 52 and
thence to the rod 41 which is secured to the block. The vertical component
of movement of the pendulum link which moves in an arcuate path about the
pivot 48 is taken up by the up and down sliding movement of the link bar
50 in the block 52.
The piston and cylinder assembly can be of any suitable type and may be
hydraulic or pneumatic.
It will be appreciated that control of the piston and cylinder assembly can
be quite separate from the other controls of the apparatus so that the rod
41 can be driven at any position of the main transporter beam and
irrespective of the position of the barrels. Indexing of the barrels will
take place if the rod 41 is reciprocated when the roller 37 is disposed
between the flanges 38 and 39. Thus, the barrel can be indexed at any time
when it is supported on the main transporter beam, as shown in FIG. 3.
However, at some stages during the machine cycle, the barrel, as referred
to above, may be deposited on support brackets 21 provided at the
treatment station whilst the main transporter beam moves downwardly and
returns towards a preceding station. Clearly, the barrel indexing means
must cease to operate during this return movement of the transporter beam.
This is allowed for in the the apparatus shown because, when the main
transporter beam drops from the position shown in FIG. 2, having deposited
the barrel on the support brackets 21 of the treatment station, the roller
37 of the bell crank lever projects above the level of the flanges 38 and
39 as shown in chain dotted lines in FIG. 2. Furthermore, the pegs 18 on
which the barrel was previously supported by the beam are now elevated
above the stops 20 to enable the beam to return towards a preceding
station to pick up a following barrel or other workload.
In the position shown in FIG. 3 of the drawings, the main transporter beam
17 has just returned to its starting position and is picking up a barrel
10. The flange 16 has just made contact with the pegs 18 and the feet 15
of the barrel are just about to lose contact with the support brackets 21
of the treatment station. From this position upwards, the lever linkage 24
can be operated.
It will be appreciated that, as long as the main transporter beam supports
the barrel, the arm 27 can be rocked by movement of the rod 41 and hence
the indexing mechanism can operate. It is immaterial whether the barrel is
submerged in a liquid at the treatment station or whether it is raised
slightly above the liquid. Indexing could even continue whilst the barrel
was being transported from one station to another if this were desired.
Thus, the barrel can be indexed whilst it is being dunked by raising and
lowering the main transporter beam.
It will be appreciated that, since the rod 41 is positioned along the main
transporter beam 17 above the flange 16, the mechanism in no way obstructs
the use of jigs or baskets to support articles to be treated. Only when
the barrel having the lever linkage 24 is introduced to the apparatus does
the drive means for the indexing mechanism have any effect. The drive
means can be operated completely independently of the transporter beam
drive so that it can be separately programmed.
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