Field of the Art
[0001] The present invention describes a device for performing a surface coating of parts
or pieces, mainly pieces obtained based on additive manufacturing techniques (according
to a method also commonly known as additive manufacturing), such as for example, stereolithography
(SL or SLA), selective laser sintering (SLS), fused deposition modeling (FDM), or
other 3D printing and/or rapid prototyping techniques.
[0002] The mentioned surface coating to be performed on said pieces is the application of
a dyeing agent to the outer surface of the pieces by means of dipping said pieces
in a water-based dye solution.
State of the Art
[0003] There is a great variety of processes and devices which allow coating the surfaces
of pieces with a substrate so that these pieces obtain an optimum and homogenous (uniform)
visual appearance for decorative or esthetic purposes and/or for modifying or improving
the surface properties of the coated pieces. Some of these processes include, among
others, coating based on:
- chemical vapor deposition,
- physical vapor deposition,
- application of thin film substrates applied to the outer surface of the pieces,
- use of aerosols or sprays, or
- dipping in a dye solution,
with the present invention referring to the latter. Dip coating consists of manually
or automatically immersing the pieces to be coated in an appropriate leak-tight bath,
cavity, or receptacle containing a dye solution at a predetermined temperature and
for a predetermined time.
[0004] Patent
US 4,726,318 describes a device for coating parts with a dye solution, formed by a cylindrical
dyeing tank having a stationary hollow shaft extending horizontally and axially therethrough
for ejecting a dye solution, with a cylindrical tank rotatably mounted on said shaft
in which the pieces are inserted, and an auxiliary tank which is coupled directly
with the bottom of the dyeing tank and integrates heating means, inside which the
mixing of dye solution is performed, and it has a recirculation system connected to
the hollow shaft.
[0005] The purpose of the present invention is to propose a new design of a device for improving
the process for the surface treatment of pieces, simplifying said process which is
carried out, combining and/or performing steps in a simultaneous manner, reducing
the size of the network of conduits integrated in the device itself, in addition to
including safety elements to assure that the device works under optimum working conditions,
while at the same time preventing possible leaks or spillage of the dye solution and
losses therein during a work cycle.
Brief Description of the Invention
[0006] The present invention describes a device for performing a surface coating of pieces,
wherein said device is formed by a housing including at least: one leak-tight cavity
containing a drum where pieces to be coated are introduced, heating means, one or
more water supply conduits and at least one dyeing agent inlet conduit for entry to
said leak-tight cavity and drum, the mentioned water inlet conduit and dyeing agent
inlet conduit being controlled by a control unit by means of a control device, and
there being provided a recovery tank in communication with said leak-tight cavity
and a fluid recirculation circuit from said recovery tank to said leak-tight cavity
and said drum.
[0007] In a particular embodiment, the drum arranged inside the leak-tight cavity has a
cylindrical geometry, is installed in a horizontal configuration, and has a plurality
of perforated holes which allow the flow of a dye solution between the leak-tight
cavity and the inside of the drum where the pieces are located, said dye solution
being the result of the prior mixing of water and a dyeing agent.
[0008] Once the pieces and the dye solution are inside the drum and the device is performing
a work cycle, the drum can be in a standby or stationary position, or preferably performs
a dynamic movement about a drive shaft operated by an actuator, wherein said dynamic
movement is preferably selected from: an oscillating or back-and-forth movement or
a rotational movement. It must be pointed out that the mentioned drive shaft actuating
the drum is preferably coaxial to an imaginary central axis defined by the geometry
of the drum.
[0009] The pieces are introduced into the drum through a gate, and they can optionally be
introduced in pouches or bags to prevent possible defects resulting from the impact
of the parts with the inner surface of the drum, causing scratches, cracks, or indentations,
among other possible defects in the parts.
[0010] The present invention is characterized in that the leak-tight cavity includes a first
level sensor which is directly or indirectly connected to the control device of the
water supply conduit, such that the entry of water to the leak-tight cavity, and therefore
to the drum in which the parts to be coated will be introduced, is interrupted if
a predetermined water level is reached inside the leak-tight cavity for performing
an optimum mixing of water and said dyeing agent inside the drum. The level sensor
of the leak-tight cavity is preferably an analog transducer, and it can also be located
inside the drum, performing the same function, instead of in the leak-tight cavity.
[0011] Furthermore, the present invention additionally has at least a second level sensor
which is integrated in the recovery tank installed below the housing of the device
and directly or indirectly connected to the control device of the at least one water
inlet conduit and the at least one dyeing agent inlet conduit, such that the entry
of water and dyeing agent to the leak-tight cavity and to the drum is interrupted
if a specific level, compatible with its capacity, is exceeded inside the recovery
tank, so as to prevent possible leaks or spillage of the dye solution.
[0012] The described device can furthermore include a dye solution discharge system which
is located in the leak-tight cavity comprising at least one outlet from said cavity,
each outlet being controlled by a discharge pump and a non-return valve, wherein each
outlet of the discharge system is connected to one or more water treatment tanks.
The discharge system is automatically activated by said control unit, after the selection
of a predetermined program stored in its memory, once the dye solution has performed
or exceeded a number of predetermined work cycles in which it has been recirculated,
or once it has exceeded a predetermined time period of service life.
[0013] Each discharge pump associated with an outlet conduit is controlled by a level sensor
integrated in at least one of the one or more water treatment tanks, such that it
is activated or deactivated according to the signal emitted by the level sensor associated
with said discharge pump, indicating if the level inside the tank is lower than or
equal to or greater than a predetermined maximum level.
[0014] Moreover, the heating means used in the device are preferably heating coils with
two thermal contacts, controlled by a programmable safety relay, and in a preferred
embodiment they are included inside the drum, although they may also be introduced
in the leak-tight cavity, obtaining a similar heating effect. It must be pointed out
that the use of other equivalent heating means, such as for example, radiator-type
heat exchangers, would be obvious for one skilled in the art and must be considered
as an equivalent as the same purpose is achieved.
[0015] In a preferred embodiment, the control device of the water inlet conduit is a solenoid
gate valve and the mentioned control device of the dyeing agent inlet conduit is a
regulating pump.
[0016] The operating principle of the device is as follows:
- i. the solenoid valve regulating the passage of water opens to enable introducing
water into the leak-tight cavity and drum until the level sensor, integrated inside
the drum or leak-tight cavity, detects that the level of water accumulated in the
drum is optimum and sends a signal which closes the solenoid valve;
- ii. once the solenoid valve has been closed, the pump regulating the passage of the
dyeing agent is activated for a predetermined time in order to introduce a predetermined
amount of dyeing agent into the drum and thereby obtain a dye solution in optimal
proportions;
- iii. the water and dyeing agent are mixed inside the drum, and the mixture is optionally
heated at a predetermined temperature the dye solution resulting from mixing;
- iv. once the dye solution has been obtained, it is discharged from the drum to the
recovery tank to enable introducing the parts that must be treated in the drum;
- v. the dye solution is recirculated from the recovery tank back to the drum by means
of a recirculation pump to perform the surface coating of the parts introduced in
the drum, and this operation is repeated in several work cycles; and
- vi. finally, once the service life cycle of the dye solution has been reached, it
is discharged from the leak-tight cavity to the treatment tanks by means of a discharge
system.
[0017] Optionally, once the dye solution has been discharged from the drum to the treatment
tanks, a leak-tight cavity washing program can be performed before starting the next
work cycle.
[0018] Before starting, during, or after completing a work cycle of the device, a user can
select different programs stored in a memory of the control unit of the device so
that the device performs actions automatically, and depending on the selected programs,
perform them sequentially. Some of the programs stored in the memory are:
- i. A mixing program in which a new dye solution is prepared by introducing water and
a dyeing agent into the drum to be mixed.
The recommended service life of the dye solution is about 5 work cycles or an approximate
duration of one week, provided that not more than 5 work cycles have been performed.
- ii. A conditioning program for conditioning the dye solution for use, i.e., the solution
being in working conditions that are optimum for use.
This program preheats the dye solution using the heating means included in the device
if a predetermined period of time, usually between 1 and 2 days, has elapsed from
the last work cycle.
- iii. A coating program for coating parts under predetermined temperature conditions,
preferably at a temperature of at least 50°C, said temperature preferably being 60°C,
and then a rinse cycle.
- iv. A discharging program for discharging the dye solution once its service life cycle
has been reached and/or exceeded after performing a predetermined number of work cycles.
- v. A cleaning program for cleaning the leak-tight cavity, the recovery tank, and the
network of conduits once the dye solution has been discharged.
[0019] Moreover, there is also the possibility of the control unit automatically selecting
one of the programs stored in its memory depending on the programs selected by the
user or the number of work cycles performed previously in other operations.
[0020] Preferably, the water introduced in the leak-tight cavity including the drum is water
that is already heated to thereby reduce the use of the heating means included in
the cavity, reducing the power consumption of the device, in addition to accelerating
the surface treatment process, limiting the use of the heating means only when the
dye solution conditioning program is selected.
[0021] The dyeing agent can preferably be selected from a group comprising at least: one
water-based liquid dye, powder or pigment dyes, coloring, or other dyeing agents available
to a user, the dyeing agent preferably being said water-based liquid dye.
[0022] Preferably, the dyeing agent used in the dye solution gives the parts a final coating
that has a dark shade, mainly a black shade, and optionally grayish shades.
[0023] In a preferred embodiment, the dye solution obtained from the mixture of water and
dyeing agent has an approximate proportion of 10 to 1, respectively, for normal working
conditions. However, this proportion can be modified depending on the dyeing agent
used, the volume of parts to be coated, the geometry or design of said parts, the
properties of the surface coating, and/or the type of final surface coating to be
obtained.
[0024] It will be understood that references to geometric position, such as for example,
parallel, perpendicular, tangent, etc. allow deviations of up to ±5° with respect
to the theoretical position defined by said nomenclature.
[0025] It will be understood that the end values of any offered range of values may not
be optimal and adaptations of the invention may be required so that said end values
are applicable, said adaptations being within reach of one skilled in the art.
[0026] Other features of the invention will become apparent in the following detailed description
of an embodiment.
Brief Description of the Drawings
[0027] The foregoing and other advantages and features will be better understood based on
the following detailed description of an embodiment in reference to the attached drawing
which must be interpreted in an illustrative and non-limiting manner, in which:
Figure 1 illustrates a schematic design of an embodiment of the device and the elements
making up the device.
Detailed Description of an Embodiment
[0028] The attached drawings show illustrative non-limiting embodiments of the present invention.
[0029] Figure 1 illustrates a schematic design of an embodiment of a device 1 for performing
the surface coating of parts and the elements making up the device. Said device 1
is formed by an electronic control unit 8, a housing 2 inside which there is arranged
a leak-tight cavity 3, a water inlet conduit 6a, and a dyeing agent inlet conduit
6b, wherein the water is preferably hot water and the dyeing agent is a water-based
liquid dye, said conduit 6a being regulated by a first control device 9a, preferably
a solenoid valve, and said conduit 6b being regulated by a second control device 9b,
preferably a regulating/drive pump, both control devices 9a, 9b being controlled by
said control unit 8 depending on signals captured by level sensors 30, 70, and 12.
[0030] There is arranged inside the leak-tight cavity 3 a drum 4 in which the parts to be
coated are arranged through a gate (not illustrated in Figure 1) which provides access
to the inside of the drum 4. To simplify the diagram of the device 1 illustrated in
Figure 1, neither the drive shaft of the drum 4, or the actuator thereof, nor the
imaginary geometric axis of the drum 4 are shown.
[0031] The cavity 3 includes a first level sensor 30 which is directly or indirectly connected
to the solenoid valve regulating the flow of water to the inside of the cavity 3 through
the water inlet conduit 6a.
[0032] There is installed below the housing 2 of the device a recovery tank 7 connected
with the cavity 3 of the device through a recirculation circuit 7a formed by multiple
conduits, which allows recirculating the dye solution in the device by means of a
drive pump 7b installed in the recirculation circuit 7a. Furthermore, the recovery
tank 7 has a second level sensor 70, the function of which is safety related to preventing
possible leaks or spillage, said sensor 70 being configured for detecting if the level
of dye solution or fluid inside the tank 7 exceeds a predetermined maximum level,
and if said maximum level is exceeded, closing or locking the control devices 9a,
9b to prevent the entry of more water or dyeing agent to the device 1, as it is directly
or indirectly connected to the control devices 9a, 9b controlled by the control unit
8.
[0033] The device 1 furthermore includes a discharge system 10 to enable discharging the
dye solution once a predetermined number of work cycles has been performed or a period
of service life of said dye solution has been exceeded, said system having at least
one outlet conduit 10a from the leak-tight cavity 3 including the drum 4, wherein
each outlet 10a has a discharge pump 10b and a non-return valve 10c arranged at the
outlet of said discharge pump 10b. As indicated above, there can be multiple outlet
conduits 10a (not illustrated), wherein each outlet 10a directs the dye solution to
a single water treatment tank 11 or to a water treatment tank 11 associated with each
outlet conduit 10a, to enable suitably treating the dye solution.
[0034] In a preferred embodiment as illustrated in Figure 1, the discharge system 10 includes
a single outlet conduit 10a from the leak-tight cavity 3, which splits into at least
two branched conduits, each of said branched conduits being equipped with a discharge
pump 10b and an associated non-return valve 10c, regulating the flow of the dye solution
to a single water treatment tank 11 or preferably different water treatment tanks
11 each independently connected to one of the at least two branched conduits, the
water treatment tanks 11 being arranged remotely with respect to the device 1.
[0035] Regardless of the number of water treatment tanks 11, each tank 11 has a level sensor
12 for regulating the flow of dye solution from the device 1 to the tank 11 through
the at least one outlet conduit 10a to prevent possible spillage, said level sensor
12 being independently connected, in a direct or indirect manner, to each discharge
pump 10b of each outlet conduit 10a, determining if it must activate or deactivate
said discharge pump 10b depending on the signal emitted by the level sensor 12 which
indicates if a maximum safety level has been reached and/or exceeded, in which case
the discharge pump 10b will be deactivated, preventing the passage of the dye solution
through the outlet conduit 10a to the water treatment tank 11 until the level inside
the tank 11 has gone down.
[0036] It must be pointed out that any other possible configuration of the discharge system
10 not contemplated above, whether in terms of the number of outlet conduits 10a,
the amount of water treatment tanks 11, or the final distribution between the outlet
conduits 10a and the water treatment tanks 11, must be considered equivalent to the
described configurations, in addition to being obvious for one skilled in the art.
[0037] In this particular embodiment, the water inlet conduit 6a, the dyeing agent inlet
conduit 6b, the recirculation circuit 7a, and the outlet conduit 10a are directly
connected to the leak-tight cavity 3 inside the device 1 which contains the drum 3
therein.
[0038] It will be understood that the different parts making up the invention described
in one embodiment can be freely combined with parts described in other different embodiments
even though said combination has not been explicitly described, provided that the
combination does not entail any drawback.
1. A device (1) for performing a surface coating of pieces, wherein said device (1) comprises
a housing (2) including at least:
- one leak-tight cavity (3) containing a drum (4) where the pieces to be coated are
introduced,
- heating means (5),
- at least one water inlet conduit (6a) and one dyeing agent inlet conduit (6b) for
entry to said leak-tight cavity (3) and drum (4), and
- a recovery tank (7) in communication with said leak-tight cavity (3) and a fluid
recirculation circuit (7a) from said recovery tank (7) to said leak-tight cavity (3)
and drum (4),
wherein said at least one water inlet conduit (6a) and dyeing agent inlet conduit
(6b) are operated by a control unit (8) by means of a control device (9a, 9b),
characterized in that said leak-tight cavity (3) includes a first level sensor (30) which is directly or
indirectly connected to said control device (9a) of the at least one water inlet conduit
(6a), such that the entry of water to the leak-tight cavity (3) is interrupted when
a specific level, compatible with its capacity, is reached inside the cavity (3),
and
in that the recovery tank (7) includes at least a second level sensor (70) directly or indirectly
connected to the control device (9a, 9b) of the at least one water inlet conduit (6a)
and of the at least one dyeing agent inlet conduit (6b), such that the entry of water
and dyeing agent to the leak-tight cavity (3) is interrupted if a specific level,
compatible with its capacity, is exceeded inside the recovery tank (7).
2. The device (1) for the surface coating of pieces according to claim 1, furthermore
including a discharge system (10) of the leak-tight cavity (3) comprising at least
one outlet (10a) of said cavity (3), each outlet (10a) being controlled by a discharge
pump (10b), wherein each outlet (10a) of the discharge system (10) is connected to
one or more water treatment tanks (11).
3. The device (1) for the surface coating of pieces according to claim 2, wherein each
discharge pump (10b) is automatically activated by said control unit (8) once the
mixture of water and dyeing agent has performed a number of predetermined recirculation
cycles.
4. The device (1) for the surface coating of pieces according to claim 2 or 3, wherein
each discharge pump (10b) is controlled by a level sensor (12) integrated in the one
or more water treatment tanks (11).
5. The device (1) for the surface coating of pieces according to claim 1, wherein the
level sensor (30) of the leak-tight cavity (3) is an analog transducer.
6. The device (1) for the surface coating of pieces according to claim 1, wherein the
drum (4) has a cylindrical geometry.
7. The device (1) for the surface coating of pieces according to claim 1 or 6, wherein
the drum (4) performs an oscillating movement or a rotational movement about a drive
shaft operated by an actuator.
8. The device (1) for the surface coating of pieces according to claim 7, wherein said
drive shaft is horizontal and coaxial to a central axis defined by the geometry of
the drum (4).
9. The device (1) for the surface coating of pieces according to claim 1, wherein said
heating means (5) are formed by heating coils with two thermal contacts, controlled
by a programmable safety relay.
10. The device (1) for the surface coating of pieces according to claim 1 or 9, wherein
the heating means (5) are included inside the drum (4).
11. The device (1) for the surface coating of pieces according to claim 1, wherein the
control device (9a) of the at least one water inlet conduit (6a) is a solenoid gate
valve and wherein the control device (9b) of the at least one dyeing agent inlet conduit
(6b) is a pump.