阅读说明：本技术 液体提取 (Liquid extraction ) 是由 S·普加德阿曼迪亚 P·莫拉尔马提 S·库鲁布莱特科塔达 于 2019-01-31 设计创作，主要内容包括：根据一个方面,提供了一种从包含构造材料和液体的构造腔室中去除液体的方法。该方法包括：开始液体提取过程以从构造腔室中提取液体；以及确定何时已从构造腔室中去除预定阈值的液体,并且从而停止液体提取过程。(According to one aspect, a method of removing liquid from a build chamber containing a build material and liquid is provided. The method comprises the following steps: initiating a liquid extraction process to extract liquid from the build chamber; and determining when a predetermined threshold of liquid has been removed from the build chamber and thereby stopping the liquid extraction process.)

1. An apparatus for extracting a liquid from a build chamber containing a build material and the liquid, comprising:

a liquid extraction system for evaporating liquid in the build chamber;

a condenser for condensing the evaporated liquid into a liquid;

a condensed liquid measurement module; and

a controller for determining when to stop the liquid extraction process based on the condensed liquid.

2. The apparatus of claim 1, further comprising:

an air flow generator for generating an air flow through the build chamber to evaporate liquid therein and to cause the air flow to flow through the condenser.

3. The apparatus of claim 1, wherein the condensed liquid measurement module comprises at least one of: a load element for allowing the weight of the condensed liquid to be determined; a level sensor for allowing determination of the volume of the condensed liquid; and a camera.

4. The apparatus of claim 1, further comprising:

a vacuum pump for removing air/gas from the build chamber to reduce the gas pressure within the build chamber to cause evaporation of the liquid and to draw the removed air/gas through the condenser.

5. The apparatus of claim 1, wherein the controller is to:

starting the liquid extraction process;

the liquid extraction process is stopped when it is determined that the rate at which the condenser condenses the liquid falls below a predetermined rate.

6. The apparatus of claim 1, wherein the controller is to:

obtaining an estimate of the amount of liquid present in the build chamber;

starting the liquid extraction process;

the liquid extraction process is stopped when it is determined that the condenser has condensed a predetermined percentage of the estimated amount of liquid.

7. A method of removing liquid from a build chamber containing a build material and liquid, the method comprising:

initiating a liquid extraction process to extract liquid from the build chamber; and

determining when a predetermined threshold of liquid has been removed from the build chamber and thereby stopping the liquid extraction process.

8. The method of claim 7, further comprising:

generating an airflow through the build chamber to evaporate liquid into the airflow;

condensing the liquid in the gas stream at a condenser; and

determining when to stop the liquid extraction process based on condensed liquid.

9. The method of claim 7, wherein the first and second light sources are selected from the group consisting of,

removing air from the build chamber to reduce its internal pressure to evaporate liquid therein;

condensing the liquid in the removed air at a condenser; and

determining when to stop the liquid extraction process based on condensed liquid.

10. The method of claim 7, further comprising: heating the contents of the build chamber to promote evaporation of the liquid.

11. The method of claim 10, wherein heating the contents of the build chamber comprises at least one of: generating an air flow having a temperature higher than an outside temperature; and applying convective and/or radiant heat to the contents of the build chamber to raise the temperature above ambient.

12. The method of claim 8, further comprising: determining when a rate at which the condenser condenses liquid falls below a predetermined rate.

13. The method of claim 8, further comprising:

obtaining an estimate of the amount of liquid present in the build chamber;

it is determined when the amount of condensed liquid is within a predetermined threshold of the obtained estimated amount.

14. A computer readable medium comprising instructions understandable by a processor, which when executed by the processor, cause the processor to initiate a liquid extraction process to extract liquid from a build chamber comprising a build material and a marking agent liquid; and

determining when a predetermined threshold of liquid has been removed from the build chamber and thereby stopping the liquid extraction process.

Background

Some three-dimensional printing systems selectively apply a liquid printing agent (such as a liquid adhesive) to successive layers of powdered build material formed on a movable build platform. Such systems may be used, for example, to produce so-called "green parts" using powdered metal build material. A green body is a loosely bonded body that must be sintered in a sintering furnace to convert it into a dense and sintered final body. Prior to sintering, the green body must be cleaned to remove any unbound build material that does not form the green part.

Drawings

Examples will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

FIG. 1 is a block diagram of a liquid extraction system according to one example;

FIG. 2 is a flow chart summarizing a method of operating a liquid extraction system, according to one example;

FIG. 3 is a block diagram of a liquid extraction system according to one example;

FIG. 4 is a flow chart summarizing a method of operating a liquid extraction system, according to one example;

FIG. 5 is a flow chart summarizing a method of operating a liquid extraction system, according to one example;

FIG. 6 is a block diagram of a liquid extraction system according to one example;

FIG. 7A is a block diagram of a liquid extraction system according to one example;

FIG. 7B is a block diagram of a liquid extraction system according to one example; and is

FIG. 8 is a block diagram of a liquid extraction controller according to one example.

Detailed Description

In powder-based 3D printing systems, a liquid printing agent, such as a binder, may be selectively applied to portions of a continuously formed layer of build material to define a generally loosely bonded green body. The printing agent may comprise a liquid vehicle, which may comprise a plurality of different reagents including one or more of: surfactants, solvents, cosolvents, buffers, biocides, viscosity modifiers, sequestering agents, stabilizing agents, wetting agents, and water. Once all layers have been formed and processed, the green body must be extracted from any unbound build material prior to sintering in the sintering furnace.

During green body production, liquid from the printing agent may leak or migrate to adjacent portions of the build material and cause these portions to adhere to the green body. Therefore, prior to sintering, the green body must be cleaned to remove any build material that is not ready to form the green part. However, due to the often brittle nature of green bodies, cleaning 3D printed green parts prior to sintering can be a complex and delicate operation.

Examples described herein provide a system and method of removing a printing agent liquid from build material present in a build chamber in which a continuous layer of build material has been formed and on which a liquid printing agent has been selectively applied. Removal of the liquid has been shown to facilitate cleaning of the green body.

Although the examples described herein refer to binders, it will be understood that in other examples, other types of marking agents may be applied during the green body production process, and thus, in addition to binder liquids, other liquids may also be present in the build chamber. For example, the green body production process may additionally apply a liquid anti-sintering agent, for example, such that the sintering stage support structures formed into the green components, once sintered, may be easily removed from the green body. In other examples, multiple types of reagents may be applied during the green body production process.

Referring now to fig. 1, a block diagram of a liquid extraction system 102 according to one example is shown, the liquid extraction system 102 for extracting liquid from a build chamber 106 containing build material and a marking agent liquid. Build chamber 106 may have been previously used in 3D printing systems to create 3D printed objects or green bodies by repeatedly forming a layer of particulate build material and selectively applying a liquid printing agent based on a 3D object model. The particulate build material may be any suitable type of build material, such as a suitable plastic, metal or ceramic build material.

In one example, the liquid extraction system 102 may be separate from the build chamber 106 and may be couplable when it is desired to remove liquid from the build chamber 106. In another example, the liquid extraction system 102 may be permanently coupled to the build chamber 106.

As will be described in more detail below, the liquid extraction system 102 can extract liquid from the build chamber 106 in a variety of different ways.

The liquid extraction system 102 includes a liquid extraction controller 104, and the liquid extraction controller 104 determines when to stop the liquid extraction process based on the extracted liquid. In this way, by actively determining when to stop the liquid extraction process based on the extracted liquid, the liquid extraction system 102 is able to optimize the duration of the liquid extraction process and thus help improve the throughput of object production in the 3D printing system while facilitating the cleaning process of the green body.

An example operation of the liquid extraction system 102 according to one example is shown in the flow chart of fig. 2. At block 202, the liquid extraction controller 104 begins the liquid extraction process. At block 204, the liquid extraction controller 104 determines when to stop the liquid extraction process based on the extracted liquid. At block 206, the liquid extraction controller 104 stops the liquid extraction process.

Referring now to fig. 3A, a liquid extraction system 300 is shown according to one example. An example operation of the liquid extraction system 300 is described with reference to the flowchart of fig. 4.

The liquid extraction system 300 includes an airflow generator 302 (such as a fan), a condenser 304, a condensed liquid measurement module 306, and a liquid extraction process controller 308.

In this example, a condenser 304 is fluidly coupleable to the build chamber 104, such as to a bottom of the build chamber, and the airflow generator 302 is fluidly coupled to the condenser. Thus, when the airflow generator 302 generates negative air pressure, this causes air outside the build chamber 104 to flow through the build chamber 104 and through the condenser 304. In this way, the airflow 303 flows through the contents of the build chamber 104, which may include powdered build material to which one or more liquid printing agents may have been applied, for example by a 3D printing system. The gas flow 303 causes the liquid present in the build chamber to evaporate into the gas flow 303, which gas flow 303 is to be removed from the build chamber 104 and condensed back into the liquid at the condenser 304.

The liquid condensed from condenser 304 is collected at measurement module 306. In one example, the condensed liquid is collected in a container coupled to a weighing module, such as a load cell, to allow the weight of the condensed liquid to be determined. In another example, the condensed liquid is collected in a container in which a level sensor is disposed. In this way, the volume of condensed liquid can be determined. In another example, a camera and suitable image processing techniques may be used to determine the level of liquid collected in the container.

In one example, the build chamber may have a porous build platform (not shown) through which the gas stream may flow. In one example, the build chamber 104 may have one or more gas inlets in one or more build chamber sidewalls.

Condenser 304 may be any suitable type of condenser, such as an air-cooled condenser or a liquid-cooled condenser. Suitable types of condensers may include, for example, an aline (Allihn) condenser and a grignard (Graham) or coiled condenser.

At block 402, the controller 308 begins the liquid extraction process by controlling the gas flow generator 302 to flow the gas flow 303 through the contents of the build chamber 104 and through the condenser 304.

At block 404, the controller 308 determines whether the rate of liquid extraction has dropped below a predetermined level or threshold. For example, by measuring the rate at which liquid is condensed by the condenser 304, the controller 308 is enabled to determine when the appropriate amount of liquid remains in the build chamber. For example, if the maximum rate of liquid condensation is determined to be 50cl per hour, the predetermined rate of liquid extraction cessation may be set to about 10%, or about 5%, or about 1% of the maximum liquid condensation rate. In other examples, the predetermined rate may be set to any other suitable rate.

At block 406, the controller 308 stops the liquid extraction process when it is determined that the liquid extraction rate has dropped below a predetermined level.

In another example, as shown in fig. 5, the controller 308 may be configured to obtain an estimate of the amount of liquid present in the construction unit 104, for example from a 3D printer. For example, a 3D printer for applying a marking agent to a layer of build material in a build chamber may determine that an amount of marking agent present in the build chamber 104 is estimated after a 3D print job has been performed therein. For example, the 3D printer may determine the number and volume of print agent drops applied to a layer of build material formed in the build chamber. In one example, the estimation may take into account an estimated level of liquid evaporation during the printing process. The controller 308 may use this information to determine when to stop the liquid extraction process.

At block 502, the controller 308 begins the liquid extraction process by controlling the gas flow generator 302 to flow the gas flow 303 through the contents of the build chamber 104 and through the condenser 304.

At block 504, the controller 308 obtains an estimate of the amount of liquid present in the build chamber 104.

At block 506, the controller 308 determines whether the amount of liquid collected at the condensed liquid measurement module 306 is within a predetermined threshold of the obtained estimated amount of liquid present in the build chamber 104. In one example, the predetermined threshold may be about 30%, or about 20%, or about 10%, or about 5%, or about 2%, or about 1% of the obtained estimate.

At block 508, the controller 308 stops the liquid extraction process.

In one example, the airflow generator 302 generates an airflow through the build chamber at about 150 liters per minute, about 100 liters per minute, about 50 liters per minute, or about 25 liters per minute. In other examples, the airflow generator 302 may generate a higher or lower airflow.

In one example, the gas flow 303 is at or near an ambient temperature of an environment in which the build chamber 104 is located.

In another example, build chamber 104 may be heated, for example, using a thermal blanket located in one or more walls of the build chamber. The heating of the configured chamber may increase the temperature of the gas stream and thus may increase the rate at which the liquid evaporates into the gas stream. In another example, the build chamber 104 may be placed in an environment where a heater is present to raise the ambient temperature to a suitable temperature to facilitate removal of the liquid. Depending on the nature of the liquid, a suitable heated gas stream temperature may be about 20 degrees celsius, about 30 degrees celsius, about 40 degrees celsius, or about 50 degrees celsius. In other examples, the temperature of the airflow may be raised to a higher temperature.

Referring now to fig. 6, another example is shown. In this example, the output of the airflow generator 302 may be coupled to an appropriate portion of the build chamber 104 (such as the top of the build chamber) such that air is forced (e.g., using positive air pressure generated by the airflow generator 302) through the build chamber 104 and through the condenser 304. The input of the condenser 304 may be connected to the bottom of the build chamber 104.

In another example, the airflow generator 302 may include a heater to generate a heated airflow. In this example, the output of the airflow generator 302 may be connected to the top of the build chamber.

Yet another example is shown in fig. 7A. In this example, the condenser 204 is fluidly coupleable to the substantially hermetically sealed build chamber 104. The condenser 204 may be coupled to any suitable portion of the build chamber 104, such as the bottom thereof or the top thereof.

The vacuum pump 702 is fluidly coupled to the condenser 304 such that, under the control of the controller 306, the vacuum pump 702 removes air/gas from the build chamber 104 to create a negative pressure within the build chamber 104. Reducing the air pressure within the build chamber 104 reduces the liquid boiling point of any liquid present in the build chamber 104. In one example, reducing the pressure to a suitable level may cause the liquid present in the build chamber to boil at ambient temperature. Depending on the nature of the liquid, a suitable pressure may be determined using, for example, the Antoine (Antoine) equation. For example, if the liquid is water, reducing the pressure to 10kPa will reduce the boiling point to 47 degrees celsius. The vacuum pump 702 draws the removed air through the condenser 304 and any liquid present in the condenser 304 is condensed back into liquid. As previously described, the controller 306 may determine when to stop the liquid extraction process based on the condensed liquid. As the pressure is reduced, the liquid evaporates to produce a gas. The gas is removed by a vacuum pump and pumped through the condenser 304 where it is condensed back to a liquid.

In yet another example, as shown in fig. 7B, a sealable chamber 704 is provided into which a build chamber, such as build chamber 104, may be inserted. In this example, the condenser 204 is fluidly coupled to the sealable chamber 704 to allow the pressure of the sealable chamber 504, and thus the pressure within the build chamber 104, to be reduced using the vacuum pump 702, as described above.

Referring now to fig. 8, the liquid extraction controller 104 is shown to include a processor 802 coupled to a computer-readable medium, such as a memory 804. The processor 802 may be any suitable type of processor, such as a microprocessor, microcontroller, or the like. Liquid extraction control instructions 806 are stored on the memory 804. The instructions 806 are machine-readable instructions that, when executed by the processor 802, cause the liquid extraction controller 104 to operate in accordance with the examples described herein.

It will be understood that the examples described herein may be implemented in hardware, software, or a combination of hardware and software. Any such software may be stored in the form of volatile or non-volatile storage (such as a storage device, e.g., ROM, whether erasable or rewritable or not), or in the form of memory (such as, e.g., RAM, memory chips, devices, or integrated circuits), or on an optically or magnetically readable medium (such as, e.g., a CD, DVD, magnetic disk, or magnetic tape). It will be understood that the storage devices and storage media are examples of machine-readable storage suitable for storing one or more programs that, when executed, implement the examples described herein. Accordingly, some examples provide a program comprising code for implementing a system or method as claimed in any preceding claim, and a machine readable storage device storing the program.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.