Claims:We claim,
1. An extruder holder assembly (100), of a 3D printing machine, the assembly comprising:
a thermoelectric cooler (104);
a heat exchanger (106); and
a housing member (102), wherein the housing member,
defines a first cavity (302) to accommodate a syringe; and
a second cavity (304) to accommodate the thermoelectric cooler (104) and the heat exchanger (106).
2. The extruder holder assembly (100) as claimed in claim 1, wherein the thermoelectric cooler (104) is a Peltier device.
3. The extruder holder assembly (100) as claimed in claim 1, wherein the heat exchanger (106):
comprises an inlet (510a) for receiving a fluid into the heat exchanger;
comprises an outlet (510b) for enabling exit of the fluid from the heat exchanger; and
defines cavity (504) that connects the inlet and the outlet, wherein the cavity (504) defines a winding path between the inlet (510a) and the outlet (510b).
4. The extruder holder assembly (100) as claimed in claim 1, wherein the thermoelectric cooler (104) and the heat exchanger (106) are coupled such that a planar surface of the thermoelectric cooler (104) directly interfaces with a planar surface of the heat exchanger (106).
5. The extruder holder assembly (100) as claimed in claim 1, wherein the first cavity (302) defines a circular cross section.
6. The extruder holder assembly (100) as claimed in claim 1, wherein the second cavity (304) defines a rectangular cross section.
7. The extruder holder assembly (100) as claimed in claim 1, wherein the second cavity (304) is accessible through a first opening provided towards a superior side of the housing member (102).
8. The extruder holder assembly (100) as claimed in claim 1, wherein the housing member (102) defines a hollow region (306), wherein the second cavity (304) is in-between the first cavity (302) and the hollow region (306).
9. The extruder holder assembly (100) as claimed in claim 8, wherein a back portion of housing member (102) that contributes to defining of the hollow region (306) defines a plurality of threaded portions (308) to engage the extruder holder assembly (100) to a frame of the 3D printing machine.
10. The extruder holder assembly (100) as claimed in claim 8, wherein the hollow region (306) opens up to, a top opening provided towards a superior side of the housing member (102) and a bottom opening provided towards an inferior side of the housing member (102).

Dated this 17th day of January 2019
(Digitally signed)
Kartik PUTTAIAH
Patent Agent-IN/PA-1809
, Description:Field of Invention
[0001] The disclosed subject matter relates to 3D printing machine. More particularly, but not exclusively, the subject matter relates to an extruder holder assembly of a 3D printing machine.
Discussion of Prior Art
[0002] In general, in a 3D printing machine, a printing material passing through a syringe is either heated or cooled to a certain temperature, wherein the properties of the printing material, for example, viscosity, yield stress, and the like, at the temperature favours the printing process. Also, one key parameter that is largely affected by the temperature of printing material in a 3D bioprinting process is cell viability. Generally, the printing material in the 3D bioprinting process consists of living cells that are encapsulated in a hydrogel medium. These cells are highly sensitive to temperature change. Hence, the failure to maintain an optimum temperature can injure these living cells thereby affecting the printing process.
[0003] For the printing material to be cooled, a cooling device is generally placed in the extruder assembly and particularly in close proximity to the syringe through which the printing material flows. The cooling device removes the excess heat from the printing material thereby maintaining the temperature of the printing material at an optimum value. Generally, different types of cooling device are employed in cooling the printing material, for example, aluminium fins, aluminium plate, Peltier device, and the like.
[0004] Predominantly, in the existing 3D printing machines, the cooling device that is used to cool the printing material is not supplemented by an additional heat exchanger, which in turn increases the load on the cooling device thereby reducing the efficacy of the cooling device. Therefore, providing a heat exchanger to remove the heat from the cooling device improves the efficiency of the cooling system.
[0005] Conventionally, in an extruder holder assembly, the syringe and the cooling device are placed in close proximity to each other. However, the syringe and the cooling device are not configured to be accommodated in a single housing member.
[0006] Additionally, the components of a 3D printing machine operate under conditions where high precision is of paramount importance. Hence, any change in the precision level or failure of a component has to be dealt with promptly. Therefore, configuring the extruder holder assembly for ease in replacement and assembling of components is necessary for efficient maintenance of the 3D printing machine.
SUMMARY
[0007] In one aspect, an extruder holder assembly is provided for a 3D printing machine. The assembly comprises a housing member, a thermoelectric cooler and a heat exchanger. The housing member defines a first cavity that accommodates a syringe and a second cavity that accommodates the thermoelectric cooler and the heat exchanger. The cold side of the thermoelectric cooler faces the first cavity. Further, the hot side of the thermoelectric cooler is in contact with the heat exchanger that extracts heat from the hot side of the thermoelectric cooler by the circulation of a coolant within the heat exchanger. The coolant enters the heat exchanger through an inlet and circulates through a cavity inside the heat exchanger and exits through an outlet.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG.1 is an assembled view of an extruder holder assembly 100.
[0009] FIG.2 depicts an exploded view of the extruder holder assembly 100.
[0010] FIG.3A illustrates a top view of a housing member 102 of the extruder holder assembly 100.
[0011] FIG.3B illustrates an isometric back view of the housing member 102 of the extruder holder assembly 100.
[0012] FIG.3C represents a vertical cross-sectional view A-A of the housing member 102 of the extruder holder assembly 100.
[0013] FIG.4 depicts an isometric view of a Peltier device 104 used in the extruder holder assembly.
[0014] FIG.5. represents the longitudinal sectional view of a heat exchanger 106 used in the extruder holder assembly 100.
[0015] FIG.6 illustrates the isometric view of the extruder holder assembly 100 engaged to a 3D printing machine.
DETAILED DESCRIPTION
[0016] The following detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show illustrations in accordance with example embodiments. These example embodiments, which may be herein also referred to as “examples” are described in enough detail to enable those skilled in the art to practice the present subject matter. However, it may be apparent to one with ordinary skill in the art, that the present invention may be practised without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to unnecessarily obscure aspects of the embodiments. The embodiments can be combined, other embodiments can be utilized, or structural, logical, and design changes can be made without departing from the scope of the claims. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope is defined by the appended claims and their equivalents.
[0017] In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one. In this document, the term “or” is used to refer to a nonexclusive “or,” such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated.
[0018] The following is a detailed description of an extruder holder assembly for a 3D printing machine. During the operation of a 3D printing machine, a printing material, at an optimum temperature, is supplied to a syringe. The syringe, controlled by a control mechanism, moves in a path that defines the geometric attributes, for example, length, diameter, and the like, of the printed article. The printing material exits through a nozzle provided on the syringe and is deposited along the path of the syringe to form the printed article.
[0019] The physicochemical and biological properties, for example, viscosity, yield stress, cell viability, and the like, of the printing material are largely dependent on the temperature of the printing material. Any undesirable change in the temperature of printing material can have a serious impact on the living cells that are encapsulated in the hydrogel medium. Therefore, in a 3D printing device, controlling the temperature of the printing material directly dictates the efficiency of the printing process.
[0020] The process of controlling the temperature of the printing material is achieved by placing a thermoelectric cooler in close proximity to the syringe. The temperature control system includes sensors that sense the temperature of the printing material, and modules that determine the optimum temperature to be maintained. The thermoelectric cooler, upon receiving instructions from modules, removes the excess heat from the printing material and maintains the printing material at an optimal temperature thereby improving the performance of the printing process.
[0021] Further, the thermoelectric cooler is cooled by an additional heat exchanger. This use of an additional heat exchanger reduces the load on the thermoelectric cooler and aids in effective functioning of the thermoelectric cooler. The heat exchanger is placed close to the thermoelectric cooler and functions as a heat sink to remove the heat discharged from the thermoelectric cooler.
[0022] Now we refer to the figures, and specifically to FIG.1, which illustrates the assembled view of an extruder holder assembly 100. The extruder holder assembly 100 comprises a housing member 102, a thermoelectric cooler 104 and a heat exchanger 106. The housing member 102 is generally made of aluminium because of its thermal properties, for example, thermal conductivity, thermal resistance, and the like. This extruder holder assembly 100 is engaged to a frame which is connected to actuators that may control the movement of the extruder holder assembly in x-y-z planes.
[0023] FIG.2 represents the exploded view of the extruder holder assembly 100. The diagram provides an exemplary understating of the positioning of components with respect to each other in the extruder holder assembly 100.
[0024] FIG.3A depicts the top view of the earlier discussed housing member 102. The housing member 102 comprises a first cavity 302, a second cavity 304, and a hollow region 306.
[0025] In an embodiment of the FIG.3A, the first cavity 302 is circular in cross section with its diameter varying at different regions of the cavity. The first cavity 302, accessible through an opening provided on the superior side of the housing member 102, accommodates the syringe through which the printing material passes through. The second cavity 304 is rectangular in cross section and it accommodates the thermoelectric cooler 104 and the heat exchanger 106. It is accessible through an opening provided on the superior side of the housing member 102.
[0026] Referring to FIG.3B, the hollow region 306 has a plurality of threaded portions 308 through which the extruder holder assembly 100 is engaged with the frame of the 3D printing machine.
[0027] FIG.3C illustrates vertical cross-sectional view A-A of the housing member 102. According to FIG.3C, the hollow region 306 has an opening both at the superior side and inferior side which allows the air to pass through it. This flow of air through the hollow region 306 further enhances the cooling of the extruder holder assembly 100.
[0028] FIG. 4 depicts the isometric view of the thermoelectric cooler 104 of the extruder holder assembly 100. In an embodiment of the FIG.4, the thermoelectric cooler is a Peltier device 104 comprising a cold surface 402, a hot surface 404, a positive terminal wire 406a, and a negative terminal wire 406b. The direct current supplied across the terminals 406a and 406b of the Peltier device 104 generates a temperature difference between the two surfaces of the Peltier device 104. The polarity of the terminals 406a and 406b is defined in such a way that the surface 402 facing the first cavity 302 is at lower temperature and the surface 404 in contact with the heat exchanger 106 is at higher temperature. Further, the cold surface 402 removes excess heat from the printing material and transfers the heat to the other surface 404 of the Peltier device 106.
[0029] FIG.5 illustrates the longitudinal section of the heat exchanger 106. In the embodiment, the heat exchanger comprises a heat exchanger block 502, a cavity 504 engraved on the heat exchanger block 502, a silicone tube inlet 506a, and a silicone tube outlet 506b, silicone tubes 508a and 508b, and inlet 510a and outlet 510b. The silicone tubes 508a and 508b are flexible and can withstand higher temperatures of the coolant flowing through it. The coolant enters the heat exchanger block 502 through the inlet 510a and circulates through the cavity 504 of the heat exchanger block 502 and exits the heat exchanger block 502 through the silicone tube outlet 510b.
[0030] In an embodiment, the heat exchanger block 502 may be made of any material that is a good conductor of heat. As an example, the heat exchanger block 502 may be an aluminium block.
[0031] In an embodiment of the FIG.2, the Peltier device 104 is placed within the second cavity 304 of the housing member 102 in a manner that, the cold surface of the Peltier device 402 faces the first cavity 302 of the housing 102 and the hot surface 404 of the Peltier device is in contact with the heat exchanger 106. The heat from the syringe is transmitted throughout the housing member 102. The Peltier device 104 extracts the heat from the printing material at its cold surface 402 and transmits it to the hot surface 404. Further, the heat from the hot surface 404 is transferred to the side of the heat exchanger block 502 of the heat exchanger 106 which is in contact with the hot surface 404 of the Peltier device. The coolant enters the heat exchanger block 502 through the inlet 510a and passes through the cavity 504 and carries away the heat. Further, the hot coolant exits the heat exchanger block 502 through the outlet 510b. The extruder holder assembly 100 is engaged with the frame of the 3D printing machine using the threaded portions 308 provided in the hollow region 306 of the housing member 102.
[0032] FIG.6 is a schematic illustration of isometric view of the 3D printing machine. The extruder holder assembly 100 is engaged to a frame which is connected to actuators that control the movement of the extruder holder assembly 100.
[0033] The present extruder holder assembly 100 is configured in such a way that it enhances the performance of the cooling system of the extruder holder assembly and thereby improving the performance of a 3D printing machine.
[0034] Also, the present extruder holder assembly 100 configuration is simple and enables easy replacement and assembling of components thereby making the maintenance of extruder holder assembly 100 easier.