Cooling systems for print heads

In some examples, an electronic device includes a print head to move relative to a platform parallel to a first axis and parallel to a second axis to deliver a print agent to the platform. The second axis is oriented at a non-zero angle relative to the first axis. In addition, the electronic device includes a cooling system having a first air duct coupled to the print head to provide air to the print head. The print head is to move with the first air duct parallel to the first axis, and to move relative to the first air duct parallel to the second axis.

BACKGROUND

Electronic devices may include cooling systems to maintain a desired operation temperature. A cooling system may include passive devices, such as a finned heat exchanger, or may include active devices, such as a fan. The cooling specifications for an electronic device establish the types and capacities of the cooling devices used in the cooling system.

DETAILED DESCRIPTION

In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” is intended to be broad enough to encompass both indirect and direct connections. Thus, if a first device couples to a second device, that connection may be through a direct connection or through an indirect connection via other devices, components, and connections. In addition, as used herein, the terms “axial” and “axially” generally refer to positions along or parallel to a central or longitudinal axis (e.g., central axis of a body or a port), while the terms “lateral” and “laterally” generally refer to positions located or spaced to the side of the central or longitudinal axis.

As used herein, including in the claims, the word “or” is used in an inclusive manner. For example, “A or B” means any of the following: “A” alone, “B” alone, or both “A” and “B.” The word “or” is used in an inclusive manner. For example, “A or B” means any of the following: “A” alone, “B” alone, or both “A” and “B.” In addition, when used herein including the claims, the word “generally” or “substantially” means within a range of plus or minus 20% of the stated value.

This disclosure describes systems and methods for cooling electronic devices and may be particularly applicable to cooling moving parts within electronic devices. For example, the examples disclosed herein are suitable for cooling the print head and associated nozzle(s) of three-dimensional (3D) printers.

In an example, a 3D printer with cooling includes a material feed mechanism, a printer head that has one nozzle or multiple nozzles, a cooling system with an air duct assembly to cool the print head and associated nozzle(s), and a heating element. A platform may be disposed below the print head. The feed mechanism holds a build material (e.g., a bulk material such as a powdered structural material, such as a polymer or metal) and distributes a layer of the build material on the platform. The printer head sprays a print agent, such as an ink or a fusing agent, with the nozzle(s) in a selected pattern across the layer of the build material previously distributed on the platform.

During 3D printing operations, the print head moves right or left parallel a first axis and may move forward or backward parallel a second axis perpendicular to the first axis to distribute or print the fusing agent on the layer of the build material at the desired locations. The heating element (e.g., a lamp) applies thermal energy to the deposited build material to cause those portions on which the fusing agent has been printed to fuse, whereas portions on which no fusing agent has been printed will not heat sufficiently to fuse. The heating element may be a lamp that moves relative to the platform, providing radiant heat, and the movement of the heating element may be synchronized with the movement of the print head. The air duct assembly of the cooling system circulates air across the print head to keep it cool and prevent excessive heating, which may cause damage to the print head, for example.

In one example in accordance with the present disclosure, an electronic device comprises a print head to move relative to a platform parallel to a first axis and parallel to a second axis to deliver a print agent to the platform. The second axis is oriented at a non-zero angle relative to the first axis. The electronic device also comprises a cooling system including a first air duct coupled to the print head and to provide air to the print head. The print head is to move with the first air duct parallel to the first axis, and to move relative to the first air duct parallel to the second axis.

In some examples, the electronic device comprises a second air duct coupled to the print head to move with the print head parallel to the first axis and the second axis. The second air duct is to deliver the air from the first air duct to the print head. The second air duct is slidably coupled to the first air duct.

In some examples, the cooling system comprises an exhaust port to exhaust the air provided to the print head by the first air duct and the second air duct. The print head is to move with the exhaust port parallel to the first axis, and to move relative to the exhaust port parallel to the second axis.

In some examples, the electronic device comprises comprising an indexing sled coupled to the print head and to move the print head. The second air duct is positioned between a surface on the print head and a surface on the indexing sled.

In some examples, the electronic device comprises a feed mechanism to distribute a layer of the build material on the platform. The print head is to deliver the print agent on a select portion of the layer of the build material. In some examples, the print agent comprises a fusing agent and the build material comprises a powdered polymer or metal.

In some examples, the electronic device comprises a heating element to apply thermal energy to the build material and the print agent on the platform to fuse the select portions of the build material on which the print agent is delivered.

In some examples, the cooling system comprises an exhaust port to exhaust the air provided to the print head by the first air duct. The print head is to move with the exhaust port parallel to the first axis and to move relative to the exhaust port parallel to the second axis.

In another example in accordance with the present disclosure, an electronic device comprises a housing. In addition, the electronic device comprises a carriage disposed within the housing to move relative to the housing parallel to a first axis. The electronic device also comprises an indexing sled disposed within the housing to move with the carriage parallel to the first axis and to move relative to the carriage parallel to a second axis. The second axis oriented at a non-zero angle relative to the first axis. Further, the electronic device comprises a print head disposed within the carriage. Still further, the electronic device comprises a cooling system including a first air duct to provide air to the print head. The print head is to move with the indexing sled parallel to the first axis and the second axis. The first air duct is to move with the carriage parallel to the first axis.

In some examples, the print head is to move with the first air duct parallel to the first axis and to move relative to the first air duct parallel to the second axis.

In some examples, the electronic device comprises a second air duct extending from the first air duct to the print head. The second air duct is defined by a surface of the print head and a surface of the indexing sled. The second air duct is slidably coupled to the first air duct. The second air duct is to move relative to the first air duct parallel to the second axis.

In some examples, the electronic device comprises an exhaust port coupled to the carriage to exhaust the air from the print head. The print head is to move with the exhaust port parallel to the first axis and to move relative to the exhaust port parallel to the second axis. In some examples, the exhaust port comprises a third air duct coupled to an exhaust fan.

In another example in accordance with the present disclosure, an electronic device comprises a print head to move relative to a platform parallel to a first axis and parallel to a second axis to deliver a print agent to the platform. The second axis oriented at a non-zero angle relative to the first axis. The electronic device also comprises a cooling system to circulate air to the print head. The cooling system includes a first air duct and a second air duct movably coupled to the first air duct, wherein the first air duct is to move with the second air duct and the print head parallel to the first axis. The second air duct is to move with the print head parallel to the second axis relative to the first air duct.

In some examples, the second air duct slidably engages the first air duct. The second air duct is to deliver the air from the first air duct to the print head.

In examples described below, the air duct assembly includes a first air duct attached to a fan and a second air duct mounted to the print head. The first air duct receives air from the fan, and the second air duct receives air from the first air duct. The second air duct cools the print head and nozzle disposed therein without the cooling air directly contacting an ejection port of the nozzle. The second air duct slidingly engages the first air duct such that the second air duct and the print head move with the first air duct parallel the first axis, but move relative to the first air duct parallel the second axis. The cooling system may include a reflective radiant barrier mounted to the print head to reduce the radiant transfer of thermal energy from the heating element to the print head. The radiant barrier moves with the print head and shields the print head from radiant energy emitted by the heating element as well as radiant energy emanating from the fused material (fused build material and fusing agent) disposed on the platform. The radiant barrier includes a through-hole to provide a passage for the print agent emitted from the nozzle to pass therethrough.

Referring now toFIG. 1, an example electronic device100in accordance with the principles disclosed herein is shown. In this example, electronic device100includes a housing102for which a coordinate system may be defined by an x-axis, a y-axis, and a z-axis. In this example, the three axes are orthogonal with the x-axis extending lengthwise (left and right inFIG. 1), the y-axis extending widthwise (into and out of the page inFIG. 1), and the z-axis extending vertically (up and down inFIG. 1).

Electronic device100includes a first print head110A, a second print head110B, and a cooling system112mounted in a pen carriage114. Electronic device100also includes a material feed mechanism116to deposit sequential layers of build material on a vertically adjustable platform126, a heating element118, a guide bar122, a bin124, and a barrier wall132. Pen carriage114, feed mechanism116, and heating element118are slidingly mounted to guide bar122to move parallel to the x-axis across bin124and platform126. Pen carriage114, feed mechanism116, and heating element118may share a drive mechanism (not shown) or may each have a separate drive mechanism to move together or separately along bar122. Device100may include a pair of laterally spaced guide bars disposed on opposite sides of pen carriage114, feed mechanism116, and heating element118and extending parallel to the y-axis. In some examples, pen carriage114, feed mechanism116, heating element118or combinations thereof are mounted to the pair of laterally spaced guide bars to move along the y-axis perpendicular to the x-axis. Heating element118is a radiant heat source such as a lamp, for example.

Platform126is disposed in bin124and can be moved along the z-axis within bin124by a lift mechanism128. Thus, lift mechanism128may move platform126vertically downward along the z-axis in increments to allow platform126to receive sequential layers of build material and print agent. Lift mechanism128may move platform126vertically upward when preparing for the removal of a printed part or when preparing for a new print task. Bin124may be for customer-installation into housing102or removable from housing102to facilitate shipping, for replacement or repair, for removal of a printed part following a print operation, or for another reason.

Referring still toFIG. 1, barrier wall132is horizontally oriented and includes an aperture134through which cooling system112extends. Wall132is designed such that aperture134may move back-and-forth along the x-axis (right and left inFIG. 1) such that aperture134moves with pen carriage114. Within housing102, a plurality of volumetric zones may be defined for convenience. These zones may be useful for describing the locations or movement of components or air. The space between wall132and housing102opposite carriage114defines a first or air source zone141. The space within carriage114defines a second or carriage zone142. A third or work zone143is positioned within housing102below wall132and around carriage114. Thus, carriage114is located in work zone143along with feed mechanism116, heating element118, and bin124. A fourth or outside zone144is located outside of housing102.

Referring now toFIGS. 2 and 3, pen carriage114is shown. InFIG. 2, guide bar122is shown in phantom. The orientation of the coordinate system shown inFIG. 2is the same as inFIG. 1. Pen carriage114includes a housing150having a base plate152, a plurality of walls154, a cover156, and a tunnel158through which cooling system112extends. InFIG. 1, tunnel158extends through aperture134and may be sealingly coupled to barrier wall132to reduce or prevent air flow in between aperture134and tunnel158. Carriage114also includes an indexing sled160mounted above an aperture162. Print heads110A,110B are mounted on top of sled160, extending through an aperture164. Sled160includes an upward facing surface161that faces a surface on the adjacent print head110A,110B. Sled160may slide parallel to the y-axis driven by an indexing motor166to adjust the position of print heads110A,110B with respect to carriage housing150, device housing102, or platform126, allowing greater control over where print heads110A,110B spray a print agent on platform126. Portions of housing150include a reflective surface(s), which performs a radiant barrier168to deflect heat from lamp118or hot material on platform126. As examples, the material of base plate152, walls154, or cover156may have reflective surface qualities, or a surface coating, such as a Miro-Silver® coating by Alanod® having an reflectivity of up to 98%, may be applied to portions of base plate152, walls154, or cover156, sled160, or a print head110A,110B. Cover154may extend vertically down, alongside walls154. In some examples, radiant barrier168includes a separate plate(s) attached outside portions of housing150and sled160, the plate(s) having a reflective surface as described.

Referring now toFIGS. 2-4, each print head110A,110B includes a body170extending from a first end171A to a second end171B. As shown inFIG. 4, first print head110A and second print head110B are mounted on indexing sled160above housing base plate152. Each print head110A,1108also includes a surface172to be cooled and a nozzle portion174in which an array of nozzles176are disposed (FIG. 3). Print head110A,110B may also be referred to as a print bar, a pen, or other name in the industry. In the present example, the surface172faces downward and sideways around the nozzle portion174, and nozzles176face downward. Surface172may be thermally coupled to nozzle portion174and may include a material with sufficient thermal conductivity to draw heat away from nozzle portion174when air flows across surface172and nozzle portion174is heated beyond the temperature of the air flow. For example, surface172may be made of aluminum, copper, sheet metal, or cast iron.

First print head110A is coupled to a source of a first print agent or agents that may include, without limitation, an ink of a first color, multiple inks having multiple colors, a fusing agent, a detailing agent, or combinations thereof. Second print head110B is coupled to a source of a second print agent or agents that may include, without limitation, an ink of a second color, multiple inks having multiple colors, a fusing agent, and a detailing agent.

Referring again toFIG. 2, cooling system112includes an inlet fan200, a first air conduit or duct202coupled to fan200, a second air conduit or duct220moveably coupled to inlet duct202, and an exhaust port240. Inlet duct202is fixably coupled to housing150, and thus, moves with housing150parallel to the x-axis. In this example, and moving from fan200to second duct220, first duct202includes an inlet portion204, a neck portion206, a y-member or splitter208, and a pair of transition elbows210. Inlet portion204extends vertically upward from fan200and transitions to the horizontal neck portion206, which extends through tunnel158of carriage housing150. Neck portion206transitions to splitter208, which divides the flow path, defined by portions204,206, into two flow paths. The outlet of each flow path defined by splitter208terminates at a corresponding transition elbow210, which extends to a horizontal discharge end212.

Referring briefly toFIG. 5, discharge end212includes a lower wall214and an upper wall213. Lower wall214extends horizontally beyond upper wall213and curves upwardly to terminate at a lip215. As a result, an upward facing exit port216is formed at discharge end212. A boss218extends downward from lip215.

Referring again toFIG. 4, second air duct220is positioned between and defined by a downward facing surface172of print head110A,110B and an upward facing surface161on indexing sled160. Thus, in this example, duct220is formed, at least in part, by print head110A,110B and indexing sled160for direct heat exchange between a supplied air flow and print head110A,110B.

Referring again toFIG. 5, air duct220includes a downward facing inlet port222immediately over and in fluid communication with exit port216. Inlet port222includes a horizontal plate224vertically above and spaced apart from a proximal end161A of surface161on indexing sled160. Plate224rests above and slidingly engages upper wall213of first air duct202. Thus, a slidable coupling230is formed between air ducts202,220at exit port216and inlet port222. InFIG. 5, coupling230couples first air duct202to the print head110A to deliver air to the print head110A for cooling. Exhaust port240includes an air filter and a louvered baffle mounted to an aperture in cover156of housing150. While the discussions ofFIG. 5, here, andFIG. 6, below, may be directed to print head110A, relationships and movements that are described also pertain to print head110B.

Referring now toFIGS. 1 and 2, a path for a supplied air flow extends from air source zone141, into fan200and through inlet air duct202to splitter208, which divides the air flow into two separate air paths. Each air path of splitter208passes through a corresponding transition elbow210into a corresponding second air duct220coupling230. The air path continues through second duct220beneath the corresponding print head110A,110B and exits second duct220proximal second end171B of print head110A,110B and into zone142within carriage114. The air exiting second ducts220rejoins in zone142and ultimately exits carriage114at exhaust port240.

As shown inFIGS. 5 and 6, sled160may move back and forth parallel to the y-axis, print head110A and second duct220move with sled160parallel to the y-axis. InFIG. 5, sled160is in a rearward position relative to first duct202and housing150with slidable coupling230in a retracted configuration with proximal end161A of surface161immediately adjacent lip215. InFIG. 6, sled160is in a forward position relative to duct210and housing150with slidable coupling230in an extended configuration. Proximal end161A of sled160is displaced by a horizontal separation distance245from lip215of duct210with coupling230in the extended configuration (FIG. 6). Similarly, plate224of sled160is displaced by the same horizontal distance245along upper wall213of duct202. Plate224and wall213slidingly engage and overlap during movement of second duct220and sled160relative to first duct202to reduce leakage of air flow. In addition, the upwardly extending lip215continues to direct the supplied air flow from first duct202into inlet port222of second duct220.

Sled160may be moved back and forth parallel to the y-axis within carriage114between the rearward position ofFIG. 5and the forward positionFIG. 6to adjust the targeted locations for ejection of the print agent from the nozzles176. Slidable coupling230facilitates fluid communication for a supplied air flow between ducts202,220while sled160and duct220move with sled160relative to duct202. Print heads110A,110B and second air ducts220move with the first air duct202parallel to the x-axis, but move relative to the first air duct202parallel to the y-axis. In this example, both print heads110A,110B move together with sled160.

Referring now toFIG. 7, another example of a pen carriage114′ is shown. Pen carriage114′ may be installed and operated in electronic device100in place of pen carriage114. A first and a second print head110A,110B as previously described and a cooling system112′ are mounted in carriage114′. Pen carriage114′ is substantially the same as carriage114previously described with the exception that exhaust port240(FIG. 2) is replaced by an exhaust port340. In this example, exhaust port340includes an outlet air duct342and an exhaust fan354. Thus, carriage114′ includes a housing150and an indexing sled160. Housing150includes a base plate152, walls154, a cover156, and a tunnel158, each as previously described. However, in this example, cover156lacks an aperture for an exhaust port. The structure and function of sled160, print heads110A,110B, and the mounting and movement of sled160with respect to base place152are as previously described. For example, sled160moves parallel to the y-axis with respect to housing150.

Similar to cooling system112previously described (FIG. 2), in this example, cooling system112′ includes an inlet fan200located exterior to housing150, an inlet air duct202coupled to fan200, a splitter208, a pair of transition elbows210, and a pair of second air ducts220as previously described. However, unlike cooling system112, exhaust port340of cooling system112′ includes outlet air duct342and exhaust fan354. Duct342includes a splitter344and a neck portion348. Splitter344includes two inlet ports346in zone142within housing150. The passages extending from ports346merge along splitter344. The outlet end of splitter344is coupled to neck portion348, which extends through housing tunnel158and connects to fan354at an exit end352. Fan354draws air out from carriage zone142through duct342.

In examples with carriage114′ installed in system100, fans200,354may be located in air source zone141and separated from work zone143. Duct342and fan354are fixably coupled to housing150, and thus, move with housing150parallel to the x-axis. Outlet air duct342extends through tunnel158and fan354draws air into zone142, rather than exhausting air into work zone143.

The above discussion is meant to be illustrative of the principles and various examples of the present disclosure. Numerous variations and modifications to the examples described above are possible. The following claims should be interpreted to embrace all such variations and modifications. For example, although various examples of the electronic devices disclosed were described in the context of a 3D printer, the cooling systems disclose herein may be implemented in other types of 3D printers, other types of printers, or other types of electronic devices.