Patent Description:
<CIT> discloses a device for building up a 3D object and having two independent feed sections for supplying build material. <CIT> discloses a rapid prototyping system having a removable build platform.

Various features of the present disclosure will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate, features of certain examples, and wherein:.

There are many build materials from which one material may be chosen for the building of a particular part. The choice of build material may be made based on the desired properties of the part. In certain additive manufacturing systems, the build material may be changed between builds accordingly. For example, in several additive manufacturing technologies, various plastic powder types can be used as the raw build material; for example thermoplastics, such as polyamide (PA) <NUM>, PA12, and thermoplastic polyurethane (TPU), etc. A specific powder may be chosen on the basis of desired performance, or properties and features of the final built part, to better match the requirements of the user for that specific part. During a build process, the build material may be spread layer by layer over a build area. Another component of the build device may sinter or fuse regions of the build material to build 3D parts.

Various devices may be used to spread build material or build powder, for example rollers or blades, etc. The properties of the surface of the spreader may, at least in part, dictate the interaction of the spreader with the build material or build powder. Other factors to be considered in selection of a spreader for an additive build are the physical and chemical properties of the powder, which include the particle size of the powder, the particle shape of the powder, the cohesiveness of the powder, and the like. Therefore, certain spreaders may be more suitable for use with certain build powers than others. Undesirable effects that can result due to poor choice of spreader surface can include build powder becoming attached to, and rubbing against, the spreader surface. This may affect the quality of a layer of a build. Layer quality can include the uniformity of the layer and the flatness of the layer. A poor layer quality may have implications on the quality of the final built part.

In the situation when different build materials are to be used for different builds, it is desirable to have a number of different spreaders for use with the different build materials in the additive manufacturing system. Furthermore, it is desirable for the process of removing a spreader and inserting a different spreader to be simple and easy for the user to perform. Complicated spreader insertion mechanisms can lead to issues such as misalignment of a spreader. Misalignment of a spreader could impact the quality of a layer of a build. It may also lead to structural complications and mechanical stresses, which may shorten the life of elements of the additive manufacturing system itself.

Certain examples described herein help to reduce the likelihood of detrimental effects related to use of an unsuitable spreader arising during additive builds. Certain examples described herein improve the ease of engaging and disengaging a spreader with or from an additive manufacturing system. Certain examples described herein enable a user to easily remove a spreader which has become worn or damaged during a build, so that disruption to the build may be reduced. Certain examples described herein enable a user to easily remove a spreader for replacement by a different spreader prior to use of a different build material.

A recoater carriage assembly for use in an additive manufacturing system may be used by moving a roller in a direction non-concentric to a longitudinal axis of the roller and relative to a recoater carriage to engage the roller with the carriage. In certain cases, a retainer may be moved relative to the carriage or roller, to retain the roller between the retainer and the recoater carriage. Certain cases described herein involve moving the roller in a direction orthogonal to a longitudinal axis of the roller. In certain cases, a recoater carriage assembly for use in an additive manufacturing system may be used by disengaging a first elongate recoater roller with a first surface characteristic from the recoater carriage, and engaging a second elongate recoater roller with a second surface characteristic with the recoater carriage, wherein the first surface characteristic is different from the second surface characteristic.

Certain approaches described herein provide benefits over comparative methods that allow use of a recoater carriage assembly in an additive manufacturing system by enabling the possibility of easily replacing the spreader used in a first build that used a first powder with a different spreader for use in a second build using a second powder. The first or second powder may include PA11, PA12, TPU, PA12 with glass beads, and PA12 with flame retardant. Further, certain approaches described herein enable easier use of different powders. Certain approaches described herein provide a greater uniformity of thickness of an uppermost surface of a build powder layer during an additive build, over comparative methods. Certain approaches described herein provide a more level uppermost surface of a build powder layer during an additive build, over comparative methods. Certain approaches described herein provide benefits over comparative methods by allowing a user to more rapidly remove a recoater roller to clean or replace the roller. Certain approaches described herein provide benefits over comparative methods by enabling a user to replace parts after part failure. This in turn can improve the productivity of the additive manufacturing system.

<FIG> show exploded views of a recoater carriage assembly <NUM> according to a non-claimed example, however, some teaching relating to this example is pertinent to the invention. The recoater carriage assembly <NUM> is to help ensure additive build powder layers have improved surface characteristics, such as for example better level uniformity, in an additive manufacturing system during a build. The recoater carriage assembly <NUM> comprises an elongate powder build material spreader <NUM> to spread powder build material in use.

The powder build material may comprise a polymer powder. In certain specific examples, the powder build material may comprise one or more thermoplastics, such as polyamide (PA) <NUM>, PA12, and thermoplastic polyurethane (TPU), or the like. During a build, a fusing agent may be applied to a layer of build material after the application of fusing energy to defined areas of the layer. Similarly, in certain cases, a detailing agent may be applied to areas of a layer of build material, for example to inhibit, or modify a degree of fusing. A three-dimensional object undergoing additive manufacture may thus be built layer-by-layer from a build powder. For correct application of any fusing agents and detailing agents, it is important that the build powder layer is substantially uniformly flat.

In the non-claimed examples according to the <FIG>, the elongate powder build material spreader <NUM> may spread the build powder material in use. The spreader <NUM> may spread the powder layer to ensure that the thickness of the layer is regular and the upper surface of the layer is flat. The spreader <NUM> may slide or press or roll the powder material to make the layer substantially uniformly flat and of a regular thickness. The spreader <NUM> may, for example, be in the form of a blade which passes across the surface of the powder layer. The spreader <NUM> may be, for example, a roller which rolls across the surface of the powder layer.

The recoater carriage assembly <NUM> comprises a recoater carriage <NUM> to support the spreader <NUM>. The spreader <NUM> is engageable with the carriage <NUM>. The spreader <NUM> is also disengageable from the carriage <NUM>. The spreader <NUM> is to engage with, and to disengage from, the recoater carriage <NUM> by movement of the spreader non-concentrically to a longitudinal axis of the spreader <NUM>. In this example, the engagement of the spreader <NUM> with the recoater carriage <NUM> enables the spreader <NUM> to move together with the recoater carriage <NUM> in use. In the specific example shown in <FIG>, the spreader <NUM> is engaged with the carriage <NUM> by movement of the spreader <NUM> in direction A relative to the carriage <NUM>. In a specific example, the spreader <NUM> is disengaged from the carriage <NUM> by movement of the spreader <NUM> relative to the carriage <NUM> in a direction opposite to direction A. In the specific example shown, the direction A is a direction orthogonal to the longitudinal axis W of the spreader <NUM>. In other examples, the spreader <NUM> can be engaged and disengaged by movement in any other direction that is non-concentric to the longitudinal axis W of the spreader <NUM>.

An advantage of this system is that a housing of the additive manufacturing system does not need to accommodate the movement of, for example, a retaining component in a direction concentric to the longitudinal axis W of the spreader <NUM>, such as direction C (or a direction opposite to direction C) shown in <FIG>. If a retaining component, housed in the carriage <NUM>, is moved in a direction C to retain the elongate spreader <NUM> in the carriage <NUM>, then the carriage <NUM> must have a width in direction C which is sufficient at least to accommodate the width of the spreader <NUM> and the retaining component end-to-end, and possibly also to accommodate the movement of the retaining component. In such a system, this requirement on carriage width increases the total size of the additive manufacturing system, but not the size of the build area. As such, this may be seen as wasted space.

In other comparative systems, to help avoid this wasted space, the spreader and carriage assembly need to be fully removed from the additive manufacturing system prior to movement of a retaining component in a direction C to retain the spreader in, or disengage the spreader from, the carriage. This arrangement clearly is not user-friendly, as the user wishes to interfere with as few components of the system as possible during engagement and disengagement of the spreader. Examples described herein provide features to help overcome these issues in such comparative systems.

In certain examples, the recoater carriage assembly <NUM> may comprise a retainer <NUM> to retain the spreader <NUM> in engagement with the recoater carriage <NUM>. In the specific non-claimed example shown in <FIG>, the retainer <NUM> is a lid to at least partially cover the spreader <NUM> when the spreader <NUM> is engaged with the recoater carriage <NUM>. The lid <NUM> is to be moved relative to the spreader <NUM> to retain the spreader <NUM> in engagement with the recoater carriage <NUM>. In this example, the retainer <NUM> is moved in a direction B to retain the spreader <NUM> in engagement with the recoater carriage <NUM>. In this example, direction B is parallel to direction A.

In the non-claimed examples of <FIG>, the retainer <NUM> comprises a resilient element <NUM> to bias the spreader <NUM> into engagement with the recoater carriage <NUM>. In other non-claimed examples, the retainer <NUM> may take the form of a resilient member on the carriage <NUM> or on the spreader <NUM> to bias the spreader <NUM> into engagement with the recoater carriage <NUM>. The resilient element <NUM> may be a spring or made of rubber or other resilient material, such as neoprene or polyurethane, for example. In a non-claimed example, the resilient element <NUM> may be positioned centrally on the retainer <NUM> or positioned towards one end of the retainer <NUM>.

In certain non-claimed examples, the retainer <NUM> may have a number of resilient elements <NUM>, <NUM>, which optionally may be positioned substantially evenly along one side of the retainer <NUM>. In a specific non-claimed example, the retainer <NUM> has two resilient elements <NUM>, <NUM> positioned towards either end of the retainer <NUM>. This arrangement provides a balance between increasing the number of resilient elements <NUM>, <NUM>, which would increase manufacturing costs and complexity of the system, and the stability offered to the spreader <NUM> when engaged with the carriage <NUM>, which is important for correct functioning of the system.

The spreader <NUM> may, for example, be a roller and may move rotationally or laterally across the build powder layer in use to flatten the layer. The resilient elements <NUM>, <NUM> are positioned to not interfere with the motion of the spreader <NUM> once the spreader <NUM> is engaged with the carriage <NUM>. In a specific example, the spreader <NUM> is a roller and the roller moves across the powder layer while counter rotating. This movement and counter rotation enables the roller to move a so-called "prism of powder" across the powder layer. The "prism of powder" is a build-up of build powder that is located in front of the roller in the direction of movement of the roller across the powder layer. In this non-claimed example, the resilient elements <NUM>, <NUM> engage the outer surfaces of roller bearings <NUM>, <NUM> that facilitate rotation of the roller relative to the carriage <NUM> in use. In this example, the roller bearings <NUM>, <NUM> are rotatable separately to the roller. In certain examples, direct rotation of the spreader <NUM>, rather than counter rotation, is used to move the "prism of powder".

In certain non-claimed examples, the recoater carriage assembly <NUM> may comprise at least one recess <NUM>. In certain non-claimed examples, the carriage <NUM> may have more than one recess <NUM>, <NUM>, and each recess <NUM>, <NUM> receives a portion of the spreader <NUM> in use. The, or each, recess <NUM>, <NUM> may be comprised in a support to support the spreader <NUM> in use. In the example shown in <FIG>, the carriage <NUM> comprises first and second recesses <NUM>, <NUM>. The first recess <NUM> is positioned towards a first end of the carriage <NUM>, and the second recess <NUM> is positioned towards a second end of the carriage <NUM>. The recesses <NUM>, <NUM> shown in <FIG> are positioned substantially equidistantly from the longitudinal ends of the carriage <NUM>. In this example, the first recess <NUM> receives a first portion <NUM> of the spreader <NUM> and the second recess <NUM> receives a second portion <NUM> of the spreader <NUM>, in use. In certain examples, the first and second portions of the spreader <NUM> may be projections <NUM>, <NUM> to project into the corresponding recesses <NUM>, <NUM> of the carriage <NUM> in use. In certain non-claimed examples, the spreader <NUM> comprises at least one projection <NUM>, the recoater carriage <NUM> comprises at least one recess <NUM>, and the at least one projection <NUM> of the spreader <NUM> projects into the at least one recess <NUM> of the carriage <NUM> when the spreader <NUM> is engaged with the carriage <NUM>.

In use, the spreader <NUM> will contact build material, and build material may attach to the spreader <NUM>. When a user wishes to clean or replace the spreader <NUM>, the user is able to move the retainer <NUM> to permit disengagement of the spreader <NUM> from the carriage <NUM>, and then disengage the spreader <NUM>. To avoid contact with the build material, which may be attached to the spreader <NUM>, a user can hold the projections <NUM>, <NUM> of the spreader <NUM>.

In certain examples, one or both of the projections <NUM>, <NUM> of the spreader <NUM> may comprise a drive element, such as a first gear, and the associated recess <NUM>, <NUM> of the carriage <NUM> may comprise a corresponding drive mechanism <NUM>, such as a second gear, for engagement with the drive element. In the specific non-claimed example shown in <FIG>, the projection <NUM> of the spreader <NUM> engages with the drive mechanism <NUM> of the carriage <NUM> when the spreader <NUM> is moved to engage with the carriage <NUM>. In certain examples, the drive element of the spreader <NUM> comprises a worm wheel and the drive mechanism <NUM> of the carriage <NUM> comprises a worm screw. In certain examples, the drive element of the spreader <NUM> and the drive mechanism <NUM> of the carriage <NUM> form a cam arrangement to enable the spreader <NUM> to move when the engaging projection <NUM> of the spreader <NUM> is received in the recess <NUM>.

In the non-claimed example shown in <FIG>, the spreader <NUM> has two projections <NUM>, <NUM>; one at either end of the spreader <NUM>. The two engaging projections <NUM>, <NUM> may help align the spreader <NUM> within the recoater carriage assembly <NUM>. Easy alignment of the spreader <NUM> helps the user to easily engage and disengage the spreader <NUM> from the recoater carriage <NUM>, while not requiring overly accurate axial alignment. This helps to ensure that, during replacement or change-over of the spreader <NUM>, the user is able to rapidly input the spreader <NUM> into the recesses <NUM>, <NUM> to engage the spreader <NUM> with the recoater carriage <NUM>.

<FIG> is a schematic exploded diagram showing the recoater carriage assembly of <FIG> along cross section Z-Z. The recess <NUM>, in this example, is a channel or slot in the carriage <NUM>. The spreader <NUM> is moved in the direction A into the channel or slot to engage with the carriage <NUM>. In certain non-claimed examples, the channel <NUM> has a drop at the end of the channel <NUM>. When a user inserts the spreader <NUM> into the channel, the spreader <NUM> will drop vertically as it fully engages the carriage <NUM>. This indicates to the user that the spreader <NUM> is fully in position, and helps to retain the spreader <NUM> positively relative to the carriage <NUM>. The projection <NUM> may comprise a rotatable ball bearing or similar to help slide the roller <NUM> along the channel or slot <NUM> and into the drop. This could help prevent wear of the channel or slot <NUM>. In cases in which the spreader <NUM> is a roller, the rotatable ball bearing or similar may also help reduce friction to aid rotation of the roller <NUM> relative to the carriage <NUM> in use.

In certain non-claimed examples, the retainer <NUM> is moved in direction B shown in <FIG> to retain the spreader <NUM> between the retainer <NUM> and the carriage <NUM>. The resilient element <NUM> may bias the spreader <NUM> into engagement with the carriage <NUM>. In an example, the retainer <NUM> is engaged with the recoater carriage by virtue of at least one connecting member. The connecting member may be, for example, a screw, pin, bolt, rivet, or nail etc. In a specific example, the retainer is engaged with the recoater carriage by four screws. A user can remove the retainer from the recoater carriage after unscrewing the four screws using a screw driver. This enables rapid removal of the retainer during the changing of a roller, while ensuring that the retainer is well secured to the recoater carriage in use. Certain examples described herein enable a user to replace a roller in a recoater carriage in up to three minutes.

The additive manufacturing system may have an electronic display to guide a user through the process of changing a roller for ease of use. The electronic display may confirm when the roller has been successfully engaged or disengaged. A user may wish to remove the roller to perform basic maintenance on the roller, such as to renew the roller powder walls. Renewing the powder walls may be required over the life of the 3D additive manufacturing system as the roller powder walls wear out. Such renewal may involve removing the existing wall and replacing it with another wall. By providing that the spreader is easily removable and/or insertable, a user is enabled to renew the spreader without need of a repair specialist. Certain examples herein describe methods which can be performed by a user, without specialist training in the equipment, to correct errors which may be inhibiting builds.

<FIG> is a schematic perspective view of a carriage to carry a recoater roller in an additive manufacturing system. The carriage <NUM> comprises a frame <NUM> comprising a first support <NUM> and a second support <NUM>. The first support <NUM> is spaced in a first direction D from the second support <NUM>. The first support <NUM> and second support <NUM> are to engage a recoater roller by movement of the recoater roller in a second direction that is different from the first direction D. The first direction D is orthogonal to the second direction.

In certain examples, the first support <NUM> and the second support <NUM> are immovable relative to each other. A set distance between the first support <NUM> and second support <NUM> ensures that any roller with projections spaced this set distance apart are usable with the carriage <NUM> of <FIG>. This allows the additive manufacturing system to accommodate many types of rollers, such as rollers with respective different surface characteristics for use in different builds.

At least one of the first support <NUM> and second support <NUM> comprises a slot in the carriage <NUM>, as shown in <FIG>. The slot(s) may each receive a portion of the recoater roller. The carriage <NUM> comprises a resilient retainer <NUM> to bias the recoater roller towards the first support <NUM> and second support <NUM>, when the roller is engaged with the first support <NUM> and the second support <NUM>.

In certain examples, the carriage comprises a lid <NUM> to at least partially cover the roller when the roller is engaged with the first support <NUM> and the second support <NUM>. In certain examples, the lid <NUM> comprises a retainer <NUM> to retain the recoater roller relative to at least one of the first support <NUM> and second support <NUM> when the roller is engaged with the first support <NUM> and the second support <NUM>. The first support <NUM> and second support <NUM> are to engage a recoater roller by movement of the recoater roller in a second direction. The lid <NUM> and retainer <NUM> are moved in a direction E towards the supports <NUM>, <NUM>, to trap the roller between the retainer <NUM> and the frame <NUM> in use. In certain examples, the direction E is parallel to the second direction.

In certain examples, the carriage comprises a gear <NUM> to engage with a gear of the recoater roller when the recoater roller is engaged with the first support <NUM> and the second support <NUM>. In an example, the gear <NUM>, shown schematically in <FIG>, is positioned adjacent or at the first support <NUM>. In certain examples, the carriage comprises a first gear <NUM> and a second gear <NUM>. In an example, the first gear <NUM> is positioned adjacent or at the first support <NUM> and the second gear <NUM> is positioned adjacent or at the second support <NUM>. The first and second gears <NUM>, <NUM> may engage respective gears of the recoater roller.

<FIG> shows an example of a spreader <NUM>. In certain examples, the spreader <NUM> comprises a spreader surface <NUM> to contact the build material in use. In certain examples, the spreader <NUM> comprises end portions <NUM>, <NUM> to engage with a recoater carriage. In the example shown, the dimension or height H' of the spreader surface <NUM> is greater than the dimension or height H" of the end portions <NUM>, <NUM>. In the example shown, the spreader surface <NUM> has a width W' and the spreader <NUM> has a total width W". The supports of a recoater carriage for use with the spreader <NUM> must be set at least the width W' of the main spreading surface <NUM> apart but not more than the width W" of the spreader <NUM> apart.

<FIG> is a flowchart showing a method <NUM> of using a recoater carriage assembly in an additive manufacturing system according to an example. This method may be used with the recoater carriage assembly <NUM> of <FIG> (not according to the appended claims) or upon a different system.

At block <NUM>, a first recoater roller is disengaged from a recoater carriage. In a specific example, the first recoater roller is an elongate recoater roller. In a non-claimed example, the direction in which the first elongate recoater roller is moved to be disengaged from the recoater carriage is opposite to the direction A shown in <FIG>. According to the invention, the direction in which the first elongate recoater roller is moved is a direction orthogonal to a longitudinal axis of the first elongate recoater roller.

At block <NUM>, a second elongate recoater roller is moved in a direction non-concentric to a longitudinal axis of the second elongate recoater roller and relative to the recoater carriage, to engage the second elongate recoater roller with the recoater carriage. In this example, the engagement of the second elongate recoater roller with the recoater carriage enables the second elongate recoater roller to move together with the recoater carriage in use. In a non-claimed specific example, the second elongate recoater roller is moved in the direction A shown in <FIG>. According to the invention, the direction in which the second elongate recoater roller is moved is a direction orthogonal to a longitudinal axis of the second elongate recoater roller.

In an example, the first recoater roller has a surface characteristic which differs from the surface characteristic of the second recoater roller. The surface characteristic may be, for example, smoothness, texture or absorbency, or the like. The surface characteristic may be affected or determined by use of grooves on the surface of a roller used to create a rough surface. The type of grooves and dimensions of the grooves will create different types of surfaces with different characteristics. This may result in a surface that is more suited for use with one type of powder over another type of powder. The surface characteristic may be affected or determined by one or more factors including the surface material, the surface finish and the surface coating (if provided).

Claim 1:
A carriage to carry a recoater roller for use in an additive manufacturing system, the carriage (<NUM>) comprising:
a frame (<NUM>) comprising a first support (<NUM>) and a second support (<NUM>), wherein the first support is spaced in a first direction (D) from the second support, and comprising a resilient retainer (<NUM>) to bias the recoater roller (<NUM>) towards the first support (<NUM>) and second support (<NUM>) when the roller is engaged with the first support and the second support;
wherein at least one of the first support (<NUM>) and the second support (<NUM>) has a slot to engage with the recoater roller by movement of the recoater roller in a second direction (E) that is different from the first direction (D); and
wherein the first direction (D) is orthogonal to the second direction (E).