US20170355019A1

Movatterモバイル変換

Info

Publication number: US20170355019A1
Application number: US15/182,456
Authority: US
Inventors: Eric Karlen
Original assignee: Hamilton Sundstrand Corp
Current assignee: Hamilton Sundstrand Corp
Priority date: 2016-06-14
Filing date: 2016-06-14
Publication date: 2017-12-14
Also published as: US10974321B2; US20200038957A1

Abstract

An additive manufacturing system for building a product includes a base plate for mounting the product thereon, and at least one heating element shaped to at least partially conform to the product and configured to apply heat to at least a portion of the product as the product is additively manufactured to reduce thermal gradients in the product.

Description

BACKGROUND1. Field

The present disclosure relates to additive manufacturing, more specifically to thermal control for additive manufacturing.

2. Description of Related Art

All welding and joining processes create non-uniform residual stress distributions as a result of the intense heat input. Residual stresses due to thermal expansion and contraction of the solidified material can cause distortion of an additively manufactured part. Distortion can occur during the additive manufacturing process and/or during the heat treatment cycles after building. The residual stress in the part can relax during heat treatment causing significant distortion to occur.

As such, thermal management is required to prevent thermal contraction/shrinkage from occurring during the process. Thermal contraction can lead to layer misregistration where the layer being fused does not dimensionally correlate to the previous layer. Traditional additive manufacturing processes and systems do not control such non-uniform residual stresses.

Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for improved thermal control for additive manufacturing. The present disclosure provides a solution for this need.

SUMMARY

An additive manufacturing system for building a product includes a base plate for mounting the product upon, and at least one heating element shaped to at least partially conform to the product and configured to apply heat to at least a portion of the product as the product is additively manufactured to reduce thermal gradients in the product (e.g., due to non-uniform heating/cooling of the product during sintering).

The heating element can be conformal to an outer shape of the product. The heating element can include an electric coil or any other suitable heating element.

In certain embodiments, the base plate can be configured to be heated. The system can include a thermal imaging device (e.g., an IR camera) positioned to view the product within the heating element for thermal monitoring of the product as it is additively manufactured.

The system can include a control unit operatively connected to the thermal imaging device and the heating element to control the heating element as a function of feedback from the thermal imaging device to prevent non-uniform heating of the product. In certain embodiments, the system can include an energy applicator positioned to apply energy within the heating element for layer-wise powder fusion.

A method for additively manufacturing a product includes additively manufacturing a product on a base plate and within a heating element, and applying heat to a portion of the product during additive manufacturing to reduce thermal gradients in the product, wherein heating the product occurs within a heating element configured to at least partially conform to the product. In certain embodiments, additive manufacturing the product can include depositing powder within the heating element.

The method can further include applying energy from an energy applicator to the powder within the heating element to sinter the powder within the heating element. In certain embodiments, the method can include controlling the heating element as a function of feedback from a thermal imaging device to prevent non-uniform heating of the product. The method can include heating the base plate.

These and other features of the systems and methods of the subject disclosure will become more readily apparent to those skilled in the art from the following detailed description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices and methods of the subject disclosure without undue experimentation, embodiments thereof will be described in detail herein below with reference to certain figures, wherein:

FIG. 1 is a perspective exploded view of an embodiment of a system in accordance with this disclosure.

DETAILED DESCRIPTION

Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, an illustrative view of an embodiment of a system in accordance with the disclosure is shown inFIG. 1 and is designated generally by reference character100. The systems and methods described herein can be used to reduce defects due to non-uniform heating/cooling during additive manufacturing.

Referring toFIG. 1, an additive manufacturing system100 for building aproduct102 includes abase plate101 for mounting theproduct102 upon and at least oneheating element103 shaped to at least partially conform to the product102 (e.g., completely around, adjacent one or more lateral sides or portions thereof) and configured to apply heat to at least a portion of theproduct102 as theproduct102 is additively manufactured to reduce thermal gradients within theproduct102. Any suitable number ofheating elements103 can be utilized. It should be understood that theheating element103 may not actually increase temperatures within theproduct102, but instead slow a rate of cooling of theproduct102. In so doing, theheating element103 may reduce thermal gradients in the product102 (e.g., due to non-uniform heating/cooling of theproduct102 during the additive manufacturing process)

In certain embodiments, theheating element103 can be conformal to the outer shape of theproduct102 such that it surrounds theproduct102, for example. The heating element can include an electric coil (e.g., an induction coil) or any other suitable heating element that extends along a build axis.

In certain embodiments, thebase plate101 can be configured to be heated (e.g., via one or more heating elements disposed within the base plate101). For example, thebase plate101 can include a resistive heating arrangement with heating elements attached to the bottom of thebase plate101 or embedded within the base plate101 (e.g., using additive manufacturing techniques). Certain embodiments of thebase plate101 can have integral heat pipes that define heating channels for a heating fluid to be pumped through to stabilize temperature. In certain embodiments, a part may be used as the base for deposition to create features or shapes instead of manufacturing the entire part through additive manufacturing methods.

The system100 can include a thermal imaging device105 (e.g., an IR camera) positioned to view within theheating element103 for thermal monitoring of theproduct102 as it is additively manufactured. In certain embodiments, the system100 can include an energy applicator109 (e.g., a laser) positioned to apply energy within theheating element103 for layer-wise powder fusion. While embodiments can be used with directed energy deposition or blown powder deposition processes (e.g., for metals), it is contemplated that molten material deposition (e.g., for thermoplastics) can also be utilized within the heating element.

As shown, the system100 can include acontrol unit107 operatively connected to thethermal imaging device105, theheating element103, thebase plate101, and/or theenergy applicator109 to control theheating element103 and/or theenergy applicator109 and/or thebase plate101 as a function of feedback from thethermal imaging device105 to prevent non-uniform heating and/or reduce thermal gradients within theproduct102. For example, if a local hot spot is detected, thecontrol unit107 can cause theheating element103 to apply more heat to theproduct102 being built.

In accordance with at least one aspect of this disclosure, a method for additively manufacturing aproduct102 includes additively manufacturing aproduct102 on abase plate101 and within aheating element103. The method also includes applying heat to theproduct102 during additive manufacturing to prevent non-uniform heating of theproduct102.

In certain embodiments, additive manufacturing theproduct102 can include depositing powder within theheating element103. For example, powder can be dropped or sprayed (e.g., via a cold spray process) in any suitable manner. Theheating element103 can be progressively submerged in powder, or powder can be deposited only within the confines of theheating element103 such as on theproduct102 only, for example. It is contemplated that any other suitable method to place powder within theheating element103 is contemplated herein.

The method can further include applying energy from anenergy applicator109 to the powder within theheating element103 to sinter the powder within theheating element103. In certain embodiments, the method can include controlling theheating element103 as a function of feedback from athermal imaging device105 to prevent non-uniform heating of theproduct102. The method can also include heating thebase plate101.

As described above, embodiments include a heating element that can be nearly conformal to the finished part. Theheating element103 extends in the z-axis (i.e., the axis in which the part is being built).Multiple heating elements103 could be used as needed to optimize the thermal management throughout the production of a part. Also, the power settings for theheating element103 could be varied as needed using pre-established parameters to create a smaller or larger induced magnetic field. Thebase plate101 can also be utilized as the starting surface for manufacturing of the part. To maintain a uniform temperature, thebase plate101 can be heated.

Embodiments as described above allow for improved distortion control, consistent registration between layers, minimized temperature differences within part, reduced risk of solidification cracking or issues with solidification (e.g., during a laser fusion additive manufacturing process).

The methods and systems of the present disclosure, as described above and shown in the drawings, provide for additive manufacturing systems with superior properties as described above. While the apparatus and methods of the subject disclosure have been shown and described with reference to embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the spirit and scope of the subject disclosure.

Claims

What is claimed is:

1. An additive manufacturing system for building a product, comprising:

a base plate for mounting the product upon; and

at least one heating element shaped to at least partially conform to the product and configured to apply heat to at least a portion of the product as the product is additively manufactured to reduce thermal gradients in the product.

2. The system ofclaim 1, wherein the base plate is configured to be heated.

3. The system ofclaim 1, wherein the heating element includes an electric coil.

4. The system ofclaim 1, wherein the heating element is conformal to an outer shape of the product.

5. The system ofclaim 1, further comprising a thermal imaging device positioned to view the product within the heating element for thermal monitoring of the product as it is additively manufactured.

6. The system ofclaim 5, further comprising a control unit operatively connected to the thermal imaging device and the heating element to control the heating element as a function of feedback from the thermal imaging device to reduce thermal gradients in the product.

7. The system ofclaim 1, further comprising an energy applicator positioned to apply energy within the heating element for layer-wise powder fusion.

8. A method for additively manufacturing a product, comprising:

additively manufacturing a product on a base plate and within a heating element; and

applying heat to a portion of the product during additive manufacturing to reduce thermal gradients in the product, wherein heating the product occurs within a heating element configured to at least partially conform to the product.

9. The method ofclaim 8, wherein additive manufacturing the product includes depositing powder within the heating element.

10. The method ofclaim 9, further comprising applying energy from an energy applicator to the powder within the heating element to sinter the powder within the heating element.

11. The method ofclaim 8, further comprising controlling the heating element as a function of feedback from a thermal imaging device to reduce thermal gradients in the product.

12. The method ofclaim 8, further comprising heating the base plate that the product is mounted on.