FIELD

This present application relates to electron beam manufacturing apparatuses and, more particularly, to improved methods for determining a location of an electron beam during the operation of such apparatuses.

BACKGROUND

Additive manufacturing is a method for forming three-dimensional articles through successive fusion of portions of powder layers applied to a work plate. Apparatuses for additive manufacturing generally include a work table on which the three-dimensional article is to be formed, a powder dispenser, arranged to lay down a thin layer of powder on the work table for the formation of a powder bed, an energy beam source for delivering an energy beam spot to the powder to fuse the powder, and a controller in which information is stored concerning representations of layers of the three-dimensional article. The three-dimensional article is formed through consecutive fusion of the layers of powder laid down by the powder dispenser.

In order to melt the powder at specific locations corresponding to the representations of the layers of the three-dimensional article, the energy beam must be accurately controlled, including the deflection speed, position, and shape of the energy beam. Although methods exist to calibrate the position of the energy beam with respect to a stationary target, such calibration methods cannot be used while the energy beam is in use and operation of the apparatus assumes that the velocity and position of the energy beam are known. However, the velocity and/or position of the energy beam may deviate over time, such as may result from failure of any one of a number of components within the apparatus. For example, power amplifiers or other components within the additive manufacturing apparatus may fail, thereby generating a dynamic velocity of the energy beam, which may lead to parts that are out of specification.

Accordingly, there exists a need for a method to quantify or track an energy beam during operation of an additive manufacturing apparatus.

SUMMARY

Various embodiments described herein provide a method for detecting a position of an energy beam comprising mapping a first density modulated x-ray signal with a plurality of locations on an energy beam target, thereby generating a model of a background x-ray intensity. The method further comprises forming an x-ray signal time series using subsequent intensity modulated x-ray signals, each resulting from scanning the energy beam along the energy beam target in one of a plurality of directions at one of a plurality of speeds, and determining the position of the energy beam based upon a received x-ray signal strength based on the x-ray signal time series and the model of the background x-ray intensity. Additional features and advantages will be described in greater detail below.

According to a first aspect disclosed herein, a method for detecting a position of an energy beam, the method comprising: mapping, using a computing device, a first intensity modulated x-ray signal with a plurality of locations on an energy beam target, thereby generating a model of a background x-ray intensity; forming, using the computing device, an x-ray signal time series using subsequent intensity modulated x-ray signals, each of the subsequent intensity modulated x-ray signals resulting from scanning an energy beam along the energy beam target in one of a plurality of directions at one of a plurality of speeds; and determining, using the computing device, the position of the energy beam based upon a received x-ray signal strength based on the x-ray signal time series and the model of the background x-ray intensity.

According to a second aspect disclosed herein, a method comprises the method according to the first aspect, wherein each of the x-ray signals is received by an x-ray detector located at a position that is closer to a first edge of the energy beam target than a second edge of the energy beam target opposing the first edge of the energy beam target and closer to a third edge of the energy beam target than a fourth edge of the energy beam target opposing the third edge of the energy beam target, wherein the third edge and the fourth edge extend from the first edge to the second edge of the energy beam target.

According to a third aspect disclosed herein, a method comprises the method according to the first or second aspects, wherein determining the position of the energy beam comprises determining the position of the energy beam along a predetermined axis.

According to a fourth aspect disclosed herein, a method comprises the method according to any one of the previous aspects, wherein determining the position of the energy beam comprises identifying two possible positions of the energy beam along the predetermined axis.

According to a fifth aspect disclosed herein, a method comprises the method according to any one of the previous aspects, wherein the model of the background x-ray intensity is based on a quadratic equation.

According to a sixth aspect disclosed herein, a method comprises the method according to any one of the previous aspects, further comprising: determining, using the computing device, that the position of the energy beam differs from a target position by an amount greater than a threshold amount; and setting a maximum energy beam speed responsive to determining that the position of the energy beam differs from the target position by the amount greater than the threshold amount.

According to a seventh aspect disclosed herein, a method comprises the method according to any one of the previous aspects, further comprising: scanning an energy beam in at least a first direction on the energy beam target for generating x-rays to be received by at least one x-ray detector; receiving the generated x-rays with the at least one x-ray detector; and generating, using the computing device, the first intensity modulated x-ray signal based on the generated x-rays received by the at least one x-ray detector.

According to an eighth aspect disclosed herein, a method comprises the method according to any one of the previous aspects, wherein determining the position of the energy beam comprises determining the position of the energy beam along a predetermined axis.

According to a ninth aspect disclosed herein, a method comprises the method according to the eighth aspect, wherein determining the position of the energy beam comprises identifying two possible positions of the energy beam along the predetermined axis.

According to a tenth aspect disclosed herein, a method comprises the method according to any one of the previous aspects, wherein the model of the x-ray background intensity and the x-ray signal time series corresponds to a first x-ray detector, the method further comprising: mapping, using the computing device, the first intensity modulated x-ray signal received by a second x-ray detector with a plurality of locations on an energy beam target, thereby generating a model of a background x-ray intensity corresponding to the second x-ray detector; and forming, using the computing device, an x-ray signal time series corresponding to the second x-ray detector using subsequent intensity modulated x-ray signals received by the second x-ray detector.

According to an eleventh aspect disclosed herein, a method comprises the method according to any one of the previous aspects, wherein determining the position of the energy beam comprises identifying a position of the energy beam in at least two dimensions.

According to a twelfth aspect disclosed herein, a method comprises the method according to any one of the previous aspects, further comprising: scanning an energy beam in at least a first direction on the energy beam target for generating x-rays to be received by at least one x-ray detector; receiving the generated x-rays with the at least one x-ray detector; and generating, using the computing device, the first intensity modulated x-ray signal based on the generated x-rays received by the at least one x-ray detector.

According to a thirteenth aspect disclosed herein, a method comprises the method according to any one of the previous aspects, further comprising: scanning an energy beam in at least a first direction on the energy beam target for generating x-rays to be received by at least one x-ray detector; receiving the generated x-rays with the at least one x-ray detector; and generating, using the computing device, the first intensity modulated x-ray signal based on the generated x-rays received by the at least one x-ray detector.

According to a fourteenth aspect disclosed herein, a program element configured and arranged when executed on a computer to implement a method for detecting a position of an energy beam, the method comprising the steps of: mapping a first intensity modulated x-ray signal with a plurality of locations on an energy beam target, thereby generating a model of a background x-ray intensity; forming an x-ray signal time series using subsequent intensity modulated x-ray signals, each of the subsequent intensity modulated x-ray signals resulting from scanning the energy beam along the energy beam target in one of a plurality of directions at one of a plurality of speeds; and determining the position of the energy beam based upon a received x-ray signal strength based on the x-ray signal time series and the model of the background x-ray intensity.

According to a fifteenth aspect disclosed herein, a program element comprises the method according to the fourteenth aspect, the method further comprising: determining that the position of the energy beam differs from a target position by an amount greater than a threshold amount; and setting a maximum energy beam speed responsive to determining that the position of the energy beam differs from the target position by the amount greater than the threshold amount.

According to a sixteenth aspect disclosed herein, a program element comprises the method according to any one of the previous aspects, the method further comprising: scanning an energy beam in at least a first direction on the energy beam target for generating x-rays to be received by at least one x-ray detector; receiving the generated x-rays with the at least one x-ray detector; and generating the first intensity modulated x-ray signal based on the generated x-rays received by the at least one x-ray detector.

According to a seventeenth aspect disclosed herein, a computer readable medium having stored thereon the program element according to any one of the preceding aspects.

According to an eighteenth aspect disclosed herein, a non-transitory computer program product comprises at least one computer-readable storage medium having computer-readable program code portions embodied thereon, the computer-readable program code portions comprising: an executable portion configured for mapping a first intensity modulated x-ray signal with a plurality of locations on an energy beam target, thereby generating a model of a background x-ray intensity; an executable portion configured for forming an x-ray signal time series using subsequent intensity modulated x-ray signals, each of the subsequent intensity modulated x-ray signals resulting from scanning the energy beam along the energy beam target in one of a plurality of directions at one of a plurality of speeds; and an executable portion configured for determining the position of the energy beam based upon a received x-ray signal strength based on the x-ray signal time series and the model of the background x-ray intensity.

According to a nineteenth aspect disclosed herein, a non-transitory computer program product comprises the non-transitory computer program product according to the eighteenth aspect, wherein the computer-readable program code portions further comprise: an executable portion configured for determining that the position of the energy beam differs from a target position by an amount greater than a threshold amount; and an executable portion configured for setting a maximum energy beam speed responsive to determining that the position of the energy beam differs from the target position by the amount greater than the threshold amount.

According to a twentieth aspect disclosed herein, a non-transitory computer program product comprises the non-transitory computer program product according to the eighteenth or nineteenth aspects, wherein the computer-readable program code portions further comprise: an executable portion configured for scanning an energy beam in at least a first direction on the energy beam target for generating x-rays to be received by at least one x-ray detector; an executable portion configured for receiving the generated x-rays with the at least one x-ray detector; and an executable portion configured for generating the first intensity modulated x-ray signal based on the generated x-rays received by the at least one x-ray detector.

Additional features and advantages of the embodiments disclosed herein will be set forth in the detailed description, which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the disclosed embodiments as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description and the following detailed description present embodiments intended to provide an overview or framework for understanding the nature and character of the claimed embodiments. The accompanying drawings are included to provide further understanding, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the disclosure, and together with the description serve to explain the principles and operations thereof.

