JP2022086619A - Device for generating electron beam and 3d printing device - Google Patents

Abstract

To obtain a large current by using an elongated hot cathode while reducing an acceleration voltage and suppressing the generation of high-energy X-rays by forming a point-shaped beam by a deflection unit.SOLUTION: In a device 1 for generating an electron beam 4, a voltage is applied between a cathode electrode 2 and an anode electrode 3 to accelerate electrons emitted from an elongated wire-shaped hot cathode, and the electron beam 4 that has passed through the opening of the anode electrode 3 is deflected by a deflection unit, such that a cross section of the electron beam 4 is changed to decrease a longitudinal extend thereof, and increase a traverse extent thereof, and in particular, such that the longitudinal and traverse extents are almost the same.SELECTED DRAWING: Figure 1

Description

The present invention relates to an apparatus for generating an electron beam and a 3D printing apparatus for producing a spatially expanded product according to the preamble of claim 12.

Devices for generating an electron beam applicable to 3D printing are known. In the case of the device, in particular, the electron beam hits the starting material formed as the metal rod material, thereby locally melting the starting material. Therefore, it is possible to place the starting material in the work area at a predetermined location in order to produce the objects to be manufactured by stacking them in layers.

In principle, accelerating electrons using a voltage of up to 100 kV has been found to be disadvantageous, and when an electron hits a starting material, it produces X-rays with an energy of up to 100 kV. This X-ray shielding requires a great deal of cost. Furthermore, the high power density of such electron beams can cause problems as it can lead to partial evaporation of the metal starting material. Furthermore, the magnets normally used to deflect an electron beam only allow low scanning speeds of the electron beam in the working area.

An underlying task of the present invention is to create a device of the type mentioned at the outset, which produces a less harmful beam and / or is more suitable for a 3D printing process. Furthermore, it is to provide the type of 3D printing apparatus mentioned at the beginning which comprises such an apparatus.

According to the present invention, this is achieved by the apparatus of the type described at the beginning, which has the characteristics of claim 1, and the 3D printing apparatus of the type described at the beginning, which has the characteristics of claim 12. A subordinate claim relates to a preferred embodiment of the present invention.

According to claim 1, the apparatus is
An elongated wire-like thermal cathode that emits an electron beam during operation of the device, and because of its elongated shape, has an elongated linear cross section perpendicular to the propagation direction and has a longer longitudinal extension than the lateral extension. With an apparently large thermal cathode,
With the cathode electrode
Anode electrode, in particular, having an opening through which an electron beam emitted from a hot cathode can pass, and a cathode electrode and an anode to accelerate electrons emitted from the hot cathode during operation of the device. An anode electrode to which a voltage is applied between the electrodes and
A deflection unit capable of deflecting an incident electron beam through the opening of the anode electrode, the cross section of the electron beam is reduced in longitudinal elongation by the deflection unit during operation of the device. , In particular, the electron beam is modified to have a rotationally symmetric cross section so that the longitudinal elongation and the lateral elongation are approximately the same. It is equipped with a deflection unit.

By using an elongated thermal cathode, an electron beam with a linear cross section is generated. Furthermore, by using an elongated thermal cathode, the current of the electron beam emitted from the thermal cathode can be significantly higher than in the case of a substantially punctate thermal cathode. For example, it can reach a current of 1 A. This makes it possible to reduce the acceleration voltage by, for example, 10 kV to 15 kV. As a result, when the starting material for 3D printing is hit by an electron beam, there is no high energy X-ray beam and there is no need for extensive shielding of the device. Nevertheless, the electron beam in the working area is formed into a relatively point-like or rotationally symmetric beam, so that the starting material can be effectively melted.

The deflection unit can be configured to include at least one deflection electrode. The at least one deflection electrode can, in particular, be configured such that the electron beam incident through the opening of the anode electrode is reflected by the at least one deflection electrode, and / or becomes so. It is possible to dispose of it in the apparatus. In contrast to magnetic field deflection, electrode deflection provides a substantially higher scanning speed of the electron beam in the working area. In the case of the deflection electrode configuration typically applied, the capacitance of the deflection electrode is so small that deflection frequencies up to 120 kHz can be achieved.

At least one deflection electrode may have a negative potential with respect to the anode electrode, particularly at the same potential as the cathode electrode, and may be preferably connected to the same voltage source as the cathode electrode. By connecting to the same voltage source, it can be guaranteed that the electrons are significantly decelerated by the deflection electrode before being accelerated towards the working area.

The deflection unit, in particular at least one deflection electrode, can be configured such that the electron beam that has passed through the opening of the anode electrode is split into several partial beams. In particular, it is possible to superimpose a plurality of partial beams in the work area. By dividing the beam into several partial beams and superimposing them in the working area, it is possible to relatively effectively convert an electron beam with a linear cross section into an electron beam with a rotationally symmetric cross section.

The deflection unit comprises at least one additional electrode that has a positive potential compared to at least one deflection electrode and is capable of accelerating electrons after interaction with at least one deflection electrode, the additional electrode. In particular, it has an opening through which an electron beam emanating from at least one deflection electrode can pass. In this way, the damped electrode can be accelerated in the direction of the further electrode. Therefore, this additional electrode should be arranged so that this acceleration occurs at the desired deflection angle.

The deflection unit includes at least two opposing deflection electrodes, in particular, which can be disposed after the additional electrodes in the direction of propagation of the electron beam, to deflect the electron beam, the voltage. In particular, it is possible to apply an AC voltage between the electrodes. Deflection electrodes can be used to shape or homogenize the beam profile of the electron beam in the work area. In particular, the AC voltage can have a relatively high frequency, for example up to 120 kHz, so that the electron beam or a partial beam thereof travels back and forth at high speed in the work area or on the starting material. It is possible. It is possible to properly affect the AC voltage in order to expose some areas of the surface of the starting material to the electron beam longer than others.

The cathode electrode can be configured to be segmented in the longitudinal direction of the wire forming the thermal cathode. This makes it possible to facilitate subdivision into partial beams. Furthermore, this allows for a modular structure of the device. This is because the source can be expanded longitudinally in the linear electron beam by stitching together several segments of the cathode electrode and by using a longer wire that acts as a thermal cathode.

According to claim 12, the device for generating an electron beam is provided to be a device according to the present invention.

The 3D printing device can be equipped with several devices for generating an electron beam, and these devices are used so that the electron beam collides with the starting material from different directions during the operation of the 3D printing device. It is arranged in the printing device. For example, the device can be arranged in a circle around the starting material, so that the electron beam can hit it from all sides at the same time. This causes the starting material to melt effectively and very uniformly.

Further features and advantages of the present invention will be apparent with reference to the accompanying figures, based on the following description of preferred embodiments.

Shown is a perspective view of the first embodiment of the 3D printing apparatus according to the invention, comprising the first embodiment of the apparatus according to the invention for generating an electron beam, generated by the apparatus for generating an electron beam. The electron beam is illustrated. FIG. 1 shows a further perspective view of the first embodiment of the 3D printing apparatus according to the present invention according to FIG. A perspective view of a second embodiment of a 3D printing apparatus according to the invention comprising a second embodiment of the apparatus according to the invention for generating an electron beam is shown, and an electron beam generated by the apparatus is illustrated. There is. FIG. 4 shows a further perspective view of a second embodiment of the 3D printing apparatus according to the invention according to FIG. FIG. 5 shows a further perspective view of a second embodiment of the 3D printing apparatus according to the invention according to FIG. FIG. 6 shows a schematic plan view of a third embodiment of a 3D printing apparatus according to the invention, comprising some apparatus according to the invention for generating an electron beam, wherein the electron beam generated by the apparatus is shown. It is illustrated.

In the figure, the same or functionally identical parts or elements are labeled with the same reference symbol. Some of the figures show the Cartesian coordinate system.

In the case of the described device, it is possible to place some or especially all parts in vacuum. The housing required for this is not shown in the figure.

The first embodiment of the apparatus 1 according to the present invention for generating an electron beam, shown in FIGS. 1 and 2, includes a thermal cathode (not shown), a cathode electrode 2 and an anode electrode 3. With respect to these parts, the device 1 basically corresponds to a piercing type electron gun. It is possible to generate an electron beam 4 propagating from the thermal cathode or in the direction from the cathode electrode 2 to the anode electrode 3 in the Z direction of the illustrated coordinate system.

The thermal cathode is configured as a wire and is disposed in the cavity of the cathode electrode 2 with the reference numeral 5. The thermal cathode extends in the longitudinal direction corresponding to the Y direction of the illustrated coordinate system. Correspondingly, the longitudinal direction is arranged perpendicular to the propagation direction of the electron beam 4. With this configuration, a linear cross section of the electron beam 4 is achieved and the longitudinal direction of the linear cross section is aligned parallel to the longitudinal direction of the wire forming the thermal cathode 1. The wire can have, for example, a diameter of 1 mm and a length in the Y direction of 100 mm to 160 mm.

A voltage is applied to the hot cathode by a voltage means (not shown) so that the current leading to the heating of the hot cathode flows through the hot cathode. In this case, the thermal cathode 1 may be at least partially at the same potential as the cathode electrode 2.

The cathode electrode 2 can have a length in the Y direction of, for example, 80 mm to 120 mm. The cathode electrode 2 has portions 6, which extend away from the thermal cathode and form an angle of 110 ° to 150 °, eg, about 135 °, with respect to each other. In the illustrated embodiment, the two parts 6 are divided into, for example, four parts 7.

It is possible not to divide it, or it is possible to divide it once into any plurality of parts.

The anode electrode 3 has an opening 8 through which the electron beam 4 emitted from the thermal cathode can pass. The opening 8 is particularly rectangular and has substantially larger dimensions in its longitudinal direction extending in the Y direction in FIG. 1 than in the lateral direction to allow the passage of the electron beam 4 having a linear cross section. It is possible.

When the device 1 is operating, a voltage is applied between the cathode electrode 2 and the anode electrode 3 in order to accelerate the electrons emitted from the thermal cathode 1. The voltage can be, for example, 10 kV to 15 kV. In this case, the cathode electrode 2 can be connected to the negative electrode of the voltage source (not shown), the anode electrode 3 can be connected to the positive electrode, and in particular, the anode electrode 3 can be connected to the ground.

The device 1 further includes a plurality of deflection electrodes 9a, 9b, 9c, 9d that function as deflection means, and these are arranged in the beam path of the electron beam 4 in the subsequent stage of the anode electrode 3. In the illustrated embodiment, four deflection electrodes 9a, 9b, 9c, 9d are provided. However, it is also possible to have more or less deflection electrodes 9a, 9b, 9c, 9d.

The individual deflection electrodes 9a, 9b, 9c, 9d are configured in a rod shape in the illustrated embodiment and have a cylindrical cross section. It is also possible that the deflection electrodes 9a, 9b, 9c, 9d have different shapes.

The deflection electrodes 9a, 9b, 9c, 9d are also at one negative potential, or several different negative potentials. In particular, one, some, or all of the deflection electrodes 9a, 9b, 9c, 9d can be at the same negative potential as the cathode electrode 2. Preferably, one, some, or all of the deflection electrodes 9a, 9b, 9c, 9d are connected to the negative electrode of the same voltage source as the cathode electrode 2. Thereby, it is possible to achieve that the electrons of the electron beam 4 substantially stall at the deflection electrodes 9a, 9b, 9c, 9d.

The electron beam 4 is deflected by, for example, the deflection electrodes 9a, 9b, 9c, 9d by about 50 ° to 60 °. It is also possible to deflect at other angles.

The deflection electrodes 9a, 9b, 9c, and 9d are three-dimensionally offset from each other, and in particular, are offset in the propagation direction or the Z direction of the electron beam 4 emitted from the anode electrode 3. This three-dimensional offset of the individual deflection electrodes 9a, 9b, 9c, 9d with respect to each other causes a portion of the electron beam 4 to be deflected closer to the anode electrode 3 than the rest of the electron beam 4. In this way, the electron beam 4 is divided into a plurality of partial beams 10a, 10b, 10c, and 10d during deflection.

From FIG. 1, from left to right in FIG. 1, that is, in the negative Y direction, the first deflection electrode 9a and the third deflection electrode 9c are arranged further below the second deflection electrode 9b and the fourth deflection, respectively. You can see that it has been done. Therefore, the electron beam 4 incident on the second and fourth deflection electrodes 9b and 9d is deflected to the right earlier than the electron beam 4 incident on the first and third deflection electrodes 9a and 9c. As a result, the partial beams 10b and 10d of the electron beam 4 in FIG. 1, which are deflected by the second deflection electrode 9b and the fourth deflection electrode 9d, have the first deflection electrode 9a and the third deflection in the upward or negative Z direction. It travels away from the partial beams 10a and 10c deflected by the electrodes 9c.

The apparatus 1 further includes an additional electrode 11 after the deflection electrodes 9a, 9b, 9c, 9d in the propagation direction of the electron beam 4 or the partial beams 10a, 10b, 10c, 10d, wherein the electrode 11 is the electron beam 4. Alternatively, it has an opening 12 for the passage of the partial beams 10a, 10b, 10c, 10d. The opening 12 is also rectangular and may have a larger dimension in its longitudinal direction than in its lateral direction. The additional electrode 10 is, for example, grounded and therefore has a positive potential with respect to the deflection electrodes 9a, 9b, 9c, 9d. Therefore, the electrons of the electron beam 4 or the partial beams 10a, 10b, 10c, 10d decelerated in the deflection electrode are accelerated toward the further electrode 11 by the deflection electrodes 9a, 9b, 9c, 9d, and the opening 12 is opened. pass.

Since the maximum value of the positive potential of the electrode 11 is substantially placed in the center of the opening 12, the partial beams 10a, 10b, 10c, 10d are slightly deflected toward the center of the opening 12 of the electrode 11 and its. As a result, they come closer to each other in the further beam path. As a result, the partial beams 10a, 10b, 10c, and 10d are finally superposed in the working area 13, and in the working area 13, the recombined electron beam 4 is preferably approximately. It will have a rotationally symmetric cross section.

For example, the working area 13 can be disposed of a metal rod-shaped starting material 20 for 3D printing that can be melted by the recombined electron beam 4.

In the embodiment according to FIGS. 1 and 2, two groups 14 and 15 of the deflection electrodes 16b and 16d; 17a and 17c further divided into a plurality of electrodes are arranged after the electrode 11 and the electrode group thereof. A further electrode 18 having an opening 19 is provided in the subsequent stage. The partial beams 10b, 10d pass between the individual parts of the deflection electrodes 16b, 16d, while the partial beams 10a, 10c pass between the individual parts of the deflection electrodes 17a, 17c. As a result, the deflection electrodes 16b and 16d of the first group 14 act on the partial beams 10b and 10d, while the deflection electrodes 17a and 17c of the second group 15 act on the partial beams 10a and 10c.

The individual parts of the deflection electrodes 16b, 16d; 17a, 17c are formed by two or four plates located opposite each other in the embodiment according to FIGS. 1 and 2, and are assigned between them. The partial beams 10a, 10b, 10c, and 10d pass through.

It is possible to apply a voltage, particularly an AC voltage, between each portion of the deflection electrodes 16b, 16d; 17a, 17c assigned to each one of the partial beams 10a, 10b, 10c, 10d. The corresponding voltage source is not shown. The AC voltage can have frequencies above, for example, 10 kHz and 10 kHz, eg, up to 120 kHz.

The deflection electrodes 16b, 16d; 17a, 17c help shape or homogenize the beam profile of the electron beam 4 in the working area 13. In particular, the deflection electrodes 16b, 16d; 17a, 17c have a relatively high frequency of AC voltage, so that the partial beams 10a, 10b, 10c, 10d are moved back and forth at high speed in the working area 13 or on the starting material 20. Move it. In particular, it is possible to appropriately change the AC voltage in order to expose some regions of the surface of the starting material 20 to the electron beam 4 longer than the other regions.

The second embodiment shown in FIGS. 3-5 is in that the openings 12 and 19 of the electrodes 11 and 18 substantially correspond to the openings 8 of the anode electrode 3 in terms of their shape and size. It is different from the first embodiment.

Further, the cathode 2 of the second embodiment has a different shape from the cathode 2 of the first embodiment.

Furthermore, the deflection electrodes 9a, 9b, 9c, 9d of the second embodiment have different shapes from the deflection electrodes 9a, 9b, 9c, 9d of the first embodiment.

Furthermore, separate deflection electrodes 16b, 16d; 17a, 17c are not provided for each of the partial beams 10a, 10b, 10c, 10d. Rather, in each of the groups 14 and 15, exactly two deflection electrodes 16 and 17 are provided, and two of the partial beams 10a, 10b, 10c and 10d pass between the electrodes, respectively.

In particular, the partial beams 10b and 10d pass between the two deflection electrodes 16 of the first group 14, while the partial beams 10a and 10c pass between the two deflection electrodes 17 of the second group 15. And proceed. As a result, the deflection electrode 16 of the first group 14 acts on the partial beams 10b and 10d, while the deflection electrode 17 of the second group 15 acts on the partial beams 10a and 10c.

FIG. 6 depicts an embodiment of a 3D printing device including a plurality of devices 1 for generating an electron beam 4. The device 1 is arranged in a circle around the rod-shaped starting material 20, so that the electron beam 4 of the device 1 collides with the starting material 20 from different directions during the operation of the 3D printing device.

Claims (13)

A device (1) for generating an electron beam (4).
An elongated wire-shaped thermal cathode that emits an electron beam (4) during the operation of the apparatus (1), and because of its elongated shape, has an elongated linear cross section perpendicular to the propagation direction and is longitudinal. With a thermal cathode whose elongation is clearly greater than in the lateral direction,
Cathode electrode (2) and
The anode electrode (3), in particular, has an opening (8) through which the electron beam (4) emitted from the thermal cathode can pass, and during the operation of the apparatus, the cathode electrode (2) and the anode electrode (2) During 3), the anode electrode (3) to which a voltage is applied to accelerate the electrons emitted from the thermal cathode,
A deflection unit capable of deflecting an incident electron beam (4) through an opening of an anode electrode (3), wherein the cross section of the electron beam (4) is deflected during operation of the device. Depending on the unit, the elongation in the longitudinal direction is changed to be small and the elongation in the lateral direction is increased, and in particular, the electron beam (4) is preferably used so that the elongation in the longitudinal direction and the elongation in the lateral direction are approximately the same. ) Equipped with a deflection unit, which is modified to have a rotationally symmetric cross section (1). The apparatus (1) according to claim 1, wherein the deflection unit includes at least one deflection electrode (9a, 9b, 9c, 9d; 16, 16b, 16d; 17, 17a, 17c). .. The at least one deflection electrode (9a, 9b, 9c, 9d) has an electron beam (4) that has passed through the opening (8) of the anode electrode (3), and the electron beam (4) has at least one deflection electrode (9a, 9b, 9c, 9d). The device (1) according to claim 2, wherein the device (1) is configured to be reflected by the device (1) and / or is disposed in the device (1). The at least one deflection electrode (9a, 9b, 9c, 9d) has a negative potential with respect to the anode electrode (3), particularly the same potential as the cathode electrode (2), preferably the cathode electrode (2). The device (1) according to claim 2 or 3, wherein the device (1) is connected to the same voltage source as the above. In the deflection unit, particularly at least one deflection electrode (9a, 9b, 9c, 9d), the electron beam (4) passing through the opening (8) of the anode electrode (3) is a plurality of partial beams (10a, 10b, 10c). , 10d) The apparatus (1) according to any one of claims 1 to 4, wherein the apparatus is configured to be divided into 10d). The apparatus (1) according to claim 5, wherein the deflection unit is configured so that a plurality of partial beams (10a, 10b, 10c, 10d) overlap each other in the working area (13). The deflection unit has a positive potential for at least one deflection electrode (9a, 9b, 9c, 9d) and electrons after interaction with at least one deflection electrode (9a, 9b, 9c, 9d). It comprises at least one additional electrode (11) capable of accelerating, the additional electrode (11) being particularly an electron beam (4) emitted from at least one deflection electrode (9a, 9b, 9c, 9d). The device (1) according to any one of claims 1 to 6, further comprising an opening (12) through which the) can pass. The deflection unit comprises at least two deflection electrodes (16, 16b, 16d; 17, 17a, 17c) facing each other, and the deflection electrodes (16, 16b, 16d; 17, 17a, 17c) are particularly electron beam (16, 16b, 16d; 17, 17a, 17c). At least two deflection electrodes (16, 16b, 16d; 17, 17a, 17c) The apparatus according to any one of claims 1 to 7, wherein a voltage, particularly an AC voltage, can be applied between them. The deflection unit is at least one additional electrode (18) disposed after at least two deflection electrodes (16, 16b, 16d; 17, 17a, 17c) facing each other in the propagation direction of the electron beam (4). 8. The device (1) of claim 8, wherein the further electrode has, in particular, an opening (19) through which the electron beam (4) can pass. Any of claims 1-9, wherein the structure and / or control of the thermal cathode, cathode electrode (2) and anode electrode (3) corresponds to the structure and / or control of the pierced electron gun. The device (1) according to item 1. The apparatus (1) according to any one of claims 1 to 10, wherein the cathode electrode (2) is divided into segments (7) in the longitudinal direction of the wire forming the thermal cathode. .. At least one device (1) for generating an electron beam (4), and
The working area (13) to which the starting material (20) exposed to the electron beam (4) for 3D printing is supplied or can be supplied, the working area (13) is the electron beam (4). Arranged in a 3D printing device so as to collide with the starting material (20), in particular the starting material (20) is configured in a rod shape and comprises a working area (13) made of or containing metal. A 3D printing device for manufacturing spatially expanding products, including
A 3D printing apparatus, wherein the apparatus (1) for generating an electron beam (4) is the apparatus (1) according to any one of claims 1 to 11. A plurality of devices (1) for generating an electron beam (4) are provided, and these devices have the electron beam (4) colliding with the starting material (20) from different directions during the operation of the 3D printing device. The 3D printing apparatus according to claim 12, wherein the 3D printing apparatus is arranged in the 3D printing apparatus.

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