JP2676755B2 - Electron beam generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an electron beam generator used for performing electron beam melting, electron beam vapor deposition, etc., in particular, a block cathode supporting mechanism in a large capacity electron beam generator. Regarding the improvement of.

[Conventional technology]

FIG. 2 shows the structure of a conventional electron beam generator. In FIG. 1, reference numeral 1 denotes a vacuum container which is an apparatus container, and 2 denotes an ion stopper. 3 is filament, 4
Is a disk-shaped block cathode (hereinafter, simply referred to as a cathode) having a through hole 4a at the center, and both constitute a hot cathode unit (thermal electron source) 5. 6 is a Wehnelt electrode for preventing the diffusion of thermoelectrons, 7 is an anode for accelerating thermoelectrons, and a through hole 7a through which the electron beam B passes is formed in the center. 8 filament heating power source (voltage V _f), E _K is an acceleration voltage, E _A is the acceleration voltage.

The filament 3 is supplied with power from the filament heating power supply 8 and rises in temperature to generate thermoelectrons e. This thermoelectron e is
In an electric field of accelerating voltage E _K makes with an electric field accelerates the cathode 4
And the cathode 4 is heated. The heated cathode 4 emits thermoelectrons e, and the thermoelectrons e are focused and prevented from being diffused by the Wehnelt electrode 6, and the focused thermoelectrons (electron beam) B are generated in the electric field generated by the acceleration voltage E _A. With anode 7
Is accelerated toward the side, passing through the passage hole 7a of the anode 7,
Although not shown, the workpiece is further subjected to a focusing action by one or a plurality of focusing electrodes, and then passes through a deflection coil to irradiate the workpiece.

By the way, the cathode 4 is generally a cathode holder which is generally set on each of a plurality of columns 10 extending from the fixed portion A in the vacuum container 1 as shown in FIGS. 3 (a) and 3 (b). 11 and the cathode supporting arm 12 and the set screw 13 support the cathode holding mechanism, and are disposed in the vacuum container 1. Each cathode holder 11
Has a hole 11a of a predetermined depth, and is set on the column 10 with the open end of the hole 11a facing the operational center O in the vacuum vessel 1. One end of the cathode support arm 12 is inserted into the hole 11a, is fixed by a set screw 13 and is cantilevered by the cathode holder 11, and the other end is inserted into a radial hole 4b that opens to the peripheral surface of the cathode 4. And supports the cathode 4. 14
Is a nut for fixing the column.

[Problems to be solved by the invention]

As described above, conventionally, a plurality of cathode support arms 12 that support the cathode 4 are individually provided in the cathode holder.
Since the cathode holders 11 are supported in a cantilever manner and the cathode holders 11 are individually set (screwed and coupled) on the columns 10, the cathode holders 11 need not be adjusted in direction when positioning the cathodes 4. In addition, the protrusion length of the cathode support arm 12 from the cathode holder 11 must be adjusted while loosening or tightening the set screw 13, and the position error of each strut 10 is likely to occur. In addition, there is a problem that it takes time and time to adjust the center of the cathode 4 so as to come to the operation center O, and the connecting portion a between the cathode 4 and the cathode support arm 12 becomes hot during the operation of the device. As a result, seizure occurs, so when replacing the cathode, loosen the nut 14 that secures the column 10 and pull the upper end side outwards.
Therefore, the cathode holder 11 has to be removed, and a large amount of adjustment time is required before the operation can be restarted.

The present invention has been made to solve the above problems, and provides an electron beam generator capable of reducing the time and effort required for setting and exchanging cathodes and shortening the time required for these operations, as compared with the prior art. The purpose is to do.

[Means for solving the problem]

According to the present invention, in order to achieve the above object, a block cathode holding mechanism is fitted and fixed to a ring body and at least two ring body radial holes penetrating from the outer peripheral surface to the inner peripheral surface of the ring body. A cathode holder having an inner end projecting from the inner peripheral surface, wherein one connecting end is fitted into a hole formed in the inner end of the holder and opening at the end, and the other connecting end The part is composed of a supporting arm fitted in a hole formed in the peripheral surface of the block cathode.

[Action]

According to the present invention, the cathode holder is composed of one ring body and a plurality of holders attached to the ring body so as to be movable in the radial direction. You can adjust the position of
Further, the engagement between the support arm and the cathode holder can be released only by moving the holder element in the radial direction.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In FIGS. 1 (a) and 1 (b), 20 is molybdenum.
A ring body made of Mo, having an inner diameter larger than the outer diameter of the cathode 4, and having radial holes (screw holes) 20a penetrating from the outer peripheral surface to the inner peripheral surface at regular intervals in the circumferential direction. Have been. The ring body 20 further includes
A hole 20b for screwing 10 is formed. Reference numeral 21 denotes a holder made of tantalum Ta or molybdenum Mo, which constitutes the cathode holder 11 together with the ring body 20, and a screw screwed into the hole 20a is engraved on the outer peripheral surface thereof. The inner end 21A is screwed so as to project.
Inner end portion protruding from the inner peripheral surface of the herring body 20 of the holder 21
A hole 21a is formed in 21A, which is open at the end face of the inner end 21A. This hole 21a has a depth not greater than the length of the inner end 21A. Reference numeral 22 denotes a support arm made of tungsten W, one connecting end of which is fitted into the hole 21a of the holder 21 to the bottom thereof, and the other connecting end of which is fitted into the radial hole 4b which is open to the outer peripheral surface of the cathode 4. Has been done.

This cathode holding mechanism has a structure in which a plurality of holders 21 each supporting a supporting arm 22 in a cantilever manner are connected by one ring body 20, and this one ring body 20 is supported by a plurality of columns 10. Since it is supported, the holder element 21 can be directed to the operation center O without adjusting the orientation of the holder element 21, and the position of the cathode 4 can be adjusted only by rotating the holder element 21. be able to.

Further, in the above embodiment, since the one connecting end portion of the support arm 22 does not extend to the inner peripheral surface of the ring body 20, the holder 21 is rotated so that the inner end portion thereof is in the radial direction of the ring body 20. When the one end of the support arm 22 is disengaged from both the holder 21 and the ring body 20 when the support arm 22 is almost pulled into the hole 20a, the other end of the support arm 22 is seized on the cathode 4. The cathode 4 can be replaced without removing the ring body 20 from the column 10.

The holder 21 in the above embodiment is a screw, but it may be any one that can be mounted on the ring body 20 so as to be movable in the radial direction.

〔The invention's effect〕

As described above, according to the present invention, since the cathode holder is composed of one ring body and a plurality of holder elements attached to the ring body so as to be movable in the radial direction thereof, it is possible to provide The number of members that need to be adjusted is reduced, and the cathode position can be adjusted only by the radial movement of the holder element, and the support arm and the cathode holder can be engaged only by the radial movement of the holder element. Since it is possible to solve the above problem, it is possible to reduce the time and labor required for positioning and replacing the cathode, as compared with the related art.

[Brief description of the drawings]

1 (a) and 1 (b) are a plan view and a side view, respectively, of an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a conventional electron beam generator, and FIGS. 3 (a) and 3 (b) are It is the top view and side view which respectively show the conventional cathode support mechanism. 20 …… Ring body, 21 …… Holder element, 22 …… Support arm.

Claims (2)

(57) [Claims] 1. Electrons for irradiating an electron emitted from a hot cathode unit with an accelerating anode to which an accelerating voltage is applied between the hot cathode unit and the electric field to irradiate a workpiece with a generated electron beam. In the beam generator, the hot cathode unit has a block cathode, and the holding mechanism for the block cathode has a ring body and at least two radial holes in the ring body penetrating from the outer peripheral surface to the inner peripheral surface of the ring body. Cathode holders each of which is fitted and fixed to the inner peripheral surface of the holder, the inner peripheral portion of which is projected from the inner peripheral surface, and the one connecting end is formed in a hole formed in the inner peripheral surface of the holder. And a supporting arm that is inserted into a hole formed in the peripheral surface of the block cathode and has the other connecting end portion. 2. The electron beam according to claim 1, wherein the ring body radial hole is a screw hole, and the holder is a screw screwed into the screw hole. Generator.