JPS6137386A - Electron-beam drilling method and device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a method and apparatus for drilling holes using electron beam energy.

BACKGROUND OF THE INVENTION Over the past twenty years, the commercial use of machines that utilize electron beam energy in metal processing has become widespread. The high voltage causes high-energy electrons to be directed toward the workpiece placed within the vacuum chamber, thereby melting the workpiece. One of the most useful uses of electron beam energy is to form holes in a workpiece. A stream of electrons that is precisely focused by a magnetic field can rapidly form relatively small holes by melting and evaporation.

72 x 106 watt/a? Since the energy density is high, as long as a hole is formed in the work piece within a few seconds,
The work piece is hardly heated.

To meet industrial applications, manufacturers of electron beam devices have had to improve the durability of their electron beam devices. To improve durability, the electron generating filament of the electron beam device must have a long life, and the energy content and density of the electron beam must be constant. Achieving such a goal is not easy.

The indoor environment where drilling takes place is filled with molten metal droplets flying around.
The metal vapor is in a state of condensation. The metal blown off the workpiece flies toward the m1jc element of the electron gun, which forms a stream of electrons and guides them toward the workpiece. Accordingly, various protection devices have been developed to protect the components of electron guns.

Generally, these preservation devices include a plurality of metal shields, typically in the form of rotating disks, that have scrapers to remove metal debris adhering to the shields. ing. The shields are spaced apart to provide space for the electromagnetic beam emitted by the electron gun to impinge on the workpiece. This space is kept small, but must be larger than the diameter of the electron beam for simple mechanical reasons and to allow for deliberate deflection of the electron beam. Therefore, a limited amount of debris tends to travel into the electron gun substantially along the path of travel of the electron beam.

Therefore, another shield is installed inside the electron gun to trap this small amount of debris.

These shields function similarly to primary shields.

Systems such as those described above work well in general applications. In most drilling operations, the conical shape of the metal expulsion (a large number of tiny pieces of metal that are blown away from the metal workpiece by the electron beam impacting the workpiece) is The shape is such that it collides with the main shield.

However, if a hole with a very small diameter and a relatively large depth is formed, a very large amount of workpiece metal expulsion will enter the electron gun through the hole defined by the main shield. . The large amount of gold 8 deposited on the interior of the electron gun was eliminated by the inner shielding previously known in the art, creating a need for improved electron beam drilling device designs.

DISCLOSURE OF THE INVENTION It is an object of the present invention to continuously form a large number of holes even when a relatively large amount of blown workpiece material attempts to move in the opposite direction along the electron beam path. The purpose of the present invention is to provide a shield for an electron beam drilling device.

According to the invention, the rotating disk-shaped shield has a peripheral edge with a step to define a recess at its edge. The shield is placed close to the electron beam path and just above the electromagnetic deflection coil.

The trajectory of the blown metal is carefully controlled by precisely adjusting the electron beam deflection angle so that the blown metal workpiece deposits in stepped recesses in the peripheral edge of the shield. In a preferred embodiment of the invention, the shield has a tab secured within the recess that removes a small amount of workpiece material that is not deposited within the recess but is deposited onto the adjacent electromagnetic deflection coil. Assists in continuous removal. In such embodiments, it is impractical to use the conventional method of using a rigid scraper in continuous contact with the rotating disk-shaped shield to remove debris deposited on the shield.

Thus, a means, such as a wire brush, which deforms elastically upon contact with the tab, is placed in contact with a recess in the shield at a distance from the electron beam. The wire brush is in continuous contact with the shield and thus continuously removes machining material deposited on the shield.

Metal deposits inside the electron gun reduce the intensity of the electron beam, resulting in poor drilling. Failure to drill properly is not detected until the workpiece is removed from the electron beam drilling device, thus failing to produce a workpiece with a perfect and uniform hole. The invention thus facilitates the manufacture of panels having a large number of holes of very small diameter closely spaced from each other.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be explained in detail below by way of example embodiments with reference to the accompanying figures.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG.
gerwald 3trahltechnik, M
esser Qriescheill Q mbl-
3 teigerwaldStr sold from 1
ahltechnik Model K6-G10
1 is a side view showing some of the essential components of an electron beam drilling device, such as a P-CNC electron beam drilling device, in which the present invention is employed; FIG. An electron beam 20 is generated in an electron gun 22 and directed toward a sheet-shaped workpiece 24 mounted on a drum-shaped rotatable workpiece holder 26 . The workpiece holder 26 is housed in a vacuum chamber 23, and an electron gun 22 is attached to the vacuum chamber 23. Many of the essential components of the electron gun 22, which generates the electron beam, have been omitted from the drawings because they are not necessary for an understanding of the invention (for the purposes of this application, the electron gun 22 is shown in the plane of the shield 38). (considered to include all equipment located above)
.

The electron beam 20 is a flow of electrons emitted from the filament 30 and accelerated toward the workpiece by an applied voltage. The electron beam is shaped and guided by a system of electromagnetic devices. Near the end of the main path in the electron gun, the electron stream passes through an electromagnetic lens 32 to ensure good density and uniform dispersion when the electron stream impinges on the workpiece. , the electron flow is focused by the electromagnetic lens 32. The electron beam then passes through a deflection coil 34. The function of the deflection coil is to move the electron beam along a second path B inclined at an angle α with respect to the Z-2 axis (along which the electron beam generated in the electron gun first moves). It is to change the axis direction of the electronic beam so that it moves. The electron beam passes from the deflection coil through small holes 36 between the plurality of protective primary shields 38 and then impinges on the workpiece 24. The energy of the electron beam is converted into heat when it impinges on the workpiece, which melts and vaporizes the workpiece, forming a hole. In the figure, workpiece holder 26 is a cylindrical body configured to rotate about axis 27 and move along the axis (perpendicular to the plane of the drawing). Generally, the workpiece holder continues to move continuously during drilling. The electron beam is pulsed in synchronization with the movement of the workpiece, thereby forming a number of holes in a predetermined pattern.

Each of the components described above are conventionally known in the art. FIG. 1 also shows components of the invention which will be described later in cooperation with various components already known.

In order to better understand the present invention, the conventional apparatus shown in FIGS. 2 and 3 will be further described. Although only three are shown in FIGS. 2 and 3, there are four discs 38 located closest to the workpiece.

These disks overlap each other as shown in FIG. 3 so as to provide a small hole 36 through which the electron beam passes when viewed along the path of the electron beam and opposite its direction of travel. It is located. When a typical workpiece hole is drilled with an aspect ratio (length to diameter ratio) greater than or less than those described herein, the expulsion may be
be thrown out as.

This spray impinges on the underside of the disk 38 and often lands on the disk as debris. The disk is continuously rotated on a shaft 39 driven by a motor during operation of the electron beam drilling device. Each disk has a scraper 42 that contacts the lower surface at a position remote from the hole 36.
The scraper continuously wipes away debris attached to the disk. - The electron beam is intentionally deflected to reduce the amount of workpiece material that moves in the opposite direction along the path of the electron beam and blocks the electron beam from the filament. However, some of the debris nevertheless moves upwardly into the electron gun 22 along the electron beam path through the hole 36. Therefore, as shown in FIGS. 1 and 2, additional disks are placed along the electron beam path in the vicinity of the filament to intercept debris. These disks also rotate, one of which is equipped with a scraper. From FIG. 2, a disk 45 is provided just above the deflection coil 34, and the electromagnetic lens 32
It can be seen that another disk 46 is provided just above the disk. These disks are located on the opposite side of the electron beam from the workpiece and have flat sides with sloped peripheries. Debris moving in the opposite direction along the electron beam path will strike the side of the electron beam drilling device where the disks 45 and 46 are located.

The above arrangement works well for forming holes that are conventionally considered to be within the scope of electron beam drilling equipment. However, the diameter is Q, about 1 mm, and the aspect ratio (
It has been found that if a hole is formed with a large length to diameter ratio, the apex angle of the expulsion cone will be much smaller, as shown in FIG. In such situations, the lower shield 38 has less effectiveness in blocking expulsion. Since the aperture 36 through which the electron beam passes during its travel to the workpiece cannot be made sufficiently small, a substantial amount of workpiece material is driven back into the electron gun. Some of such workpiece material adheres to the inner shield 4542, after which they are removed and removed by the scraper. However, other portions of the above-mentioned patch material may cause deposits 50 on the deflection coil 34.
Cover up in season.

Thus, in some cases, such as after 105 holes have been formed, debris accumulates radially inward to the extent that it begins to interfere with the electron beam 20 and prevents uniform drilling of the holes. Further, if the debris becomes loosely attached to the deflection coil 34, the debris may fall into the hole 36. If the debris does not pass through the holes 36, this creates a problem. Furthermore, even if debris passes through the hole 36, the path of the electron beam is temporarily blocked.

Typically holes are drilled at a rate of many holes per second, so even if a temporary object passes through the electron beam path, the electron beam drilling machine is programmed to drill many holes per second. It becomes impossible to drill holes.

From FIG. 4, it can be seen that even if the deflection angle is increased, the above-mentioned effect is obtained.

Similarly, a small deflection angle is also not effective. This is because when the deflection angle is small, the expulsion more easily enters the inside of the electron gun, causing the same problem.

The present invention is required to form workpieces having a large number of micropores (106 or more) that must all be of substantially uniform size and spacing. To achieve this economically, the holes need to be formed continuously and at high speed. Although forming a matching hole involves removing a relatively small amount of workpiece material, the collective effect of the large number of holes displaces a substantial amount of workpiece material back into the electron gun. be moved to

1, 5 and 6 show how a shield placed above the deflection coil is modified according to the invention. The inner shield 44 is a disk having a stepped edge thereby defining a recess 54 around its edge. A portion of the outer circumferential surface 56 of the recess 54 substantially aligns with a portion of the inner circumferential surface 58 of the deflection coil 34 . The outer periphery 60 of the shield 44 is formed and positioned in close proximity to the beam. The outer periphery 60 is located at substantially the same location as the outer periphery of a conventional shield. The inventors of the present application have an outer diameter of 27.60IIl,
It has been found that a brass disc 7°6l1m thick with a step diameter of 25.8mm is effective. The radial width of the recess is approximately 9 mm, and the axial width is approximately 3.8 n+m. In use, the deflection angle is carefully varied so that the expulsion impinges within the recess 54. The standard deflection angle α in the illustrated electron beam drilling apparatus is 10°±30'. But only if the deflection angle is set critically, e.g.
In the case of the del K6-G10P-CNC electron beam drilling device, the reference distance D of the drilling device (see Figure 4) is 2.
0IIlm, good results are obtained only when set to 9.75°. Of course, there is a certain tolerance range for the deflection angle, but the deflection angle must be maintained within a range of ±o, 25° or less in order to concentrate deposits within the recess. Deflection angles somewhat different from the above values may be used with other parameters or when drilling other materials with other electron beam drilling equipment, but in order to practice the present invention, debris The deflection angle required to concentrate within the recess of the inner shield 44 is determined experimentally. Once the deflection angle is set, it is important that the reference distance of the workpiece is maintained accurately relative to the reference plane of the electron gun. In practicing the present invention, the inventors maintained the aforementioned reference distance within a range of ±0.2n+m, or about 0.5%.

The inner shield 45 is appropriately placed on the same shaft 39 as the main shield 38 at the left end in the figure, and has a diameter of about 4 r.
It is rotated continuously at a speed of pm.

A scraper 66 for removing debris engages the recess 54 on the side of the disk remote from the electron beam. Despite the improvements described above, a small amount of workpiece material is deposited on the deflection coil 34 at a point 62 proximate to the shield and opposite the direction of electron beam deflection. Although such debris takes longer to deposit and poses fewer problems to the electron beam than if a recessed shield were not provided, such debris still must be removed to maintain the drilling process. Must be. Thus, in the present invention, at least one tab 64 is provided within the recess at one point on the outer periphery. Tab 64 is shown in more detail in FIG. Tab 64 continuously removes small build-up of debris on the deflection coil. Other protrusions similar to tabs may be used as long as they can periodically contact debris deposited on the deflection coil at point 62. Of course more than one tab may be used, but this is not necessary.

Providing tabs on the shield is the simplest way to continuously remove 1' flash, but other methods can be used to scrape workpiece material from the inner circumferential surface of the deflection coil near the shield and prevent it from accumulating. It is useful that effective mechanical means also be arranged to cooperate with the shield.

Debris scraped from the inner circumferential surface of the deflection cocoil will fall down along the electron beam path onto the lower shield, possibly through the hole 36, but this does not actually cause any problems. .

If tabs are provided, discs 38.45.46
Conventional scrapers 42, such as the rigid knife-shaped plates used in conventional scrapers, cannot be used. Thus the first
As shown in the drawings and FIG. 6, a wire brush 66 supported by a support 68 is used in the present invention. The wire brush bristles are sufficiently flexible so that they bend aside when the tabs engage them and spring back to their original position after the tabs have passed. Other means than a wire brush may be employed to remove deposits from the recess provided at the periphery of the disk. Such other means include any member configured to flex under the action of the tab but having sufficient strength and force to contact the disk and remove metal deposits.

Other embodiments of the invention may also be implemented. The general method and principle to which the invention is based is to allow the expulsion to impinge within the recess of the movable inner shield. To accomplish this, a shield with a recess must be placed above the deflection coil, and the deflection angle must be adjusted to direct the blown workpiece material in a predetermined direction. Other configurations may be employed to achieve objective 1 of the present invention. For example, FIG. 7 shows a belt member 70 having a cross-section shaped like a cross-section and wrapped between two pulleys 72 and 74. The pulley 74 is located within the electron gun at the same location as the disk 44 in Figures m1 and 5.

The importance of adjusting the deflection angle so that the blown workpiece material impinges into the recess provided in the edge of the shield is explained. This is very important. This is because if a large amount of workpiece material is blown back into the electron gun, even a small amount of workpiece material that is not captured at the edge of the inner shield may cause various This is because it causes problems. The inventor of this application is at fault, Danbe.
That is, we have discovered the utility of a movable shield having an edge with a recess. The present invention is also useful when more vertical holes are drilled, in which case control of the deflection angle is less important.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited to such embodiments, and it is understood that various embodiments are possible within the scope of the present invention. It will be clear to those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view, partially cut away, of essential parts of an electron beam drilling apparatus incorporating the present invention, in a state in which a workpiece is being drilled. FIG. 2 is a partial view showing the main parts of a conventional electron beam drilling device. FIG. 3 is a plan view showing the main parts of a conventional electron beam drilling device. FIG. 4 is a diagram illustrating the problems that arise when holes of very small diameter are formed in conventional electron beam drilling equipment. FIG. 5 is a partial elevational view showing a main part of the electron beam drilling apparatus of the present invention incorporating a shield having a recess at the edge. FIG. 6 is a perspective view of the shield shown in FIG. 5. FIG. 7 is a perspective view showing a part of another embodiment of the present invention in which a belt having an angular cross section is wound between two pulleys. 20...electron beam, 22...electron gun, 23...
Vacuum chamber, 24... Work piece, 26... Work piece small-ruder, 30... Filament, 32... Electromagnetic lens, 3
4... Deflection coil, 36... Hole, 38... Shield (disk). 39...shaft, 40...spray, 42...
Scraper, 44.45.46... Disc (shield). 50... Deposition, 54... Recess, 56... Outer peripheral surface, 58... Inner peripheral surface, 60... Outer peripheral edge, 64...
Tab, 66... Wire brush, 68... Support, 7
0...Belt member. 72.74...Pulley Patent Applicant United Chiknorrhea Corporation

Claims (2)

[Claims] (1) A method for forming a large number of holes with minute diameters in a workpiece, the method comprising: generating a flow of electrons flowing along a first axis of an electron gun; deflecting the electrons as they are emitted from the electron gun as an electron beam so as to move along a second axis forming an angle at which the electron beam forms a large number of microdiameter holes in the workpiece; , arranging the workpiece along the second axis so that the blown-off molten workpiece material moves into the electron gun along the second axis. adjusting the angle of deflection so that the blown workpiece material adheres to a recess in the edge of a movable inner shield disposed within the electron gun; and moving the shield. 3. A method comprising: moving material deposited on said edge to a location away from where it was deposited; and successively removing said material from said edge. (2) A device for forming holes in a work piece using an electron beam, which has a chamber for receiving and holding the work piece, and an electron gun attached to the chamber, which has a filament inside that generates electrons. an electron gun and a system of electromagnets for shaping and guiding the electrons into an electron beam that travels along a main path within the electron gun and proximate a workpiece holder retention zone within the chamber; a main shield disposed at an end of the electron gun; a movable inner shield mounted along the main path within the electron gun within the system of electromagnets; The shield has a recess at its periphery for receiving debris in the form of workpiece material blown away from the workpiece and traveling substantially along said main path, the shield being received into said recess by movement of said shield. The apparatus is configured to transport the debris to a position away from the main path, and further includes means disposed at the position away from the main path to remove the debris from the recess.