U.S. patent number 3,632,398 [Application Number 04/735,299] was granted by the patent office on 1972-01-04 for process for the treatment of internal surfaces of recesses.
Invention is credited to Dieter Konig.
United States Patent |
3,632,398 |
Konig |
January 4, 1972 |
PROCESS FOR THE TREATMENT OF INTERNAL SURFACES OF RECESSES
Abstract
Process for the treatment of the internal surfaces of recesses
including slots, depressions, bores and the like of any required
cross-sectional configuration in which the treatment is carried out
by means of beam energy which is introduced into the recess.
Inventors: |
Konig; Dieter (8 Muenchen 55,
DT) |
Family
ID: |
7461222 |
Appl.
No.: |
04/735,299 |
Filed: |
June 7, 1968 |
Foreign Application Priority Data
|
|
|
|
|
Jun 9, 1967 [DT] |
|
|
ST 26993 |
|
Current U.S.
Class: |
427/582; 65/121;
427/585; 427/586; 65/DIG.4; 204/157.44; 427/596 |
Current CPC
Class: |
B23K
15/085 (20130101); B01J 19/081 (20130101); H01J
37/16 (20130101); B23K 26/16 (20130101); C23C
14/048 (20130101); B23K 26/127 (20130101); B29C
59/165 (20130101); B23K 26/389 (20151001); B26F
1/31 (20130101); C21D 1/09 (20130101); B23K
26/123 (20130101); B23K 26/12 (20130101); B29C
59/16 (20130101); C23C 14/046 (20130101); B29L
2023/00 (20130101); B29C 2035/0838 (20130101); B29C
2035/0877 (20130101); B29L 2007/008 (20130101); Y10S
65/04 (20130101); B29L 2031/737 (20130101) |
Current International
Class: |
B29C
59/16 (20060101); B29C 59/00 (20060101); B26F
1/31 (20060101); B26F 1/00 (20060101); C23C
14/04 (20060101); C21D 1/09 (20060101); B01J
19/08 (20060101); H01J 37/02 (20060101); H01J
37/16 (20060101); B23K 15/08 (20060101); B23K
26/16 (20060101); B23K 26/38 (20060101); B23K
26/12 (20060101); B23K 26/00 (20060101); B29C
35/08 (20060101); C23c 013/00 () |
Field of
Search: |
;117/93.3,212,93,93.31,16R ;204/DIG.11,157.1,156,156HE |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Leavitt; Alfred L.
Assistant Examiner: Newsome; J. H.
Claims
1. A process for treating internal surfaces of recesses in
workpieces, including slots, depressions, bores, and the like by
means of beamed radiant energy in order to effect a permanent
change in the condition of said internal surfaces, comprising
placing the workpiece which contains the recess to be treated
adjacent to a material which has an auxiliary substance which is in
an inactive state incorporated therein in finely divided form, and
applying beamed radiant energy to the said auxiliary substance of
an intensity sufficient to locally activate and release the said
auxiliary substance to enable it to enter the said recesses and
to
2. A process for treating internal surfaces of recesses in
workpieces, including slots, depressions, bores, and the like by
means of beamed radiant energy in order to effect a permanent
change in the condition of said internal surfaces, comprising
placing a carrier member consisting of a permeable mass containing
an auxiliary substance which is in an inactive liquid or gaseous
state dispersed throughout the carrier member adjacent to one side
of the workpiece which contains the recess to be treated, and
applying beamed radiant energy of an intensity sufficient to
activate and release the said auxiliary substance at the opposite
side of said workpiece to extend through said recess and to act on
the auxiliary substance contained in the carrier member located on
the opposite side of the workpiece, the auxiliary substance which
is locally released and activated by the beamed radiant energy
being caused thereby to enter said recesses to act on the internal
surfaces thereof and to alter the
3. A process for treating internal surfaces of recesses in
workpieces, including slots, depressions, bores, and the like by
means of beamed radiant energy in order to effect a permanent
change in the condition of said internal surfaces, comprising
placing a carrier member consisting of a porous mass containing
within its pores an auxiliary substance which is in an inactive
state adjacent to one side of the workpiece which contains the
recess to be treated, and applying beamed radiant energy at the
opposite side of said workpiece to extend through said recess and
to act on the auxiliary substance located on the opposite side of
the workpiece, the beamed radiant energy being applied at an
intensity sufficient to activate and release the said auxiliary
substance from said pores and to cause it to enter the said
recesses and to act on and alter the condition
4. A process in accordance with claim 3 in which the said pores are
closed pores, and in which said carrier member consists of a
material which is
5. A process in accordance with claim 3 in which the substance
contained in said pores is oxygen and in which the beamed radiant
energy applied thereto keeps the temperature of the internal
surfaces of the recess sufficiently high to permit reaction of the
workpiece material with the oxygen released from the pores to
produce an oxide coating on the internal
6. A process for treating internal surfaces of recesses in
workpieces, including slots, depressions, bores, and the like by
means of beamed radiant energy in order to effect a permanent
change in the condition of the internal surfaces, comprising
placing an auxiliary substance which is in an inactive state
adjacent to the recess to be treated and applying beamed radiant
energy to the said auxiliary substance of an intensity sufficient
to activate and release the said auxiliary substance to enable it
to enter the said recesses and to alter the condition of the
internal surfaces thereof, the auxiliary substance comprising at
least two components which react with one another under the action
of the beamed radiant energy to form at least one reaction product
which alters the
7. A process for successively treating internal surfaces of a
plurality of spaced recesses in workpieces, including slots,
depressions, bores, and the like by means of beamed radiant energy
in order to effect a permanent change in the condition of said
internal surfaces, comprising placing an auxiliary substance which
is in an inactive state adjacent to the recesses to be treated and
applying beamed radiant energy to the said auxiliary substance of
an intensity sufficient to activate and release the said auxiliary
substance to enable it to enter the said recesses and to alter the
condition of the internal surfaces thereof, the beamed radiant
energy being applied successively at recesses the distance between
which is greater than the distance between adjacent recesses.
Description
The present invention concerns a process for the treatment of
internal surfaces of recesses of any cross-sectional shape such as,
for example, depressions, slots, blind holes or continuous
bores.
When the internal surfaces of a recess in a workpiece are to be
treated in a special manner without simultaneously treating the
whole workpiece, a multitude of difficulties are encountered since
the internal surfaces have difficult access. This is particularly
the case when relatively small recesses are concerned, such as
small diameter bores or perforations. Treatments which may be
required for the internal surfaces of recesses are, for example,
hardening, smoothing, coating with a layer of a different material
etc. It may, for example, be necessary to treat the surface of a
member sliding in a guide groove so as to make the surface less
subject to wear. Additionally, it may, for example, be necessary
with finely perforated flexible plastics material foils or plastics
material panels, to consolidate the surface of the perforation
holes or to harden them to such an extent so as to eliminate a
gradual closing of the perforation holes by cold flux of the
plastics material. A further example of possible use for the
process of the invention is in the reduction of the weight of a
panel of material by forming perforations and simultaneously
surface hardening the internal surfaces of the perforation holes to
compensate the loss of strength caused by the perforations. It is
clear that in this and numerous similar cases in which treatment of
the internal surfaces of recesses is required, considerable
difficulties can occur, especially when it concerns recesses of
relatively large depth and small cross section.
It is an object of the invention to provide a process enabling the
internal surfaces of recesses to be treated rapidly and reliably in
a multitude of ways.
The object is attained in accordance with the invention by a
process of the kind referred to above, which is characterized by
the feature that the treatment is effected by beam energy which is
introduced in the recess.
Beam energy, for example, in the form of light, laser or electron
beams, has the advantage that it can be proportioned and directed
with considerable accuracy and is controllable substantially
without inertia. Moreover, very high performance densities may be
obtained with beam energy, so that, with extremely short period
actions, the required treatment effects are thus obtainable only if
required over closely defined surface regions and penetration
depths.
In the art, numerous processes and apparatus are known with which
beam energy can be produced, directed, focused, proportioned and
controlled; therefore it is unnecessary to describe processes and
apparatus herein in detail.
The term "treatment" is to apply in this case to any required
operation with which a permanent or temporary change of the
properties required of the surface regions concerned can be
obtained.
Often it may be advantageous for the treatment to take place during
and/or directly after producing the recesses; the workpiece may
thus be left in one and the same processing or treatment
device.
The process in accordance with the invention may be carried out
without difficulties and also in such a manner that the internal
surface of the recess may be treated differently in regions. For
example, in a blind hole serving as axial bearing it may be
required to harden the end face to a high degree, or it may be
required to provide a region of particular wear resistance in a
slot or a groove. By accordingly controlling the direction of the
beam energy used for the treatment it is readily possible, in
accordance with the process of the invention, for only
predetermined regions of the internal surface of a recess to be
treated.
A particularly simple embodiment of the process in accordance with
the invention consists in that for the internal surfaces to be
treated an energy beam at least is used which also serves to
produce the recess. It is known by using energy beams such as
electron beams, to carry out cutting operations and to produce
recesses of optional shape; in accordance with the invention it is
possible by way of one and the same energy beam, to produce the
recess and also to treat its surface in a manner required. The
transition from production to treatment may, for example, be
effected after the recess has been produced by varying the
intensity and/or the distribution of power density of the energy
beam. The diameter of the energy beam may also be changed after the
recess has been produced. Such measures, given by way of example,
enable the recess to be first produced without difficulty with a
high power density and then with reduced power density in which no
longer any material reduction occurs; the surface is treated in the
required manner, for example, surface hardened, smoothed or
annealed.
In many cases an alternative embodiment of the process in
accordance with the invention may be expedient and it is
characterized by the feature that for producing the recess and for
the treatment a beam energy of varying quality is used. For
example, a recess may be produced with one kind of beam and
subsequently the surface of the recess produced treated with an
alternative kind of beam which is absorbed with diminished quality
so that a uniform transition is obtained of the material properties
changed by the treatment from the surface of the recess inwardly
into the depth of the material.
A further particularly advantageous embodiment of the process in
accordance with the invention is characterized by the feature that
during the treatment an auxiliary material is supplied to the
recess. The use of an auxiliary material allows numerous further
methods of treatment to be realized such as the formation of a
surface layer, a cooling effect, a smoothing, roughening and so
forth.
Also in accordance with the invention it may be particularly
favorable for an auxiliary material to be used which, with the
internal surface of the recess, causes a reaction thus changing the
internal surface. If, for example, an auxiliary substance is used
which chemically attacks the workpiece of the material concerned,
the internal surface of the recess can be roughened in this manner.
An alternative possibility consists in that by suitably selecting
auxiliary materials, oxide, carbide or other surface coatings may
be produced on the internal surface of the recess; such embodiments
are characterized by the feature that the internal surface of the
recess is partially or wholly coated with the auxiliary material or
a reaction product of the auxiliary material.
In many cases favorable effects may also be obtained by using an
auxiliary material which enters an energy exchange with the
internal surface of the recess. Such an energy exchange for
example, is then obtained when an auxiliary material is used which
acts as a coolant, thus especially a solid or liquid auxiliary
material which has a considerable evaporation heat. With such
processes a relatively rapid cooling-off or thermal quenching of
the internal surface of the recess is obtainable and thereby often
favorable changes of the workpiece material, such as a hardening,
are brought about.
Localized use of an auxiliary material is provided in a further
embodiment of the invention in a simple manner in that the
auxiliary material is arranged in the action region of the beam
energy and caused to enter the recess by the beam energy introduced
in the recess. A particularly simple possibility of this kind is
provided in accordance with the invention, in that the workpiece
containing the recess to be treated has the auxiliary material
inserted therein in a finely distributed form or as a coating. In
this way, without any special measures, the auxiliary material
comes into action only at the position where the energy beam
impacts the material and releases and activates the auxiliary
material.
An auxiliary material arranged in the action region of the beam
energy can also be brought into action according to a further
embodiment of the process in accordance with the invention in which
the energy beam after producing in known manner the recess by means
of an alternative and if required, different energy beam, is
introduced in the recess; the timed interval from the end of the
production operation being so selected that the temperature of the
internal surface of the recess drops below a predetermined value.
This method of operation is particularly expedient when the
auxiliary material is to be vapor deposited on the internal wall
surface of the recess and therefore a certain cooling-off of the
internal wall is required. The process in accordance with the
invention may, as evident, also be carried out in connection with
processed and perforated workpieces. An expedient further
embodiment of the process in accordance with the invention may
consist in that the energy beam triggering the treatment of the
internal surfaces may have a different and especially a smaller
diameter than the energy beam used to produce the recess. By this
means, for example, undesired overheating of the internal surfaces
of the recess during the treatment operation can be avoided or at
least diminished.
The supply of auxiliary material in accordance with the process of
the invention may further be so effected that the auxiliary
material is provided on the side of the workpiece remote from the
beam in a solid or liquid state adapted to evaporate under the
action of the energy beam. For example, simply a foil sheet or
panel may be fed comprised partially or wholly of the auxiliary
material or containing the auxiliary material. This process may be
used both in completed continuous recesses, passages, ducts or
perforation holes, as also in the case in which the continuous
recess has first to be formed in the workpiece by action of the
beam energy.
A further alternative embodiment of the process in accordance with
the invention is characterized by the feature that the auxiliary
material is provided on the side of the workpiece facing the beam
in a solid or liquid state adapted to evaporate with the action of
the energy beam. With this method of operation, favorable effects
may be obtained in many cases; for example it has been found that
with sufficient rapid penetration of a treating energy beam into a
workpiece the gases released from the auxiliary material layer
placed thereon spread explosionlike into the recess produced and
forcibly eject the molten material in the direction of the beam
through the continuous recess produced.
According to a still yet further embodiment of the process in
accordance with the invention the auxiliary material is fed in
liquid or gaseous form through a porous gas-permeable mass arranged
on the workpiece. In further embodiment however of the process in
accordance with the invention, the auxiliary material may be
released from a porous mass which is placed in position on the side
of the workpiece remote from the beam; to enable the available
quantity of auxiliary material to be increased it is possible in
accordance with the invention for the pores to be closed and have
an elongated shape in the direction of the beam. In any case the
action of the energy beam and/or the temperature increase occurring
during the action of the energy beam causes the auxiliary material
to be released from the porous mass, possibly by the destruction of
pores. Generally it will be simply sufficient to use a mass
saturated with the solid or liquid auxiliary material.
In many cases, especially when using energy in a vacuum, it is
advantageous to use an auxiliary material which evaporates without
trace. In such a case it may also be advantageous to use an
auxiliary material which when subjected to the action of the beam
energy generates a large quantity of vapor; this is particularly
expedient if it is desired to ensure substantial removal of waste
material during processing or treatment.
In accordance with the invention an auxiliary material may be
formed of a plurality of components, especially such in which at
least two components are selected so that, subject to the action of
the beam energy or conditions prevailing at the treatment point,
they react with one another or at least to one reaction product and
assists the required treatment.
The application of the process in accordance with the invention is
particularly advantageous when perforating panel or sheetlike
workpieces. Since the beam energy supplies extremely high power
densities and can be closely localized and controlled substantially
without inertia, a large number of closely adjacent bores may be
produced within a short period of time and their internal surfaces
treated.
When the beam energy has been caused to act successively at several
points of treatment, as is the case for example when perforating,
it is possible for the process to be so conducted that the beam
energy is caused to act successively at treatment points the
spacing of which is greater than the spacing between two adjacent
treatment points. This sudden control of the beam energy allows a
more considerable cooling of the individual treatment points and
hence the use of a higher overall output per surface unit of the
material to be processed treated.
A load carrier beam is preferably used as beam energy and more
particularly an electron beam or a considerably focused
electromagnetic energy beam, especially a light or laser beam.
The invention will be described further, by way of example, with
reference to the accompanying drawings, in which:
FIG. 1 shows by way of a schematic perspective view, one embodiment
of the process;
FIG. 2 shows by way of a similar embodiment as FIG. 1, the
workpiece in section;
FIG. 3 shows schematically the treatment of a cylindrical blind
hole;
FIG. 4 shows schematically the regional treatment of a cylindrical
hole;
FIG. 5 shows by way of a schematic sectional view, a further
embodiment;
FIGS. 6 and 7 are schematic views of possible intensity courses of
an energy beam during treatment;
FIGS. 8 to 12 show by way of schematic sectional views, possible
methods of keeping the auxiliary material in readiness;
FIG. 13 shows in section an apparatus for carrying out the process
of the invention;
FIG. 14 shows schematically the method of operation of an
alternative embodiment of the process of the invention; and
FIG. 15 shows schematically the working sequence of a perforating
operation in accordance with the invention.
FIG. 1 shows a workpiece 1 with a recess 2 to be treated and in the
form of a continuous groove of rectangular cross section. At 4a, 4b
and 4c energy beams, for example electron beams, are shown
schematically and by means of which beams the internal surfaces of
the recess 2 may be treated. An energy beam 4a is shown which
extends substantially in the longitudinal direction of the recess 2
and which, when suitably focused, generates its energy along a path
extending in the workpiece 1 against the sidewalls of the grooves
2.
FIG. 2 shows, by way of a sectional view the workpiece of FIG. 1,
that with an inclined beaming of a suitably wide energy beam 4 it
is possible to treat the whole depth of one sidewall of the recess
2.
In FIG. 3 the base of a cylindrical recess 2 is treated by means of
a bundle 4 of energy beams of suitably large cross section. Of
course, a beam having a smaller cross section could also be used
and moved over the surface of the base.
FIG. 4 shows a workpiece 1 in which a recess 2 is provided in the
form of a continuous bore. A slender energy beam 4 is so beamed
into the bore that only a region of the cylindrical internal
surface of the recess 2 is impacted and treated by the beam; it is
readily seen that by suitable relative movements between workpiece
1 and beam 4 any regions of the internal surface can be
treated.
FIG. 5 shows schematically a section through a workpiece 1, in
which recesses in the form of bores are to be produced and the
internal surfaces of the bores are to be treated with an auxiliary
material. At the left of FIG. 5 a completed bore 2 is shown, the
internal surface 3 of which has a coating 6 which has been produced
by the action of an auxiliary material on the heated material of
the workpiece 1. In this embodiment, the auxiliary material is
placed in position in the form of a layer or panel 5 on the side of
the workpiece 1 remote from the beam 4. At the right-hand side of
FIG. 5 there is shown schematically, the production of a bore with
the aid of the energy beam 4. The beam 4 at the stage shown has not
yet penetrated the full thickness of the workpiece 1 so that the
internal surface of the bore produced has as yet not been treated.
As soon as the beam penetrates the full thickness of the workpiece,
it acts on the auxiliary material so as to cause it to evaporate
and to flow through the bore 2 just produced. Thus, the desired
action of the auxiliary material 5 against the internal wall
surface of the bore 2 occurs. When, for example, the internal
surface of the bore is to be coated by evaporation with a layer of
the auxiliary material, it is expedient to reduce the beam cross
section after penetrating the full thickness of the workpiece, so
that the internal surface 3 of the bore 2 can become somewhat
cooler.
In the case of readily evaporatable auxiliary materials, it is
advisable to reduce the intensity of the beam 4. This is
schematically illustrated in FIG. 6 in which the dependency of the
beam intensity i upon the time t used in the process described is
shown. In a first time section t.sub.1 the bore 2 is produced and,
after the workpiece 1 has been completely bored through, the beam
intensity is then reduced for a second time section t.sub.2 to
avoid evaporating to excess the readily evaporatable auxiliary
material 5.
FIG. 7 shows a possibility of allowing a certain time lapse T
between the production of the recess in the time section t.sub.1
and the treatment by means of the auxiliary material in the time
section t.sub.2, to allow the internal surface 3 of the bore to
cool off to a predetermined temperature. Similar two- or multistage
controls of the intensity and/or the beam cross section are often
advantageous also when carrying out treatment without auxiliary
material.
In some case of course, it is also expedient after the production
of a recess with the assistance of an energy beam for its intensity
not to be reduced but to be increased and generally by
simultaneously changing the beam cross section, e.g. when carrying
out the treatment with an auxiliary material which reacts, for
example, evaporates, only at a suitably high temperature.
In the process illustrated in FIG. 5 the energy beam used to
produce the bore simultaneously serves to bring about the desired
treatment of the internal surface of the bore. This, of course, is
not compulsive in any way. According to the process of the
invention, internal surfaces of bores may also be treated which
have already been produced by way of any method in the workpiece.
Possibilities are known, especially when using an electron beam as
energy beam, to conduct the energy beam so over the workpiece that
it automatically seeks the bores and, when engaging a bore,
permeates it long enough to carry out the desired treatment
operation in the interior of the bore. In the case of electrically
nonconductive workpieces, it is possible for example to provide on
the side remote from the beam of the workpiece (in FIG. 5 thus
between the workpiece 1 and the layer 5 of the auxiliary material),
an electrically conductive sheet or evaporation, by means of which
each control impulse can be tapped when the beam conducted in a
search over the workpiece is incident in a bore. Such an apparatus
may also be used for the purpose of indicating the complete
perforation of the workpiece when producing bores.
The use of one and the same beam to produce the recess and for the
desired treatment of the internal surface of the recess allows the
auxiliary material also to be used as a component of the workpiece
material. The schematic sectional view of FIG. 8 indicates the
possibility of arranging the auxiliary material 5 in distribution
in the material of the workpiece 1; this possibility is provided
particularly in workpieces made of plastics material. FIG. 9
illustrates, by way of a similar sectional view as FIG. 8, the
possibility of inserting the auxiliary material 5 at least in the
form of a layer in the workpiece material 1. When the treatment
occurs directly after producing the recess, it is also possible to
supply the auxiliary material in a liquid or gaseous state to the
workpiece by means of a permeable porous mass placed against the
workpiece and, this is shown in FIG. 10. On the side of the
workpiece 1 remote from the beam (the lower side in FIG. 10), a
short pipe 7 of relatively large cross-sectional area is mounted so
as to abut and hermetically seal the workpiece surface. A feed pipe
8 as connected to the pipe 7 for a gaseous or liquid auxiliary
material. The pipe 7 is filled with a permeable porous mass 9 which
sets up a high flow resistance against the auxiliary material
supplied so that only a correspondingly small proportion of the
entire auxiliary material, fed via the pipe 8, can escape. This is
of particular importance when as energy beam 4 for the treatment,
only such is used which can be maintained in a vacuum, for example,
an electron beam. When using a gaseous auxiliary material the
vacuum pump need pump away only relatively small quantities of gas
which flows via the completed bores 2.
FIGS. 11 and 12 each illustrate by way of similar sectional views
as FIGS. 5, 8, 9 and 10, an alternative possibility in accordance
with the invention. In FIG. 11 the auxiliary material is released
from a porous mass 10 which is placed in position on the side of
the workpiece 1 remote from the beam (the lower side in FIG. 11);
the pores 11 of the mass being substantially closed and enclosing
an auxiliary material. By action of an energy beam incident through
a bore 2 at least one pore in the vicinity of the bore to be
treated is opened and the auxiliary material contained in the pore
flows through the bore concerned; the treatment operation resulting
in the desired manner. When using liquid or solidified auxiliary
materials, it is also possible to use a porous mass 10 without
closed pores, for example, a fibrous mass which is saturated with
the auxiliary substance. Accordingly it is also possible for the
method of operation shown in FIG. 10 to be so modified that the
short pipe socket 7 is provided without the feed pipe 8, thus, with
the exception of the top being closed on all sides, the porous mass
9 contained in the pipe 7 can then also be saturated with a liquid
or solid auxiliary substance.
FIG. 12 shows a further possibility in which the pores 11 of the
mass 10 are elongated in the direction of the beam so that they are
able to absorb a larger quantity of the normally gaseous auxiliary
substance. When using masses with closed pores, the pore density
relative to the surface density of the bores in the workpiece 1
must be large enough to enable the energy beam incident through a
bore 2 to open at least one pore 11. Incidentally, the use of solid
or liquid auxiliary substances permits at the given action point
the development of a relatively large volume of vapor or gas. If
this is desired when producing, for example, a recess, to eject the
traces of liquified workpiece material out of the recess, it is
also possible to use an auxiliary substance which per unit of
volume or weight supplies a large quantity of vapor or gas.
Normally it will also be expedient, when using liquid or solid
auxiliary substances, to employ such auxiliary substances which
evaporate without trace, for example, monomers or polymers of
unsubstituted or halogenated hydrocarbons, alcohols and the like
nonresidual compounds. The process in accordance with the invention
may also be used with advantage for cooling when perforating panels
or sheetlike workpieces, the auxiliary substance entering the bore
acting as coolant. Particularly when using a solid or liquid
substance as auxiliary substance considerable cooling effects can
be obtained which, for example, can be used to enable a
considerably greater processing power per surface unit of the
workpiece to be employed and thus, when perforating, more holes per
time and surface unit to be produced. Cooling as such may also be
advantageous, e.g. for hardening.
FIG. 13 illustrates schematically a possible embodiment of an
apparatus for carrying out the process in accordance with the
invention. The perforating of a panellike or sheetlike workpiece 1
is shown with its lower side remote from the beam 4 the workpiece
abutting against a porous mass 10 which contains the auxiliary
substance, such as gas. On the upper side of the workpiece 1,
facing the beam there are mounted the lower edges 14 of the
sidewalls 13 of a treatment chamber 12 formed as sliding packings
in which chamber the beam source 15 is accommodated. The treatment
chamber 12 is connected via a socket 16 to a pump (not shown). As
readily shown in FIG. 13, the gas flow entering the treatment
chamber from the porous mass 10 via the bores 2 already produced is
determined by the flow resistance of the porous mass 10 and the
number of bores produced and situated in the treatment chamber; if
necessary the free underside of the mass 10 may be provided with a
sealing layer. It is seen that a certain connection exists between
the performance of the pump (not shown) connected to the socket 16
and the gas pressure maintained in the treatment chamber 12.
Suitable dimensioning of the cross section of the lower
constricting section of the treatment chamber 12 allows the size of
the gas or vapor quantity inflowing through the bores 2 already
produced to be influenced within a wide range. During the
processing, the processing apparatus is moved relative to the
workpiece 1 in accordance with the arrow 17. It is also possible
for the backing mass 10 to be moved with the treatment apparatus
relative to the workpiece so that one support suffices and which is
considerably smaller than the whole workpiece. In this case the
support must be so fashioned that it is able to bear repeated
actions of the energy beam 4. Normally, on the lower free side of
the underlay mass 10 atmospheric pressure will simply prevail; it
is, however, also possible to adjoin a gas chamber to the free side
of the underlaid mass 10 and which gas chamber is filled with any
other fluid at any other suitable pressure.
FIG. 14 shows an embodiment fundamentally similar to the embodiment
of FIG. 12, in which the same energy beam is used both to produce
the bores 2 in a workpiece 1 and to release the auxiliary
substance. In this embodiment a mass 10 is laid beneath the side of
the workpiece 1 remote from the beam and contains the auxiliary
substance in closed pores; in FIG. 14 elongated bores similar to
those in FIG. 12 are shown. The upper ends of the elongated pores
are located close to the surface nearer to the beam of the underlay
mass 10, so that a region 17 of the underlaid mass located at the
lower end of the bore 2 produced is destroyed by the energy beam
used for treatment after completely perforating the workpiece 1.
The region 18 is destroyed to such an extent that the upper ends of
the passagelike pores 11 are opened and the auxiliary substance
contained in the pores allowed to enter the bore 2 produced.
Normally the number of elongated pores located per unit surface
area of underlaid mass 10 is greater than the number of bores per
unit surface area produced in the workpiece, so that at least one
pore per bore is opened reliably.
As already mentioned, it is desired in many cases, such as when
vapor-depositing the internal surface of a recess with an auxiliary
substance, to keep the temperature of the internal surfaces of a
recess just produced as low as possible. Also, for reasons of
strength of the workpiece material, it is often required to avoid
excessive overall heating of the workpiece by the energy beam
acting thereon. This excessive overall heating may be avoided by
utilizing the knowledge that with a number of treatment points the
energy beam is caused to act successively on treatment points, the
distance of which is greater than the distance between two adjacent
treatment points. The energy beam thus does not jump from one
treatment point to the next adjacent treatment point but first to a
more remote treatment point, so that the surrounding area of the
first treatment point may cool off before a further treatment point
located in the direct surrounding is treated. A very simple
treatment diagram of such a kind is explained in FIG. 15 which is a
schematic plan view of the workpiece 1 provided or to be provided
with perforation bores 2. The workpiece, for example, is moved in
accordance with the arrow 19 relative to the energy beam used for
treatment. The energy beam for example is lead in sequence over the
workpiece and the sequence is indicated by the numbers in the
left-hand column of the perforation holes. It will be seen that
with the selected sequence only the bores 4 and 5 have been
produced directly adjacent to one another. Of course, numerous
kinds of nonsequential control systems of the energy beam may be
used in which any size of spacing may result between successively
treated treatment points. It must be noted, however, that the
accuracy with which a bore position is impacted by the treatment
beam becomes all the smaller the greater the nonsequential moves
carried out by the beam between two successive treatment
operations. The possibility described above also allows an
annealing substance acting as coolant in order to obtain a further
increase of energy supply permissible per time and surface unit to
the workpiece 1; this in turn allows accordingly smaller spacings
between directly successively treated bore positions.
In the process in accordance with the invention the use of an
energy beam, apart from the reasons given initially, is also of
particular advantage because the energy beam has practically no
mass flow so as to eliminate mutual obstruction between beam and
the auxiliary substance flowing into the recess.
According to the process of the invention manifold treatments of
the internal surfaces of recesses may be carried out. For example,
bores in nonmetal materials may be coated by evaporation with an
electrically conductive metallization; conversely, of course, bores
in a metal workpiece may have an electrically insulating layer
vapor-deposited thereon. Of particular importance is the process of
the invention for producing plastics material filters in which the
filter openings have been bored with electron beam. Hitherto it was
not possible for these very fine bores to be treated on their
internal surface in a desired manner, for example, by application
of an auxiliary substance to be smoothed and/or mechanically
strengthened. Mutual chemical reactions between auxiliary
substances and/or the workpiece material allow manifold effects to
occur; for example, an auxiliary substance distributed in a manner
as shown in FIG. 8 in the workpiece material and comprising a
mixture reacting chemically when heated can also be used to cause
special effects.
The following examples further illustrate the process of the
invention in a nonlimitative manner:
EXAMPLE I
An aluminum plate of 1 mm. thickness was provided by means of an
electron beam with bores of 0.2 mm. diameter. The action period for
each bore amounted to 2 msec. with an acceleration voltage 150 kv.
and a beam output of 100 Watt. Beneath the aluminum plate as shown
in FIG. 5 a polyurethane foam, foamed with oxygen, was arranged.
The boring electron beam after each boring action released the
contents of a few pores of the foamed material; the oxygen so
released entered the highly heated bore where it produced a desired
layer of aluminum oxide which has a considerably higher resistance
than the pure aluminum.
EXAMPLE II
A foil of polytetrafluorethylene of 0.7 mm. thickness was placed on
a copper support and perforated with an electron beam. The beam was
impulse controlled; each impulse of 20 -microsecond duration
produced a hole (perforation) of about 0.8 mm. diameter. The
acceleration voltage amounted to 150 kv., the beam current amounted
to 10 ma. The intensity of each electron beam impulse was
controlled substantially according to the pattern of FIG. 6, so
that in the second half of the overall impulse duration the beam
current dropped to about 2 mm. Moreover, in the second half of the
impulse duration the beam diameter was reduced by about half. A
clean vapor-depositing of the internal wall surfaces with copper
resulted.
EXAMPLE III
A sheet of 0.3 mm. thickness of stainless steel was perforated with
electron beam impulses of 150 kv., 25 ma. and 15microseconds; the
diameter of the holes produced amounted to 0.33 mm. Beneath the
steel sheet there was placed a disc pressed from aluminum oxide. In
the perforation holes there resulted an insulation layer of
vapor-deposited aluminum oxide of about 0.0005 to 0.005 mm.
thickness.
EXAMPLE IV
A hardenable steel sheet of 0.3 mm. thickness was perforated with
electron beam impulses of 140 kv., 20 ma. and 45microseconds
duration; the diameter of the holes produced was 0.125 mm. Beneath
the steel sheet there was placed a polyvinyl chloride fiber
material of 1.2 mm. thickness saturated with methyl alcohol and
provided on the surface not supported against the steel sheet with
a sealing surface layer. The extensive cooling action of the methyl
alcohol vapor entering the bore after it was produced caused a
surface hardening of the internal wall surface of the perforation
holes, thus the thickness of the layer applied was about 0.015 to
0.02 mm.
EXAMPLE V
A sheet of synthetic leather of 0.5 mm. thickness on a polyvinyl
chloride base was perforated with electron beam impulses of 125
kv., 7 ma. and 12microseconds duration; the diameter of the holes
produced was about 0.03 mm. Beneath the synthetic leather sheet
there was placed a polyvinyl chloride fibrous material of 1.5 mm.
thickness which was saturated with ethyl alcohol and on the side
not supported against the synthetic leather sheet was provided with
a sealing surface layer. The cooling action of the ethyl alcohol
vapor entering each bore produced allowed the obtainable surface
density of the perforation holes to be increased from 2,000 holes
per cm..sup.2 to 4,000 per cm..sup.2 and the applicable impulse
frequency could be increased from 500 holes per second to 2,000
holes per second.
Other embodiments are possible without departing from the scope of
the invention. It is especially clear that, in accordance with the
process of the invention, recesses of optional shape and cross
section form can be treated.
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