U.S. patent number RE48,685 [Application Number 15/880,232] was granted by the patent office on 2021-08-17 for method for controlling an ultrasonic machining process.
This patent grant is currently assigned to HERRMANN ULTRASCHALLTECHNIK GMBH & CO. KG. The grantee listed for this patent is Herrmann Ultraschalltechnik GmbH & Co. KG. Invention is credited to Volker Aust, Thomas Herrmann.
United States Patent |
RE48,685 |
Herrmann , et al. |
August 17, 2021 |
Method for controlling an ultrasonic machining process
Abstract
Invention relating to a method for controlling an ultrasonic
machining, in which an ultrasonic vibration is transmitted via a
sonotrode into the material to be machined. During the first
machining interval, a first welding variable of the group S,
consisting of the frequency f and the amplitude u of the ultrasonic
vibration, the force F, which the sonotrode exerts on the material
to be machined, the power P, which the generator delivers, and the
speed v, with which the sonotrode is moved in the direction of the
material to be machined, is kept constant until a first target
variable of the group Z adopts a predetermined value. During an
adjoining second machining interval, a second welding variable of
the group S is kept constant until a second target variable of the
group Z adopts a predetermined value, wherein the first and the
second target variable differ.
Inventors: |
Herrmann; Thomas (Karlsruhe,
DE), Aust; Volker (Birkenfeld, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Herrmann Ultraschalltechnik GmbH & Co. KG |
Karlsbad |
N/A |
DE |
|
|
Assignee: |
HERRMANN ULTRASCHALLTECHNIK GMBH
& CO. KG (Karlsbad, DE)
|
Family
ID: |
1000005599723 |
Appl.
No.: |
15/880,232 |
Filed: |
January 25, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
13940743 |
Jul 12, 2013 |
8702883 |
Apr 22, 2014 |
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Foreign Application Priority Data
|
|
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Jul 18, 2012 [DE] |
|
|
10 2012 106 491.1 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C
66/92445 (20130101); B29C 66/93431 (20130101); B23K
20/10 (20130101); B29C 65/08 (20130101); B29C
66/961 (20130101); B29C 66/9512 (20130101); B29C
66/9516 (20130101); B29C 66/942 (20130101) |
Current International
Class: |
B23B
37/00 (20060101); B23K 20/10 (20060101); B29C
65/00 (20060101); B29C 65/08 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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34 29 776 |
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Feb 1986 |
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DE |
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37 23 333 |
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Jan 1989 |
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DE |
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43 21 874 |
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Jan 1995 |
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DE |
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692 16 761 |
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Jul 1997 |
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DE |
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101 26 943 |
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Dec 2002 |
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DE |
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10 2007 053 853 |
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May 2009 |
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DE |
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11 2007 001 925 |
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Jul 2009 |
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DE |
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2004 096 480 |
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Nov 2004 |
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WO |
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Other References
Dukane Corporation, DPC IV Plus Generator User's Manual, pp. 81-84.
(Year: 1997). cited by examiner.
|
Primary Examiner: McKane; Elizabeth L
Attorney, Agent or Firm: Paul & Paul
Claims
The invention claimed is:
.[.1. Method for controlling an ultrasonic machining process, in
which an ultrasonic vibration of the frequency f is transmitted
with the aid of a sonotrode made to carry out an ultrasonic
vibration under a pressure into the material to be machined,
wherein, during a first machining interval, a first welding
variable of the group S, consisting of the frequency f of the
ultrasonic vibration, the amplitude u of the ultrasonic vibration
of the sonotrode, the force F, which the sonotrode exerts on the
material to be machined, the power P, which the generator delivers,
and the speed v, with which the sonotrode is moved in the direction
of the material to be machined, f is kept constant) until a first
target variable of the group Z, consisting of the force F, the
power P, the welding time t since the beginning of this machining
interval, during which the excited sonotrode transmits the
ultrasonic vibration under pressure into the material to be
machined, the welding path s, which the sonotrode has covered since
the beginning of the machining interval, and the energy E,
calculated from the product of P and t, adopts a predetermined
value, and, during a second machining interval, which adjoins the
first machining interval, a second welding variable of the group S
is kept constant until a second target variable of the group Z
adopts a predetermined value, wherein the first and the second
target variable differ..].
.[.2. Method according to claim 1, characterised in that the first
and the second welding variable are the same..].
.[.3. Method according to claim 2, characterised in that the first
and the second welding variable are the force F, which the
sonotrode exerts on the product to be machined..].
4. .[.Method according to any one of claims 1 to 3, characterised
in that,.]. .Iadd.Method for controlling an ultrasonic machining
process, in which an ultrasonic vibration of the frequency f is
transmitted with the aid of a sonotrode made to carry out an
ultrasonic vibration under a pressure into the material to be
machined, wherein, during a first machining interval, a first
welding variable of the group S, consisting of the frequency f of
the ultrasonic vibration, the amplitude u of the ultrasonic
vibration of the sonotrode, the force F, which the sonotrode exerts
on the material to be machined, the power P, which the generator
delivers, and the speed v, with which the sonotrode is moved in the
direction of the material to be machined, is kept constant until a
first target variable of the group Z, consisting of the force F,
the power P, the welding time t since the beginning of this
machining interval, during which the excited sonotrode transmits
the ultrasonic vibration under pressure into the material to be
machined, the welding path s, which the sonotrode has covered since
the beginning of the machining interval, and the energy E,
calculated from the product of P and t, adopts a predetermined
value, and, during a second machining interval, which adjoins the
first machining interval, a second welding variable of the group S
is kept constant until a second target variable of the group Z
adopts a predetermined value, wherein the first and the second
target variable differ, and wherein .Iaddend.during the first
machining interval, a third target variable of the group Z is
detected and the second target variable is selected depending on
the result of the detection.
5. Method according to claim 4, .[.characterised in that.].
.Iadd.wherein .Iaddend.the third target variable is the welding
time t.
.[.6. Method according to any one of claims 1 to 3, characterised
in that the first machining interval ends when the first target
variable adopts the predetermined value or when a fourth target
variable of the group Z adopts a predetermined value..].
7. .[.Method according to any one of claims 1 to 3, characterised
in that.]. .Iadd.Method for controlling an ultrasonic machining
process, in which an ultrasonic vibration of the frequency f is
transmitted with the aid of a sonotrode made to carry out an
ultrasonic vibration under a pressure into the material to be
machined, wherein, during a first machining interval, a first
welding variable of the group S, consisting of the frequency f of
the ultrasonic vibration, the amplitude u of the ultrasonic
vibration of the sonotrode, the force F, which the sonotrode exerts
on the material to be machined, the power P, which the generator
delivers, and the speed v, with which the sonotrode is moved in the
direction of the material to be machined, is kept constant until a
first target variable of the group Z, consisting of the force F,
the power P, the welding path s, which the sonotrode has covered
since the beginning of the machining interval, and the energy E,
calculated from the product of P and the welding time t since the
beginning of this machining interval, during which the excited
sonotrode transmits the ultrasonic vibration under pressure into
the material to be machined, adopts a predetermined value, and,
during a second machining interval, which adjoins the first
machining interval, a second welding variable of the group S is
kept constant until a second target variable of the group Z adopts
a predetermined value, wherein the first and the second target
variable differ, and wherein .Iaddend.an upper and/or lower limit
.[.optionally depending on the welding time t.]. is predetermined
for the first and/or the second target variable and, when the upper
limit is exceeded or the lower limit is fallen below, the machining
interval is ended and a transition is made into the next machining
interval or the welding process is discontinued .Iadd.wherein the
upper and/or the lower limit is dependent on the welding
time.Iaddend..
8. .[.Method according to any one of claims 1 to 3, characterised
in that.]. .Iadd.Method for controlling an ultrasonic machining
process, in which an ultrasonic vibration of the frequency f is
transmitted with the aid of a sonotrode made to carry out an
ultrasonic vibration under a pressure into the material to be
machined, wherein, during a first machining interval, a first
welding variable of the group S, consisting of the frequency f of
the ultrasonic vibration, the amplitude u of the ultrasonic
vibration of the sonotrode, the force F, which the sonotrode exerts
on the material to be machined, the power P, which the generator
delivers, and the speed v, with which the sonotrode is moved in the
direction of the material to be machined, is kept constant until a
first target variable of the group Z, consisting of the force F,
the power P, the welding time t since the beginning of this
machining interval, during which the excited sonotrode transmits
the ultrasonic vibration under pressure into the material to be
machined, the welding path s, which the sonotrode has covered since
the beginning of the machining interval, and the energy E,
calculated from the product of P and t, adopts a predetermined
value, and, during a second machining interval, which adjoins the
first machining interval, a second welding variable of the group S
is kept constant until a second target variable of the group Z
adopts a predetermined value, wherein the first and the second
target variable differ, and wherein .Iaddend.during a third
machining interval, which adjoins the second machining interval, a
third welding variable of the group S is kept constant until a
fifth target variable of the group Z adopts a predetermined value,
wherein the second and the fifth target variable differ.
9. Method according to claim 8, .[.characterised in that.].
.Iadd.wherein .Iaddend.more than three machining intervals are
provided, during which, in each case, a welding variable of the
group S is kept constant until, in each case, a target variable of
the group Z adopts a predetermined value.
.Iadd.10. Method according to claim 4, wherein the first and the
second welding variable are the same. .Iaddend.
.Iadd.11. Method according to claim 10, wherein the first and the
second welding variable are the force F, which the sonotrode exerts
on the product to be machined. .Iaddend.
.Iadd.12. Method according to claim 7, wherein the first and the
second welding variable are the same. .Iaddend.
.Iadd.13. Method according to claim 12, wherein the first and the
second welding variable are the force F, which the sonotrode exerts
on the product to be machined. .Iaddend.
.Iadd.14. Method according to claim 8, wherein the first and the
second welding variable are the same. .Iaddend.
.Iadd.15. Method according to claim 14, wherein the first and the
second welding variable are the force F, which the sonotrode exerts
on the product to be machined. .Iaddend.
.Iadd.16. Method for controlling an ultrasonic machining process,
in which an ultrasonic vibration of the frequency f is transmitted
with the aid of a sonotrode made to carry out an ultrasonic
vibration under a pressure into the material to be machined,
wherein, during a first machining interval, a first welding
variable of the group S, consisting of the frequency f of the
ultrasonic vibration, the amplitude u of the ultrasonic vibration
of the sonotrode, the force F, which the sonotrode exerts on the
material to be machined, the power P, which the generator delivers,
and the speed v, with which the sonotrode is moved in the direction
of the material to be machined, is kept constant until a first
target variable of the group Z, consisting of the force F, the
power P, the welding time t since the beginning of this machining
interval, during which the excited sonotrode transmits the
ultrasonic vibration under pressure into the material to be
machined, the welding path s, which the sonotrode has covered since
the beginning of the machining interval, and the energy E,
calculated from the product of P and t, adopts a predetermined
value, and, during a second machining interval, which adjoins the
first machining interval, a second welding variable of the group S
is kept constant until a second target variable of the group Z
adopts a predetermined value, wherein the first and the second
target variable differ, wherein said first target variable and a
fourth target variable of the group Z are detected during the first
machining interval, and wherein the first machining interval ends
when the first target variable adopts the predetermined value or
wherein the first machining interval ends also when the fourth
target variable of the group Z adopts a predetermined value,
whichever occurs first. .Iaddend.
.Iadd.17. Method according to claim 16, wherein the first and the
second welding variable are the same. .Iaddend.
.Iadd.18. Method according to claim 17, wherein the first and the
second welding variable are the force F, which the sonotrode exerts
on the product to be machined. .Iaddend.
Description
The present invention relates to a method for controlling an
ultrasonic machining process and, in particular, a method for
controlling an ultrasonic welding process. During ultrasonic
welding, two components are frequently connected to one another by
inner friction in the joining zone. For this purpose, an ultrasonic
welding apparatus, consisting of a generator, a converter and a
sonotrode, is used. The generator produces an electric alternating
voltage, which is converted with the aid of the converter into a
mechanical vibration. The converter in turn makes the sonotrode
connected therewith carry out an ultrasonic vibration.
The sonotrode made to carry out an ultrasonic vibration then
transmits the ultrasonic vibration under pressure to one of the two
components to be connected. If the components to be connected
touch, boundary surface friction occurs between the two components
in the so-called joining or welding zone and, as a result, local
heating of the boundary surfaces occurs. If the heating is so great
that the boundary surfaces melt, the two components are welded. The
two components are generally pressed onto one another with the aid
of the sonotrode.
A weld connection with a short welding time can be produced by
ultrasonic welding as the welding energy is provided so as to be
virtually limited to the joining zone.
In order to achieve an optimal welding result, it is necessary for
the welding process to take place as rapidly as possible in order
to avoid heating the material outside the joining zone. The longer
the welding process lasts, the more heat dissipates from the
joining zone and heats the components. On the other hand, the
welding time has to be at least long enough for a uniform material
melting to occur in the joining zone, as only then is a lasting
weld connection ensured.
There are applications, in which the best welding result is
achieved in the shortest time if the force, with which the
sonotrode is pressed onto the components, is varied during the
welding process. It is thus, for example possible, to press the
sonotrode onto a component with a first force F.sub.1 during a
first time interval and to press the sonotrode onto this component
with a second force F.sub.2 during an adjoining second time
interval, wherein F.sub.2 is less than F.sub.1. In this case, the
first time interval is selected such that, at the end of the first
time interval, the beginning of the melting process can be
expected. As the contact faces of the two components to be
connected then melt and consequently become soft, the further
welding process can be carried out with less force, so the welding
quality is improved.
Because of sensitive component geometries and structures, other
processes require smaller welding forces during the first time
interval. Only after the beginning of the plastification can the
welding force be increased in a following time interval.
The known methods are, however, not optimal for all applications.
Thus, for example, the necessary welding period up to the melting
of the joining faces also depends on the flatness of the joining
faces. Because of component tolerances, the optimal welding period
for welding a first pair of components can therefore differ from
the optimal welding period for welding a second pair of components.
In addition, the use of two or more forces, with which the
sonotrode is pressed onto the component, is not always the best
solution to obtain an optimal welding result.
Proceeding from the described prior art, it is therefore the object
of the present invention to disclose a method for controlling an
ultrasonic machining process, with which a reliable processing
result can be achieved in a large number of application
possibilities.
According to the invention, this object is achieved in that, during
a first machining interval, a first welding variable of the group
S, consisting of the frequency f of the ultrasonic vibration of the
sonotrode, the amplitude u of the ultrasonic vibration of the
sonotrode, the force F, which the sonotrode exerts on the material
to be machined, the power P, which the generator consumes, and the
speed v, with which the sonotrode moves in the direction of the
first component, is kept constant until a first target variable of
the group Z, consisting of the force F, the power P, the welding
time t since the beginning of this machining interval, during which
the excited sonotrode transmits the ultrasonic vibration under a
specific pressure into the material to be machined, the welding
path s, which the sonotrode has covered since the beginning of the
machining interval in the direction of the first component, and the
energy E, calculated from the product of the power P and the
welding time t, adopts a predetermined value.
Obviously, a plurality of welding variables of the group S can also
be kept constant.
It is seen that some variables, such as, for example, the force F,
are suitable both as a welding variable and as a target variable.
However, it is obvious that no variable which is kept constant as a
welding variable can be selected as the target variable. If the
force F which the sonotrode exerts on the material to be machined
is therefore kept constant during the first machining interval, the
target variable cannot be the force F. However, the target variable
could, for example, be the power P, which the generator
delivers.
During the first machining interval, a first force could therefore
be applied by the sonotrode to the material to be machined until
the power P which the generator delivers adopt a predetermined
value or exceeds it.
According to the invention, it is then furthermore provided that,
during a second machining interval, which adjoins the first
machining interval, a second welding variable of the group S is
kept constant until a second target variable of the group Z adopts
a predetermined value, wherein the first and the second target
variable differ.
Thus, for example, during a first machining interval, a specific
force could be applied for a specific time t and, in a second
machining interval, the amplitude u could be kept constant until a
specific energy E has been delivered by the generator.
In a preferred embodiment of the method, the first and the second
welding variable are the same. However, this does not mean that the
welding variable is kept constant at the same value in the first
and in the second machining interval. On the other hand, the
welding variable will generally be kept constant at a different
value in the first machining interval than in the second machining
interval.
Thus, for example, during a first machining interval, a first force
could be applied for a specific time t and a second force could be
applied in a second machining interval until a specific energy E
has been delivered by the generator.
In a further particularly preferred embodiment, both in the first
and in the second machining interval, the force F, which the
sonotrode exerts on one of the components, is selected as the
welding variable. It has namely been shown that by applying
specific forces to the material, welding results that can be
reproduced well can be achieved. As, the material pieces to be
consecutively machined differ slightly under some circumstances,
however, the period for which the sonotrode machines the material
is then, for example, varied between the individual materials in
that the target variables are selected such that they are reached
at different speeds depending on the material to be machined.
In a further particularly preferred embodiment, it is provided
that, during the first machining interval, a third target variable
of the group Z is detected and, depending on the result of the
detection, the second target variable is selected. In other words,
at the beginning of the first machining interval, it is not yet
established which target variable of the group Z is selected for
the second machining interval. For example, during the first
machining interval, the force F, which the sonotrode exerts on the
material to be machined, could be kept constant, until the path s,
which the sonotrode has covered since the beginning of the
machining interval in the direction of the material to be machined,
has reached a predetermined value. If, at the same time, the time
is measured, the target variable for the second machining interval
can be made to depend upon whether the predetermined path s has
been reached within a specific time interval or not.
In a preferred embodiment, it is therefore provided that the third
target variable is the welding time t.
Obviously, it is also possible for two target variables to be
detected during a machining interval, for example a first target
variable and a fourth target variable of the group Z, and for the
machining interval to end when one of the two target variables
adopts it predetermined value.
Furthermore, it is provided in a preferred embodiment that an upper
and/or lower limit optionally depending on the welding time t is
predetermined for the first and/or second target variable and, when
the upper limit is exceeded or the lower limit is fallen below, the
machining interval is ended and a transition is made into the next
machining interval or the welding process is discontinued.
In other words, an observation of the ultrasonic machining control
takes place. If the machining should not take place within a
predetermined tolerance band, the machining can either be
discontinued or a transition can be made into the next machining
interval.
Obviously, the method according to the invention is not limited to
two machining intervals. Rather, it is possible to select three or
even still more machining intervals, wherein directly adjoining
machining intervals preferably use different target variables in
each case.
Further advantages, features and application possibilities become
clear with the aid of the following description of a preferred
embodiment and the associated FIGURE. In the drawing:
FIG. 1 shows a flow chart of a preferred embodiment.
FIG. 1 shows a flow chart of a preferred embodiment of the method
according to the invention. The first machining interval starts in
step 1. The machining time t0 is measured in step 2. This
measurement is merely used to determine the starting time.
The sonotrode is then pressed with the predetermined force F.sub.1
onto the workpiece to be machined in step 3. The force F is
selected as the welding variable. It is obvious that instead of the
force F, a different welding variable of the group S could have
also been selected.
In step 4, the machining time t is measured. The machining time t
is the target variable which has been selected for the first
machining interval. A check is now made in step 5 whether since the
beginning of the machining time measurement in step 2 a
predetermined time interval t1 has already been exceeded or not. If
the predetermined time period t1 has not yet been exceeded, the
method continues with step 3, i.e. the sonotrode continues to be
pressed with the predetermined force F.sub.1 onto the workpiece to
be machined and, in step 4, the machining time t is measured again
until the predetermined time period t1 has been reached. In this
case, the first machining interval ends in step 6. In step 7, the
second machining interval starts. The welding path s0 is measured
here in step 8, i.e. the position of the sonotrode relative to the
workpiece or a counter-tool, on which the workpiece is
positioned.
In step 9, the sonotrode is now pressed with a predetermined force
F.sub.2 onto the workpiece to be machined. Ultrasonic machining
takes place.
In step 10, the welding paths is measured again. A check is now
made in step 11 whether, since the beginning of the measurement in
step 8, the sonotrode has moved relative to the workpiece by a
distance which is greater than the predetermined welding path s1.
If the predetermined welding path s1 has not yet been reached, the
process is continued with step 9. If the desired welding path s1
has been reached, the second machining interval ends in step
12.
Since the machining method according to the invention provides the
division of the machining into at least two machining intervals,
the target variables being selected differently, a very good
welding result can be achieved.
* * * * *