U.S. patent application number 10/621553 was filed with the patent office on 2004-03-25 for method and device for quality assurance of crimp joints.
This patent application is currently assigned to Schaefer Werkzeug-und Sondermaschinen GmbH. Invention is credited to Anton, Erhard.
Application Number | 20040055354 10/621553 |
Document ID | / |
Family ID | 27798315 |
Filed Date | 2004-03-25 |
United States Patent
Application |
20040055354 |
Kind Code |
A1 |
Anton, Erhard |
March 25, 2004 |
Method and device for quality assurance of crimp joints
Abstract
A method for the quality assurance of crimp joints on crimping
devices, in which, based on a setpoint dimension of crimp force
and/or crimp height, the actual value of crimp force and/or crimp
height is measured continuously within defined upper and/or lower
tolerance dimensions of crimp force and/or crimp height, and a
corrected re-adjustment of crimp height is effected after the
actual values have reach a correction value.
Inventors: |
Anton, Erhard; (Marxzell,
DE) |
Correspondence
Address: |
DAVIDSON, DAVIDSON & KAPPEL, LLC
485 SEVENTH AVENUE, 14TH FLOOR
NEW YORK
NY
10018
US
|
Assignee: |
Schaefer Werkzeug-und
Sondermaschinen GmbH
Bad Schoenborn
DE
|
Family ID: |
27798315 |
Appl. No.: |
10/621553 |
Filed: |
July 17, 2003 |
Current U.S.
Class: |
72/372 ; 72/16.1;
72/17.3; 72/380 |
Current CPC
Class: |
H01R 43/0488 20130101;
H01R 43/0486 20130101 |
Class at
Publication: |
072/372 ;
072/380; 072/016.1; 072/017.3 |
International
Class: |
B21C 051/00; B21D
055/00; B21D 005/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 17, 2002 |
DE |
102 32 470.0-34 |
Claims
What is claimed is:
1. A method for assuring a quality of a crimp joint on a crimping
device, the method comprising: continuously measuring an actual
value of a crimp parameter of the crimp joint based on a respective
setpoint value of the crimp parameter within a defined upper and
lower tolerance value; and effecting a readjustment of a crimp
height after the actual value reaches a correction value of the
crimp parameter.
2. The method as recited in claim 1 wherein the crimp parameter
includes at least one of a crimp height and a crimp force.
3. The method as recited in claim 1 wherein the correction value is
a mean value of the measured actual values.
4. The method as recited in claim 1 wherein the correction value
corresponds to approximately half of the upper or lower tolerance
value.
5. A device for providing a crimp joint, comprising: a movable die
part; a stationary die part; a driving connecting rod for moving
the moveable die part back and forth in a longitudinal direction,
wherein a longitudinal position of the moveable die part with
respect to the stationary die part is adjustable; a positioning
drive for adjusting the longitudinal position; and a comparative
setpoint/actual value regulating system controlling the positioning
drive.
6. The device as recited in claim 5 further comprising an actual
value sensor disposed on the positioning drive for providing an
actual value to the regulating system.
7. The device as recited in claim 5 further comprising an operator
control unit for providing a setpoint value to the regulating
system.
8. The device as recited in claim 7 wherein the setpoint value
corresponds to a crimp force measurement.
9. The device as recited in claim 8 wherein the setpoint value is
determined using a force curve during the crimping process.
10. The device as recited in claim 5 further comprising a
comparator for storing the setpoint value for the
setpoint/actual-value regulating system.
11. The device as recited in claim 5 wherein the positioning drive
includes a stepping motor and a gear unit.
12. The device as recited in claims 5 wherein the driving
connecting rod includes a hole perpendicular to the longitudinal
direction and wherein the positioning drive includes a positioning
member disposed in the hole.
13. The device as recited in claim 12 further comprising a
comparator and an actual value sensor disposed on the positioning
drive, wherein the positioning member includes an eccentric pin
having an axis of rotation connected to the actual-value sensor,
the actual value sensor transmitting a position value of the
eccentric pin to the comparator.
14. The device as recited in claim 12 wherein the eccentric pin has
a positioning accuracy of 0.002 mm.
15. The device as recited in claim 5, further comprising a
comparator, wherein the actual value of a crimp force curve is
measured during a crimping process and compared with a setpoint
value defined in the comparator, the positioning drive adjusting
the longitudinal position so as to correct the crimp force curve in
a direction of the setpoint value when a deviation between the
actual value and the setpoint value occurs.
Description
[0001] Priority is claimed to German Patent Application DE 102 32
470.0-34, filed on Jul. 17, 2002, the subject matter of which is
incorporated by reference herein.
BACKGROUND
[0002] The present invention relates to a method and a device for
the quality assurance of crimp joints on crimping devices.
[0003] Quality assurance is of great importance in series
manufacture of crimp joints. The electric wire must be tightly
enclosed by the electric terminal in order to guarantee good
current transfer and also to prevent cavities that can lead to
corrosion. The closing height of the tool in relation to the
thickness of the electric wire is especially important in this
process. If the closing height is too high, then the joint can have
excessively low tensile strength. If the closing height is too low,
then this can cause the strands to break off and in this case also
result in excessively low tensile strength. The setting of correct
crimp height is therefore an important issue in connection with
crimping devices.
[0004] In German Patent Application DE 43 37 796 A1, a method for
monitoring the quality of crimp joints is specified in which the
force curves over time for a plurality of reference measurements
are recorded as measured curves, and an averaged measured curve is
formed, to which an upper and a lower curve, each some distance
away, are applied so that a tolerance band results. When a crimping
process is being monitored, the measured curve that is determined
from this crimping process is checked to see whether it lies
completely within the area of the tolerance band. Faulty crimping
processes can be determined in this way.
[0005] In German Patent Application DE 198 43 156 A1, a method is
described in which measured data that is obtained from a
force-displacement characteristic measured during the crimping
process is compared with stored setpoint data. If the
force-displacement characteristic deviates from the setpoint curve,
a fault is indicated. In this method, the force-displacement
characteristic of the tool parts is recorded for each tool during
the crimping process and stored as the setpoint characteristic of
the crimping device. When this tool is again used, an initial
crimping process is carried out, and then it is possible to
determine immediately whether this crimping process agrees with the
setpoint data or not. The force-displacement curve is used for this
purpose.
[0006] German Patent Application DE 691 24 421 T2 disclosed a
method or a device for adjusting crimp height in which the crimp
height is automatically adjusted as a function of the crimp force.
The crimp force that occurs during a crimping process is compared
with optimum values, and when there are deviations from those
values, precision adjustment of crimp height is effected.
[0007] All methods cited above relate to individual crimping
processes and their quality assurance. When there is a faulty
crimping process, the affected part is indicated as faulty and
sorted out. Not considered are long-term processes in which an
overall deterioration in quality can occur without being detected
in individual crimping processes. This is the case, for example, if
the crimping device is put into operation again after having been
idle.
SUMMARY OF THE INVENTION
[0008] An object of the present invention is to provide a method
for the quality assurance of crimp joints by which it is also
possible to measure and record long-term processes reliably.
[0009] The present invention provides a method for the quality
assurance of crimp joints on crimping devices, wherein, based on a
setpoint dimension (X) of a crimp parameter (i.e. a crimp force
and/or crimp height (H)), the actual value (I) of the crimp force
and/or crimp height (H) is measured continuously within defined
upper and/or lower tolerance dimensions (X1, X2) of crimp force
and/or crimp height (H), and a corrected re-adjustment of crimp
height (H) is effected after the actual values (I) have reached a
correction value (Y).
[0010] The present invention also provides a device for carrying
out the aforesaid method that includes a movable die part that is
moved back and forth by a driving connecting rod, a stationary die
part, and a mechanism for press height adjustment. The driving
connecting rod (11) is provided with a sliding die part (10) that
slides along the rod in its longitudinal direction and with a
positioning drive (14) for precision adjustment of the press height
(H). The positioning drive (14) is controlled by a comparative
setpoint/actual-value regulating system (15).
[0011] Based on a determined setpoint dimension of crimp force
and/or crimp height for a specific tool, the actual value of crimp
force and/or crimp height during the crimping processes is measured
continuously within defined upper and/or lower tolerance dimensions
of crimp force and/or crimp height, and a corrected re-adjustment
of crimp height is carried out after a plurality of measured actual
values has reached a correction measured value. When a crimping
device is started up, the machine temperature is approximately
constant at the start of production. The device heats up over time,
however, and the machine body expands, which results in an increase
in crimp height and, at the same time, a reduction in crimp force.
Over time, this leads to a situation in which a deviation from the
crimp height setpoint value occurs. As soon as this deviation
reaches a calculated correction dimension, which is still clearly
within the upper tolerance dimensions of crimp height and/or the
lower tolerance limit of crimp force, a corrected re-adjustment of
crimp height is effected. This is carried out by appropriate
mechanisms on the crimping device.
[0012] A correction dimension that is preferably approximately half
of a tolerance dimension is defined as the correction measured
value. This correction measured value is at the same time the mean
value of the measured actual values of the individual crimping
processes.
[0013] During the crimping device's heatup phase, a plurality of
corrected re-adjustments of crimp height normally take place. This
is carried out until the crimping device has reached its
temperature stability and the setpoint value of crimp height is
maintained within a defined minimum range.
[0014] The device for carrying out the method is provided with a
movable die part that is moved back and forth by a driving
connecting rod and a stationary die part that includes a mechanism
for press height adjustment. The device is distinguished by the
fact that the driving connecting rod is provided with a sliding die
part that slides along the rod in its longitudinal direction and
with a displacement-causing positioning drive for precision
adjustment of the press height, the positioning drive being
controlled by a comparative setpoint/actual-value regulating
system.
[0015] The actual value of the regulating system is picked up by an
actual-value sensor mounted on the positioning drive. The setpoint
value may be set on the device's operator control unit or be
defined by a calculated reference quantity from the crimp force
measurement. The setpoint value of the regulating system is then
determined by the force curve during the crimping process.
[0016] For the setpoint/actual-value regulating system, a
comparator is provided in which the setpoint value from the
operator control unit or from the crimp force curve during the
crimping process is stored.
[0017] The positioning drive conveniently includes a stepping motor
and a gear unit. The positioning member itself is an eccentric pin
that is inserted into a hole in the driving connecting rod at right
angles to the rod's direction of movement. The axis of rotation of
the eccentric pin is connected to the actual-value sensor, which
transmits the position value of the eccentric pin to the
comparator. The positioning accuracy of the eccentric pin is 0.002
mm.
[0018] The actual value of the crimp force curve is measured during
the entire crimping process and compared with the setpoint value of
the crimp force curve as defined in the comparator. When there are
deviations between the actual value and the setpoint value, the
crimp force curve is corrected in the direction of the setpoint
value by changing the press height.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The invention is explained in greater detail below with
reference to an exemplary embodiment shown in the drawings, in
which:
[0020] FIG. 1 shows a schematic diagram of the production run with
regulation by the press height precision adjustment feature;
and
[0021] FIG. 2 shows the device with a mechanism for precision
adjustment of press height.
DETAILED DESCRIPTION
[0022] FIG. 1 shows a schematic diagram of the method as it takes
place during a production run. X designates the setpoint dimension
for crimp height H. On time axis Z, this is a straight line. X1
designates the lower tolerance dimension of crimp height H, and X2
designates the upper tolerance dimension of crimp height H. No
objections may be raised regarding the quality of crimp joints
manufactured within these tolerance dimensions, X1 and X2. The
production run is subdivided into phases 1 through 6. In phase 1
after the crimping device is started up, the device temperature is
approximately constant. The actual values of crimp height H are not
shown in detail here and move within a narrow tolerance band around
setpoint dimension X. In phase 2, initial heating takes place and
consequently expansion of the device body as well, which leads to
an increase in crimp height H. Actual values I of the individual
crimping processes show a downward trend in the diagram, i.e., in
the direction of a higher crimp height H or lower crimp force. When
these actual values I reach defined correction value Y,
re-adjustment of crimp height H takes place through reduction of
crimp height H, i.e., the individual crimping processes are brought
again to the level of setpoint dimension X. Correction measured
value Y is a mean value of a plurality of measured actual values I.
This correction measured value Y amounts to approximately half of a
tolerance dimension, such as tolerance dimension X2 in this case.
This process for phase 2 may be repeated a number of times, namely
until the crimping device has reached its operating temperature and
process stability has been established, as shown in the drawing
during phase 6. Heatup E of the crimping device includes phases 2
through 5 in the present exemplary embodiment. In phase 6,
temperature stability T has been established. Entire production run
P consequently includes phase 1, which involves approximately
constant crimping device temperature, phases 2 through 5; or range
E, in which heatup of the crimping device takes place, and phase 6,
in which the crimping device has reached its operating temperature
T and therefore its process stability.
[0023] FIG. 2 shows the mechanism for press height adjustment, as
it is used on a device for carrying out the method. The mechanism
essentially includes driving connecting rod 11, die part 10,
positioning drive 14 and comparative setpoint/actual-value
regulating system 15. Driving connecting rod 11 is driven by
eccentric 30. The eccentric itself is driven by shaft 31. Die part
10 is held in guide 32 and is movable in its longitudinal
direction. Toolholder 33 is mounted on die part 10. The second tool
part located below it is not shown. Press height H is the distance
between these two tool parts when the tool is open. Driving
connecting rod 11 contains hole 17 in which positioning member 12
is installed. At the same time, positioning member 12 forms the
connection between driving connecting rod 11 and die part 10. In
the area of hole 17 of driving connecting rod 11, positioning
member 12 is designed as an eccentric pin 18. Positioning member 12
is connected to positioning drive 14, which is driven by stepping
motor 20. Gear unit 21 is located in between. In addition, axis of
rotation 22 of eccentric pin 18 is connected to an actual-value
sensor 23, which transmits the position value of eccentric pin 18
to comparator 24. Setpoint value X of crimp height H is input into
comparator 24 from the operator console via line 26.
[0024] Comparator 24 compares actual values I with setpoint value X
and gives corresponding regulating signals to stepping motor 20 via
line 27. At the same time, actual value I of the crimp force
monitoring device is input into comparator 24 via line 28 so that
the crimp force may also be used for regulating the mechanism.
* * * * *