JPH03118934A - Crimping press for crimping conduction terminal to conductor and method for measuring quality of crimped terminal end thereof - Google Patents

Abstract

PURPOSE: To assess the quality of crimped electrical terminations of a terminal accurately and to make high quality crimped terminations over the long life of crimp tooling by providing means for measuring the maximum force produced in the crimp press and for generating control signals accordingly. CONSTITUTION: A crimp press is provided with a tooling adjusting assembly 32. This assembly 32 is equipped with a first adjusting cam 38 for adjusting the height of tooting 34 to a fixed anvil 42 and a second adjusting cam 40 for adjusting the height of tooling 36. A controller 52 generates electrical signals while a motor 48, 50 drives a rod 44, 46, driving a cam wedge 38, 40. The relative position of the cam wedge 38, 40 changes the height position of a punch die 34, 36 to the anvil 42, changing the crimp height. With a strain gauge 54 incorporated in the rear face 56 of the crimp press 30, the maximum strain measurement is stored in the controller 52. As a result, the strain measured during the crimping operation comes to indicate the actual crimp height accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field] The present invention relates to a method and a device for ensuring high-quality crimping of conductive terminals to conducting wires. The electrical terminal includes a wire attachment end that is crimped to create a mechanical and electrical connection with the wire. Peel the end of the wire to reveal the conductor inside.

At least a first portion of the mounting end of the terminal is crimped into electrical contact with a conductor of the lead wire. The second part of the terminal's mounting end should also be crimped to engage the insulated part of the conductor to release any strain in the electrical connection, and also to prevent pull-out failures at the end unless strong force is applied. .

[Prior Art] Terminals are crimped onto conductive wires using a crimping press. Conventional crimping presses take many forms, but most often include at least one fixed tooling element, or anvil, and at least one movable tooling element, or punch.
The fixed element and the movable element cooperate with each other to securely crimp the terminal onto the conductor. The movable element may be hydraulically or pneumatically powered, or may include an electromechanical motor with rotary cam means for repeatedly driving the movable tooling element.

Conventional crimping presses also include means for directing the terminals and/or conductors into position relative to the tooling of the crimping press.

That is, a large number of terminals are mounted on a carrier strip that facilitates feeding the terminals one after the other into a crimping press. Conductive wires are also sent close to the touring. Once the terminal and conductor are properly positioned relative to each other, a crimping cycle begins to crimp the appropriate portion of the terminal around the determined portion of the conductor.

The degree of automation continued to vary in prior art crimping presses.

Many prior art crimping presses require the conductor to be bristled into position relative to the terminal; once the conductor and terminal are properly positioned relative to each other and to the anvil, the operator must actuate a foot pedal to crimp the wire. Press to punch - complete the cycle. Other prior art crimping presses include sensing means that actuate the crimping press punches in response to sensing proper positioning of the end of the conductor relative to the crimping press punches. . Still other prior art crimping presses include suitable means for feeding, cutting, stripping, and positioning the conductive wire for self-termination into terminals that can be crimped.

The quality of the crimp termination affects both the durability and quality of the electrical connection.

That is, as stated above, proper crimping will help relieve strain and ensure that normal insertion and removal forces exerted on the terminated conductor will not damage the electrical connection; Affects the electrical ability of conductors and terminals. There should be no voids at the ends to ensure proper electrical operation, but applying too much crimp force can significantly reduce the cross-sectional area of the conductor near the crimp, thereby causing influence the strength and current carrying capacity of the

The quality of crimp terminations is affected by many factors; for example, crimp press tooling is subject to wear due to the significant crimp forces exerted during termination operations. Because of wear on the crimping press tooling, the opposing dies no longer fit together at the end of their mutual movement. Thus, tooling wear progressively increases the crimp height. Higher crimp heights cause terminations to fail with lower pull-out forces and reduce crimp quality by creating voids within the terminations. In some cases, the crimp height may be too low for the conductor and terminal, which may occur when the crimp tooling is replaced or the crimp press is adjusted in any way. A crimp height that is too low will reduce the current carrying capacity discussed above and may break some of the loose wires.

Unacceptable quality terminations occur even more in highly automated prior art crimping presses.1 For example, improper feeding of terminals or conductors can result in multiple terminations on a single conductor. There is.

This can cause damage to expensive tooling and significant downtime on the crimping press, and may result in the crimping cycle being completed without the NA being properly fed into the crimping press. - It may be necessary to crimp two terminals to two conductors, or to crimp one terminal to a combination of at least one conductor and a grounding clip.

Improperly feeding one of the conductors or the grounding clip can result in an unacceptable product that is not known until later in the manufacturing or assembly process.

Some quality assurance is required due to the risk of unacceptable termination. In less automated crimping operations, quality assurance is provided by experts who inspect each end. This inspection is supplemented with a tensile test on the entire or extracted end of the sample. -Visual inspection becomes impractical in highly automated crimping operations. In such cases, great reliance is placed on time-consuming destructive tensile tests, and the prior art has very complex and expensive optical scanning equipment to assess the quality of the crimp terminations. Optical scanning is shown in US Pat. No. 4.555.799, issued to Kodama et al. on November 26, 1985. The device of this US patent; No. 6 evaluates the profile of a crimp end and optically compares the profile to an acceptable optical profile for that particular crimp end.

This complex and expensive device is far from foolproof; the crimp ends will have a defined profile even if some of the multiconductor wires are not crimped, and even if fewer or more wires are crimped than the specified number. There is.

The punch and anvil of the crimping press are always subject to friction.
Accordingly, the user or owner of the crimping press should replace it periodically after a specified number of crimping cycles. The prescribed number of crimping cycles is determined based on the evaluation of the life of the crimping tool based on past experience with similar tooling. In many cases, if you do this, you may end up thinking that you don't need to replace it, or you may end up using it without replacing it even though you should.

It is known to use strain gauges in metal stamping equipment. Strain gauges operate on the principle that each cycle of the stamping machine causes a slight deformation of the various structural members of the machine. Typical strain gauges use transducers mounted at selected remote locations on the stamping device. This transducer is connected to means for measuring the voltage developed therein.

The voltage changes proportionally in response to dimensional changes that occur during operation of the stamping device. For example, many strain gauges use piezoelectric crystals connected to the strain gauge's transducer. The voltage across a piezoelectric crystal changes proportionally to its changing dimensions. Strain gauges for these purposes can be purchased from International Measurement and Control Company (IMCO) of Frankfurt, Illinois.

The strain gauges described above are used in stamping operations to sense irregular movements of the stamping machine and to determine whether the hardness of the material handled by the stamping machine deviates from a specified hardness. Examples of prior art strain gauges for these purposes are Reissue Patent No. 3.257°652, issued to Koehler on June 21, 1980, and U.S. Pat. 257.
652. A general explanation of strain gauges and their construction was published on September 29, 19535f.
U.S. Patent No. 2.654.0 granted to Barr Jr.
No. 60, and U.S. Pat. No. 3,853,000 to Barnett et al.

[Problems to be Solved by the Invention] Accordingly, an object of the present invention is to provide an apparatus and method for evaluating the quality of a crimp termination.

Another object of the present invention is to provide an apparatus and method for producing high quality crimp terminations over a long life of crimp tooling.

Yet another object of the present invention is to provide an accurate crimp quality evaluation apparatus and method using manual crimp equipment and techniques.

Yet another object of the present invention is to provide an apparatus and method for automatically adjusting crimping tooling to compensate for wear and tear.

SUMMARY OF THE INVENTION The present invention provides a method for evaluating the electrical performance of crimp terminations of conductive terminals to conductive wire, and for evaluating the performance and wear of crimp tooling that completes such electrical terminations. The apparatus of the invention includes means for measuring the forces experienced by and/or exerted by the punches of the crimping press during the crimping scan. These forces are measured by strain gauges attached to or integrated into the crimping press. The strain gauge includes a transducer attached to the crimping press by a plurality of spaced attachment means. Strain gauges convert dimensional changes within the transducer into electrical signals. That is, the strain gauge includes piezoelectric means within the strain gauge's transducer. The voltage of the piezoelectric means changes proportionally to the change in size.

Strain gauges or other such force measuring devices should be
For example, a press subjected to a force on the order of 10,000 pounds per square inch will experience a dimensional change of about 400 microinches, which the force sensing of the present invention will recognize. It can be detected by means.

The strain gauge or other such force measuring device is connected to an interface circuit, which circuit is connected to control means such as a microprocessor and a suitable display device.

This display provides a visual indication of the maximum measurement due to strain occurring during each crimp scan.

The device of the invention also includes crimp height adjustment means.

Crimp height is the height at the end of the crimp cycle.
The crimp height adjusting means includes means for adjusting the crimp stroke or the length of the cam means for adjusting the relative position of the crimp punch and the anvil. Cam refers to at least one wedge cam that slides relative to a ram or other drive means of the crimping press.

The apparatus and method of the present invention includes a control means for comparing the measured crimp force with a range of allowable crimp forces for a particular crimp height. (5) and using control means.

The control means comprises a microprocessor or computer connected to the strain gauge or such force measuring device by suitable interface circuits.

The control means further comprises display means for presenting the measurement data in a readable form. This control means is also connected to the crimp height adjustment means. For example, the control means of the apparatus of the present invention may
Data is received and compared for both the strain measured by the strain gauge and the crimp height set by the crimp adjustment means.

The crimp force data and crimp height data are based on the method of the present invention and H'R.
and are employed to evaluate the quality and predictive electrical performance of crimp terminations. That is, it has been found that the performance of a crimp termination can be accurately determined as a function of crimp force at crimp height. I can become This extrusion defect can be recognized by a force lower than the specified crimp force for its specified height. Conversely, two conductors are accidentally fed into a single terminal and crimped to the specified height. There is. However, in this case, the crimping force is considerably greater than the specified crimping force.

In both of these cases, the crimping force is greater than the specified
or in response to a sensed condition in which a small crimp force is simply measured by a strain gauge or other such force measuring device and is identified by the control means to indicate that the crimp termination is unacceptable. A fail signal is issued to indicate defective termination.

Variations in crimp force and/or crimp height are obvious defects in the termination process, e.g. not feeding conductors or terminals,
It does not indicate that the crimping tooling has been sent too many times, but rather that unacceptable termination is likely due to progressive wear of the crimp tooling. This wear and tear on the crimp tooling gradually increases the crimp height and reduces the crimp force.

Wear of the crimp tooling is continuously monitored by the apparatus of the present invention. Thus, the apparatus of the present invention can monitor the gradual departure of the crimp end from a defined range of acceptable crimp force and crimp height. The apparatus of the present invention also includes means for generating an adjustment signal as the crimp termination progressively moves toward unacceptable crimp force and crimp height. Alternatively, the part of the device that measures the crimp force is connected to the crimp adjustment means, and the position of the punch and anvil of the crimp tooling or the length of the crimp stroke is adjusted so that the crimp end is at the center position within the specified range of the measurement data. 0
The I11 control of the apparatus of the invention stores a number of adjustments and/or magnitudes of crimp tooling adjustments and provides tooling change signals when further adjustments are not permissible and when tooling requires repair and/or replacement. occurs.

The apparatus of the present invention is capable of producing proper reports indicating crimp termination quality and/or crimp tooling adjustment trends and crimp tooling life.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A typical prior art crimping press, generally indicated at 10 in FIG. It is sequentially sent to an anvil 16 equipped with appropriate tooling.

The crimping press 10 includes a ram I8 having a punch tooling 20 attached thereto. The action of an electric motor 21, hydraulic or pneumatic device which exerts a crimping force on the tooling attached to the anvil 16 drives the ram downwardly towards the anvil 16.

The crimping press 10 is employed with sequentially advancing conductors (not shown) aligned with the terminals of the five strips 14. Once the conductors and terminals are properly positioned relative to each other and the anvil, the ram 18 is actuated to force the punch tooling 20 toward the anvil 16.

The crimping press 10 has a pressure of 10 per square inch per crimping operation.
．． Generates the power of 000 bonds. The force generated by the rapid movement of ram 18 creates a reaction force on the crimping press frame. That is, as shown in FIG. 2, a first section 24 of the prior art crimping press 22 experiences compression and a second section 26 thereof experiences tension as a result of the crimping cycle. The magnitude of the compression and tension varies proportionally with distance from line 28, as shown in FIG. 2, where the area of the frame of the crimping press 22 which is subject to neither compression nor tension is indicated by dashed line 22. Maximum compression is at the rear of the crimp press 22 frame.

The crimping press of the present invention is shown generally at 30 in FIG. Crimping press 30 is substantially the same as crimping press 10 of FIG. However, in the crimping press 30, 32
An adjustment tooling assembly is provided as shown in
Its details are shown in Figure 4.5, namely the crimping press 3
0 includes first and second independently adjustable bunch dies 34 and 36, respectively. The bunch 34 is used to crimp the tip of the terminal to the portion of the conductor wire from which the insulation coating has been stripped. When crimped with the punch 34, the terminal is electrically connected to the conductor of the covered conductor. Bunch 36 defines a large crimp height and crimp the rearwardly disposed portion of the terminal to the coated insulation area of the coated conductor. The crimp created by the punch 36 contributes to strain relief at the end and high pullout force.

The punch dies 34, 36 are independently adjustable to vary the individual portions of the crimp height. That is, the tooling assembly 32 includes a first nm cam 38 for height adjustment of the tooling 34 and a second nm cam 38 for height adjustment of the tooling 36 relative to the fixed anvil shown at numeral 42 in FIG. cam 40. stepper motor 48.50
Install H adjustable cams 38, 40 to drive rods 44, 46 attached to. Motor 48.50 is No. 4.5
Although not shown, it is connected to control means shown in FIG. Control means 52 as explained later
generate electrical signals to drive the motors 48, 50, respectively, the rods 44, 46, and thereby the cams l'13g, 46, respectively. Inclined cam l'J! ! 3
The relative position of g and 40 changes the height position of the punch die 34 and 36 with respect to the anvil 42. (5) The crimp height is changed accordingly. Controller 52 also receives signals from elsewhere in crimp press 30, as described herein, and they generate signals that control crimp adjustment motors 48,50.

See Figure 3. The crimping press 30 includes a strain gauge 54 mounted to the rear surface 56 of the crimping press 30. The strain gauge 54 shown in Figure 6.7 includes a top mounting blanket 58, a bottom mounting blanket 60, and a transducer 62 mounted therebetween.

Wire glues 64,66 are attached to terminals 68,70 which are separately attached to the L of transducer 6z. Conductors 64,66 extend to controller 52, which conducts current through conductors 64,66 and through transducer 62. The piezoelectric means included in the transducer 62 is attached to the mounting blanket 58.
and 60 in response to a slight dimensional change between terminals 68 and 7.
Change the voltage between 0 and 0 proportionally. A preferred strain gauge for this purpose is sold by International Measurement and Control Company (IMCO) under the name Ton Limit Detector. controller 52
stores the maximum strain value measured by the strain gauge 54.

The use of strain gauge 54 and crimp height adjustable tooling assembly 32 in crimp press 30 is illustrated in Figures 8-11. That is, FIG. 8 shows the results of a test in which the strain was determined to be 1 lllll at three different crimp height settings on the crimp press. The actual crimp height was measured with a micrometer for each crimp. Line 72 in FIG.
It represents the measured strain versus pressure stone height distribution. What was found within each group was that the distribution around the mean value was very dominant, such that the strain measured during the crimp operation was a good indication of the actual crimp height. . Other similar tests were conducted on crimp terminations where the specified crimp height must be between 0.080 and 0.084 inches. It was determined that for these crimp height ranges the piezoelectric voltage output was between 42 and 44 volts. Figure 9.10 shows a test comparing the piezoelectric voltage output with a standard prior art crimp quality measurement, i.e., Figure 9 compares the piezoelectric voltage output (in volts) to the relative difference of the void. It is compared to the measurement of existence. The vertical line in Figure 9 is
Indicates the minimum and maximum range of piezoelectric output corresponding to the specified range of crimping. By changing the crimp height of the press, we reached the continuation of the downward distortion. The crimp these readings create is then analyzed to determine the relative absence of voids. Piezoelectric output values below the value corresponding to the permissible crimp height range indicate the absence of void reduction,
In other words, this indicates that the number of voids has increased, which indicates that the electrical performance of the termination is poor. Figure 1O compares the piezoelectric output to the tensile force. That is, the test pull force that produced a piezoelectric output within the specified range was greater than 110 pounds, which is the minimum standard pull force for this type of termination.

FIG. 11 is the same as FIG. 8, but the data is well clustered around the average value. This figure shows how to use the relationships described for apparatus 30 described with reference to Figures 3-7. That is, the collection of data indicated by the number 80 in Figure 10 shows the distribution of distortion and crimp height that may be present in a crimp press with new tooling; as the tooling begins to wear, the crimp height increases; The average strain sensed by the strain gauge 54 then moves to a lower level indicating wear on the tooling. 52, controller 52 generates appropriate signals to indicate the need for tooling adjustment or replacement. The signal generated by the controller 52 shown in FIG.
8 and/or 50 and adjust tooling 34.36. That is, the motor 48.50 drives the rod 44.
and/or 46 proceed in a straight line, so that by adjusting the repositioning of each cam wedge 38 and/or 40, the average distortion is the minimum allowable without unnecessarily restricting the flow through the end. The first one that corresponds to the standard crimp height of
Return to near location 80 in diagram O. Controller 52 in FIG.
allows such adjustment of a specified number of times without close observation by the operator, but requires inspection and/or replacement of the tooling if the average strain falls to the minimum allowable average value of 82 after the maximum number of adjustments. Generates a tool change signal.

FIG. 1I shows the maximum and minimum allowable distortions. Values of distortion measured above these limits are rejected ignoring the ongoing evaluation of the average distortion. For example, distortions exceeding the maximum specification limit 84 shown in FIG. A tangled or damaged tool is shown in the crimping press 30.

This will immediately generate a rejection signal indicating that the termination is to be rejected and/or indicating that press 30 is to be terminated. Similarly, a reading below the minimum specification strain level of 86 indicates either a crimp that does not engage all strands of the conductor or the conductor or terminal is not being routed properly, as discussed above. As before, this immediately generates a rejection signal indicating the rejection of that termination conductor below the minimum specification strain, and possibly indicating the need to inspect the crimping press.

In short, a crimping press for crimping electrical terminations incorporates a strain gauge, a controller connected to the strain gauge indicates the strain for each crimp, and calculates the average strain over a predetermined number of IDNL series. A reading above or below the specified range will generate a rejection signal that rejects the terminal. The controller generates a fii requesting inspection of either the rejected terminal or the crimp press tooling. As the touring gradually wears out, that! The tooling average moves towards the minimum acceptable average; when the minimum acceptable average is reached, a signal is generated indicating the need to adjust the tooling.

The crimping press includes tooling and il# adjustment means.

The tooling adjustment means is connected to the controller and automatically adjusts the crimp height when the average strain reaches a minimum allowable average value. The controller generates a signal after a selected number of crimp adjustments or after an adjustment is made to equalize the selected distances.

Although preferred embodiments of the invention have been described, it will be obvious that various modifications may be made within the spirit of the invention.

Force measuring means other than piezoelectric strain gauges may be used to measure the force during crimping, and furthermore, the crimping press and the adjustment of the crimping height may take other forms than those shown.

[Effects of the Invention] As is clear from the above description, the present invention provides an apparatus and method for evaluating the quality of crimp terminations, and provides an apparatus and method for producing high quality crimp terminations over a long life of crimp tooling. is provided, and an apparatus and method for accurate crimp quality evaluation using available crimp equipment and techniques is provided;
An apparatus and method for automatically adjusting crimp tooling to compensate for wear and tear is provided.

[Brief explanation of drawings]

FIG. 1 is a front view of a prior art crimping press, FIG. 2 is a side view of a prior art crimping press, showing changes in internal forces at different locations of the crimping press, and FIG. FIG. 4 is a side view of a crimping press incorporating a force sensor according to the invention; FIG. 4 is a front view of a crimping tooling adjustment device according to the invention;
5 is a top view of the crimp tooling adjustment device of FIG. 4; FIG. 6 is a front view of the strain gauge attached to the crimp press; FIG. 7 is a cross-sectional view taken along line 6--6 of FIG. 8 Figure I: l-
Q! is a graph showing a comparison of strain vs. crimp height, Figure 9 is a graph showing a comparison of crimp end voids vs. strain, Figure 10 is a graph comparing pullout force vs. strain, and Figure 11 is a graph comparing Figure 8. FIG. 3 is a similar graph but showing different data. io, crimping press 12, reel 14, strip 16, anvil 18, ram 20, punch tooling 21 8. Electric motor 22, Prior art crimping press 308, Inventive crimping press 32, , I-alignment tooling assembly 34, 36
．． ,,, punch die 38.40. ,, Adjustment cam 42, , Anvil 44.46. , , Rod 48.50 , Stepper motor 52 , , , 1171111 Means 54 , ,
Strain gauge 58, Bracket 68.70. , terminal

Claims (1)

[Claims] (1) A crimping press for crimping a conductive terminal to a conductor,
a frame; an anvil mounted to the frame and having means for receiving at least one electrically conductive terminal and at least one electrical conductor; and an anvil that is moved relative to the frame and the anvil to crimp selected portions of the terminal and engage the electrical conductor. a force measuring means that is attached to the crimping press and measures the maximum force generated in the crimping press in each crimping cycle; and a force measuring means that is connected to the force measuring means and allows the measured force to be A crimping press comprising: control means for comparing a force within a range and generating a signal in response to a force outside an acceptable range. (2) The crimping press according to claim 1, wherein the force measuring means is attached to a frame of the crimping press. (3) The pressure bonding press according to claim 1, wherein the force measuring means includes a strain gauge. (4) The crimping press according to claim 1, wherein the strain gauge includes piezoelectric means for converting changes in dimensions of the crimping press into electrical signals. (5) the control means includes averaging means for calculating an average force for a selected number of crimping cycles; the control means compares the average force to a minimum allowable average force; and the control means compares the average force to a minimum allowable average force; 2. The crimping press of claim 1, wherein the crimping press generates a signal, whereby the adjustment signal indicates a need for adjustment of the crimping tooling to compensate for wear on the crimping tooling. (6) further comprising crimp height adjustment means for adjusting the height of the termination, the adjustment means being connected to a control means, the control means further generating a signal causing adjustment of the adjustment means; The crimping press described in . (7) A crimping press according to claim 6, wherein said adjusting means comprises motor means for making the adjustment, said motor means being connected to control means. (8) The pressure bonding press according to claim 6, wherein the adjusting means includes means for adjusting the position of the punch with respect to the anvil. (9) An insulating punch for crimping the first portion of the terminal to the insulation coating of the conductor wire, and a conductor punch for crimping the second portion of the terminal to the conductor of the conductor wire, and the crimp height adjusting means is adapted to respond to a signal from the control means. 9. The crimping press of claim 8, wherein the positions of the insulating punch and the conductive punch are independently adjusted in response. 10. The crimping press of claim 1 further comprising visual display means connected to said control means for producing a visual indication of the force sensed by said force sensing means. (11) placing at least one terminal on the crimping press;
A method for determining the quality of a crimp termination of a conductive terminal to a conductive wire comprising the steps of placing a conductive wire proximate the terminal and activating a crimping press to engage a selected portion of the terminal with the conductor. Measures the maximum force generated in the crimping press during the operation of crimping, compares the measured maximum force with the maximum force within the permissible range, and issues a rejection signal if the maximum force measured is outside the maximum force within the permissible range. A method characterized by occurring. (12) Measure the maximum force generated in the crimping press during the selected number of consecutive operations of the crimping press, and store the value of the force measured during the selected number of continuous operations of the crimping press; average the force measured during the number of crimp cycles, compare this average value to a tolerance average value, and generate an adjustment signal in response to the measured average value being outside the tolerance range for the average crimp force. 12. The method according to claim 11. 13. The method of claim 12, further comprising the step of: automatically adjusting punch movement in response to the measured average force being outside an acceptable range of average values. 14. The method of claim 13, further comprising counting the number of adjustments automatically made to punch movement and generating a tool change signal after the selected number of adjustments.