EP1211761B1 - Method and apparatus for determinating the quality of a crimped connection - Google Patents

Description

The invention relates to a method and a device for determining the quality of a crimp connection between a conductor and a contact, the device having a Crimp force generated by means of which the contact with the Ladder electrically and mechanically insoluble connectable.

The term "crimping" is internationally established and determined by standardization. In practice, however, will be also expressions like pressing, bruising, striking or Applying used. By crimping one understands the Production of a non-releasable electrical and mechanical connection between a conductor and a Contact. During crimping, the material to be joined becomes plastic, permanently deformed. In doing so, if present, poorly conductive surface layers broken up what the electrical conductivities favored. Correct crimping also prevents this Penetration of corrosive media even under difficult Operating conditions such as temperature changes or vibration.

The aim of crimping is to produce a good one mechanical and electrical connection in the long run qualitatively unchanged.

For crimping contact-specific crimping tools used with a fixed crimp anvil down and vertically displaceable crimp punches above. (FIGS. 1 to Fig. 3). In the crimping tool are the wire crimper and the Insulation crimper mounted, which mostly over Grid discs with different height cam independently from each other in the vertical direction to the wire diameter or insulation diameter can be adjusted. These Settings directly affect the quality of the Crimp.

With open crimp contacts (FIGS. 4 and 5), the Conductor feed above the contact. The before stripped conductors are commonly used by vending machines simultaneously in the radial and axial direction with respect to the Contact correctly positioned for the crimping process. By the downward movement of the crimping die becomes the first Head over a mechanism in the upwards opened Wire and insulation crimping claws lowered, then begins the actual crimping process with forming the tabs according to the crimping die shapes. After the stroke of Crimp stamp, the crimp has the desired form-pressing. (Fig. 5), in turn, from the contact plate used, from Wire cross section, from the copper of the wire and the Stripping is dependent. For closed contacts must after radial alignment axially into the tube retracted molded crimping.

A sectional view of a faultless running Crimp connection shows the original single round Litz wires of the conductor compact to polygons against each other pressed. The inner surface in the crimp area of the contact shows deformations of the contact points of the individual strands. When wire crimping all individual wires must be included. At the the front end of the wire crimps must have the individual wires each protrude after cross section about 0.5 mm and may not disappear in the crimp. In between wire crimp and Isolation crimp lying windows must be ladder and Conductor insulation visible. The insulation crimp must be the Enclose isolation without entering it.

Important criteria for the evaluation of a Crimp connection are the crimp shape, the crimp height and the Drahtausreiss strength. These types of criteria are suitable but only when setting up the crimping machine and during the Production by sampling. To the today Quality requirements for all crimp connections too Sufficient means must be available, which over each Crimp connection during crimping Crimp data record, evaluate, save and result-oriented Machine data. To judge the Crimp connection (without mechanical destruction of the Crimped) is the crimp force in relation to Crimping path or set at crimping time. With appropriate Evaluation of the crimp data can be the goodness of a Crimp connection can be reliably assessed.

A method and a device for assessing the Quality of a crimped connection must be crimped as wrong Insulation crimp height, wrong wire crimp height, not detected strand wires at wire crimp, wrong or none Stripping length, incorrect insertion depth or stripping Detect cut stranded wires and corresponding Generate error messages.

The application EP 0 460 441 discloses a method for Detection of missing strands or of crimped ones Conductor insulation in a crimp connection using the Crimp force history has become known. During one Crimping processes are value pairs consisting of crimping force and position of the crimper are measured and stored. The during the production of a crimped connection measured value pairs yield the crimp force curve of the Crimping with the crimping force in dependence of Position of the crimping die. The curve section with strong Force increase is linearized and a point from the mean the minimum and maximum crimp force determined. The point is compared with a reference value. If the point within a predetermined deviation from the reference value is the crimp connection of acceptable quality. In the evaluation of the Crimpkraftverlaufes the Crimping process will also increase the maximum crimping force taken into account. If the maximum crimping force over If a reference value deviates too much, the Crimp connection rejected as unusable. The point in the curve section with strong force increase and the maximum crimping force provides information about missing strands or via crimped conductor insulation in the Crimp.

In a marketable crimping press detects a force sensor during the crimping process the force, in digital form is stored as a force-dependent curve. This is compared with a reference curve. Depending on Size of the deviation from the reference is based on the type of Crimpfehlers closed.

A disadvantage of this device or in this method is that despite large computer, memory and Computational effort no differentiated statement about the Quality of the crimp connection is possible.

The invention aims to remedy this situation. The invention, as characterized in claim 1 solves the task to avoid the disadvantages of the known device and a method and a device with improved To create error sensitivity.

The advantages achieved by the invention are in essential to see that with the better Resolution of the error an increase in quality is possible that with the more sensitive fault diagnosis less waste arises and that consequential errors, such as a breakdown a passenger car because of loose contact in one Plug connection can be avoided.

Fig. 1 bis Fig. 3

eine schematische Darstellung eines Crimpvorganges,

Fig. 4

eine Crimpverbindung zwischen einem Leiter und einem Kontakt,

Fig. 5

Einzelheiten eines Drahtcrimps,

Fig. 6

eine Crimppresse mit einem Crimpsimulator zur Kalibrierung eines Kraftsensors,

Fig. 7

den Crimpsimulator mit einem Stempel in der unteren Totpunktlage,

Fig. 8

den Crimpsimulator mit dem Stempel in der oberen Totpunktlage,

Fig. 9

Einzelheiten des Crimpsimulators,

Fig. 9a

einen Spannungs-Crimpkraftverlauf des Kraftsensors,

Fig. 10 und Fig. 11

Einzelheiten des Kraftsensors,

Fig. 12

Einzelheiten einer Pressensteuerung,

Fig. 13 bis Fig. 15

den Verlauf der Crimpkraft bei unterschiedlichen Crimpfehlern,

Fig. 16

den Crimpkraftverlauf mit einer Zoneneinteilung,

Fig. 17

Zonenabhängige Mess- und Rechenwerte und

Fig. 18a bis Fig. 18c

Grenzwerte für Fehlertypen.

In the following the invention will be explained in more detail with reference to drawings showing only one embodiment. Show it:

Fig. 1 to Fig. 3

a schematic representation of a crimping process,

Fig. 4

a crimp connection between a conductor and a contact,

Fig. 5

Details of a wire crimp,

Fig. 6

a crimping press with a crimping simulator for calibrating a force sensor,

Fig. 7

the crimp simulator with a punch in the bottom dead center,

Fig. 8

the crimp simulator with the punch in the top dead center position,

Fig. 9

Details of the crimp simulator,

Fig. 9a

a voltage crimp force curve of the force sensor,

10 and FIG. 11

Details of the force sensor,

Fig. 12

Details of a press control,

FIGS. 13 to 15

the course of the crimping force at different crimping errors,

Fig. 16

the Crimpkraftverlauf with a zoning,

Fig. 17

Zone-dependent measurement and calculation values and

Fig. 18a to Fig. 18c

Limits for error types.

Figs. 1 to 3 show a crimping process in which the end a conductor 1 is connected to a contact 2. A open crimping zone 3 of the contact 2 has a first Double lug 4 for the insulation crimp 5 and a second Double lug 6 for a wire crimp 7 on. Fig. 1 shows Crimping dies 8, 9 in the top dead center, the end of Conductor insulation is in the first double lug 4 and the stripped conductor piece lies in the second double lug 6. As shown in Fig. 2 when lowering the Crimping ram 8, 9 the double lugs 4, 6 means wedge-shaped recesses 10 of the crimping dies 8, 9 pressed against each other. The edition is an Ambos 9.1. A dome-shaped upper end of the recess 10 is the Double lug 4, 6 together with the conductor insulation or the Conductor wire the final shape. Fig. 3 shows the finished Crimped connection with the insulation crimp 5, in which the first double lug 4 is pressed around the conductor insulation 11 and with the wire crimp 7, in which the second double tab 6 is pressed around a conductor wire 12.

FIG. 4 shows an error-free crimp connection in which a window 13, the insulation 11 of the conductor end 1 and the Individual strands of the conductor wire 12 are visible. At the contact-side end of the wire crimps 7 are the Individual strands visible again.

Fig. 5 shows how a fault-free Drahtcrimp 7 the second double tabs 6 with the trained as a stranded wire Conductor wire 12 are squeezed.

In FIGS. 6 to 12, 14 is a stand without right Sidewall designated at which a motor 15 and an am Stand 14 mounted gear 16 is arranged. Moreover 14 first guides 17 are arranged on the stand, where a crimping rod 18 is guided. One from the transmission 16 driven shaft 19 has at one end an eccentric pin 20 on the other end is a resolver 21 for detecting the Angle of rotation coupled. The Crimpbär 18 consists of a in the first guides 17 guided slider 22 and out a tool holder 23 with force sensor 23.1 and holding fork 24. The slider 22 is in loose connection with the Eccentric pin 20, wherein the rotational movement of the Eccentric 20 in a linear movement of the slider 22 is implemented. The maximum stroke of the slider 22nd is determined by top dead center and bottom dead center of the Eccentric 20 determined. The tool holder 23 is actuated Usually a tool that works together with a for Tool belonging anvil 9.1 the crimp connection manufactures. To calibrate the force sensor 23.1 is a crimping simulator 25 is used instead of the tool. By means of an adjusting screw 26, the stroke can be precise to be adjusted. As interface between operator and Crimping press is an operator terminal 27 is provided. to Input of operating data and commands to a controller 28 the operator terminal 27 has a rotary knob 29 and a Keyboard 30 on and to visualize data is one Display 31 is provided.

FIGS. 7, 8 and 9 show details of the crimping simulator 25 for calibration of the force sensor 23.1. One in one Tool housing 32 guided punch 33 has a Carrier head 34 which in loose connection with the Holding fork 24 of the tool holder 23 is. On one foot 35 of the tool housing 32 is for example by means of a Screw 36 a base plate 37 attached, the one Load cell 38 carries. The power of the punch 33 is via an intermediate piece 39 on the force transducer 38th transfer. The intermediate piece 39 is elastic and has the Consequence that in the calibration of the force increase in time is stretchable. The force transducer 38, for example a Quartz force transducer, is expensive, calibratable and has a very linear characteristic. The built-in tool holder 23 Force sensor 23.1 is cheaper and has a bigger one Linearity error. For calibration of the force sensor 23.1 is the stamp 33 from the top dead center in the bottom dead center and back to the top dead center moves and a force in the course and in the order of magnitude a real crimping generated. It is the Force progression simultaneously and exclusively depending on Force sensor 23.1 and detected by the force transducer 38 and stored, wherein the force transducer 38 the calibratable Force history detected. This is also a force calibration at Force sensor 23.1 possible. The force curve and the through the nonlinearity of the force sensor 23.1 conditional Force deviations from the measured force curve of Force transducer 38 are detected and in one Correction table filed. After the calibration process is the Crimpsimulator 25 removed and the usual Crimping tool used. If the force sensor 23.1 is replaced, the calibration process must be repeated. For measuring the crimping force in the production of Crimp connections satisfies the force sensor 23.1, because of Force sensor 23.1 is calibrated and by the Nonlinearity of the force sensor 23.1 conditional Measurement deviations corrected by means of the correction table become. That way, having a cheap, in itself inaccurate force sensor of the crimp force curve accurate and be absolutely determined. Another advantage is that a Manufacturer of crimp connections for its usually consisting of several identical crimping presses Machinery just an expensive crimping simulator for the Calibration of all crimp presses needs.

Fig. 9a shows a voltage Crimpkraftverlauf the Force sensor 23.1. On the vertical graph axis is the Voltage U, for example in Volts and on the horizontal diagram axis is the crimp force CK, for example, in kilonewtons. With undressed Line is the nonlinear voltage curve of the Force sensor 23.1 shown. The broken line shows the linear voltage curve of the crimping simulator 25. In a calibration process, for example, one hundred Force values the respective associated voltage differences between solid line and broken line detained and in the above correction table as Power / voltage value pair stored. In the production of Crimp connections become the corresponding force values read the correction table and the respectively associated Voltage differences to the corresponding current added voltages.

Fig. 10 shows the force sensor 23.1, as in the Tool holder 23 is installed. Fig. 11 shows the Individual parts of the force sensor 23.1. The force sensor 23.1 consists of a sensor housing 40 with an example plastic existing bottom 41 and cover 42. The Inside the bottom 41 and the lid 42 are provided with a electrically conductive layer, for example one Copper layer 43, laminated. The layer 43 of the floor 41 is by means of a lead wire 44 to the inner conductor a connection socket 45 connected. The case of the Socket 45 is directly connected to the coating of the Cover 42 connected. The sensor housing 40 has one Plastic existing intermediate bottom 46 with lesser Thickness than the sensors 48, on the recesses 47th are arranged, the holder of the sensors 48, For example, piezo ceramic discs serve. The at Calibration or crimping on the lid 42 exerted force is exclusively on the sensors 48 and transferred from these to the ground 41. The pressure on the sensors 48 generate an electrical charge which is at the Socket 45 is measurable.

Fig. 12 shows details of the controller 28 for the Crimping press. One at the entrance with a net filter 49 Equipped Converter 50 puts the mains voltage in one DC voltage at which an inverter 51 is fed. Controlled semiconductor switches Gu ... Gz of the inverter 51 chop up the DC voltage in one Pulse width modulation method in three pulsed AC voltages in the motor 15, for example, a Asynchronous motor ASM, sinusoidal currents of variable frequency produce. The rotational movement is from the engine 15 to the Transmission 16 and then transferred to the shaft 19, at the one end of the eccentric pin 20 and at the other end the resolver 21 is arranged. The eccentric pin 20 puts the crimping rod 18 in a linear motion. One Pulse generator 52 generates in function of a Sollgeschwindigkeitsverlaufes that for the control of Semiconductor switch Gu ... Gz necessary pulse pattern, the a driver stage 53 is fed to the output with the control lines of the semiconductor switches Gu ... Gz connected is. A computer 54 controls all the functions of Crimping press. For the exchange of data between the computer and the peripheral modules is the bus system 55 to Available. An automatically different Network adaptive power supply 56 also generates the necessary for the operation of the controller 28 Auxiliary voltages.

A battery-backed write-read memory 57 is used for Calculator 54 as a working memory. In a read memory 58 the program for controlling the crimping press is stored. Other machines involved in the crimping process, such as for example, conductor feed or contact feed, Control devices, safety circuits, etc. are with the Reference numeral 59 denotes and communicate for example, for synchronization via bus system 55 with the Control 28. The control terminal 27 is by means of a serial interface 60 connected to the computer 54. If the crimp press to a parent Kabelkonfektioniereinheit 63 heard takes place the Communication of the controller 28 with the assembly unit 63 also via the serial interface 60. A Evaluation unit 61 detects the measured values of the force sensor 23.1 and the force transducer 38 and processes the Measurement data as shown above.

At the operating terminal 27 menu-guided user-specific Data such as password, language, units, etc., operation-specific data such as acceleration, deceleration, Frequency of the motor, position points along the stroke to the Synchronization of the peripherals involved in the crimping process Machinery and equipment are entered. Moreover can access system information via operating terminal 27, service-relevant data, statistical evaluations, Log data of the communication, drive data etc. be accessed. Operating modes such as calibration of the Starting position of the crimping rod 18, calibration of the Force sensor 23.1, Einrichtbetrieb to specify the for the respective tool necessary stroke, triggering a one-time crimping process for testing the crimped connection, Crimping with intermediate stop for positioning the Contact and subsequent pressing of the contact, Crimping with preselected stroke, etc. can also menu guided via operating terminal 27 of the controller 28 given, wherein the Crimpbär 18 and thus the Crimping tool can be positioned by means of knob 39.

The resolver 21 used in the crimp press serves the Measurement of angular positions. He delivers an absolute Signal per revolution and is insensitive to Vibration loads and temperature. Because of his Mechanical construction also maintains its angle information received in case of power failure. The resolver 21 consists of a stator and a driven by the shaft 19 Rotor. At the stator is a first stator winding and a second stator winding and a rotor winding on the rotor arranged. The rotor winding is replaced by a Alternating voltage U1 with constant amplitude and frequency, For example, 5000 Hz excited. The second stator winding is shifted from the first stator winding by 90 ° arranged. By electromagnetic coupling generates the AC voltage U1 at the terminals of the stator windings the both voltages Usin or Ucos. These two tensions have the same frequency as U1. The amplitude is however proportional to the sine or cosine of the mechanical Deflection angle . The supply of the rotor winding takes place via an oscillator. For a resolver with a pole pair goes through the amplitude of the two voltages Usin and Ucos one sinusoidal oscillation per mechanical one Revolution. A resolver interface 62 evaluates that Sine signal and the cosine signal of the resolver 21 with for example, a resolution of 0.35 ° and converts the angle  to a digital value.

Fig. 13 to 15 show the course of the crimping force of a typical contact family at different Crimpfehlern. On the vertical graph axis is the Crimping force is CK and on the horizontal graph axis the time, the deflection angle or the Crimpweg applied. The Crimpweg CW is the deflection angle  of Resolver 21 derived. The curve with a solid line is one out of, say, ten faultless crimps determined and the mean of these crimping forces representative reference curve. With broken line shown is the force curve of a faulty Crimping.

Fig. 13 shows the force curve of a crimping, in the Drahtcrimp 7 three of nineteen single strands of the Conductor wire 12 is missing. The three individual strands are either pushed back when positioning the conductor been and / or cut off during stripping. In a first zone Z1 of the force curve, which is about the Closing operation of the double tabs 4, 6 reproduces lie the reference curve and the faulty crimp curve on each other, which is represented by the sign + -. In a second zone Z2 of the force curve, which is about the Pressing the first double lug 4 in the conductor insulation 11 and the pressing of the second double lug 6 in the Conductor 12 reproduces, the values of the faulty crimping well below the reference values, what is represented by the sign ---. In a third zone Z3 of the force curve, which is about the final plastic deformation of the double lugs 4, 6 reproduces, the values of the faulty crimping are still something below the reference values, what about the signs is shown. The area to the right of the third zone Z3 reflects the force curve during the opening process of the tool. In this area, the curves cover largely independent of the error of crimping.

Fig. 14 shows the force curve of a crimp, in which the Conductor insulation 11 extends into the wire crimp 7. In the first zone Z1 and at the beginning of the second zone Z2, the Force curve of the faulty crimping a significant Elevation compared to the reference curve on what with the Sign ++++ is shown. The closing of the second Double lug 6 requires 11 more because of the conductor insulation Force.

Fig. 15 shows the force curve of a crimp, in which the Lead wire 12 only partially extends into the wire crimp 7. In the second zone Z2 and in the third zone Z3 is the Force curve of the faulty crimping clearly below the reference curve, what with the sign - or with the Sign --- is shown. The deformation of the Double lugs 4, 6 in case of incomplete filling Insulation crimp 4 and wire crimp 6 requires less force.

As mentioned above, the crimping force CK is determined by means of a Force sensor 23.1 measured. The crimping force CK divides into the crimping dies 8, 9 on.

Claims (6)

1. Crimping equipment for producing a crimping force, by means of which a contact is electrically and mechanically non-detachably connectible with a conductor, consisting of a drive (15, 16, 18, 19, 20) for a crimping tool, which is arranged at a tool holder (23), with at least one crimping die, a control (28), a transmitter (21) for determining a crimping travel (CW) and a force sensor (23.1) for determining the crimping force (CK), characterised in that the force sensor (23.1) can be loaded with the entire crimping force (CK), which is generated by the drive (15, 16, 18, 19, 20) in vertical direction, and is arranged above the crimping die.
2. Crimping equipment according to claim 1, characterised in that the force sensor (23.1) for determination of the crimping force (CK) has in vertical direction more than one sensor element (48), which sensor elements together produce an evaluatable signal.
3. Crimping equipment according to claim 2, characterised in that the sensor element (48) is a piezo element arranged between a base (41) and a cover (42) of the housing (40), wherein the inner side of the base (41) and of the cover (42) has an electrically conductive coating (43).
4. Crimping equipment according to one of the preceding claims, characterised in that a crimping simulator (25) is provided, instead of the crimping tool, for precise detection of the crimping force (CK) during a calibrating process serving for calibration of the force sensor (23.1).
5. Crimping equipment according to claim 4, characterised in that the control (28) comprises a correction table in which the force deviations, which are caused by the nonlinearity of the force sensor (23.1), compared with the force path measured by means of the crimping simulator (25) are filed and that the force sensor (23.1) can be calibrated to a force path by means of the crimping simulator (23).
6. Crimping equipment according to claim 5, characterised in that the control (28) comprises a correction device which during the crimping process linearises the crimping force path, which is measured by means of the force sensor (23.1), by way of the correction table.

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