EP2937953A1 - Method and device for manufacturing a crimp connection - Google Patents

Abstract

In a method for producing a crimped connection, first a cable end of a cable (3) is guided by means of a gripper (4) to a crimping press (2). For this feed movement of the gripper (4) is moved with an actuator in the axial direction along the cable axis (x). Thereafter, the cable end is connected to a crimp contact (9). During the crimping operation, the gripper (4) is moved to compensate for the elongation of the cable during crimping along the cable axis (x) of the cable (3) in a return movement (e), which takes place in the opposite direction to the feed movement.

Description

The invention relates to a method for producing a crimp according to the preamble of claim 1. Furthermore, the invention relates to a crimping device for producing such a crimp connection.

"Crimping" means the production of a non-releasable electrical and mechanical connection (crimp connection) by plastic deformation between a conductor and a crimp contact. Crimping devices are often part of Kabelkonfektioniervorrichtungen for assembling electrical cables, in which the cables cut to length, stripped and then brought with a crimping press crimp on the stripped conductor end of the cable. The known crimping devices contain cable grippers with which the cable ends are guided to the crimping press. Once the cable gripper has reached the final axial position over the crimp contact, it remains in an unaltered axial position until completion of the crimping operation and is lowered if necessary using a squeegee connected to the crimping press part. Such crimpers are for example from the EP 1 447 888 A1 known. Known crimping devices have been well-proven in practice for conventional cables containing copper conductors or strands. For reasons of cost and weight, electrical cables with aluminum conductors have been growing in popularity for some time now. Especially with the latter cables, crimping problems can occur with conventional methods and devices. For example, when crimping cables with aluminum conductors or strands, it is possible for the strand material to deform so strongly in the direction of the cable axis that the cable between the crimping location and the cable gripper buckles. This unwanted elongation of the cable can cause a permanent deformation of the cable.

It is therefore an object of the invention to avoid the disadvantages of the known and in particular to provide a method for producing a crimped connection and a crimping device with which the disadvantageous consequences of the unwanted longitudinal expansion of the cable during crimping can at least be reduced.

This object is achieved by a method having the features of claim 1. The method for producing the crimp connection comprises, as a first step, feeding the cable end to the crimping press. For the feeding process, a gripper is used, which detects the cable end and can move the cable along the longitudinal direction of the cable or in the direction of the cable axis. Depending on the design, the gripper can additionally perform a pivoting movement about a vertical axis of rotation. After completion of the feeding process, the cable with the preferably previously stripped cable end is in the correct axial position. Thereafter, the cable end is connected to the crimp contact, for example, by pressing a crimping part of the crimping press in the vertical direction. The fact that, during the crimping operation, the gripper is moved passively or actively along the cable axis of the cable to compensate for the elongation of the cable as a result of the plastic deformation of the conductor during crimping (ie, in the opposite direction to the aforementioned feed motion), the undesirable effects The elongation during crimping can be avoided in a simple manner. A kinking of the cable piece between the joint and the impact by the gripper can be practically eliminated.

For feeding the cable end to the crimping press, the gripper can be moved in the axial direction using an actuator. Suitable actuators mechanical, pneumatic or hydraulic systems in question. To compensate for the elongation of the cable during crimping, the actuator can be adjusted such that it allows a return movement corresponding to the length extension of the cable during crimping. By way of a corresponding control signal, for example, the actuator can be instructed to execute the return movement actively.

If an electric motor is provided as the actuator with which the gripper can be moved axially and with which a predetermined holding torque can be applied to the gripping head, it may be advantageous for the electric motor to be actuated in a compensation mode assigned to the return movement for allowing the resetting movement the holding torque is reduced. Thanks to the reduced holding torque, it is easily possible to effect a passive movement of the gripper in the opposite direction to the feed movement taking advantage of the longitudinal forces occurring in the cable by the conductor material deformations during crimping.

If the crimping device has a pneumatic cylinder as actuator, for example instead of an electric motor, it may be advantageous if the pressure in the cylinder is lowered, whereby a return movement of the gripper can be permitted to compensate for the length expansion.

For example, using a touch sensor or by way and / or time detection, a contact between the crimp contact and the movable pressing part of the crimping press can be determined. Alternatively, the crimp force could be measured using, for example, a force sensor. The compensation mode is started as soon as the contact between crimped contact and pressed part is detected or as soon as a predetermined value for the crimping force is exceeded.

According to a further embodiment, the gripper can be actively moved during the crimping process by activating a drive or another actuator to perform the return movement. This active mode of operation is particularly advantageous when very thin or less stiff cables are used, since the friction and inertial forces to be overcome for moving the gripper are too great and the cable could buckle despite the lowering of the previously described holding torque.

It can be advantageous if the gripper is moved by a predetermined compensation path. The compensation path can be determined by calculation. However, it is also conceivable to determine the compensation path as a test.

Preferably, the gripper is in comparison to the drive power, which is for example for the feeding process, moved in view of the compensation of the elongation of the cable during crimping with reduced drive power, whereby a gentle treatment of the cable can be ensured.

It may then be particularly advantageous if the tensile force on the cable is measured and monitored during the return movement to compensate for the length extension of the cable. In this way, an undesirable overstretching of the cable during the compensation step can be prevented.

In terms of the device, the invention is characterized in that the gripper is at least partially movable or movable in the axial direction during the crimping process in which a vertically movable pressing part of the crimping press is moved against the cable end. The gripper is part of a feed unit for feeding the cable end to the crimping press. The gripper is movable for the feeding process in the axial direction along the cable axis. The crimping device further comprises a crimping press, wherein the crimping press has a drivable and vertically movable pressing part with which the cable end of the cable can be connected to the crimping contact.

In a first embodiment, the gripper may be designed such that it is axially fixed at the beginning of the crimping operation and is only axially movable or axially movable after a first vertical movement of the pressing part. At the beginning of the crimping operation, the instant at which the movable pressing part of the crimping press executes a lowering movement from a starting position is understood here. The first vertical movement of the pressing part ends, for example, with contact of the crimping contact by the pressing part of the crimping press.

The crimping means may include a controllable gripper operable in addition to a feed mode for feeding the cable end to the crimping press and optionally stripping the cable end in a compensation mode in which the gripper is axially displaceable or movable to compensate for the longitudinal extension of the cable during crimping. The gripper can therefore also be used as a trigger gripper for stripping the cable end.

The delivery unit may include an actuator for axially moving the gripper. The crimping means may comprise control means for actuating the actuator. In this case, the control means are designed such that, in order to compensate for the length extension of the cable during crimping, the actuator allows a return movement corresponding to the longitudinal extent of the cable.

The feed unit can have as an actuator an electric motor for axially moving the gripper, with which a predetermined holding torque can be applied to the gripper. The electric motor may further comprise a motor control, with which the holding torque for allowing the return movement for the compensation of the linear expansion is temporarily herabsetzbar.

The feed unit may be formed as a linear drive with pinion and rack, wherein the pinion is preferably driven by a servo motor. With such a servo motor, the desired axial position of the gripper can be precisely controlled. The servo motor, which is connected directly or via a gear with the pinion, can apply a precisely determinable holding torque on the pinion. The motor control can be used to easily reduce the holding torque, allowing the return movement to compensate for the length of the cable when crimping is simple and efficient.

Another aspect of the invention may relate to a computer program product which, when loaded into the memory of a controller for the crimping process, performs the function of the method as previously described.

Figur 1

eine Seitenansicht mit Teilschnittdarstellung einer Crimpeinrichtung,

Figur 2

eine Draufsicht auf eine Zuführeinheit mit einem Greifer für die Crimpeinrichtung gemäss Figur 1,

Figur 3

eine schematische Darstellung einer erfindungsgemässen Crimpeinrichtung, und

Figur 4

der Ablauf eines Crimpvorgangs mit grafischen Darstellungen für die Pressenposition der Crimppresse sowie Steuersignal und Haltemoment des den Greifer antreibenden Servomotors.

Further individual features and advantages of the invention will become apparent from the following description of an embodiment and from the drawings. Show it:

FIG. 1

a side view with a partial sectional view of a crimping device,

FIG. 2

a plan view of a feed unit with a gripper for the crimping according to FIG. 1 .

FIG. 3

a schematic representation of an inventive crimping, and

FIG. 4

the course of a crimping process with graphical representations for the press position of the crimping press and control signal and holding torque of the gripper driving servo motor.

FIG. 1 shows a generally designated 1 crimping device for the production of crimp connections. The crimping device 1 comprises a crimping press 2 which has an over an electric motor drivable and movable in the vertical direction pressing part 6, with which a cable end of a cable 3 with a crimp contact 9 is connectable. The longitudinal axis of the cable 3 is designated by x. The pressing member 6 has a carriage, on the underside of a tool holder is arranged. The tool holder carries a crimping tool, on which a crimping die for pressing the crimp contact with the cable end is arranged. This crimping stamp cooperates in a manner known per se with an anvil, which forms the counterpart to the crimping die. Regarding constructional details is exemplified on the in EP 1 351 349 A1 or EP 1 447 888 A1 referenced crimping devices shown. The cable 3 is held by a gripper 4. The gripper 4 has a gripper head with mutually movable gripper jaws 16 for detecting the cable 3. The gripper jaws can be pneumatically actuated, for example. The gripper head with the gripper jaws 16 is mounted vertically movable relative to a gripper arm 15 of the gripper 4. In the illustration according to FIG. 1 is the pressing member 6 in a lowermost position in which the crimp contact 9 has been completely pressed with the conductor of the cable end of the cable 3. The necessary closing movement of the pressing part 6 is indicated by an arrow k. The gripper head with the gripper jaws 16 can be moved vertically via a lowering member 12, which is rigidly connected to the carriage of the pressing part 6.

Since the gripper 4 is fixed during the crimping process according to the known methods with respect to the cable axis x, it may happen that the cable piece, which is clamped between the gripper jaws 16 and crimping tool, bulges due to elongation of the cable due to the deformation of the conductor material. This cable curvature of the cable piece is in FIG. 1 hinted at and designated 23. Excessive bulging may cause the cable to buckle, causing the finished cable to be faulty and no longer needed for the intended use. To avoid this, the solution described below was developed.

FIG. 2 shows a feed unit with a gripper 4 for feeding the cable end to a (not shown here) crimping press. The gripper 4 has a gripper arm 15, at the front end of the gripper head with the gripper jaws 16 is arranged. The feed movement is indicated by an arrow f. The gripper 4 has an actuator with which the gripper head is movable in the x-direction back and forth. This adjustment mechanism for the axial movement of the gripper includes a drivable pinion 13, which cooperates with a toothed rod 14 attached to the gripper arm 15. Furthermore, in FIG. 2 recognizable that the entire gripper 4 is pivotable about a vertical axis. The axial direction x will be - like out FIG. 2 can be seen - defined by the cable end. When the cable end is swung out, the rear part of the cable may have a different orientation. The x-axis also corresponds to the machine axis of the crimping press (cf. Fig. 1 ). For the pivoting movement, the feed device has a drivable pinion 17 and a toothed belt 22. The two motors for the swivel movement and for the axial feed movement have angular encoders for position feedback. The opposite direction to the feed movement is indicated by an arrow e. With the gripper 4 can also realize the removal of the insulation during stripping. Consequently, the gripper 4 can also be part of a draw-off axis for an upstream withdrawal process for creating a stripped-off cable end.

To produce the crimped connection, the cable end of the cable 3 must first be fed to the crimping press 2 by means of a gripper 4. The feed movement in the axial direction x is indicated by the arrow f. The cable 3 thus supplied is now ready for the crimping process. The cable with the previously stripped cable end is in the correct axial position. During the crimping process, in which the crimping press part (not shown here) is moved vertically against the cable end and the crimp contact, the gripper compensates for the lengthwise extension of the cable as a result of the plastic deformation of the conductor during crimping passively or actively along the cable axis of the cable in the opposite direction e moves to the feed movement. This indicated by the arrow e return movement ensures that the unwanted buckling of the cable piece between the joint and place of action can be excluded by the gripper. The undesirable effects of elongation during crimping can thus be avoided.

FIG. 3 shows the crimping device 1 in a highly schematic representation. The crimping press 2 has a vertically movable pressing part 6 which can be driven via the motor 24. The crimping press is equipped with a crimp force monitor which can detect the crimping force via the path. The pressing member 6 is equipped with a force sensor 19, with which the crimping force can be measured. Furthermore, it is possible via the encoder 20 to detect the path w for the lowering movement of the pressing part 6. Additionally or alternatively, the crimping press could also have a linear measuring system on the press slide feature. The gripper 4 can be controlled with the aid of the motor controller 10 such that the gripper 4 for compensating for the longitudinal expansion of the cable during crimping in a return movement (arrow e) is axially movable or movable (compensation mode).

FIG. 4 relates to a configuration in which the gripper is passively moved in a return movement to compensate for the elongation of the cable during crimping. The first curve diagram shows the vertical position of the crimping press part (press position w) as a function of time t. The middle curve diagram concerns the control of the gripper during the crimping process. S denotes the control signal for the gripper. The lower curve diagram finally shows the holding torque H of the servomotor for the axial movement of the gripper as a function of the time t. At the beginning of the crimping process t ₀ , the gripper is axially fixed. Only after a first vertical movement of the pressed part does the gripper move axially. This time is designated t ₁ . The time t ₁ may be about the time of the application of the crimp contact and / or the conductor of the cable through the pressing member. At time t ₁ , the servomotor connected to the pinion is instructed via a control signal S to reduce the holding torque H from 100% to, for example, 5%. Depending on the engine type and the cables to be crimped, it might be sufficient to reduce the holding torque from 100% to 30%. The reduced holding torque now allows the desired return movement to compensate for the elongation of the cable during crimping. The control signal is maintained until time t ₂ (control on "on"), then the original holding torque is set again (holding torque H = 100%). How out FIG. 4 As can be seen, the time t ₂ can be located approximately in half of the upward movement of the pressing part 6. With t ₃ , the time is designated, in which the pressed part is back in its original starting position.

Alternatively, an embodiment is conceivable in which the gripper is actively moved during the crimping process by activating a drive or actuator. The gripper is advantageously moved by a predetermined compensation path. Furthermore, in the compensation mode, the gripper must advantageously be operated in such a way that the drive power is reduced compared with the drive power for the feed operation. For a safe procedure, finally, the tensile force on the cable during the return movement to compensate for the linear expansion of the cable during crimping should be measured and monitored.

Claims (15)

Method for producing a crimped connection, comprising the following steps: a) feeding a cable end of a cable (3) by means of a gripper (4) to a crimping press (2), b) connecting the cable end with a crimp contact (9), characterized in that during the crimping process according to step b, the gripper (4) is moved in a return movement (e) in order to compensate for the longitudinal extension of the cable during crimping along the cable axis (x) of the cable (3). A method according to claim 1, characterized in that for feeding the cable end to the crimping press (2), the gripper (4) is moved in the axial direction along the cable axis (x) using an actuator, and in order to compensate for the elongation of the cable during crimping, the actuator is adjusted so that the actuator allows the return movement (e) according to the length expansion. A method according to claim 2, characterized in that as an actuator, an electric motor (5) for axially moving the gripper (4) is provided, with a predetermined holding torque on the gripper (4) can be applied, to allow the return movement of the electric motor (5 ) is controlled such that the holding torque of the electric motor is reduced. A method according to claim 3, characterized in that by means of travel and / or time detection, a contact between the crimp contact (9) and a movable pressing part (6) of the crimping press (2) is determined or that the crimping force is measured, and that the return movement (e ) is started or permitted as soon as the contact between the crimped contact (9) and pressed part (6) is detected or as soon as a predetermined value for the crimping force is exceeded. A method according to claim 1, characterized in that the gripper (4) is actively moved during the crimping process according to step b by activating a drive or actuator. A method according to claim 5, characterized in that the gripper (4) is moved by a predetermined compensation path. Method according to one of claims 4 to 6, characterized in that the gripper (4) is moved compared to the drive power for the feeding process according to step a with reduced drive power. Method according to one of claims 4 to 7, characterized in that the tensile force on the cable (3) during the return movement (e) to compensate for the linear expansion of the cable is measured and monitored. Crimping device for producing a crimp connection with a crimping press (2), a feed unit (8) with a gripper (4) for feeding the cable end to the crimping press (2), the gripper (4) being movable in the axial direction along the cable axis (x) for the feed operation, characterized in that the gripper (4) at least in sections during the crimping process, in which a vertically movable pressing part (6) of the crimping press is moved against the cable end, in the axial direction (x) is movable or movable. Crimping device according to claim 9, characterized in that the gripper (4) is designed such that it is axially fixed at the beginning of the crimping and only after a first vertical movement of the pressing part (6) is axially movable or axially movable. Crimping device according to claim 9 or 10, characterized in that it comprises a controllable gripper (4) which is operable in addition to a feed mode for feeding the cable end to the crimping press and optionally for stripping the cable end in a compensation mode, in which to compensate for the longitudinal extension of the cable when crimping the gripper (4) in the axial direction (x) is movable or movable. Crimping device according to one of claims 9 to 11, characterized in that the feed unit (8) comprises an actuator for axially moving the gripper (4), and in that the crimping device (1) comprises control means (10) for actuating the actuator, wherein the control means are designed in such a way that, in order to compensate for the elongation of the cable during crimping, the actuator allows a return movement (e) corresponding to the longitudinal extension. Crimping device according to one of claims 9 to 12, characterized in that the feed unit (8) has an electric motor (5) for axially moving the gripper (4), with a predetermined holding torque on the gripper (4) can be applied, wherein the electric motor a motor control (10), with which the holding torque is temporarily lowered. Crimping device according to one of claims 9 to 13, characterized in that the feed unit (8) as a linear drive with pinion (13) and rack (14) is formed, wherein the pinion (13) preferably via a servo motor (5) is drivable. Crimping device according to one of claims 9 to 14, characterized in that the crimping device (1) has a system for detecting the crimping force.

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