EP3644461A1 - Method for monitoring a crimping device, monitoring unit and crimping device - Google Patents

Abstract

The invention relates to a method for monitoring a crimping device, a monitoring unit and a crimping device. Such a crimping device is used to connect contact parts and electrical conductors. For example, a contact part and a conductor are non-positively connected to one another by plastic deformation of the contact part.

Description

Technical field

The invention relates to a method for monitoring a crimping device, a monitoring unit and a crimping device. Such a crimping device is used to connect contact parts and electrical conductors. For example, a contact part and a conductor are non-positively connected to one another by plastic deformation of the contact part.

State of the art

It is already known to determine a so-called crimp force curve during a crimping process. The crimping force curve can be used, for example, to determine whether a successful crimping process has been carried out or whether, when the crimping process has been carried out, no crimp contact may have been inserted into the crimping press or a stranded wire was missing.

For example, the DE 101 44 322 A1 a method for producing an electrical insulation displacement connection. It is preferred in the press-in or joining process A corresponding force and / or displacement sensor system is introduced in order to detect the forces or paths that arise during the press-in or joining process, the measured values supplied by the sensor system being fed to an evaluation unit in order to determine the process-actual curve from this . According to one embodiment, a process-specific tolerance range is assigned to a respective process-actual curve, and a bad or error message is only issued if the determined process-actual curve lies at least substantially outside this tolerance range. When dimensioning the tolerance range, the permissible process fluctuations in particular can be taken into account. On the basis of the process curve comparison carried out, errors in the press-in or joining process, material errors, a respective tool break or corresponding defects in the press-in or joining device, contacting errors and all other significant manufacturing or production errors can be recorded.

Such a procedure has generally proven itself in the area of quality assurance. However, if a deviation is detected outside the tolerance range, you can only react if the error has already occurred. If it is determined that the material supply fails because, for example, the corresponding workpiece store has been emptied, the operation of the crimping device is stopped. This leads to undesirable downtimes of the system.

Subject of the invention

The invention aims to ensure the availability of a crimping device while maintaining a high quality level and to avoid or reduce downtimes.

The subject matter of claim 1 provides a corresponding method. Preferred embodiments are listed in the dependent claims. The invention further relates to a monitoring unit and a crimping device.

According to the invention, the production of bad parts (faulty crimp connections) can be prevented accordingly at an early stage. On this basis, predictive maintenance for the elements of a crimping device, in particular a crimping die and anvil, can be implemented. The state of wear and the upcoming change can be predicted based on the model. This means that the production process can adapt to an upcoming change situation in advance and significantly reduce set-up and / or downtimes.

The crimping force curve mentioned below can also be referred to as a crimping process curve.

The invention provides a method for monitoring a crimping device, which comprises the following steps: detecting a crimping force curve (or also called crimping process curve), determining at least one characteristic value of the crimping force curve, comparing the determined characteristic value with at least a first threshold value, which has a (wear) State of one or more tools, in particular the crimping die or the anvil that defines the crimping device.

In particular, such a crimping device can comprise a crimping die and an anvil, which attach a contact element to a conductor by means of a movement relative to one another. The crimp force curve or crimp process curve is the force curve during a work cycle or a part thereof. A can be used to determine the force curve Force or pressure sensor can be provided in the area of the crimping die or the anvil or the eccentric press.

According to a preferred embodiment, it is provided that the integral of the crimping force curve is determined as the characteristic value. The integral corresponds to the work carried out by the crimping device, which is converted during a specific forming process. As wear progresses, the work / energy required for the crimping process increases, so that a state of wear can be deduced accordingly.

According to a further embodiment, a local maximum can be determined as the characteristic value, which can be read out precisely from the determined or documented crimping force curve / crimping process curve.

In particular, a (first) local maximum (k1; K2) in the crimp force curve can describe the point in time at which the tabs of the crimp contact begin to roll in the apexes of the radii of the crimping die.

It has been shown that the (first) local maximum changes in the force level and / or position when the radii of the crimping tool are subject to wear. Thus, for example, with the force level and / or path or angular position of the first local maximum k1 or its distance from the point of the maximum compressive force (bottom dead center of the crimping die), it can be used as a parameter for the wear of the crimping die.

The force level can be an absolute force level or a relative force level, for example in relation to the maximum pressure force. The path or angular position can be an absolute path or angular position or a relative path or angular position, for example in relation to the maximum compressive force.

A (second) local maximum (k2) in the crimp force curve can preferably describe the point in time at which the tabs of the crimp contact touch. If the crimping process takes place symmetrically, there is a kind of "collision" between the crimping tabs.

This leads to a corresponding increase in force and thus to the (second) local maximum (k2). A second local maximum is thus designed for tools in such a way that it can be seen that the crimping stamp has not yet worn out. If, on the other hand, there is wear, the crimping takes place asymmetrically, so that the second local maximum (k2) is also no longer pronounced.

The second local maximum (k2) can thus also be an indication of a corresponding state of wear of the tool. The second local maximum (k2) can also change in the force level and / or position or angle position when the radii of the crimping tool wear out. The change can be recorded accordingly and used to determine a corresponding degree of wear.

As already mentioned, the force level can be an absolute force level or a relative force level, for example in relation to the maximum pressure force. The path or angular position can be an absolute path or angular position, or a relative path or angular position, for example in relation to the maximum compressive force.

Furthermore, a local minimum k3 is formed in the crimp force curve, which describes the beginning of the so-called compression phase. If the tool is worn, the distance between the local minimum k3 and the point of maximum pressure is shortened. The distance of the local minimum k3 to the point of maximum pressure (dead center of the press) can can also be used to assess the state of wear of the tool.

As already mentioned, the force level can be an absolute force level or a relative force level, for example in relation to the maximum pressure force. The path or angular position can be an absolute path or angular position, or a relative path or angular position, for example in relation to the maximum compressive force.

It is preferred that the characteristic value or values (k1, k2, k3) are taken from a region of the crimping force curve before the start of a compression phase of the crimping force curve. In the compression phase, the crimp contact with the strands is compressed.

The previously described points in the crimp force curve (k1, k2, k3) are thus removed in the so-called preparation phase, in which the crimping stamp comes into contact with the crimp contact and the tabs of the crimp contact bend. It has been shown that points in the so-called preparatory phase (the area of the crimp force curve before compression of the crimp contact with the strands takes place) are well suited to carry out an appropriate evaluation.

Furthermore, a point k4 at the end of the compression phase has proven to be suitable and advantageous as a characteristic value. It has been shown that if the tool is worn, jamming of the crimp contact in the crimping die can occur, which would be shown by a further local minimum k4 in the crimping force curve.

It is further preferred that a time-based or path-based distance from the local maximum is determined as the characteristic value.

It is preferred that a plurality of characteristic values are ascertained, and the ascertained characteristic value is compared in each case with an assigned first threshold value. In this way, the precision is further increased.

In a further embodiment it is provided that the crimp force curve is plotted over an angle of rotation of a press moving the crimping die. These values can be determined without increased effort, so that an inexpensive solution is provided.

The first threshold value can be a percentage value of a maximum wear value. The percentage value is determined empirically, numerically or on an analytical basis, for example.

In one embodiment it is provided that the first threshold value is stored in a manufacturer's database or a cloud-based database. During the operation of the crimping device, a threshold value can be loaded into a local memory of the crimping device. The storage in a manufacturer's database enables particularly quick access. A cloud-based database, on the other hand, has the advantage that universal access can be carried out from different production locations.

According to a further embodiment, it is preferred that a plurality of threshold values are provided. In particular, when a first threshold value is exceeded, information can be given to a user (for example by means of a display on the machine display or by transmission of an electronic message), an order can be requested when a second threshold value is exceeded and the machine can be stopped at a third threshold value . The third threshold value is the one on which the maximum wear condition is reached is next or corresponds to the value of the maximum wear condition. The user can thus be informed in good time about the steps to be taken.

The invention also provides a monitoring unit for monitoring a crimping device. The monitoring unit is set up to determine a characteristic value of the crimping force curve on the basis of a crimping force curve. The monitoring unit is also set up to compare the determined characteristic value with at least one first threshold value, which defines a state of one or more tools, in particular the crimping die or the anvil of the crimping device. The monitoring unit can be set up to carry out a method according to one of the aforementioned aspects (or claims 1-12).

According to a further aspect, the invention relates to a crimping device. The crimping device comprises a crimping die and an anvil, a sensor that is set up to determine a crimping force, a monitoring unit, in particular the aforementioned monitoring unit or the monitoring unit according to claim 13, wherein the monitoring unit is set up to give a characteristic value of the crimping force curve based on a crimping force curve determine, wherein the monitoring unit is further configured to compare the determined characteristic value with at least a first threshold value, which defines a state of one or more tools, in particular the crimping die or the anvil, of the crimping device.

Brief description of the drawings

Fig. 1

shows a crimp force curve plotted against the angle of rotation of an eccentric press or the (process) time, which results from the crimping die stroke results, on the basis of which various characteristic values are illustrated.

Fig. 2

shows a crimp force curve plotted over the travel path of the crimping die for comparison of a crimping device in the initial state and a crimping device with a worn tool.

Fig. 3

shows another example of a crimp force curve plotted over the travel path of the crimping die.

Fig. 4

illustrates an interaction of a device with databases

Detailed description of the preferred embodiments

The invention is described in more detail below using an illustrative example. Although the following explanation is intended to be exemplary and not restrictive, features of the following description can also be used individually to specify the invention.

As explained in the introduction, it is known in principle to determine a crimp force curve during a crimping process in which a contact part is connected to an electrical conductor and to carry out basic monitoring of the crimping device and possible processing errors based on the detection result. However, no statements can be made as to whether an intolerable deterioration in the processing quality or even a tool failure is indicated.

The monitoring of the crimping device can be integrated into a monitoring unit of the crimping device, which is already provided on the crimping device for determining the crimping force profile, or the monitoring unit can be designed as a separate unit. In this context, it is also possible to provide the monitoring unit as a retrofit solution. In this way, existing crimping devices can be expanded.

First, a reference crimp force curve is determined when the crimping device is started up or a tool change is performed, which defines a setpoint value of the crimping device without any further signs of wear. The target crimp force curve is stored in a storage device of the crimping device or the monitoring unit, or alternatively in an external storage device, for example a cloud, and serves as a reference for further quality monitoring.

In operation, a crimping force curve is subsequently determined during each crimping process, which is as in FIGS Figures 1-2 shown, can be applied via the angle of rotation (the (process) time) of the eccentric press or the path covered by the crimping die. The actual crimp force curve determined in this way is stored for further evaluation.

It has been shown that one of the following characteristic values can be used for evaluating a state of wear of the crimping device, in particular of the crimping tool.

In particular, based on the in Fig. 1 The area under the curve or the integral of the crimp force curve can be evaluated via the angle of rotation of the crimp force curve plotted by the eccentric press (characteristic value K1). This area under the crimp force curve corresponds to that performed by the crimping device Work that is needed and converted in a specific forming process. As the wear progresses, the work / energy required for the crimping process increases, so that this can be derived from the determined area.

A local maximum can be used as a further possibility of a characteristic value. This is in Fig. 1 marked with the characteristic value K2, which indicates a deviation of the force at the local maximum from the maximum compressive force (bottom dead center of the crimping die). As an alternative or in addition, an absolute force can also be used as a characteristic value.

It has also been shown that a characteristic value (characteristic value K3) can be determined on the basis of a time-based or path-based distance from the local maximum, which characteristic value can also be used to evaluate the tool wear.

One or more threshold values can be defined for each of the aforementioned characteristic values K1-K3, on the basis of which it is determined that the tools of the crimping device, in particular the crimping die and the anvil, should be replaced.

The threshold value (s) can be stored as fixed values, for example in the control of the crimping device, in a database of the user of the crimping device or in a cloud server. The characteristic values can be determined empirically or numerically, or be based on an analytical basis.

A threshold value may need to be updated over the life of a crimping device based on certain findings. To make this easier, the updated threshold value must be stored in a variant in a user database or on a cloud server so that the threshold value can be queried. Alternatively, it is also possible to update the Perform control device of the crimping device so as to update the threshold.

Based on the present embodiment, there is thus the possibility of recognizing bad parts and recognizing at an early stage whether a production with reduced quality is foreseeable.

In addition, it is possible to provide predictive maintenance for wear parts of the crimping device on the basis of the determined values, so that in particular the crimping die and the anvil can be replaced. The current state of wear and the corresponding, possible change of the tool can be forecast based on models, so that the required tool changes can be planned and carried out in a certain time window. In this way, surprising set-up and downtimes are avoided.

To integrate a model-based wear condition forecast in a crimp force monitoring / crimp process monitoring, a characteristic value Ki _{C1 of} the new parts can be documented at the start of production. This value serves as a reference for a characteristic value Ki _Ci at any point in time i before the point in time of the maximum or critical state of wear (Ki _C2 ). For example, a relative difference can be formed to record wear progress: $$\mathrm{\Delta }\mathit{Ki}=\frac{{\mathit{Ki}}_{\mathit{Ci}}-{\mathit{Ki}}_{\mathrm{C.}1}}{{\mathit{Ki}}_{\mathrm{C.}1}}$$

Threshold values can also be defined for this relative difference, at which a critical state of wear of the wearing parts is reached (for example Ki _C2 ). The value Ki _C2 can be determined, for example, on the basis of empirical or numerical basis or on the basis of analytical calculations.

A threshold value can thus be set for ΔKi to record the progress of wear, and if this is exceeded a wear part change is required. In order to be able to react earlier and thus avoid bad parts, a message e.g. when 70% is reached (first threshold for information to the user). If an approximately linear wear is assumed over time, the wear progress can be approximated, for example, by interpolation. Alternatively, non-linear wear can be assumed and modeled accordingly.

In particular, due to the exceeding of a first threshold for information of the user, a service message can appear in the display of the machine or such a message can be transmitted to the machine manufacturer.

In addition to the above-mentioned threshold value for information to the user, which is displayed, for example, on a display of the machine or transmitted to the user by means of an electronic message, it is possible to define a further (second) threshold value, which the user uses to order a specific spare part prompts. The level of the threshold value for requesting an order lies between the value Ki _C2 (critical wear condition) and the threshold value for information to the user.

In this way, an order process can be triggered or prepared, for example to reorder the crimp stamp or anvil. The reordered tool thus reaches the manufacturer in good time before an exchange of the corresponding tool would be absolutely necessary. The producer can integrate the time of the exchange of the tool into the daily workflow, for example if the machine is to be shut down for other reasons anyway.

Furthermore, a third threshold value can be defined, which lies between the value Ki _C2 (critical wear condition) and the second threshold value. If the third threshold is exceeded, the machine is stopped.

Fig. 2 shows a crimp force curve, which is plotted over the path of the crimping die. The crimp force curve C1 illustrates the course of a crimping process with crimping tools (crimping dies and anvil), which are considered new. The crimping force curve C2 represents a crimping process in which the crimping tools (crimping dies and anvil) are already worn out and must be replaced in the foreseeable future.

In Fig. 3 shows a crimp force curve C3 which, similar to the crimp force curves in Fig. 2 , is applied over the path of the crimp stamp. Differences in the course of the crimp force curve result from a specific, processed crimp contact type.

Several characteristic values k1, k2, k3 and k4 are shown in the crimp force curve. For these characteristic values, the corresponding positions of a crimping die 100 are shown, in which a crimp contact with crimping tabs 200 as well as strands lying between the crimping tabs 200 is inserted. An evaluation can be carried out as explained above.

The characteristic value k1 is a first local maximum of the crimping force curve C3. The first local maximum k1 describes the point in time in the crimping force curve C3 at which tabs 200 of the crimping contact begin to roll in the apexes of the radii of the crimping die. It has been shown that the first local maximum is in the (force level and / or Position) changed if the radii of the crimping tool are subject to wear. Thus, the position (force level) of the first local maximum k1 or its distance from the point of the maximum compressive force (bottom dead center of the crimping die 100) can be used as a parameter for the wear of the crimping die.

A second local maximum k2 describes the point in time in the course of the crimp force curve C3 at which the tabs 200 of the crimp contact touch. If the crimping process takes place symmetrically, there is a kind of "collision" between the crimping tabs. This leads to a corresponding increase in force and thus to the second local maximum k2. A second local maximum is thus designed for tools in such a way that it can be seen that the crimping stamp has not yet worn out. If, on the other hand, there is wear, the crimping takes place asymmetrically, so that the second local maximum k2 is also no longer pronounced. The second local maximum k2 is thus also an indication of a corresponding state of wear of the tool. The second local maximum k2 can also change in position (force level and / or position) when the radii of the crimping tool wear out. The change can be recorded accordingly and used to determine a corresponding degree of wear.

Furthermore, in the crimp force curve according to Fig. 3 a local minimum k3 is drawn, which describes the beginning of the so-called compression phase. If the tool is worn, the distance between the local minimum k3 and the point of maximum pressure is shortened. The distance between the local minimum k3 and the point of maximum pressure (dead center of the press) can also be used to assess the state of wear of the tool.

The previously described points in the crimp force curve (k1, k2, k3) are in the so-called preparation phase removed, in which the crimp stamp comes into contact with the contact and bends the tabs of the crimp contact. It has been shown that points in the so-called preparatory phase (the area of the crimp force curve before compression of the crimp contact with the strands takes place) are well suited to carry out an appropriate assessment.

Furthermore, in Fig. 3 a point k4 is drawn at the end of the compression phase. It has been shown that if the tool is worn, jamming of the crimp contact in the crimping die can occur, which would be shown by a further local minimum k4 in the crimping force curve. In Fig. 4 there is no such local minimum in the area of point k4.

To assess the state of wear of the crimping tool, in particular the crimping die, one of the aforementioned points k1-k4 can be used individually or in combination with other points.

In Fig. 4 Communication of a crimping device X1 operated by a user is clearly shown. In particular, the crimping device X1 can communicate via a local network with a user-side database X2, in which device-specific information is stored. There is also a communication interface that allows the crimping device X1 to communicate with a cloud-based database C. For example, characteristic values and threshold values can be documented and managed in the cloud-based database C.

On the manufacturer side, a communication interface and a manufacturer-side database Y are provided, which enable Internet-based communication with the cloud-based database C. In this way, data determined by the manufacturer can be re-evaluated in Threshold values or the like, which are stored in the cloud-based database C, are incorporated.

In Fig. 4 A communication option is also provided between the manufacturer's database Y and the crimping device X1, which is designed, for example, as a teleservice connection. Furthermore, the user can possibly enable data exchange between the user-side database X2 and the manufacturer-side database Y. Such communication can also be made possible only on one side, in particular from the manufacturer's database Y to the user side database X2, in order to provide the user with specific data for the operation of the crimping device X1.

Claims (15)

Method for monitoring a crimping device, comprising the steps: Acquisition of a crimp force curve, Determining at least one characteristic value (K1; K2; K3; k1, k2, k3, k4) of the crimping force curve (C1, C2, C3), Comparison of the determined characteristic value with at least one threshold value which defines a state of one or more tools, in particular the crimping die or the anvil, of the crimping device. A method according to claim 1, characterized in that the integral of the crimping force curve is determined as the characteristic value (K1). A method according to claim 1, characterized in that a local maximum (K2; k1, k2) is determined as the characteristic value,
it is preferred that the local maximum (k1) of the crimping force curve describes a point in time in the crimping force curve at which tabs (200) of a crimping contact begin to roll in the apexes of the radii of the tool, in particular crimping dies, and / or
the local maximum (k2) describes the point in time in the crimp force curve at which tabs (200) of a crimp contact touch. Method according to claim 1, characterized in that a local minimum (k3) is determined as the characteristic value the local minimum (k3) describes the beginning of a compression phase. Method according to claim 3 or 4, characterized in that a time or distance-based distance from the local maximum or local minimum is determined as the characteristic value (K3). Method according to Claim 1, characterized in that a value of the crimping force curve which describes an end of a compression phase is determined as the characteristic value (k4). Method according to one of the preceding claims, characterized in that a plurality of characteristic values (K1; K2; K3; k1, k2, k3, k4) are determined, and the determined characteristic value is compared in each case with an assigned threshold value. Method according to one of the preceding claims, characterized in that the crimp force curve is plotted over an angle of rotation of a press moving the crimping die or a process time. Method according to one of the preceding claims, characterized in that the threshold value is a percentage value of a maximum wear value. Method according to one of the preceding claims, characterized in that the threshold value is stored in a manufacturer's database (Y) or a cloud-based database (C). Method according to one of the preceding claims, characterized in that a plurality of threshold values are provided, it being preferred that when a first threshold value is exceeded, information is sent to a user, when a second threshold is exceeded An order is requested and the machine is stopped at a third threshold. Method according to one of the preceding claims, characterized in that a relative difference is determined using the following formula to record the progress of wear: $$\mathrm{\Delta }\mathit{Ki}=\frac{{\mathit{Ki}}_{\mathit{Ci}}-{\mathit{Ki}}_{\mathrm{C.}1}}{{\mathit{Ki}}_{\mathrm{C.}1}}$$

where Ki _{C1 is} a characteristic value for a new part and Ki _{Ci is} a characteristic value at a point in time i before the threshold value is reached, in particular the point in time of the maximum state of wear (Ki _C2 ). Monitoring unit for monitoring a crimping device, the monitoring unit being set up to determine a characteristic value (K1, K2, K3; k1, k2, k3, k4) of the crimping force curve using a crimping force curve,
wherein the monitoring unit is also set up to compare the determined characteristic value (K1, K2, K3; k1, k2, k3, k4) with at least one threshold value that defines a state of one or more tools, in particular the crimping die or the anvil, of the crimping device. A crimping device comprising: a crimp stamp and an anvil, a sensor which is set up to determine a crimping force, a monitoring unit, the monitoring unit being set up to determine a characteristic value (K1, K2, K3; k1, k2, k3, k4) of the crimping force curve on the basis of a crimping force curve, wherein the monitoring unit is also set up to compare the determined characteristic value (K1, K2, K3; k1, k2, k3, k4) with at least one threshold value that defines a state of one or more tools, in particular the crimping die or the anvil, of the crimping device. System comprising a crimping device according to claim 14 and a database, in particular a user-side database (X2) and / or a cloud-based database (C), the threshold value being stored in the database.

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