Setting device and method for its operation

Abstract

The present invention relates to a setting device for fastening a functional element to a workpiece, in particular to a sheet metal part. It comprises a guide channel and a punch that is axially movable in the guide channel and with which the functional element can be moved through the guide channel. Furthermore, a feed device is provided, which comprises a feed channel that opens into the guide channel, wherein an eddy current unit is provided, with which a magnetic field can be generated that permeates a braking section of the feed channel, so that the speed of a functional element moving in the feed channel can be reduced. The present invention further relates to a method for using such a setting device.

Description

[0001] The present invention relates to a setting device for fastening a functional element to a workpiece, in particular to a sheet metal part.

[0002] Functional elements are used in a wide variety of applications, particularly in automotive engineering. They serve, for example, to create fastening options for other workpieces on a workpiece or to provide other functionalities that cannot be easily implemented on the workpiece itself or only with great effort. It is, of course, important that the elements can be connected to the respective workpiece efficiently. The connection must also be resilient and reliable.

[0003] Functional elements can be, for example, bolt elements, whose shafts may be threaded, or nut elements, which may have an internal thread. Other designs are conceivable. For example, functional elements can also have components or sections designed for a snap-in or plug-in connection.

[0004] Functional elements are known in various designs. For example, there are rivet elements that have a rivet section that is deformed when attached to a sheet metal part to form a rivet flange and, with a head section, to form an annular receptacle for the edge of a hole in the sheet metal part. With such rivet elements, the functional element is deformed when attached to the sheet metal part. Rivet elements can be self-piercing. This means that there doesn't need to be a prepared hole in the workpiece into which the rivet section is inserted; instead, the rivet section—in other words, punches its own hole.

[0005] Furthermore, press-in elements are known in which the element itself is not intentionally deformed during attachment to a sheet metal part. Rather, the sheet metal material is deformed to engage the undercuts of the respective press-in element. Press-in elements are also known in which no undercuts are provided. These are then held in place solely by a pressing force. In principle, press-in elements can also be self-piercing.

[0006] The workpiece can be made of a metal, for example it is a sheet metal component.

[0007] Setting devices are provided for fastening a functional element to the workpiece. These devices usually comprise a guide channel and a punch that is axially movable in the guide channel and with which the functional element can be moved through the guide channel. The punch can be provided to bring the functional element into the position suitable for the setting process in the setting device or in the guide channel and, in some cases, to fix it in this position during the setting process. The element can be set or joined by an axial movement of a setting head of the setting device that encompasses the guide channel. In principle, however, it is also conceivable for the setting or joining to occur by a movement of the punch.

[0008] Furthermore, a feed device is provided, which comprises a feed channel that opens into the guide channel. The functional elements are fed through the feed channel, for example, by compressed air. When transitioning from the feed channel to the guide channel, the functional element must be redirected. In doing so, the functional element may encounter an internal migration of the guide channel or other components of the setting device. The associated stresses lead to wear on the components of the setting device, and can also cause damage to the functional element itself.

[0009] It is an object of the present invention to provide a setting device in which the problems described above are avoided.

[0010] This object is achieved by a setting device having the features of claim 1.

[0011] According to the invention, an eddy current unit is provided with which a magnetic field can be generated which passes through a braking section of the feed channel, so that a speed of a functional element moving in the feed channel can be reduced.

[0012] In other words, the inventive concept is based on providing a magnetic field in the braking section of the supply channel that generates eddy currents in a functional element passing through the braking section. The induced eddy currents are the source of magnetic fields that oppose the magnetic field of the eddy current unit, thus decelerating the functional element.

[0013] Compared to conventional setting devices, the functional elements that move from the feed channel into the guide channel move significantly slower, reducing the associated stresses. This, in turn, leads to less wear on the setting device components and significantly reduces the risk of damage to the functional elements.

[0014] The inventive concept can be applied to any type of functional element, such as bolt elements or nut elements, which can be designed as (self-piercing) rivets or press-in elements. It is applicable not only to single-piece but also to multi-piece functional elements. The only requirement is that the functional elements are electrically conductive at least in sections. Particularly good results are achieved with at least partially, and especially completely, metallic functional elements.

[0015] Further embodiments of the invention are set forth in the claims, the description and the accompanying drawings.

[0016] According to one embodiment of the present invention, the eddy current unit comprises at least one coil unit. Several eddy current units can also be provided, arranged one behind the other in the axial direction of the braking section. Alternatively or additionally, it is conceivable to provide coil units distributed in the circumferential direction of the braking section.

[0017] For example, the eddy current unit comprises at least one pair of coils arranged opposite each other on both sides of the supply channel. The pair of coils can be energized in such a way that a (e.g., as homogeneous as possible) magnetic field is generated in at least one section of the braking section, which is oriented substantially perpendicular to the direction of movement of the functional element in the region of the braking section.

[0018] According to a structurally very simple design, the eddy current unit comprises, in addition to or alternatively to the at least one coil unit, permanent magnetic elements for generating the braking magnetic field in the braking section.

[0019] The design of the magnetic field (e.g., geometry and / or field strength and / or degree of homogeneity / inhomogeneity in the braking section) can be selected as needed to best accommodate the prevailing conditions. The magnetic field can also be adapted, in particular, with regard to the properties and / or geometry of the functional elements to be braked.

[0020] According to a further embodiment of the setting device, a control unit is provided with which the eddy current unit can be operated as needed. It is generally conceivable for the eddy current unit to be supplied with a substantially constant current during operation of the setting device. However, the AC unit can preferably be supplied with variable current using the control unit in order to accommodate changing conditions.

[0021] The control unit can be configured and designed to determine at least one characteristic operating parameter of the eddy current unit. For example, it can be provided that a specific magnetic field is generated by the eddy current unit. When an element passes through the braking section and the braking of the functional element occurs there, the magnetic field in the braking section is changed, which results in a (short-term) change in the electrical operating parameters of the eddy current unit. Such a temporal change, for example a voltage change, can be used to increase process reliability. For example, the extent of the change is an indication of whether an electrically conductive functional element passes through the braking section at all. The characteristics of the change (e.g. with regard to amplitude and / or duration) can be an indication of the properties of the element (e.g.electrical conductivity and / or shape of the element) and / or the movement of the element (e.g. its speed).

[0022] An analysis of the temporal progression of at least one characteristic operating parameter of the eddy current unit thus enables simple monitoring of the setting device. If the analysis reveals an excessive deviation from the expected or specified values, a warning signal can be issued, which can be used, for example, to (automatically) influence (e.g., shut down) the setting device. In other words, the eddy current unit can also be used as a measuring device.

[0023] The supply device can comprise at least one sensor unit with which at least one characteristic parameter of the functional element and / or at least one characteristic parameter of a movement of the functional element in the supply channel can be detected. Such a sensor unit can be, for example, an inductive sensor or a magnetic field sensor (e.g., a Hall sensor). One or more coils can also be used as sensors.

[0024] The sensor unit is preferably arranged upstream of the eddy current unit, but can also be arranged downstream of the eddy current unit in the direction of movement of the element.

[0025] The sensor unit can be used, for example, to determine the electrical conductivity and / or magnetization of the functional element. It can also be used—additionally or alternatively—to determine at least one movement parameter (e.g., the speed) of the functional element.

[0026] The data determined by the sensor unit or the properties of the functional element or the movement of the functional element determined on the basis of the determined data can be used to operate the eddy current unit as required.

[0027] In order to be able to remove magnetization generated during operation of the eddy current unit from components of the setting device and / or the functional element, at least one demagnetization device can be provided. Magnetization of components of the setting device can be reduced or even removed by the eddy current unit with appropriate design and control, for example during a production break. For this purpose, the eddy current unit creates an alternating magnetic field that gradually decays. Alternatively or additionally, a separate demagnetization device can be provided, such as a corresponding coil arrangement. Downstream of the eddy current unit, the functional elements magnetized by the braking process could be at least partially demagnetized with the aid of such a coil arrangement.

[0028] The invention further relates to a method for operating a setting device for fastening a functional element to a workpiece, in particular a setting device according to at least one of the embodiments described above, wherein the setting device comprises a guide channel and a punch which is axially movable in the guide channel and with which the functional element can be moved through the guide channel, wherein a feed device is provided which comprises a feed channel which opens into the guide channel, wherein an eddy current unit is provided with which a magnetic field is generated which penetrates a braking section of the feed channel, so that a speed of a functional element moved in the feed channel is reduced.

[0029] The eddy current unit may comprise at least one coil unit which is energized as required.

[0030] The current supply to the coil unit can be adjusted depending on a characteristic parameter of the functional element and / or a characteristic parameter of a movement of the functional element in the supply channel.

[0031] According to one embodiment of the method, the characteristic parameter of the functional element and / or the characteristic parameter of the movement of the functional element are determined by means of a sensor unit, in particular wherein the sensor unit is arranged upstream or downstream of the eddy current unit.

[0032] Additionally or alternatively, a characteristic operating parameter of the eddy current unit can be detected in order to determine a characteristic parameter of the functional element and / or a characteristic parameter of a movement of the functional element.

[0033] Advantageous embodiments of the invention are explained purely by way of example with reference to the accompanying drawings. They show: Fig. 1 an embodiment of the setting device according to the invention and Fig. 2 to 5 different embodiments of a coil arrangement of the eddy current unit.

[0034] Fig. Figure 1 shows a setting device 10 of a generally known design. It is used to fasten a functional element 12, here, for example, a metallic bolt element with an external thread, to a workpiece 14, here, for example, a flat sheet metal part. The operation of the setting device 10 is sufficiently well known, so detailed explanations are unnecessary. Unlike conventional setting devices, however, an eddy current brake 16 is provided, which is described in more detail below.

[0035] The setting device 10 has a setting head 18, which includes an axial guide channel 17 through which a functional element 12 can be guided to the free end of the head 18 with the aid of a punch 17A in the setting direction A. The functional element 12 is provided by a feed device 20, which is connected to a storage device for the functional elements 12 via a hose (not shown). The feed device 20 includes a feed channel 22, which opens into the guide channel 16. A longitudinal axis L1 of the channel 22 and a longitudinal axis L2 of the channel 17 enclose an insertion angle.

[0036] The elements 12 are transported pneumatically, for example. The elements 12 reach comparatively high speeds in the feed channel 22, so that with conventional setting devices, they impact an inner migration of the guide channel 17 with considerable kinetic energy at approximately the angle of entry. This causes wear in the area of ​​the guide channel 17. Furthermore, the element 12 can be damaged, for example, in an inlet area of ​​the external thread of the bolt element 12 shown as an example.

[0037] To resolve the problem described above, the eddy current brake 16 is provided, which is arranged in a section of the feed channel 22. Its action decelerates the bolt element 12, so that it enters the guide channel 17 at a significantly lower speed than with conventional setting devices. This reduces wear on the setting device 10 and reduces the load on the element 12. A positive side effect is that the transition of the element 12 from the feed channel 22 to the guide channel 17 is more controlled.

[0038] In the present embodiment, the eddy current brake 16 is symbolized by a coil 24 surrounding the supply channel 22 in the circumferential direction (see also Fig. 5). It is understood that the arrangement and design of the eddy current brake 16 (e.g. arrangement and number of coils, axial extension of the eddy current brake 16) can be adapted to the respective requirements. Further exemplary coil arrangements are shown in the Fig. 2 to 4 shown.

[0039] In the Fig. 2 to 5 each show a cross section through the feed device 20 in the region of the eddy current brake 16 (i.e. in the braking section) in a plane perpendicular to the longitudinal axis L1.

[0040] Fig. Figure 2 shows a coil arrangement of two coils 24 arranged on either side of the supply channel 22. They are preferably energized in such a way that they generate a magnetic field in the region of the supply channel 22 that is arranged parallel to the image plane, i.e., perpendicular to the direction of movement of the bolt element 12 as it travels through the braking section. It is understood that multiple coil arrangements can be arranged one behind the other in the axial direction. This also applies to other coil arrangements.

[0041] In the Fig. 3 shows a coil arrangement of four coils 24, each arranged offset by 90°. In the Fig. 4, the arrangement comprises three coils 24, which are arranged rotationally symmetrically offset by 120°. Fig. 5 is the one in the Fig. 1, the arrangement of the coil 24 is shown schematically again.

[0042] The coils 24 can, if necessary, have a core to increase the magnetic flux density. In principle, it is also conceivable to use suitable arrangements of permanent magnets instead of coils 24 (or in addition) to generate the magnetic field required for the eddy-current braking effect.

[0043] The AC brake 16 can be controlled by a control unit (not shown) to achieve the desired braking effect. When an element 12 passes through the eddy-current brake 16, its magnetic field is changed, which can, for example, cause a voltage spike. The temporal variation of the voltage can be analyzed and allows conclusions to be drawn, among other things, about the electrical conductivity of the element 12 and its speed. Temporal monitoring of the characteristic electrical parameters of the eddy-current brake 16 thus enables monitoring of the element feed and thus increases process reliability.

[0044] Additionally or alternatively, sensors may be provided with which characteristic properties of the element 12 and / or characteristic parameters of its movement can be determined.

[0045] Purely as an example, in Fig. 1, a measuring coil 26 is provided, which is arranged behind the eddy current brake 16 in the direction of movement of the element 12. When the element 12 passes through the measuring coil 26, a voltage is induced in it, the temporal variation of which allows conclusions to be drawn about characteristic properties of the element 12 and / or characteristic parameters of its movement.

[0046] The data from the measuring coil 26 can be combined with those from the cyclone 16 to obtain additional information.

[0047] It is understood that a wide variety of sensor types can be used, for example, inductive sensors, optical sensors, magnetic sensors, and / or electrical sensors. The number and / or arrangement of the sensors can be selected as required. It is also possible to provide sensors upstream of the eddy current brake 16, for example, to estimate the speed of the element 12 approaching the eddy current brake 16 and to be able to control the eddy current brake 16 accordingly. List of reference symbols 10 Setting device 12 functional elements 14 Workpiece 16 Eddy current brake 17 Guide channel 17A stamp 18 setting head 20 Feed device 22 Supply channel 24 coil 26 measuring coil A setting direction L1, L2 Longitudinal axis of channel 22 or channel 17

Claims

[1] Setting device for fastening a functional element (12) to a workpiece (14), in particular to a sheet metal part, comprising a guide channel (17) and a punch (17A) which is axially movable in the guide channel and with which the functional element can be moved through the guide channel, wherein a feed device (20) is provided which comprises a feed channel (22) which opens into the guide channel, and wherein an eddy current unit (16) is provided with which a magnetic field can be generated which penetrates a braking section of the feed channel, so that a speed of a functional element moved in the feed channel can be reduced. [2] Setting device according to claim 1, wherein the eddy current unit (16) comprises at least one coil unit (24). [3] Setting device according to claim 1 or 2, wherein the eddy current unit (16) comprises at least one pair of coils (24) arranged opposite one another on both sides of the feed channel (22). [4] Setting device according to one of the preceding claims, wherein a control unit is provided with which the eddy current unit (16) can be operated as required, in particular with variable current supply. [5] Setting device according to claim 4, wherein the control unit is arranged and designed to determine at least one characteristic operating parameter of the eddy current unit (16). [6] Setting device according to one of the preceding claims, wherein the feed device (20) comprises at least one sensor unit (26) with which at least one characteristic parameter of the functional element (12) and / or at least one characteristic parameter of a movement of the functional element in the feed channel (22) can be detected. [7] Setting device according to one of the preceding claims, wherein the setting device comprises at least one demagnetization device [8] Setting device according to claim 7, wherein a control unit is provided which is arranged and designed to operate the eddy current unit (16) as a demagnetization device. [9] Method for operating a setting device (10) for fastening a functional element (12) to a workpiece (14), in particular a setting device according to at least one of the preceding claims, wherein the setting device comprises a guide channel (17) and a punch (17A) which is axially movable in the guide channel and with which the functional element can be moved through the guide channel, wherein a feed device (20) is provided which comprises a feed channel (22) which opens into the guide channel, wherein an eddy current unit (16) is provided with which a magnetic field is generated which penetrates a braking section of the feed channel, so that a speed of a functional element moved in the feed channel is reduced. [10] Method according to claim 9, wherein the eddy current unit (16) comprises at least one coil unit (24) which is energized as required. [11] Method according to claim 9 or 10, wherein the energization of the coil unit (24) is adapted as a function of at least one characteristic parameter of the functional element (12) and / or at least one characteristic parameter of a movement of the functional element in the supply channel (22). [12] Method according to claim 11, wherein the characteristic parameter of the functional element (12) and / or the characteristic parameter of the movement of the functional element is determined by means of at least one sensor unit (26), in particular wherein the sensor unit is arranged upstream or downstream of the eddy current unit (16). [13] Method according to claim 11 or 12, wherein at least one characteristic operating parameter of the eddy current unit (16) is detected in order to determine at least one characteristic parameter of the functional element (12) and / or at least one characteristic parameter of a movement of the functional element.

Images