Device for moving connecting elements, joining tool having the device, and method for connecting at least two elements

Abstract

The invention relates to a device (100) for moving connecting elements (10) along a transport path (12) for the connecting elements (10); as well as a joining tool (200) for connecting at least two elements (30, 40) by driving in a connecting element (10) in the form of a self-piercing rivet (10), comprising a device (100) of this type; and a method for connecting at least two elements (30, 40) by means of a self-piercing rivet (10). The device (100) comprises multiple coils (14) which are arranged one behind the other along the transport path (12), wherein the transport path (12) extends through the multiple coils (14). A control unit (20) generates respective current flows through the respective coils (14) in order to move or accelerate the connecting element (10) along the transport path (12) directly by means of electromagnetic forces. The self-piercing rivet (10) can be accelerated on the transport path (12) in order to drive the self-piercing rivet (10) from the transport path (12) directly into the elements (30, 40) to be connected and to connect the elements (30, 40) by means of the self-piercing rivet (10).

Description

[0001] Atlas Copco IAS GmbH, Case: 12N2024PA1066DE

[0002] Device for moving connecting elements, joining tool with the device and method for joining at least two elements

[0003] The present invention relates to a device for moving connecting elements along a transport path, in particular in the direction of a joining tool; a joining tool for connecting at least two elements by driving in a connecting element; and a method for connecting at least two elements by means of a punch rivet.

[0004] Technical background

[0005] Joining tools are, among other things, mechanical tools for connecting at least two elements made of different materials such as high-strength steel, aluminum, cast iron, magnesium, carbon fiber, or plastics with varying strength properties. One method used with a joining tool to join, for example, two metal sheets, involves the use of self-piercing rivets.

[0006] In this process, a fastener, particularly a self-piercing rivet, acts as a cutting die and is deformed during the joining process. The sheets are placed on a die, the rivet element is positioned at the joint, and fixed in place by the advance of the blank holder. In the subsequent joining process, the self-piercing rivet penetrates the upper sheet and plastically deforms the lower sheet into a rivet head. Such self-piercing rivets are also known as "seif piercing rivets (SPR)." This eliminates the need for pre-drilling the materials to be joined and ensures a tight joint. In particular, this type of self-piercing riveting process can be used to join various material combinations, especially carbon fiber workpieces. Even high-strength or ultra-high-strength steels can be joined without pre-drilling.

[0007] Corresponding tools and processes are used particularly in the automotive industry. The joining process is carried out by advancing the rivet setter of the joining tool and driving the self-piercing rivet into the workpiece. Due to the materials being processed and the requirements for joint quality and reliability, high demands are placed on the rivet setter or joining tool and the precise advancing procedure. Accordingly designed joining tools, and thus efficient and robust joining processes, result in expensive, large, and heavy tools with high maintenance costs and wear.

[0008] When feeding fasteners, they must be transported over long distances in a short time. Among other solutions, transport via a feed hose is widely used. With common joining tools connected to a central compressed air supply, the fasteners are transported by compressed air. This is not energy-efficient. Another disadvantage is that the effectiveness or efficiency depends heavily on the quality of the compressed air supplied by the central compressed air system. Atlas Copco IAS GmbH, Case: 12N2024PA1066DE

[0009] Disclosure of the invention

[0010] It is an object of the present invention to provide a novel device with which a self-piercing rivet can be effectively transported or accelerated. It is also an object to provide a novel joining tool with which elements can be joined by means of a self-piercing rivet, and a corresponding method. It is desirable to avoid the disadvantages of the prior art.

[0011] These and other problems arising for a person skilled in the art from the present disclosure are solved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0012] Aspects and embodiments of the present disclosure may include one or more of the optional features mentioned in relation to the aspects described below.

[0013] According to a first aspect of the present disclosure, a device for moving fasteners along a transport track for the fasteners, in particular towards a joining tool, is disclosed. The device comprises at least one coil arranged on the transport track. The device may comprise several coils arranged one behind the other (in a row) along the transport track. The transport track passes through the coil or the several coils. In particular, each of the several coils may be wound around the transport track. The device further comprises a control unit configured to activate the coil or the several coils.The control unit can be configured to activate the respective coils to move or accelerate a connecting element along the transport path using electromagnetic forces, in particular to move or accelerate it directly using electromagnetic forces and / or to generate a linear movement of the connecting element. Activating a coil can, in particular, include generating a current flow in the coil. The control unit can be configured to generate a current flow through the coil or respective current flows through the respective coils to move or accelerate a connecting element along the transport path using electromagnetic forces, in particular to move or accelerate it directly using electromagnetic forces and / or, in particular, to generate a linear movement of the connecting element. The control unit can, in particular, be configured to sequentially activate several coils arranged in series.

[0014] In some embodiments, the connecting element is moved or accelerated directly by the electromagnetic forces (originating from / caused by the coils). Alternatively, the electromagnetic forces can move an actuator or element of the device, for example, a riveting punch, which carries (e.g., pushes) the connecting element and moves or accelerates it. Atlas Copco IAS GmbH, Case: 12N2024PA1066DE

[0015] The control unit can be configured to generate the required axial force through the linear movement of the connecting element, which drives the connecting element (especially the punch rivet) into the elements to be joined.

[0016] The fasteners are, in particular, metallic and / or ferromagnetic fasteners. The fasteners can be, for example, self-piercing rivets, especially "seif piercing rivets" (SPR).

[0017] The generation of the current flow(s), or the movement or acceleration of the connecting element, can be achieved according to the principle of a coilgun, sometimes also referred to as a Gaussian gun. In other words, the transport path can be configured as a coilgun: a single-stage coilgun in the case of a single coil, and a multi-stage coilgun in the case of multiple coils. To accelerate a ferromagnetic connecting element, the coils can act as electromagnets due to the current flows. The connecting element is attracted to and accelerated by each current-carrying coil. As the connecting element passes through the coil, the coil is switched off, and the connecting element is attracted to and (further) accelerated by the next current-carrying coil. The current flows through the respective coils are thus generated in a coordinated manner, specifically according to a temporally coordinated sequence.In particular, the generation of the respective current flows is coordinated with the (possibly varying, e.g., increasing) linear speed of the connecting element along the transport path. In the case of a non-ferromagnetic, but metallic (or electrically conductive) connecting element, acceleration can occur through induced eddy currents, whereby a repulsive force is exerted on the connecting element.

[0018] The device or control unit can include one or more electrical energy storage devices, configured to provide the energy for the respective current flow through a respective coil. Capacitors can be used as energy storage devices.

[0019] The device for moving fasteners provides a compressed air-free alternative to conventional compressed air transport systems (for example, for fasteners such as self-piercing rivets). Moving or accelerating the fasteners using electromagnetic forces can replace the drive and, if necessary, the actuator of known joining tools. This offers significant advantages over the prior art. Since no mechanical drive is required, there is less friction and wear, which reduces maintenance costs. Furthermore, this leads to higher reliability and a longer service life. By controlling the coil current (and thus the magnetic field), the movement can be precisely and flexibly controlled, adapted to the properties of the fastener. Atlas Copco IAS GmbH, Case: 12N2024PA1066DE

[0020] The transport path can be straight. It can also be called a conveyor path. The transport path can run towards a joining tool, with, for example, a deflection station between the transport path and the joining tool. The transport path can run directly to the joining tool. The transport path can be located within a joining tool and / or lead to a joining point where elements are to be joined by the fastener. The transport path can also be an acceleration path.

[0021] The transport path can include a transport hose, tube, or conveying tube. The transport hose can be configured to guide the connecting element. The connecting element can be moved or accelerated within the transport hose by electromagnetic forces. A transport hose simplifies the movement of the connecting element, particularly along non-linear transport paths.

[0022] According to another aspect of the present disclosure, a joining tool (in particular a self-piercing riveting device) for connecting at least two elements by driving in a connecting element in the form of a self-piercing rivet is specified. The location where the at least two elements are joined is also referred to as the joining point. The joining tool comprises the device described herein (a device for moving connecting elements along a transport track for the connecting elements). The device is configured to accelerate the self-piercing rivet on the transport track in order to drive the self-piercing rivet directly from the transport track into the elements to be joined (at the joining point). Driving in the self-piercing rivet comprises connecting the elements to be joined by the self-piercing rivet.In particular, the device can be configured to accelerate the self-piercing rivet on the transport track, so that the rivet is driven directly into the elements to be joined by the generated (applied) final velocity. Driving the self-piercing rivet is also referred to as rivet setting.

[0023] In some embodiments, the connecting element is moved or accelerated directly by the electromagnetic forces (originating from / caused by the coils). Alternatively, the electromagnetic forces can move an element of the joining tool, for example a rivet punch, which guides (e.g., pushes) the self-piercing rivet and moves or accelerates it.

[0024] In embodiments, the device is configured to accelerate the self-piercing rivet to a speed at which its kinetic energy is sufficiently high to drive it into the elements to be joined. In these embodiments, the energy required to drive the self-piercing rivet into the at least two elements is supplied solely by the kinetic energy of the rivet achieved through acceleration. The self-piercing rivet can thus be accelerated to a very high speed sufficient to set the rivet in the application / metalworking process, or to drive it into the elements to be joined, without applying any additional axial force to the rivet. This method can be referred to as extremely high-speed riveting or extremely high-speed SPR setting.Acceleration can be achieved by several small coils in a series, each attracting the rivet. Control of the movement or acceleration can be achieved by adjusting the charge, voltage, and / or current, and / or by alternating the operation (use) of the coils. This device can, for example, replace both the drive mechanism and the triggering / activation of a riveting punch.

[0025] According to another aspect of the present disclosure, a method for joining at least two elements by means of a self-piercing rivet is specified. The method comprises the steps of: providing the at least two elements; feeding the self-piercing rivet to an acceleration section that runs through several coils arranged in series; generating current flows through the respective coils to accelerate the self-piercing rivet along the acceleration section by electromagnetic forces; and joining the at least two elements with the self-piercing rivet. The self-piercing rivet can be driven into the elements to be joined by utilizing the kinetic energy of the self-piercing rivet applied to it by acceleration. In particular, the self-piercing rivet can be driven into the elements to be joined by the kinetic energy of the self-piercing rivet (generated by acceleration).The punch rivet is thus accelerated towards a point where the at least two elements are to be joined by electromagnetic forces.

[0026] In some embodiments, the self-piercing rivet is accelerated directly by the electromagnetic forces (originating from / generated by the coils). Alternatively, the electromagnetic forces can move an element, such as a riveting die, which carries (e.g., pushes) the self-piercing rivet and accelerates it.

[0027] In embodiments, the method comprises: accelerating the punch rivet on the acceleration track in order to drive the punch rivet directly from the acceleration track into the elements to be joined.

[0028] In embodiments, the method comprises accelerating the self-piercing rivet to a speed at which the kinetic energy of the rivet is sufficiently high to drive the rivet into the elements to be joined. In embodiments, the energy for driving the rivet into the at least two elements is provided (solely) by the kinetic energy of the rivet achieved (through acceleration).

[0029] The method can be a method for joining at least two elements by means of a self-piercing rivet using the device described herein. Atlas Copco IAS GmbH, Case: 12N2024PA1066DE

[0030] Brief description of the characters

[0031] Embodiments of the present disclosure are described in detail below with reference to figures, which show:

[0032] Fig. 1 schematically shows a joining tool for connecting at least two elements, with a device for moving connecting elements according to embodiments of the present disclosure; and

[0033] Fig. 2 shows two elements joined by a punch rivet.

[0034] Detailed description

[0035] Fig. 1 shows a joining tool 200 with a device 100 for moving fasteners 10 along a transport track 12 for the fasteners 10. The transport track 12 is an acceleration track. The device 100 comprises several coils 14 arranged one behind the other along the transport track 12. The transport track 12 runs through the several coils 14. A control unit 20 is configured to generate respective current flows through the respective coils 14 in order to accelerate a fastener 10 (a self-piercing rivet) along the transport track 12 directly by electromagnetic forces.

[0036] The joining tool 200 is used here to connect two elements 30, 40 by driving in the punch rivet 10. The device 100 is configured to accelerate the punch rivet 10 on the transport track 12 in order to drive the punch rivet 10 from the transport track 12 directly into the elements 30, 40 to be joined.

[0037] The device 100 is configured to accelerate the punch rivet 10 to a speed at which the kinetic energy of the punch rivet 10 is sufficiently high to drive the punch rivet 10 into the elements 30, 40 to be joined.

[0038] Figures 1 and 2 schematically illustrate the steps involved in joining two elements 30 and 40 using a self-piercing rivet 10. Figure 1 shows a first element 30 and a second element 40. The first and second elements 30 and 40 can be positioned relative to each other and, if necessary, held in place. The first element 30 can at least partially contact the second element 40. The first element 30 can be a steel component. The second element 40 can be an aluminum component. The thickness of the first element 30 can be between 1.0 mm and 2.0 mm.A method for joining elements 30 and 40 using a self-piercing rivet 10 comprises the steps of: providing the two elements 30 and 40; feeding the self-piercing rivet 10 to the acceleration section 12, which runs through several coils 14 arranged in series; generating current flows through the respective coils 14 to directly accelerate the self-piercing rivet 10 along the acceleration section 12 by electromagnetic forces; and joining the at least two elements 30 and 40 using the self-piercing rivet 10, wherein the self-piercing rivet 10 is driven into the elements 30 and 40 to be joined by the kinetic energy of the self-piercing rivet 10. Atlas Copco IAS GmbH, Case: 12N2024PA1066DE.

[0039] Fig. 2 shows the connection of elements 30 and 40 made by the punch rivet 10. As the punch rivet 10 penetrates the first and second elements 30 and 40, a bulge 42 (also called a closing head) can form on the second element 40. The bulge 42 can protrude from the surface of the second element 40.

Claims

Atlas Copco IAS GmbH, Case: 12N2024PA1066DE Claims 1. Device (100) for moving connecting elements (10) along a transport path (12) for the connecting elements (10), in particular in the direction of a joining tool, comprising: several coils (14) arranged one behind the other along the transport path (12), the transport path (12) passing through the several coils (14); and a control unit (20) configured to generate respective current flows through the respective coils (14) in order to move or accelerate a connecting element (10) along the transport path (12) directly by electromagnetic forces.

2. Joining tool (200) for joining at least two elements (30, 40) by driving in a connecting element (10) in the form of a punch rivet (10), comprising a device (100) according to claim 1, configured to accelerate the punch rivet (10) on the transport track (12) in order to drive the punch rivet (10) from the transport track (12) directly into the elements (30, 40) to be joined.

3. Joining tool (200) according to claim 2, wherein the device (100) is configured to accelerate the punch rivet (10) to a speed at which the kinetic energy of the punch rivet (10) is sufficiently high to drive the punch rivet (10) into the elements (30, 40) to be joined.

4. Method for joining at least two elements (30, 40) by means of a punch rivet (10), comprising the steps: Providing at least two elements (30, 40); Feeding the punch rivet (10) to an acceleration section (12) which runs through several coils (14) arranged one after the other; Generating respective current flows through the respective coils (14) in order to accelerate the punch rivet (10) directly along the acceleration path (12) by electromagnetic forces; and Connecting the at least two elements (30, 40) by means of the punch rivet (10), wherein the punch rivet (10) is driven into the elements (30, 40) to be joined by the kinetic energy of the punch rivet (10).

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