Connection system and method for transporting fasteners

Abstract

A method for conveying fasteners and a connection system (10) for connecting fasteners (18) to a workpiece, comprising:-a head (12) having a nose (14) provided with a holding device (16) for receiving fasteners to be connected to a workpiece,-a feeder for conveying fasteners from a storage bin to the holding device, a feed tube adapted to receive the fasteners from the storage bin and to drive the fasteners to the nose (14) by entering the feed tube; -an air supply means (S) comprising a compressed air source (30) for delivering compressed air to the feeder (22) and for driving the fasteners from the storage bin to the holding means within the feed tube (24), where the air supply means (S) further comprises a plurality of valves (V1, V2, V3), and a plurality of compressed air pulses arranged such that a plurality of compressed air pulses are provided to move fasteners (18) from the storage bin to the holding device within the feed tube.

Description

Technical Field

[0001] The present invention relates to a connection system for connecting fasteners to workpieces, and a method for feeding fasteners into the nose of a connector by compressed air. Background Technology

[0002] In this context, the terms "fastening" or "connection" are intended to refer to all methods of attaching components to parts, particularly methods of attaching metal or plastic components to metal or plastic parts, such as by bonding, screwing, forming (e.g., riveting, self-piercing riveting, blind riveting with rivets or nuts, rivetless riveting), or fusion welding (e.g., welding, including short-cycle arc welding or stud welding). Short-cycle arc welding is often referred to as stud welding, although studs are not the only parts welded in this manner.

[0003] Self-piercing rivets, and the related tools or devices used to fasten two or more material parts together, are well-known in the automotive industry. Self-piercing rivets are typically used for non-critical connections to join two or more material parts together, such as in the assembly of car bodies at chassis workstations.

[0004] Stud welding is primarily used, but not limited to, automotive production. In this context, metal components, such as threaded and unthreaded metal studs, eyelets, nuts, etc., are welded to metal panels or workpieces on the vehicle body. These metal components then act as anchor points or mounting elements, for example, for connecting passenger compartment trim, pipes, wiring harnesses, etc., to the vehicle body metal parts. The metal component can be a welding stud, having a shank and a head with a diameter slightly larger than the stud shank. This head is welded to the workpiece.

[0005] Such connection or fastening devices are typically attached to a movable frame, particularly a robot, and include a connector with a nose that has a retaining device for receiving and holding the connecting element to be attached to a workpiece. A drive mechanism can move this retaining device along the connection direction to attach the fastener to the workpiece.

[0006] Once the fastener is positioned in the retaining device, conventional fastening or joining methods can be performed. For example, a conventional stud welding process, preferably using the arc welding method, can be performed as follows: First, the fastener is placed on the workpiece using a drive mechanism and a retaining device. Then, a pre-conducting current is applied, flowing through the fastener and the workpiece. Next, the fastener (or stud) is lifted relative to the component by the drive mechanism (e.g., a linear actuator). An electric arc is formed. The system then switches to welding current. The opposing end faces of the fastener and the workpiece (or component) begin to melt due to the high welding current. The fastener is then lowered back onto the workpiece, allowing the two molten materials to join. The welding current is turned off at or shortly before the short circuit between the contact parts and the arc. All molten material solidifies, and the welded joint is established.

[0007] Fasteners need to be supplied to the connectors and retaining devices. For this purpose, the feeder is equipped with a feed tube to transport the fasteners (or connecting elements) from the hopper to the retaining device. Typically, a stationary supply device separates the fasteners and then delivers them to the connectors via compressed air through the feed tube. Individual, separate fasteners (such as studs) are blown from the hopper to the connector by compressed air through the feed tube or feed hose.

[0008] While compressed air is widely used in such connection systems for conveying fasteners, this method has several drawbacks. Compressed air systems are known to be less energy efficient compared to other power sources. The process of compressing air requires a significant amount of energy, and energy losses can occur during transmission and conversion. This inefficiency leads to higher energy consumption and operating costs.

[0009] To promote energy conservation and "green manufacturing" in connected systems, alternative power sources or improved efficiency of compressed air systems must be considered, and measures must be taken to reduce energy waste and environmental impact.

[0010] Various solutions have been proposed to address these issues.

[0011] US2018222696A1 discloses a connection device in which the supply of compressed air can be interrupted by residual momentum and gravity at the end of the fastener's journey along the feed tube to ensure that the fastener reaches the connector. A connection element channel sensor is provided such that the compressed air is shut off when the sensor detects the presence of the fastener.

[0012] Such systems can reduce compressed air consumption. However, specific designs for the supply or feeding devices are required. Summary of the Invention

[0013] Therefore, the object of the present invention is to provide a connection system and a method for conveying fasteners to enhance energy efficiency and provide modularity.

[0014] Accordingly, the present invention provides a connection system.

[0015] More specifically, the present invention relates to a connection system for connecting fasteners to a workpiece, comprising:

[0016] - The head has a nose equipped with a retaining device for receiving fasteners to be attached to the workpiece.

[0017] - A feeder for conveying fasteners from a storage bin to the retaining device, wherein the feeder includes a feed tube adapted to receive fasteners from the storage bin and drives the fasteners to the nose by entering the feed tube.

[0018] - An air supply mechanism, including a compressed air source for supplying compressed air to the feeder and driving the fasteners from the storage bin to the holding device within the feed tube.

[0019] in,

[0020] The air supply mechanism also includes multiple valves arranged such that multiple pulses of compressed air are provided to move the fastener from the storage hopper to the retaining device within the feed pipe.

[0021] By avoiding a continuous flow of compressed air within the feed hose, compressed air consumption can be significantly reduced without substantially affecting cycle time or the delivery of connecting components. Furthermore, due to the presence of multiple valves, the compressed air pulse can be adapted to different feed pipe or fastener geometries. Ultimately, a predetermined compressed air pulse profile can be defined.

[0022] According to one disclosure of this application, the connection system may include:

[0023] - The head has a nose equipped with a retaining device for receiving fasteners to be attached to the workpiece.

[0024] - A feeder for conveying fasteners from a storage bin to the retaining device, wherein the feeder includes a feed tube adapted to receive fasteners from the storage bin and drives the fasteners to the nose by entering the feed tube.

[0025] - An air supply mechanism, including a compressed air source for supplying compressed air to the feeder and driving the fasteners from the storage bin to the holding device within the feed tube.

[0026] in,

[0027] The air supply unit also includes a quick-acting valve. This valve can open and close within milliseconds or even microseconds, enabling rapid adjustment and precise flow control. This quick-acting valve constitutes a pulse valve.

[0028] In one embodiment, the air supply unit includes at least:

[0029] - The first and second valves are connected in parallel.

[0030] - A third valve connected in series with the first and second valves.

[0031] Different valves have different configurations or properties, allowing for modular compressed air profiles adapted to drive fasteners from the storage bin to the connector (or more specifically, from the first end of the feed tube to the second end of the feed tube).

[0032] In one embodiment, the air supply mechanism includes a throttle valve, through which a first valve can be regulated. A second valve is a non-throttle valve. The two valves, connected in parallel, are configured to supply a maximum amount of air to a third valve during a single pulse.

[0033] In one embodiment, the air supply mechanism includes at least one quick-acting valve, and a third valve is also a quick-acting valve. The quick-acting valve can open and close within milliseconds or even microseconds, enabling rapid adjustment and precise flow control. Therefore, the third valve is a pulse valve.

[0034] In one embodiment, the air supply mechanism includes a sensor unit for recording air consumption data and / or detecting the presence of fasteners within the feed tube. Recording consumption data allows for direct detection and handling of abnormal consumption. The presence of sensors enables precise switching of compressed air as needed, preventing losses.

[0035] The present invention also relates to a method for feeding a fastener into the nose of a connector, comprising the following steps:

[0036] - Provide the connection system as described above,

[0037] - A fastener is provided and fed by a feeder, so that the fastener is moved up to the nose by pulsed air from the air supply mechanism, such that:

[0038] During the conveying phase, the movement of the fasteners is controlled by pulsed air.

[0039] During the arrival phase, the delivery of the fastener into the nose is controlled, and at least one valve is closed.

[0040] Thanks to the air supply mechanism equipped with multiple valves, the different delivery stages are fully adjustable. For example, a smooth, controlled acceleration of the fastener can be achieved in the first stage before the delivery stage. This first stage is particularly suitable, for example, when the fastener is a rivet. When the fastener is, for example, a weld stud, acceleration may not be necessary, and the weld stud can be driven directly with a fully compressed airflow according to the pulse profile during the pulse.

[0041] In one embodiment, the air supply mechanism includes a first valve and a second valve connected in parallel, and a third valve connected in series with the first and second valves. In one embodiment, in a first stage, the first valve and the second valve are turned on one after the other. In one embodiment, in a second stage, the first valve and the second valve are opened, and the third valve is pulsed with a predetermined pulse sequence. In one embodiment, in a third stage, the second valve and the third valve are closed one after the other, while the first valve remains on.

[0042] In one embodiment, the sensor unit detects the presence of fasteners in the feeder. Therefore, the initiation of the compressed air pulse sequence is precise.

[0043] In one embodiment, the control unit adjusts the opening and closing of the valve based on data sent by the sensor unit.

[0044] In one embodiment, the control unit regulates the opening and closing of the valve according to a predetermined given sequence. Attached Figure Description

[0045] The present invention and its advantages will be better understood through the following description, which is by way of example only and with reference to the accompanying drawings:

[0046] Figure 1 A schematic perspective view of a connection system is shown, particularly a stud welding system, including a connector with a retaining device, a feeder, a drive mechanism, and an air supply mechanism;

[0047] Figure 2 The arrangement of valves in the air supply mechanism is shown schematically;

[0048] Figure 3A , Figure 3B and Figure 3C The time delay graph is displayed, where the X-axis represents time. The graph illustrates the detection of fasteners at the feed tube inlet and feed tube outlet. Figure 3A , Figure 3B and Figure 3C ), the opening and closing of the first valve ( Figure 3A ), the switch of the second valve ( Figure 3B ) and the switching of the third valve ( Figure 3C ). Detailed Implementation

[0049] Embodiments of this disclosure will be best understood by referring to the accompanying drawings, wherein like reference numerals designate like or similar elements. It will be readily understood that the components of the disclosed embodiments, as generally described and illustrated in the accompanying drawings, can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the systems and methods of embodiments of the invention is not intended to limit the scope of the invention as claimed, but merely represents possible embodiments of the invention. Furthermore, unless otherwise stated, the steps of the method do not necessarily need to be performed in any particular order, or even sequentially, nor do they need to be performed only once.

[0050] In some cases, well-known features, structures, or operations are not shown or described in detail. Furthermore, the described features, structures, or operations can be combined in any suitable manner in one or more embodiments. It will also be readily understood that the components of the embodiments generally described and illustrated in the accompanying drawings can be arranged and designed in a variety of different configurations.

[0051] Figure 1 A connection system 10 according to the present invention is shown. The connection system 10 is adapted to be driven by a robot (not shown) having a fixed base from which two arms extend and are hinged together. Flanges may be provided at the ends of the arms, and the connection system 10 may be attached to said flanges. The connection system 10 includes a connector 12. The connector 12 has a nose 14 with a retaining device 16. The retaining device 16 is configured to receive a fastener 18 to be connected to a component or workpiece. The fastener 18 is, for example, a stud, such as a welded stud or adhesive stud. In other embodiments, the connecting element may be a rivet, a self-piercing rivet, a self-cutting rivet, a self-flowing rivet, a blind rivet, a nut, a blind nut, a screw, etc. The retaining device 16 is, for example, a retaining element that holds the connecting element (or fastener) before and / or during the connection step. If the connecting element is a welded stud, the retaining device may be a stud holder. If the connecting element is a rivet, the retaining device 16 may also be a receiver. Although the connection system 10 can be used in design for various types of connections, Figure 1 The connection system 10 shown is particularly suitable for welding fasteners 18 (especially welding studs) to workpieces (e.g., metal plates). Configurations as bolt welding systems or short-time arc welding systems with lift ignition are particularly preferred, but not without general applicability.

[0052] The connection system 10 (or more specifically the connector 12) may also include a drive mechanism 20 adapted to move the retaining device 16 along the connection direction to attach the fastener to the workpiece.

[0053] A feeder 22 is also provided. The feeder 22 includes a feed tube 24 (also called a feed hose or feed channel) adapted to receive fasteners from the storage hopper M, within which the fasteners move from a first end 26 to a second end 28. More specifically, the first end faces the storage hopper, while the second end faces the nose of the connector or the retaining device or receiver. At the second end 28, the feed tube 24 communicates with the retaining device 16 so that the connecting element 18 is conveyed from the feed tube 24 to the retaining device 16. Compressed air is used to push and guide the fasteners from the storage hopper or the first end of the feed tube toward the second end of the feed tube or the retaining device or nose.

[0054] The feed pipe 24 receives the separated fasteners 18, and each fastener 18 is driven by compressed air from the air supply mechanism S. The air supply mechanism includes a compressed air source 30 and at least one valve, and more specifically, multiple valves V1, V2, and V3. More specifically, the air supply mechanism includes a first valve, a second valve, and a third valve V1, V2, and V3.

[0055] like Figure 2 As shown, the first valve and the second valves V1 and V2 are arranged in parallel, while the third valve V3 is connected in series with the first and second valves V1 and V2 and is located at the outlet of the first and second valves V1 and V2. The first valve V1 can be adjusted by the throttle valve 32. The second valve V2 is a non-throttle valve.

[0056] The third valve V3 is, for example, a quick-acting pulse valve. A quick-acting valve can open and close within milliseconds or even microseconds, enabling rapid adjustment and precise flow control. Therefore, the third valve can supply pulsed compressed air to the feed pipe 24. In one embodiment, the air supply mechanism may be equipped with only one valve, which is a quick-acting valve.

[0057] The specific arrangement of the first, second, and third valves V1, V2, and V3 allows for the regulation of compressed air, and more specifically, the supply of pulsed compressed air via the third valve, to accommodate the condition of the fastener at different stages within the feed tube. The air supply mechanism S provides a specific sequence or profile of compressed air suitable for moving the fastener from the first end to the second end without requiring a continuous flow of compressed air within the feed tube.

[0058] The connection system 10 may be equipped with a sensor unit 34. The sensor unit 34 may include a presence sensor at the first end 26 of the feed pipe 24. A second presence sensor may be provided at the second end 28 of the feed pipe 24. A sensor for recording air consumption data may also be provided. The recorded air consumption data can be used, for example, to detect potential defects or adjust the compressed air delivery sequence.

[0059] Compressed air delivery sequence in Figure 3A , Figure 3B and Figure 3C There is a more detailed description in the text. Figure 3A , Figure 3B and Figure 3C It's a chart; the X-axis displays time.

[0060] exist Figure 3A In the image, we can see the fasteners being inspected at the first end (D) and the second end (E) of the feed tube. Figure 3AThe dotted line in the diagram represents the state of the first valve V1. The first valve V1 closes shortly after detecting the fastener at the first end of the feed pipe at time X1. The first valve V1 closes shortly after detecting the fastener at the second end of the feed pipe.

[0061] exist Figure 3B In the image, we can see the fasteners being inspected at the first end (D) and the second end (E) of the feed tube. Figure 3B The mixed line in the diagram represents the command for the second valve, V2. The second valve opens at time X2, following the first valve, V1. When a fastener is detected at the second end of the feed tube, the second valve closes before the first valve, V1.

[0062] exist Figure 3C In the image, we can see the fasteners being inspected at the first end (D) and the second end (E) of the feed tube. Figure 3C The dashed line in the figure represents the command of the third valve V3. The third valve V3 opens and closes during the movement of the fastener within the feed tube to provide pulsed compressed air to drive the fastener throughout its entire stroke within the feed tube.

[0063] In another embodiment, the first valve may be turned on before a sensor signal is present at the first end of the feed tube. In this case, for example, the second and third valves may be turned on after a sensor signal is present at the first end of the feed tube. In yet another embodiment, the third valve may be turned on before a sensor signal is present at the first end of the feed tube. In this case, for example, the second and first valves may be turned on after a sensor signal is present at the first end of the feed tube.

[0064] The first and second valves, V1 and V2, are located at the outlet of the compressed air source and supply the maximum air volume to the third valve (which is a fast-circulation valve) during the cycle (when the fastener moves from the first end to the second end). The outlet of the third valve works in conjunction with the feed pipe and provides multiple air pulses to move the fastener from the first end to the second end.

[0065] The combination and interconnection of valves allow the entire feeding process to be divided into stages or phases, and adapted to different feeding conditions.

[0066] For example, two or three main stages can be implemented. The first stage (which is optional, for example, more relevant to certain types of fasteners such as rivets or self-piercing rivets, and less relevant to fasteners such as welded studs) corresponds to the start of feeding (the fastener is at the first end of the feed tube). A smooth, controlled acceleration can be achieved by sequentially activating the first and second valves V1, V2 after a predetermined time (X2-X1). Stage 2 (corresponding to the feeding stage) is a pulsed feeding sequence in which the first and second valves V1, V2 are activated, and the third valve is in pulse mode, opening and closing regularly at a predetermined rhythm. The opening and closing rhythm is automated and may depend on the length of the feed tube and / or the type of fastener and / or the required feeding pace or speed. The third stage (or arrival stage) corresponds to controlled feeding to the nose, which is achieved by sequentially closing the second and third valves (V2, V3) after a predetermined time and after fasteners are detected at the second end. Feeding is exclusively achieved through the throttle valve V1 (therefore, the feeding speed is adjustable).

[0067] Control unit 36 ​​can command the air supply mechanism S. The control unit can implement self-referencing in terms of feeding time. The control unit controls feeding time and air consumption via the pulse ratio of the third valve. This process can be customized according to requirements (air consumption or time optimization).

Claims

1. A connection system (10) for connecting fasteners (18) to workpieces, comprising: - The head (12) has a nose (14) with a retaining device (16) for receiving fasteners to be attached to a workpiece. - A feeder for conveying fasteners from a storage bin to the retaining device, wherein the feeder includes a feed tube adapted to receive fasteners from the storage bin and drives the fasteners to the nose (14) by entering the feed tube. - An air supply mechanism (S) including a compressed air source (30) for supplying compressed air to the feeder (22) and driving the fastener from the storage bin to the holding device within the feed pipe (24). The air supply mechanism (S) is characterized in that it further includes a plurality of valves (V1, V2, V3) arranged such that a plurality of compressed air pulses are provided to move the fastener (18) from the storage hopper to the holding device within the feed pipe.

2. The connection system (10) according to claim 1, wherein the air supply mechanism comprises at least: - The first valve (V1) and the second valve (V2) are connected in parallel. - A third valve (V3) connected in series with the first valve and the second valve.

3. The connection system (10) according to claim 2, wherein the air supply mechanism includes a throttle valve (32), wherein the first valve can be adjusted by the throttle valve, and wherein the second valve is a non-throttle valve.

4. The connection system (10) according to any one of claims 1 to 3, wherein the air supply mechanism includes at least one quick-acting valve, and wherein the third valve (V3) is a pulse valve.

5. The connection system (10) according to any one of claims 1 to 4, wherein the air supply mechanism (S) includes a sensor unit (34) for measuring air consumption or detecting the presence of fasteners (18) in the feed tube (24).

6. A method for feeding a fastener into the nose (14) of a connector (12) includes the following steps: - Provide a connection system (10) according to any one of claims 1 to 5, - Provide fasteners and feed them via the feeder, such that the fasteners are moved onto the nose by pulsed air from the air supply mechanism, such that: During the conveying phase, the movement of the fastener is controlled by pulsed air. During the arrival phase, the delivery of the fastener into the nose is controlled, and at least one valve is closed.

7. The method of claim 6, wherein the air supply mechanism (S) comprises a first valve and a second valve connected in parallel, and a third valve connected in series with the first valve and the second valve.

8. The method of claim 7, wherein in the first stage, the first valve and the second valve are switched on one after the other after a predetermined time X.

9. The method according to claim 7 or 8, wherein in the second stage, the first valve and the second valve (V1, V2) are opened, and the third valve is pulsed at a predetermined pulse rhythm.

10. The method according to any one of claims 7 to 9, wherein in the third stage, the second valve and the third valve (V2, V3) are closed one after another, while the first valve remains open.

11. The method according to any one of claims 6 to 10, wherein the sensor unit (34) detects the presence of fasteners in the feeder.

12. The method according to claim 11, wherein the control unit (36) adjusts the opening and closing of the valves (V1, V2, V3) based on the data sent by the sensor unit.

13. The method according to any one of claims 6 to 12, wherein the control unit regulates the opening and closing of the valves (V1, V2, V3) according to a predetermined given sequence.

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