Setting device for press-fit elements and method for operating a setting device

Abstract

Insertion device for press-fit elements (2, 2a) comprising: a setting unit (10) with an element holder (12) for receiving a press-fit element (2, 2A) during a setting process, an automatic feeding device (20) for feeding press-fit elements (2, 2A) into the element holder (12), an optical sensor (30) configured to detect a press-fit element (2, 2A) received in the element holder (12), at least one air distribution body (40, 50) with a compressed air channel (44, 54) with a compressed air connection opening (42, 52) for connection to a compressed air supply and at least one nozzle opening (46, 56, 76), wherein the nozzle opening (46, 56, 76) is configured to generate an airflow (D) towards a sensor surface of the optical sensor (30) when compressed air is supplied via the compressed air connection opening. (42, 52) is introduced into the compressed air channel (44, 54), a valve (64,66) for interrupting and releasing the airflow (D) between the compressed air supply and the nozzle opening (46, 56, 76) characterized by a control device (70) configured to actuate the valve (64, 66) to generate a compressed air pulse (D), wherein the control device (70) is configured to generate a signal for generating the compressed air pulse (D) time-coupled to a signal for supplying a press-fit element (2, 2A) into the element holder (12).

Description

The invention relates to a setting device for press-fit elements and a method for operating a setting device. A variety of press-fit elements are used in vehicle manufacturing. These elements can serve as functional components, for example, providing a thread or ball stud on a thin-walled sheet metal part, or creating a welding point for another component. Press-fit elements can also act as rivets to permanently join two or more components. Examples of press-fit elements include semi-tubular rivets, blind rivet nuts, blind rivet (threaded) bolts, and other riveting elements. During an insertion process, the press-fit elements are inserted into one or more components (with or without a pilot hole), deformed, and form a positive fit with the component(s). The insertion process is automated, with the press-fit elements being conveyed via a feeding system into an element holder of a insertion unit and inserted into the component(s) by means of the insertion unit. An insertion device is known, for example, from German patent applications DE 19731222 A1 and DE 10 2005 048 325 B4. Feeding systems for press-fit elements are known, for example, from German patent application DE 10 2008 018 428 A1. From publication DE 696 32 309 T2, a device for inserting fasteners is known, comprising a camera system for detecting the orientation and size of the fastener. To prevent deposits, a continuous airflow is blown as a curtain of clean air over the diffusing body of the camera system. Document WO 2015 / 090 749 A1 further discloses a method for cleaning an optical entry window of a fire detector, in which an intermittent gas flow with a number of pressure pulses is released from a gas outlet opening onto the surface of the optical entry window. Against this background, the object of the invention is to provide a cost-effective solution for improving the reliability of an automated setting process for press-fit elements. The problem is solved by a device according to claim 1 and a method according to claim 9. Further advantageous embodiments are described in the dependent claims and the following description. A setting device for press-fit elements is described, comprising a setting unit with an element holder for receiving a press-fit element during a setting process. The setting unit is designed to press the press-fit element into a component. For this purpose, the setting unit may also include, for example, a hold-down device, a die, and devices for moving the element holder, the hold-down device, and / or the die. During the setting process, the press-fit element is correctly oriented in the element holder and pressed into the component. The necessary relative movement between the press-fit element and the component can be achieved by moving the element holder, which then acts as a setting punch, and / or by moving the die. Furthermore, the setting device features an automatic feeding device for feeding press-fit elements into the element holder. The press-fit elements can be transported, for example, by means of the feeding device (e.g., using compressed air) into a magazine on the setting unit and from there individually inserted into the element holder (e.g., by means of a pneumatic slide). Furthermore, the setting device features an optical sensor designed to detect a press-fit element held in the element holder. For this purpose, the sensor can be positioned, for example, near or on the element holder, so that its detection range is directed towards the holding area of ​​the element holder. The sensor detects whether a press-fit element is present in the element holder or not. The sensor signal can then be used, for example, by a control device to enable or disable the setting device for the actual setting process. Furthermore, the setting device comprises at least one air distribution element with a compressed air channel, a compressed air inlet, and at least one nozzle opening. The compressed air inlet is designed for connection to a compressed air supply. For example, the compressed air inlet can be connected to the compressed air supply via a compressed air hose. Compressed air enters the compressed air channel through the compressed air inlet and exits through the at least one nozzle opening. The nozzle opening is designed to generate an airflow towards a sensor surface of the optical sensor when compressed air is introduced into the compressed air channel via the compressed air inlet. The setting device also includes a valve for interrupting and releasing the airflow between the compressed air supply and the nozzle opening, as well as a control device designed to actuate the valve. In a further aspect of the invention, a method for operating the aforementioned insertion device for press-fit elements is specified. In this method, press-fit elements are automatically fed to an element holder of the insertion unit and pressed into at least one component by means of the insertion unit. The presence of a press-fit element in the element holder is monitored by means of the optical sensor, and the sensor surfaces of the optical sensor are cleaned by means of an airflow from the at least one nozzle opening. Sensor surfaces are defined as the surfaces accessible to the environment where the light signal exits or enters the sensor or sensor housing. The device and method provide a means of performing the insertion process only when an insertion element is present in the element holder. Faulty insertion processes "without" an insertion element can be reliably prevented, as its absence can be detected before the insertion process begins. The optical sensor allows for simple and cost-effective detection of the insertion element. The optical sensor's sensitivity to contamination can be compensated for by integrating a cleaning mechanism into the insertion device. The invention is based on the consideration that such insertion processes take place in environments and under conditions where the sensors are exposed to high levels of contamination. This is because the insertion element is moved into the element holder by means of the feeding device to load it. This process also introduces coating abrasion, such as zinc, nickel, Almac, etc.Contaminants are carried from the feeding device into the setting device. Furthermore, such setting processes typically take place in production halls where fumes and dust from various welding and joining processes contaminate the air. The solution according to the invention integrates a cleaning function into the setting device, allowing it to be automated and performed virtually at any time. This prevents or eliminates sensor contamination, which in the worst case could lead to false detection. By integrating the cleaning function into the setting device, the cleaning step can be incorporated into the setting process, thus reducing system downtime and increasing system availability. The control device is configured to actuate the valve to generate an air pulse. An air pulse is defined as a short burst of air lasting less than one second. Preferably, the duration of the air pulse is 100 ms or less, and particularly preferably between 50 and 100 ms. Preferably, compressed air with an overpressure in the range of 0 bar to 1 bar above ambient pressure is used. It is understood that the shape and size of the nozzle opening are adapted to the air pulse to achieve an appropriate cleaning effect on the sensor surfaces. By using an air pulse, sensor cleaning can be integrated into the production process without significantly increasing the process time, or even increasing it at all. In one particular embodiment, it can be especially advantageous to use an electromagnetic valve to switch such a short burst of air. This type of valve is characterized by particularly fast closing times. The conversion between signal and actual air pulse is therefore very rapid. Cleaning can be performed at predetermined times, e.g., after a specific number of setting cycles. Due to the minimal time required for cleaning, the overall process time is hardly extended. According to the invention, it is even possible to ensure that the cleaning process has no effect on extending the insertion process. Accordingly, the control device is configured to generate a signal for the compressed air pulse, time-coupled to a signal for the insertion of an insertion element into the element holder. In the process control, the air pulse is switched by means of a control unit, and the signal for the air pulse is time-coupled to a signal for the insertion of an insertion element into the element holder. Thus, the cleaning by the compressed air pulse can take place while the element holder is being fitted with another insertion element. It is particularly preferred if the two signals are generated simultaneously, i.e., if the insertion of an insertion element into the element holder is initiated at the same time as the generation of the air pulse.The valve switching, especially in the case of an electromagnetic valve, occurs virtually instantly and without delay. However, due to the inertia of the mechanical feeding device, the next insertion element is fed in with a certain time lag after the signal. By generating both signals simultaneously, the compressed air cleaning process is completed before or when the next insertion element is advanced into the element holder. The cleaning thus takes place precisely within the time window allocated for feeding the next insertion element. This makes it possible to perform the cleaning, for example, during each insertion process without increasing the overall process time. In one embodiment, particularly simple and precise positioning between the sensor and the nozzle opening is achieved by having the at least one air distribution element continue to serve as a receptacle for the optical sensor. For this purpose, the air distribution element can, for example, have a recess or a mounting point in or to which the sensor can be attached. In one embodiment, the at least one air distribution element is manufactured using an additive manufacturing process. The air distribution element can be produced, for example, using 3D printing or lithography processes made of plastic or metal. An air distribution element manufactured in this way offers a high degree of freedom with regard to the geometry of the compressed air channel and the nozzle opening, allowing the airflow to be optimized for the sensor. Furthermore, an additive manufacturing process offers the possibility of integrating a sensor mounting directly into the air distribution element. This reduces the number of parts, simplifies assembly, and optimizes the cleaning effect. For optimal removal of dust and coating abrasion from the sensor surfaces, it is advantageous in one design if the at least one nozzle opening is positioned relative to the optical sensor such that the airflow is directed along the longitudinal axis of the element holder and in the insertion direction, i.e., towards the component. This arrangement blows dust and coating abrasion away from the element holder. In addition to cleaning the sensor, this also allows for additional cleaning of the element holder, which in turn reduces the dust load on the sensor and the risk of re-contamination. In a further embodiment, the blowing out of dust from the element holder can be improved by having the nozzle opening be ring-shaped and extending radially around a longitudinal axis of the element holder. For example, a reflection sensor can be used, in which the light source and light-receiving element are arranged in a common housing. This optical sensor detects the presence of a press-fit element by receiving the light from the light source reflected by the press-fit element. For this purpose, the sensor is positioned such that the press-fit element (when held in the element holder) is located within the sensor's beam path or sensor area. In a preferred embodiment, a photoelectric sensor is used as the optical sensor. This sensor has a structurally separate transmitter (light source) and receiver (light-receiving element). The transmitter and receiver are arranged on opposite sides of the element holder, so that the light emitted by the transmitter is directed towards the receiver. On its path, the light passes through the element-receiving area of ​​the element holder, i.e., the area in which the press-fit element is held by the element holder. If there is no press-fit element in the element holder, the light reaches the receiver unimpeded. If, on the other hand, a press-fit element is arranged in the element holder, it interrupts the light beam, which is detected by the receiver. When using a photoelectric sensor, it can be advantageous to provide two separate air distribution bodies in one embodiment.One air distribution element has a first nozzle opening directed at the transmitter to clean it, and the second air distribution element has a second nozzle opening directed at the receiver to clean it. This design allows for a particularly flexible arrangement of the transmitter and receiver relative to the element holder. The nozzle openings can be slot-shaped, ensuring effective cleaning even with large sensor areas. However, when using a light barrier sensor, only a single air distribution body may be provided, which then has, for example, two separate nozzle openings (for transmitter and receiver) or one nozzle opening with which both transmitter and receiver are cleaned. Features and details described in connection with the device also apply in connection with the method according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, mutual reference is always made or can be made. Further advantages, features, and details of the invention will become apparent from the following description, in which exemplary embodiments of the invention are described in detail with reference to the drawings. The features mentioned in the claims and in the description can be essential to the invention individually or in any combination. Where the term "can" is used in this application, it refers to both the technical possibility and the actual technical implementation. The following are exemplary embodiments explained with reference to the accompanying drawings. These show, in schematic representation: Fig. 1 an exemplary setting device in a sectional view, Fig. 2 the setting device from Fig. 2 in a bottom view, Fig. 3 a schematic representation of another possible arrangement of the nozzle opening. Figures 1 and 2 show an exemplary setting device 1 for carrying out the method. The setting device 1 comprises a setting unit 10 with an element holder 12 and a die (not shown). The element holder 12 and the die work together to generate the setting force necessary for the setting process and press the insertion element 2 into a component (not shown). The element holder 12 and / or the die can be moved during this process. For the insertion process, the insertion element 2 is automatically fed to the element holder 12 and held in a receiving section 14. A feeding device 20 is used for this purpose, which first conveys insertion elements 2, 2A, ... into a magazine 22 and from there inserts them individually into the element holder 12. Insertion can be carried out, for example, with a pneumatic slide (not shown). A control device 24 is provided, which is configured to control the feeding of insertion elements 2 and generates a signal to insert the next insertion element 2A from the magazine 22 into the element holder 12. The insertion device 1 further comprises a sensor 30 in the form of a photoelectric sensor, which is configured to detect the presence of a press-fit element 2 in the element holder 12. The sensor 30 includes a transmitter 32 and a receiver 34. The transmitter 32 and receiver 34 are arranged on opposite sides of the element holder 12 (relative to the longitudinal axis L of the element holder 12), with the orientation being such that the photoelectric sensor 36 passes through the receiving section 14 of the element holder 12 via recesses 15, 16. As long as no press-fit element is present in the element holder 12, the light from the photoelectric sensor can travel from the transmitter 32 to the receiver 34, as indicated by the dashed line in Fig. 2. If a press-fit element 2 is received in the element holder 12 (Fig. 1), the photoelectric sensor 36 is interrupted, which is detected by the sensor 30. The sensor signal can be detected by a control device 38 and e.g.This must be taken into account when controlling the setting process. For cleaning the photoelectric sensor 30, the setting device 1 further comprises two air distribution bodies 40, 50. Each air distribution body 40, 50 has a compressed air connection opening 42, 52, a compressed air channel 44, 54, and a nozzle opening 46, 56. On the side of the compressed air connection opening 42, 52, the air channels 44, 54 are each connected to a compressed air supply (not shown) via a compressed air line 60, 62 and an electromagnetic valve 64, 66. The valves 64, 66 are switched by means of a control device 70, which releases or interrupts the airflow from the compressed air supply into the air distribution body. The airflow D (represented by the arrows in Fig. 1) exits the air distribution bodies 40, 50 at the nozzle openings 46, 56 and is directed towards the transmitter 32 and receiver 34, respectively. The airflow is designed such that the sensor surfaces, i.e.,The surfaces where the light signal exits the transmitter and enters the receiver are cleaned of dust and abrasion. In the example shown, the nozzle openings 46, 56 are slot-shaped. Preferably, the nozzle openings 46, 56 extend in length over at least 2 / 3 of the width of the sensor 30, as shown in Fig. 2; however, the length of the nozzle opening can also substantially correspond to the width of the sensor. Compressed air with an overpressure relative to ambient pressure in the range of 0 bar to 1 bar can preferably be used. The control device 70 is configured to actuate the valves 64, 66 such that the airflow exits the nozzle openings 46, 56 as a short compressed air pulse lasting 1 second or less, and preferably in the range of 50 ms to 100 ms. Furthermore, the control device 70 generates the signal for the compressed air pulse in such a way that it is temporally coupled to a signal for filling the element holder 12. Preferably, both signals are generated simultaneously. The air pulse is generated almost instantaneously because the electromagnetic valves 64, 66 switch very quickly. However, due to the inertia of the feed device 20, several milliseconds elapse before the next press-fit element 2A is actually inserted into the element holder 12.As a result of this coupled control, the sensor 30 can be cleaned with compressed air within the same time window required for filling the element holder 12 with the next press-fit element 2A. This makes it possible to clean the sensor 30 during each insertion process without interrupting the process or increasing the cycle time. The air distribution body 40, 50 is manufactured using an additive manufacturing process, such as 3D printing. The air distribution body 40, 50 also serves as a receptacle for the sensor 30. More precisely, the transmitter 32 is housed in the first air distribution body 40, and the receiver 34 is housed in the second air distribution body 50. Fig. 3 shows an alternative embodiment of the nozzle opening 76. Reference numerals already used in Fig. 1 or Fig. 2 represent features already described and are not described again. In this embodiment, only a single nozzle opening is provided, which runs in an annular shape around the element holder 12 (or the longitudinal axis of the element holder 12). This also allows for cleaning of the element holder 12, further reducing the dust load on the sensor. An annular nozzle opening can be formed in a single air distribution body and connected to the compressed air supply as described in Fig. 1 and Fig. 2. It is understood that the shape, size, arrangement and number of nozzle opening(s) as well as the duration and strength of the airflow can be varied to adjust and optimize the cleaning effect. Reference symbol list 1 Setting device 2, 2A Press-in element 10 Setting unit 12 Element holder 14 Receiving section 15, 16 Recesses 20 Feeding device 22 Magazine 24 Control device 30 Sensor 32 Transmitter 34 Receiver 36 Light barrier 38 Control device 40, 50 Air distribution body 42, 52 Compressed air connection opening 44, 54 Air channels 46, 56, 76 Nozzle opening 48, 58 Receptacle 60, 62 Compressed air line 64, 66 Valve 70 Control device D Compressed air pulse L Longitudinal axis

Claims

Insertion device for press-fit elements (2, 2a) comprising: a setting unit (10) with an element holder (12) for receiving a press-fit element (2, 2A) during a setting process, an automatic feeding device (20) for feeding press-fit elements (2, 2A) into the element holder (12), an optical sensor (30) configured to detect a press-fit element (2, 2A) received in the element holder (12), at least one air distribution body (40, 50) with a compressed air channel (44, 54) with a compressed air connection opening (42, 52) for connection to a compressed air supply and at least one nozzle opening (46, 56, 76), wherein the nozzle opening (46, 56, 76) is configured to generate an airflow (D) towards a sensor surface of the optical sensor (30) when compressed air is supplied via the compressed air connection opening. (42, 52) is introduced into the compressed air channel (44, 54), a valve (64,66) for interrupting and releasing the airflow (D) between the compressed air supply and the nozzle opening (46, 56, 76) characterized by a control device (70) configured to actuate the valve (64, 66) to generate a compressed air pulse (D), wherein the control device (70) is configured to generate a signal for generating the compressed air pulse (D) time-coupled to a signal for supplying a press-fit element (2, 2A) into the element holder (12). Setting device according to claim 1, wherein the valve (64, 66) is an electromagnetic valve. Setting device according to one of the preceding claims, wherein the signal for generating the compressed air pulse (D) is generated simultaneously with the signal for feeding a press-in element (2, 2A) into the element holder (12). Setting device according to one of the preceding claims, wherein the at least one air distribution body (40, 50) further serves as a receptacle (48, 58) for the optical sensor (30). Setting device according to one of the preceding claims, wherein the at least one air distribution body (40, 50) is formed by means of an additive manufacturing process. Setting device according to one of the preceding claims, wherein the at least one nozzle opening (46, 56, 76) is arranged in relation to the optical sensor (30) such that the airflow (D) is directed along a longitudinal axis (L) of the element holder (12) and in the setting direction. Setting device according to one of the preceding claims, wherein the nozzle opening (46, 56, 76) is annular and extends radially around a longitudinal axis (L) of the element holder (12). Setting device according to one of the preceding claims, wherein the optical sensor (30) is a light barrier sensor with a structurally separate transmitter (32) and receiver (34). Method for operating a setting device for press-fit elements (2, 2a) according to one of the preceding claims, in which press-fit elements (2, 2A) are automatically fed to the element holder (12) of the setting unit (10) and are pressed into at least one component by means of the setting unit (10), wherein the presence of a press-fit element (2, 2A) in the element holder (12) is monitored by means of the optical sensor (30), and a sensor surface of the optical sensor (30) is cleaned by means of an airflow (D) exiting the nozzle opening (46, 56, 76), wherein the airflow (D) is directed onto the sensor surface in the form of a compressed air pulse (D) and the compressed air pulse (D) is switched by means of a control device (70) and the signal for generating the compressed air pulse (D) is temporally coupled to a signal for feeding a press-fit element (2, 2A) into the element holder (12). Method according to claim 9, wherein the signal for generating the compressed air pulse (D) is generated simultaneously with the signal for supplying a press-in element (2, 2A) into the element holder (12).

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