Application element and method for nondestructively monitoring the setting process when applying adhesive elements
Patent Information
- Application Number
- EP2023801691
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-10-18
- Filing Date
- 2023-10-17
- Publication Date
- 2025-08-27
Smart Images
Figure 1.1
Abstract
Description
[0001] Application element and method for non-destructive setting control when applying adhesive elements
[0002] Description
[0003] The invention relates to an application element for applying adhesive elements to substrates to be bonded, an application device based thereon, and a method for applying adhesive elements to substrates to be bonded using a corresponding application element or a corresponding application device. Furthermore, the use of the corresponding application element or the corresponding application device for non-destructively checking the correct positioning of adhesive elements is disclosed.
[0004] The use of adhesive elements is an important component of many modern manufacturing processes. These adhesive elements are not only used to attach components to a substrate, but also, in particular, to close openings in such a substrate. Such openings are usually due to manufacturing processes and represent potential weak points in the final product through which moisture or contaminants can penetrate. The use of suitable, usually single-sided adhesive elements to close corresponding openings in substrates represents a simple, time- and cost-effective solution for closing these openings and preventing the unwanted penetration of contaminants. Adhesive elements, which are also referred to as die-cuts due to their manufacturing process, are already regularly used for this purpose in the state of the art.In principle, it is conceivable to manually place the corresponding adhesive elements on a substrate to seal holes. However, with increasing automation and in view of the continued interest in process control that is as error-free and efficient as possible, automated application devices have been developed for applying adhesive elements to a substrate to be bonded. These application devices must meet diverse requirements. In particular, such application devices must enable reliable and reproducible application of adhesive elements to the substrates, ideally with a high throughput.
[0005] A type of application device known from the prior art, which has great industrial relevance, relies on the fact that provided adhesive elements are picked up by an application element and applied to a substrate to be bonded using the application element, a process sometimes referred to as "pick and place." The application devices are often end effectors, which are arranged, for example, on robot arms and thus make it possible to bond different parts of the substrate at one workstation, even on large substrates such as vehicle bodies. The adhesive elements can be provided, for example, by a separate dispenser arrangement or by possibly replaceable cassette units integrated into the end effector.
[0006] In many manufacturing processes, particularly in vehicle production, the precise bonding of recesses in substrates is an essential quality criterion that must be ensured by the application devices used. In practice, however, there are regularly numerous influencing factors that can contribute to an adhesive element not being applied optimally over the opening to be closed. In particular, it can happen in many production lines that the substrates to be bonded are not always provided in exactly the same place, so that the automated application process generates an undesirable offset. In addition, malfunctions in the guidance and / or control of the end effector or defects in the applied adhesive elements can lead to inadequate bonds.
[0007] To prevent substrates with insufficiently bonded openings from leaving the corresponding workstation, it is therefore regularly necessary to provide a separate inspection step to verify the correct application of the adhesive elements. In the current state of the art, this verification is usually performed by a visual inspection performed by the employees involved in the process.
[0008] This additional visual inspection step is often perceived as disadvantageous, as it negatively impacts the time and cost efficiency of the manufacturing process. In order to ensure adequate quality assurance, visual inspection by the personnel involved in the process usually requires comprehensive training of the personnel involved. Even trained personnel can often have difficulty reliably identifying defective bonding that is only slightly outside the tolerance range.
[0009] The automated testing methods known from the state of the art, in particular optical testing methods which, for example, rely on the use of cameras in combination with image recognition, are in many cases considered to be too error-prone, meaning that the necessary process reliability cannot be achieved. For example, it may happen that the adhesive elements are not able to be captured well enough by the cameras used. In addition, these testing methods usually require a comparison of before and after images, which in many cases makes the production process more complex and slower. Furthermore, the testing methods known from the state of the art often place high demands on the necessary devices and the required computing power, which disadvantageously increases the space required for equipping a workstation.The primary object of the present invention was to eliminate or at least reduce the above-described disadvantages of the prior art.
[0010] In particular, it was the object of the present invention to provide an application element for applying adhesive elements to substrates to be bonded, as well as an application device based thereon, with which a reliable and precise application of adhesive elements is possible, desirably at a high production speed.
[0011] It was an object of the present invention that the application element to be specified should enable a reliable, process-safe possibility for non-destructive testing of the positioning accuracy of applied adhesive elements on taped holes.
[0012] It was an object of the present invention that the application element to be specified should enable more time- and cost-efficient process control as well as the greatest possible degree of automation. It was desirable to provide the option of verifying the correct positioning of adhesive elements without excessively increasing the required space or computing power, and preferably without requiring separate sensor units, such as cameras.
[0013] The inventors of the present invention have now discovered that the above objects can surprisingly be achieved by providing an application element with a receiving unit, for example a so-called application stamp, with integrated surface sensors for force monitoring, which enables spatially resolved pressure measurement during the application of the adhesive elements, as defined in the claims. This advantageously makes it possible to compare the spatially resolved pressure profile with a target pressure profile during the application of the adhesive elements, thereby determining the correct fit of the applied adhesive element. This provides an efficient and process-reliable way of non-destructively verifying the correct fit of applied adhesive elements during the application step, so that specified cycle times can be more easily adhered to.
[0014] The above-mentioned objects are thus achieved by the subject matter of the invention as defined in the claims. Preferred embodiments of the invention emerge from the subclaims and the following statements.
[0015] Such embodiments, which are designated as preferred below, are combined in particularly preferred embodiments with features of other embodiments designated as preferred. Combinations of two or more of the embodiments designated as particularly preferred below are thus very particularly preferred. Likewise preferred are embodiments in which a feature of one embodiment designated as preferred to any extent is combined with one or more further features of other embodiments designated as preferred to any extent. Features of preferred application devices, methods, and uses emerge from the features of preferred application elements.
[0016] The invention relates to an application element for applying adhesive elements to substrates to be bonded, comprising: a) a movement unit, and b) a receiving unit arranged on the movement unit and having a receiving surface, wherein the receiving unit is designed to form a reversibly and non-destructively detachable connection with an adhesive element contacting the receiving surface, wherein the receiving unit comprises a pressure sensor arrangement with at least two pressure measuring points, wherein the pressure sensor arrangement is designed to measure a pressure acting in the region of the pressure measuring points, wherein the pressure sensor arrangement is arranged in the application element such that the pressure acting on the receiving surface can be determined at at least two spaced-apart points on the receiving surface using the pressure sensor arrangement.
[0017] The application element according to the invention serves to apply adhesive elements to substrates to be bonded, being particularly suitable for the application of so-called die-cuts in the field of vehicle manufacturing. The application element according to the invention can, for example, be provided in various application devices as the unit that carries out the final application step, in particular in a "pick and place" process, in which it picks up the provided adhesive elements and places them on the substrate. Those skilled in the art will readily understand that the adhesive elements, for whose application the application element according to the invention is intended and with reference to which the functionality can be defined, are not themselves part of the application element according to the invention.
[0018] The application element according to the invention comprises a receiving unit, which serves to receive provided adhesive elements and subsequently apply them, as well as a movement unit, which is intended to move the receiving unit and guide it, for example, from a dispenser arrangement for adhesive elements to the substrate to be bonded. In other words, this is an application element according to the invention, wherein the movement unit is configured to move the receiving unit into an application position after receiving an adhesive element.
[0019] The movement unit can thus, for example, be a robot arm, at the end of which the receiving unit is arranged, which in this case would function as an end effector. In the opinion of the inventors, however, movement units with which the application element according to the invention can be efficiently used in application devices designed as end effectors are particularly relevant, so that the movement enabled by the movement unit is comparatively limited spatially and in many cases serves primarily to bridge the last distances to the substrate. In the opinion of the inventors, such a movement can be realized primarily by a possibly rotatable piston arrangement. An application element according to the invention is therefore preferred, wherein the movement unit comprises a piston arrangement with a cylinder and a piston that can be moved in the cylinder.Additionally or alternatively, an application element according to the invention is preferred, wherein the movement unit comprises a rotation device for rotating the piston arrangement, preferably for three-dimensional rotation.
[0020] The focus of the present invention, however, lies particularly on the receiving unit. In principle, various designs are conceivable for the receiving unit and the configuration of the receiving surface. However, in the inventors' estimation, it is practical for many applications to design the receiving unit as a stamp. Accordingly, an application element according to the invention is preferred, wherein the receiving unit is designed as a stamp, with the stamp body preferably being made of metal, particularly preferably aluminum or steel.
[0021] The application element comprises, as part of the receiving unit, a receiving surface which can be formed, for example, by the underside of the stamp. In accordance with the expert understanding, this receiving surface is the part of the receiving unit intended for contacting the adhesive elements to be received, wherein the reversibly and non-destructively detachable connection between the receiving unit and the adhesive element is formed at the interface between the receiving surface and the adhesive element. In order to ensure reliable reception of the adhesive elements and also to guarantee uniform contact pressure when pressed against the substrate, the inventors believe it is expedient to design the shape of the receiving surface essentially complementary to the shape of the adhesive elements to be applied, so that, for example, they do not protrude beyond the receiving surface or protrude only slightly at the sides.In view of the mostly substantially round or polygonal shape of the die-cuts used, an application element according to the invention is preferred in most cases, wherein the receiving surface has a polygonal or circular, preferably a circular, shape.
[0022] To configure the functionality of the receiving unit so that it is configured to form a reversibly and non-destructively detachable connection with an adhesive element contacting the receiving surface, the skilled person can resort to various solutions known from the prior art. The reversibly and non-destructively detachable connection can, at least in theory, be achieved, for example, by a magnet arrangement that interacts, for example, with a magnetic carrier layer of the adhesive elements, or theoretically also by suction cups or a pressure-sensitive adhesive. However, the use of a vacuum-based suction solution is particularly preferred due to the high reliability, simple design implementation, and longevity of such a solution.Accordingly, an application element according to the invention is particularly preferred, wherein the receiving unit comprises a plurality of suction recesses in the receiving surface, wherein the suction recesses are connected or connectable in a fluid-conducting manner to a pump device, wherein the receiving unit is designed to form a reversibly and non-destructively detachable connection with the adhesive element via a negative pressure acting through the suction recesses.
[0023] Those skilled in the art will understand that the provision of the receiving unit with an adhesive element contacting the receiving surface to form a reversibly and non-destructively detachable connection does not require the dissolution of the connection to occur by removing the connecting force, as would be possible, for example, by switching off a magnetic field in the case of a magnetic connection or by deactivating a suction function. Rather, it is also possible, and in practice often particularly efficient, if the reversible and non-destructive dissolution occurs against the acting forces that determine the connection.In particular, it can be exploited that the adhesion of the adhesive elements to the substrate is in many cases significantly greater than the force causing the connection to the receiving unit, so that the connection can be made, for example, against a suction-acting negative pressure when the receiving unit is moved away from the substrate.
[0024] A preferred embodiment with a suction function can be achieved, for example, by a surface in which a plurality of separate suction recesses are formed, for example, as bores. In the inventors' opinion, it is particularly preferred to realize the corresponding functionality through the use of a porous material, for example a closed-pore foam, through which the suction pressure is conveyed by means of bores. Accordingly, an application element according to the invention is preferred, wherein the receiving surface is formed by a first material layer, wherein the first material layer preferably comprises a foam, particularly preferably a closed-pore foam, in particular an elastically deformable foam, preferably made of an elastomeric plastic, in particular a rubber material.
[0025] The use of such a foam with holes not only advantageously achieves a very uniform, flat suction effect, but the use of deformable foams also reduces the risk of the adhesive elements being damaged during pickup. Furthermore, a deformable foam makes it easier to compensate for surface irregularities on the substrate to be sealed. In the context of the invention, however, it is particularly advantageous in that the easy deformability of typical foams makes it possible to efficiently determine the pressure acting on the pickup surface using the pressure sensor arrangement even when the pressure sensor arrangement does not extend to the surface of the pickup surface, but lies completely beneath the elastically deformable foam, so that the foam can communicate the pressure acting on the pickup surface to the underlying pressure sensor arrangement.
[0026] In light of the above statements regarding the communication of the pressure through the first material layer, the person skilled in the art understands that even when foamed materials are omitted, an application element according to the invention is generally preferred, wherein the receiving surface is formed by a first material layer, wherein the first material layer is elastically deformable and / or comprises an elastomeric material.
[0027] A central component of the application elements according to the invention is the pressure sensor arrangement. Those skilled in the art will understand that this pressure sensor arrangement serves the purpose of enabling a spatially resolved measurement of the pressure acting on the receiving surface.
[0028] The idea underlying the invention can be understood using an example. In this example, a round adhesive element with radius n located on the receiving surface is applied to a substrate in order to cover a round hole with radius r2, where r2< , so that the adhesive element protrudes beyond the hole over the entire circumference in a perfectly concentric bond. By moving the movement unit, an application pressure is now exerted which has a direct effect in the edge areas where the adhesive element contacts the substrate. In the area of the underlying opening, however, a lower pressure will act on the receiving surface. The pressure sensor arrangement now allows information about the pressures acting during application to be collected and compared with the desired target pressure profile, whereby correct application can be verified.Assuming an arbitrarily high spatial resolution, the pressure sensor arrangement in the example described above would, in an optimal application, have to detect a largely uniform, higher pressure in the annular area between r and r2, and a reduced pressure in the inner circle with radius r2. A deviation from this optimal pressure profile, for example, the measurement of lower contact pressures in the annular area, would indicate a deviation from the desired positioning.
[0029] Those skilled in the art will understand that the above assumption of a pressure measurement with arbitrarily good resolution is limited in practical implementation by the available pressure sensor arrays and their arrangement in application elements according to the invention. The number of separate pressure measurement points of the pressure sensor arrays, i.e., points at which the pressure sensor arrays can determine the pressure and, if necessary, register a difference in pressure, will generally not be arbitrarily large in practice. However, those skilled in the art will understand that a perfect, spatially resolved pressure measurement across the entire recording surface is not necessary in practice anyway, and in many cases, given the design effort, is not even desired.Rather, according to the inventors' assessment, even with a relatively low spatial resolution, such as that achievable with two pressure measurement points spaced apart from one another, basic information can be obtained, which may be sufficient for simple applications, for example. This can again be understood using an illustrative example that ties in with the previous example. If the pressure sensor arrangement comprises two pressure measurement points, the application element can be designed such that the first pressure measurement point detects the total pressure on the entire left side of the receiving surface and the second pressure measurement point detects the total pressure on the entire right side of the receiving surface, for example by using a two-part receiving surface, each part of which is connected to a pressure measurement point of the pressure sensor arrangement.In the above example, a perfect application of the adhesive element on the hole would be recognizable by the fact that both pressure measuring points measure the same total pressure, so that at least a pronounced offset of the adhesive element would be recognizable in deviating pressure measuring values.
[0030] However, the inventors propose that the advantages of the present invention become more apparent the greater the density of pressure measurement points is chosen, since an increasingly precise detection of the pressure profiles becomes possible, through which even small deviations from the desired target pressure profile can be better registered.An application element according to the invention is preferred, wherein the pressure sensor arrangement comprises three or more, preferably four or more, particularly preferably five or more, very particularly preferably ten or more, in particular preferably fifteen or more, pressure measuring points, wherein the pressure sensor arrangement is arranged in the application element such that the pressure acting on the receiving surface can be determined at at least three, preferably at least four, particularly preferably at least five, very particularly preferably at least ten, in particular preferably at least fifteen, spaced-apart points of the receiving surface with the pressure sensor arrangement.In other words, an application element according to the invention is preferred, wherein the pressure sensor arrangement is designed to detect a spatially resolved pressure profile when pressure is applied to the receiving surface, wherein the resolution is preferably three or more, particularly preferably four or more, very particularly preferably five or more, particularly preferably ten or more, most preferably fifteen or more, pressure measurement points per area of the receiving surface.
[0031] Those skilled in the art will understand that a variety of possible pressure sensor types are suitable for the design of the pressure sensor arrangement, which can be used as pressure sensor elements in the pressure sensor arrangement, for example, piezoresistive pressure sensors or piezoelectric pressure sensors, with suitable pressure sensors being commercially available from numerous suppliers. The pressure sensor arrangement can, for example, comprise a plurality n of pressure measuring points, each formed by separate pressure sensor elements, so that the application element according to the invention comprises n separate pressure sensor elements. However, in accordance with the understanding of those skilled in the art, many of the modern pressure sensors, in particular so-called film sensors or thin-film sensors, are themselves capable of performing a spatially resolved pressure measurement. These pressure sensor elements thus themselves comprise several pressure measuring points.In a preferred example, the pressure sensor arrangement with n pressure measuring points described above can comprise only one pressure sensor element which is designed as a thin-film sensor and comprises the n pressure measuring points which the thin-film sensor can resolve.
[0032] In light of these embodiments, an application element according to the invention is preferred, wherein the pressure sensor arrangement comprises at least one pressure sensor element with two or more, preferably three or more, particularly preferably four or more, pressure measuring points, preferably a film sensor and / or thin-film sensor. In this respect, an application element according to the invention is particularly preferred, wherein the pressure sensor arrangement comprises precisely one pressure sensor element with two or more pressure measuring points. Additionally or alternatively, an application element according to the invention is preferred, wherein the pressure sensor arrangement comprises two or more, preferably three or more, particularly preferably four or more, separate pressure sensor elements.
[0033] In particular, by using film sensors or thin-film sensors, which themselves have a large number of pressure measuring points and can therefore detect pressure differences with a very high resolution, particularly preferred pressure sensor arrangements can be obtained in application elements according to the invention, the minimum distinguishable resolution of the measured pressures of which is in many cases many times smaller than the dimensions of typical adhesive elements.Accordingly, an application element according to the invention is preferred, wherein the pressure sensor arrangement comprises a plurality of pressure measuring points, preferably as part of pressure sensor elements with a plurality of pressure measuring points, and is designed to enable a pressure measurement at least in a section of the receiving surface, preferably over substantially the entire receiving surface, wherein the minimum distance between two distinguishable pressure measuring points is 1 mm or less, preferably 0.1 mm or less, particularly preferably 0.01 mm or less, very particularly preferably 0.001 mm or less, particularly preferably 0.0001 mm or less.
[0034] According to the inventors' assessment, many modern flat pressure sensor elements, for example film sensors or thin-film sensors, can achieve a pressure measurement resolution on the recording surface that is not actually required for many applications. In view of the storage and computing capacity required for the evaluation, it will therefore be expedient in many cases to only read out individual pressure measurement points from the flat sensor elements and / or to combine several pressure measurement points in the evaluation and create a combined or averaged common pressure measurement value for the evaluation. Against this background, a similar task arises when using both several separate pressure sensor elements and flat pressure sensor elements with a large number of pressure measurement points, namely how the separate pressure sensor elements or, in the case of flat pressure sensor elements, the pressure measurement points actually read out, orGroups of pressure measuring points can be efficiently distributed over the recording surface in order to enable the most efficient setting control possible with a minimal requirement of pressure sensor elements or storage and computing capacity.
[0035] In this respect, the inventors recognized that the distribution of the pressure measurement points should be based on the expected target pressure profile and the most probable deviations in order to be able to resolve them efficiently. In this respect, an application element according to the invention is preferred, particularly for rotationally symmetric adhesive elements, wherein the pressure measurement points in the pressure sensor arrangement are arranged symmetrically, preferably with Cs rotational symmetry or higher, more preferably with Cß rotational symmetry or higher, most preferably with C12 rotational symmetry or higher, and especially preferably with C16 rotational symmetry or higher.
[0036] The inventors consider it particularly preferred to subdivide the recording surface via the pressure sensor arrangement into pressure measurement segments for which a pressure value is determined. This subdivision can be achieved both structurally and via the evaluation scheme. One structural embodiment could, for example, comprise the physical separation of the recording surface into at least partially independently movable segments, each of which is assigned, for example, to a pressure sensor element of the pressure sensor arrangement or to a pressure measurement point. Segmentation via the evaluation scheme can be achieved by a person skilled in the art by defining a group from a plurality of pressure measurement points in a specific segment of the recording surface, which group is evaluated together, wherein the plurality of pressure measurement points and / or the group of pressure measurement points can, for example, be assigned to the same film sensor.Against this background, an application element according to the invention is preferred, wherein the receiving surface comprises a plurality of pressure measuring segments, wherein each pressure measuring segment is assigned at least one pressure measuring point of the pressure sensor arrangement, wherein the pressure sensor arrangement preferably comprises four or more, particularly preferably five or more, very particularly preferably ten or more, especially preferably fifteen or more, pressure measuring segments. In principle, pressure measuring segments can take any shape and, for example, be formed as squares or other polygons. In practice, the shape of the pressure measuring segments will probably be primarily based on the shape of the adhesive elements and the shape of the receiving surface.An application element according to the invention is particularly preferred for the application of mostly round die-cuts, wherein the pressure measuring segments are designed as pressure measuring segments, preferably as circular segments, of the same size, wherein the circular segments are preferably divided into sub-segments along the radial direction.
[0037] For an optimal adaptation of the application elements according to the invention to one of the most relevant applications in practice, namely the over-gluing of mostly substantially circular openings in substrates, the inventors propose that it is advantageous to provide an inner and an outer pressure measuring area, wherein the shape and size of the inner pressure measuring area should preferably correlate with the shape and size of the hole to be glued over, which leads to particularly good results in applications in which substantially uniform openings are to be glued over.Particularly preferred is an application element according to the invention, wherein the pressure sensor arrangement comprises an inner pressure measuring region located on the inside in the radial direction and an outer pressure measuring region surrounding the inner pressure measuring region and lying on the outside in the radial direction, wherein the inner pressure measuring region and / or the outer pressure measuring region preferably comprise a plurality of pressure measuring points, wherein the pressure measuring points in the inner pressure measuring region and / or in the outer pressure measuring region are preferably arranged symmetrically, particularly preferably rotationally symmetrically. Accordingly, also preferred is an application element according to the invention, wherein the pressure sensor arrangement is arranged in the application element such that the pressure acting on the receiving surface can be determined in an inner pressure measuring region located on the inside in the radial direction and in an outer pressure measuring region surrounding the inner pressure measuring region and lying on the outside in the radial direction.Such a design can be realized particularly efficiently for the mostly round punched pieces with the above-disclosed subdivision of the receiving surface into circular segments, wherein for each circular segment at least one radially inner partial segment is provided in the inner pressure measuring area and at least one radially outer partial segment is provided in the outer pressure measuring area.
[0038] Those skilled in the art will understand that the pressure sensor arrangement is arranged in the application element in such a way that the pressure acting on the receiving surface can be determined. In simple embodiments, this could be achieved, for example, by arranging the pressure sensor elements of the pressure sensor arrangement on the surface of the receiving surface, for example by countersinking them in the first material layer. However, in the inventors' opinion, this embodiment is disadvantageous with regard to durability and maintenance effort, in particular with regard to slight contamination of or damage to the sensor elements. An application element according to the invention is therefore preferred, wherein the receiving surface is formed by a first material layer, wherein the pressure sensor arrangement is arranged on the side of the first material layer facing away from the receiving surface.
[0039] This preferred arrangement of the pressure sensor arrangement could be realized for rigid first material layers, for example, by having a pin or a similar movable element extending through the first material layer for each of the pressure sensor units forming the pressure measurement points, so that a pressure acting on the receiving surface can be detected through the first material layer. Alternatively, the receiving surface could also be divided into two or more segments, which can be moved at least partially independently of one another, so that the respective underlying pressure sensor units can be selectively acted upon.However, the inventors consider it particularly preferred if the corresponding positioning of the pressure sensor arrangement on the side of the first material layer facing away from the receiving surface is combined with an elastically deformable first material layer, in particular in the form of a foam, as disclosed above.
[0040] Particularly when using film sensors, the inventors consider it advantageous if the pressure sensor arrangement is positioned on an elastic carrier layer. An application element according to the invention is preferred, wherein a second material layer is arranged between the pressure sensor arrangement and the stamp body, wherein the second material layer preferably comprises an elastomeric plastic, in particular a rubber material.
[0041] The application element according to the invention can be advantageously used in an application device, which in particular allows for efficient upgradeability of existing application devices. Accordingly, the invention also relates to an application device for applying adhesive elements to substrates to be bonded, comprising: x) an application element according to the invention, and y) a supply unit for providing an adhesive element, wherein the application device is configured to receive an adhesive element provided by the supply unit with the application element and to apply it to a substrate to be bonded.
[0042] The application device according to the invention is used to apply adhesive elements to substrates to be bonded, and is particularly suitable for the application of so-called die-cuts in the field of vehicle production. The application device according to the invention can be integrated in a variety of ways into existing production lines in which adhesive elements must be applied to substrates. For example, a largely stationary application device is conceivable in which, for example, only the application element according to the invention picks up the adhesive elements provided from the supply unit and places them on the substrate as part of a "pick & place" process. In the opinion of the inventors, however, for the vast majority of cases, an embodiment of the application device according to the invention in which it is designed as a so-called end effector will be preferred.In accordance with the expert understanding, an end effector is the executing and / or concluding element of automated movement units, for example robot arms. In other words, end effectors in the field of robotics are the last components of a kinematic chain, which are usually configured to execute an execution instruction specified by an external control device, optionally together with the automated movement unit to which they are attached. Accordingly, an application device according to the invention is preferred, wherein the application device is an end effector for an automated movement unit, preferably a robot arm. Likewise preferred is an application device according to the invention, wherein the application device is arranged on an automated movement unit, preferably a robot arm.
[0043] The person skilled in the art will understand that the application device according to the invention comprises a plurality of automated or automatable components, for example for moving the application element. In addition to controlling these components, the control and / or readout function of the pressure sensor arrangement, as well as optionally also the evaluation by comparing the measured pressure values with the target pressure values, can also be carried out by an electronic data processing device, which can be integrated into the application device according to the invention or - in practice probably less frequently - into the application element according to the invention. Accordingly, an application device according to the invention is preferred, wherein the application device comprises an electronic data processing device for controlling the application device, wherein the electronic data processing device is preferably configured toWhen applying the adhesive element, the pressure acting on the receiving surface is to be determined with the pressure sensor arrangement in order to obtain a pressure profile. The invention further relates to a method, already comprehensively described above in connection with application elements according to the invention, for applying adhesive elements to substrates to be bonded, using an application element according to the invention or an application device according to the invention, comprising the method steps: i) producing or providing a substrate to be bonded, wherein the substrate to be bonded comprises a recess to be bonded over, ii) providing an adhesive element, iii) receiving the provided adhesive element with the application element, forming a reversibly and non-destructively detachable connection between the application element and the adhesive element, iv) applying the received adhesive element to the substrate to be bonded,so that the recess to be glued over is at least partially glued over, and v) dissolving the connection between the application element and the applied adhesive element, wherein in method step iv) the pressure acting on the receiving surface during application of the adhesive element is determined with the pressure sensor arrangement to obtain a pressure profile at at least two mutually spaced points of the receiving surface.
[0044] Based on the method according to the invention, the obtained pressure profile can be used in various ways. To implement non-destructive setting control, it is particularly advantageous to compare it with the target pressure profile, as explained above. A method according to the invention is preferred, wherein the obtained pressure profile for each applied adhesive element is compared with a target pressure profile, wherein the deviation from the target pressure profile is preferably documented, particularly preferably in an electronic storage unit, and the documented deviation is most preferably provided as information for further processing steps of the substrate.
[0045] The direct non-destructive setting control advantageously makes it possible in the method according to the invention to immediately initiate corrective measures in order to prevent a faultily bonded substrate from being fed from the workstation to further processing steps after which a correction of the bond would not be possible or at least would only be possible with great effort, wherein such corrective measures can in particular comprise the removal of the inadequately applied adhesive element and the application of a new adhesive element.Accordingly, a method according to the invention is preferred, wherein one or more corrective measures are triggered if the deviation of the obtained pressure profile from the target pressure profile lies outside a predetermined tolerance range, wherein the corrective measures are selected from the group consisting of manual corrective measures for correcting the position of the adhesive element and automated corrective measures for correcting the position of the adhesive element.
[0046] The setting control directly correlated with the application also makes it possible to detect systematic deviations in the application of adhesive elements at an early stage and to adapt the application process in such a way that these systematic errors are compensated. A method according to the invention is preferred, wherein the operating parameters are adjusted in process step iii) and / or iv) if the deviation of the obtained pressure profile from the target pressure profile detected during a plurality of consecutive application processes exhibits a systematic deviation.
[0047] Regardless of whether a comparison with a target pressure profile was previously performed, the detected pressure profiles can be stored and digitally saved for a bonded substrate, for example, to make it traceable as part of quality assurance whether the bonding was carried out correctly during the manufacturing process, so that a comparison with a target pressure profile can only be carried out when necessary, for example. A method according to the invention is preferred, wherein the obtained pressure profile is documented for each applied adhesive element, preferably in an electronic storage unit, wherein the documented pressure profile is particularly preferably provided as information for further processing steps of the substrate.
[0048] Even though the focus of the present invention is particularly on pressure measurement during the application step, the inventors have fortunately found that the advantageous functionality of application elements according to the invention can also be utilized in other ways. The inventors have recognized that in the vast majority of cases, pressure is exerted on the receiving surface when the provided adhesive element is picked up with the application element, for example when the adhesive element comes into contact with the receiving unit and / or as a result of a force that causes the connection, for example, due to suction pressure. This makes it possible to also use the pressure sensor arrangement to detect whether an adhesive element has been picked up correctly, wherein, in particular, an undesired offset of the adhesive element relative to the receiving surface can be registered due to an uneven initial pressure profile.Accordingly, a method according to the invention is also preferred, wherein in method step iii) the pressure acting on the receiving surface when receiving the adhesive element is determined to obtain an initial pressure profile at at least two mutually spaced points of the receiving surface with the pressure sensor arrangement, wherein the obtained initial pressure profile is preferably compared with a desired initial pressure profile for each applied adhesive element.
[0049] The inventors have succeeded in identifying preferred application pressures suitable for the application of adhesive elements in typical manufacturing processes, particularly in the automotive industry, and which, when using commercially available sensor elements, enable particularly efficient detection of the pressure profile without unduly adversely affecting the service life of the sensor elements. A method according to the invention is preferred, wherein the application of the adhesive element to the substrate to be bonded in process step iv) is carried out with a pressure force in the range of 2 to 10 N / cm 2 , preferably in the range of 3 to 8 N / cm 2 , particularly preferably in the range of 4 to 6 N / cm 2 , takes place.
[0050] A method according to the invention is relevant for essentially all modern applications, wherein the method is at least partially controlled by an electronic data processing device.
[0051] Due to the great relevance of corresponding bonding steps in vehicle production, a method according to the invention is preferred, wherein the substrate to be bonded is a vehicle component, for example a vehicle body.
[0052] It can be seen as an advantage of the application device according to the invention and the method according to the invention that they are suitable for applying a wide range of different adhesive elements. In the majority of cases, this will be a method according to the invention, wherein the adhesive elements comprise an adhesive layer and a carrier layer connected to the adhesive layer. Due to their high practical relevance, the application of so-called diecuts is of particular importance. These are adhesive elements that can be obtained, for example, by die-cutting the adhesive element out of a larger adhesive composite, wherein the adhesive composite comprises an adhesive layer and a carrier layer arranged on the adhesive layer, from which the adhesive layers or carrier layers of the adhesive elements result after the die-cutting process. A method according to the invention is therefore preferred, wherein the adhesive elements are die-cuts.
[0053] The adhesive elements applied in the process according to the invention with application devices according to the invention will, in the vast majority of cases, be pressure-sensitive adhesive elements, i.e., adhesive elements which have pressure-sensitive adhesive properties as a result of an adhesive layer made of pressure-sensitive adhesive. Such pressure-sensitive adhesive elements are advantageously self-adhesive without an additional curing step and can be applied particularly easily to substrates. As an additional advantage, pressure-sensitive adhesive elements can also be removed relatively easily if necessary, for example, to subsequently correct the position of an incorrectly applied pressure-sensitive adhesive element. Therefore, a process according to the invention is preferred in which the adhesive elements are pressure-sensitive adhesive elements.A method according to the invention is also preferred, wherein the adhesive layer of the adhesive elements comprises a pressure-sensitive adhesive, wherein the adhesive layer preferably consists of a pressure-sensitive adhesive.
[0054] According to expert understanding, a pressure-sensitive adhesive is an adhesive that possesses pressure-sensitive adhesive properties, i.e., the ability to form a permanent bond to a substrate even under relatively light pressure. Such pressure-sensitive adhesive elements are generally permanently tacky even at room temperature, meaning they exhibit a certain viscosity and tackiness, allowing them to wet the surface of a substrate even under light pressure. Without wishing to be bound by this theory, it is often assumed that a pressure-sensitive adhesive can be considered an extremely viscous liquid with an elastic component, which consequently possesses characteristic viscoelastic properties that lead to the permanent tackiness and pressure-sensitive adhesive capacity described above.It is assumed that, in the case of corresponding pressure-sensitive adhesives, mechanical deformation results in both viscous flow processes and the build-up of elastic restoring forces. The partial viscous flow serves to achieve adhesion, while the partial elastic restoring forces are particularly necessary to achieve cohesion. The relationships between rheology and pressure-sensitive tack are known in the art and described, for example, in "Satas, Handbook of Pressure Sensitive Adhesives Technology", Third Edition, (1999), pages 153 to 203. To characterize the degree of elastic and viscous components, the storage modulus (G') and the loss modulus (G") are usually used. These can be determined by means of dynamic mechanical analysis (DMA), for example using a rheometer, as disclosed, for example, in WO 2015 / 189323.In the context of the present invention, an adhesive is preferably understood as pressure-sensitive adhesive and thus as a pressure-sensitive adhesive if, at a temperature of 23 °C in the deformation frequency range from 10° to 10. 1 rad / sec G' and G“ each at least partly in the range of 10 3 up to 10 7 Pa lie.
[0055] It can be seen as an advantage of the application device according to the invention and the method according to the invention that they are very flexible with regard to the chemical composition of the adhesive used in the adhesive layer, so that essentially all adhesives familiar to the person skilled in the art can be used and the person skilled in the art essentially bases the selection of a suitable adhesive on the respective application requirements.
[0056] In addition to the adhesive layer, the adhesive elements also comprise a carrier layer. Within the scope of the present invention, the term "carrier layer" is to be understood broadly and functionally, so that even thinner coatings, for example a varnish with a layer of varnish, are to be understood as a carrier layer. Those skilled in the art will understand that, within the scope of the invention, the carrier layer in most cases primarily has the task of reducing the stickiness of the side of the adhesive elements facing away from the adhesive side, or desirably eliminating it entirely. This serves the particular purpose of ensuring that the adhesive elements can be efficiently absorbed by the application element on the non-sticky carrier layer without sticking to the application element.
[0057] In the inventors' opinion, in practice it will therefore be expedient to have at least a temporary coating which, at least at the time of application, reduces the stickiness in the area of contact with the application element. In the vast majority of cases, however, the adhesive elements will have a permanent carrier layer which is essentially permanently non-sticky, so that after application of the adhesive elements to the substrate, the smallest possible sticky surface advantageously remains. The person skilled in the art will understand in this respect that, even if it would at least theoretically be conceivable to use adhesive elements which are sticky on both sides, i.e. adhesive elements which have an adhesive layer on both sides of the carrier layer, such a process is significantly less preferred with regard to clean handling of the application process.For the vast majority of cases, a method according to the invention is therefore preferred, wherein the side of the adhesive elements facing away from the adhesive layer is formed by the carrier layer. Accordingly, a method according to the invention is preferred, wherein the receiving unit is configured to form a reversibly and non-destructively detachable connection with an adhesive element contacting the receiving surface via the carrier layer.
[0058] It can be seen as an advantage of the application device and method according to the invention that the carrier layer can be produced from typical materials that are used in the field of adhesive technology for corresponding carrier layers. An example of this is a method according to the invention, wherein the carrier layer comprises one or more materials selected from the group consisting of polyethylene, polypropylene, cyclic olefin copolymers, polyvinyl chloride, polyester, ethylene-vinyl alcohol, polyvinylidene chloride, polyvinylidene fluoride, polyacrylonitrile, polycarbonate, polyamide, polyethersulfone and polyimide, preferably selected from the group consisting of polyethylene, polypropylene and polyethylene terephthalate, wherein the carrier layer preferably consists of these materials.
[0059] Finally, the use of an application element according to the invention or an application device according to the invention in the application of adhesive elements to substrates to be bonded for the non-destructive control of the correct positioning of the adhesive element is also disclosed.
[0060] Preferred embodiments of the invention are explained and described in more detail below with reference to the accompanying figures. In the figures:
[0061] Fig. 1 is a schematic representation of an application element according to the invention in a preferred embodiment;
[0062] Fig. 2 is a schematic representation of a receiving unit of an application element according to the invention in a preferred embodiment; Fig. 3 is a schematic representation of a pressure sensor arrangement of an application element according to the invention in various preferred embodiments; and
[0063] Fig. 4 is a schematic representation of an application element according to the invention with visualization of exemplary pressure profiles in the application process.
[0064] Fig. 1 shows an application element 10 according to the invention for applying adhesive elements to substrates to be bonded, comprising a movement unit 1 and a receiving unit 14 in a preferred embodiment. In the example shown, the movement unit 12 is designed as a rotatable piston assembly, with the receiving unit 14 being attached to an end of a piston movable within the piston assembly, protruding from the piston assembly.
[0065] Fig. 2 shows a preferred embodiment of a receiving unit 14 of an application element 10 according to the invention. The preferred receiving unit 14 shown is designed as a round stamp and accordingly comprises a stamp body 26 and, arranged thereon in layers, a second material layer 28 made of an elastomer, a pressure sensor arrangement 18 and a first material layer 24 made of a closed-cell foam provided with bores, which forms the receiving surface 16.
[0066] When used in a method according to the invention, the receiving unit 14 shown in Fig. 2 can receive a provided adhesive element, for example a pressure-sensitive adhesive die-cut, when it is brought into contact with the carrier layer of the adhesive element via the receiving surface 16 by the movement unit 1 of the application element 10. In the example shown, a reversibly and non-destructively detachable connection between the receiving surface 16 and the adhesive element can be established by a negative pressure, which is generated via a pumping device (not shown) and acts on the receiving surface 16 through the open-pore foam of the first material layer 24, so that the adhesive element is fixed by the applied negative pressure. After receiving, the adhesive layer of the adhesive element is exposed and prepared for application.By subsequent rotation of the movement unit 1, the receiving unit 14 can be brought into an application position before the piston is extended in order to apply the adhesive element to a substrate, for example a vehicle body, with a recess to be bonded over, for example with a contact force in the range of 4 to 6 N / cm. 2 . The reversibly and non-destructively detachable connection between the adhesive element and the receiving unit 14 can be released, for example, by the suction pressure being lower than the adhesion of the adhesive element to the substrate, so that the connection to the receiving unit 14 can be released, for example, by moving the application unit.
[0067] Fig. 3a) and 3b) show a top view of the recording unit, visualizing the pressure sensor arrangement 18 arranged below the recording surface 16. In the example shown, this is formed by a flat foil sensor and comprises sixteen symmetrically arranged pressure measuring points 20.
[0068] As shown in Fig. 3b), the pressure measuring points 20 of the pressure sensor arrangement 18 are each assigned to a pressure measuring segment 22a, 22b of the receiving surface 16. For reasons of clarity, only one outer pressure measuring segment 22a and one inner pressure measuring segment 22b are highlighted in Fig. 3b. This means that the receiving unit 14 has a total of sixteen pressure measuring segments 22a-b on the receiving surface 16.The dimensions of these pressure measuring segments 22a-b are determined by eight equally sized circular measuring segments, each of which is divided into a radially inner sub-segment as the inner pressure measuring segment 22b and a radially outer sub-segment as the outer pressure measuring segment 22a, so that eight inner sub-segments form an inner pressure measuring area, which is surrounded by an outer pressure measuring area, which in turn is formed by eight outer sub-segments, each sub-segment being assigned a pressure measuring point 20.
[0069] During the application of the adhesive element in the method according to the invention, the pressure acting on the receiving surface 16 in the area of the pressure measuring segments 22a-b is determined by the pressure sensor arrangement 18 via the pressure measuring points 20, thus obtaining a spatially resolved pressure profile. The obtained pressure profile visualizes the measured pressure within the pressure measuring segments 22a-b and can be compared with a desired pressure profile, as shown in different representations in Figs. 4a) and 4b).
[0070] Fig. 4a) visualizes a pressure profile in the case of optimal application of a round die-cut to a circular recess, with the recess of the substrate to be bonded being represented as a dashed circular line. In Fig. 4a), the circular recess is optimally positioned over the inner pressure measurement area, so that the eight inner pressure measurement segments 22b detect a low pressure resistance, which is indicated by hatching, whereas the eight outer pressure measurement segments 22a register a higher pressure resistance. The resulting pressure profile corresponds exactly to the target pressure profile. The difference representation between the resulting pressure profile and the target pressure profile would accordingly show no deviations.
[0071] In contrast to the pressure representation in Fig. 4a), Fig. 4b) visualizes such a difference representation, i.e. the result of a comparison between the obtained pressure profile and the target pressure profile, for an application process in which the adhesive element was not placed centrally over the circular recess. Hatching indicates that the obtained pressure profile deviates from the target specification taking into account a predetermined tolerance. The difference representation in Fig. 4b) shows six pressure measuring segments 22a-b in which the obtained pressure profile deviates particularly strongly from the target pressure profile, so that previously defined tolerances are exceeded. The three marked inner pressure measuring segments 22b in the inner pressure measuring area detect excessive pressure resistance, while the three marked outer pressure measuring segments 22a in the outer pressure measuring area register insufficient pressure resistance.If a deviation from the target pressure profile according to Fig. 4b) is detected in a method according to the invention, it would in most cases be advisable to initiate corrective measures, for example to effect a manual correction of the position of the adhesive element on the recess.
[0072] List of reference symbols
[0073] 10 Application element 12 Movement unit
[0074] 14 Recording unit
[0075] 16 Recording surface
[0076] 18 Pressure sensor arrangement
[0077] 20 Pressure measuring point 22a-b Pressure measuring segment
[0078] 24 first layer of material
[0079] 26 stamp bodies
[0080] 28 second layer of material
Claims
Claims 1. Application element (10) for applying adhesive elements to substrates to be bonded, comprising: a) a movement unit (12), and b) a receiving unit (14) arranged on the movement unit (1) and having a receiving surface (16), wherein the receiving unit (14) is designed to form a reversibly and non-destructively detachable connection with an adhesive element contacting the receiving surface (16), wherein the receiving unit (14) comprises a pressure sensor arrangement (18) with at least two pressure measuring points (20), wherein the pressure sensor arrangement (18) is designed to measure a pressure acting in the region of the pressure measuring points (20), wherein the pressure sensor arrangement (18) is arranged in the application element (10) such that the pressure acting on the receiving surface (16) can be determined at at least two spaced-apart points on the receiving surface (16) using the pressure sensor arrangement (18).
2. Application element (10) according to claim 1, wherein the receiving unit (14) comprises a plurality of suction recesses in the receiving surface (16), wherein the suction recesses are connected or connectable in a fluid-conducting manner to a pump device, wherein the receiving unit (14) is designed to form a reversibly and non-destructively detachable connection with the adhesive element via a negative pressure acting through the suction recesses.
3. Application element (10) according to one of claims 1 or 2, wherein the pressure sensor arrangement (18) comprises three or more pressure measuring points (20), wherein the pressure sensor arrangement (18) is arranged in the application element (10) such that the pressure acting on the receiving surface (16) can be determined at at least three spaced-apart points of the receiving surface (16) with the pressure sensor arrangement (18).
4. Application element (10) according to one of claims 1 to 3, wherein the pressure sensor arrangement (18) comprises at least one film sensor and / or thin-film sensor.
5. Application element (10) according to one of claims 1 to 4, wherein the pressure sensor arrangement (18) is configured to detect a spatially resolved pressure profile when pressure is applied to the receiving surface (16), wherein the resolution is three or more pressure measurement points (20) per area of the receiving surface (16).
6. Application element (10) according to one of claims 1 to 5, wherein the receiving surface (16) comprises a plurality of pressure measuring segments (22a, 22b), wherein each pressure measuring segment (22a, 22b) is assigned at least one pressure measuring point (20) of the pressure sensor arrangement (18).
7. Application element (10) according to claim 6, wherein the pressure measuring segments (22a, 22b) are designed as pressure measuring segments of the same size.
8. Application element (10) according to one of claims 1 to 7, wherein the receiving surface (16) is formed by a first material layer (24), wherein the first material layer (24) comprises a foam.
9. Application element (10) according to one of claims 1 to 8, wherein a second material layer (28) is arranged between the pressure sensor arrangement (18) and the stamp body (26), wherein the second material layer (28) preferably comprises an elastomeric material.
10. Application device for applying adhesive elements to substrates to be bonded, comprising: x) an application element (10) according to one of claims 1 to 9, and y) a provision unit for providing an adhesive element, wherein the application device is designed to receive an adhesive element provided by the provision unit with the application element (10) and to apply it to a substrate to be bonded.
11. A method for applying adhesive elements to substrates to be bonded, using an application element (10) according to any one of claims 1 to 9 or an application device according to claim 10, comprising the method steps: i) producing or providing a substrate to be bonded, wherein the substrate to be bonded comprises a recess to be bonded over, ii) providing an adhesive element, iii) receiving the provided adhesive element with the application element (10) to form a reversibly and non-destructively detachable connection between the application element (10) and the adhesive element, iv) applying the received adhesive element to the substrate to be bonded so that the recess to be bonded over is at least partially bonded over, and v) dissolving the connection between the application element (10) and the applied adhesive element,wherein in method step iv) the pressure acting upon application of the adhesive element to the receiving surface (16) to obtain a pressure profile at at least two mutually spaced points of the receiving surface, (16) is determined with the pressure sensor arrangement (18). 1 . Method according to claim 11 , wherein the application of the adhesive element to the substrate to be bonded in process step iv) with a pressure force in the range of 2 to 10 N / cm 2 occurs.
13. The method according to any one of claims 11 or 12, wherein the pressure profile obtained is documented for each applied adhesive element.
14. The method according to any one of claims 11 to 13, wherein the pressure profile obtained Pressure profile for each applied adhesive element is compared with a target pressure profile.
15. The method according to claim 14, wherein the operating parameters in method step iii) and / or iv) are adjusted if the deviation of the obtained pressure profile from the target pressure profile detected in a plurality of successively performed application processes shows a systematic deviation.