[0001] The present invention relates to a method for detecting irregularities on a material strand made of an elastomeric material such as thermoplastic elastomere (TP) or ethylene propylene diene monomer rubber (EPDM), comprising the steps of providing a material strand which defines a longitudinal axis along which the material strand is to be conveyed, and the step of detecting an irregularity like a joint in the material strand.

[0002] Further, the present invention relates to a corresponding apparatus for detecting irregularities on a material strand. Finally, the present invention relates to a method for applying a material strand strip on a body portion. [0003] The material strand is preferably a sealing profile strand for sealing body openings of vehicle bodies.

[0004] In the technical field of manufacturing vehicle bodies, it is known to apply material strands to body openings, for example door openings or window openings. The material strand is typically made from a radially elastically deformable material, so as to provide the necessary sealing properties. Typical material examples are TPE (thermo plastic elastomer) and EPDM (ethylene propylene diene monomer rubber).

[0005] Other types of material strands can be used for trimming or fastening purposes in relation to body openings, particularly doors, windows, lids etc.

[0006] The material strands are typically produced by an extrusion process. In many cases, material strand strips with a predefined strip length are cut off from the extruded material at a manufacturing site, and are then collectively shipped to an applica tion site, typically an OEM.

[0007] Another concept for transporting the material strands to an application site, is the so-called "endless" concept. Here, at the manufacturing site, an extruded material strand is continuously wound on a reel, thus forming a material strand assembly. The reel with the material strand wound thereon is then transported to the application site, where the material strand is un-wound from the reel and material strand strips are cut-off at the predefined strip length.

[0008] The application of the material strand strips to the vehicle body can be made manually, or can be conducted by robots. The step of cutting-off material strand strips from an un-wound material strand can also be conducted automatically.

[0009] From document EP 3431 250 A1, there is known a method for manufac turing a material strand assembly for a vehicle, particularly for sealing a body opening of a vehicle part, including the steps of: extruding strand material in an extruder so that a material strand is produced; monitoring the quality of the extruded material strand so as to detect faults of the material strand; in case of a detection of a fault, cutting out the fault from the material strand, using a cutting arrangement, and re-joining cutting end faces, thus producing a joint, so that a faultless material strand is produced, wherein the cutting- out step or the step of detection and cutting-out is conducted such that any two adjacent joints are at a minimum joint distance from each other; storing the faultless material strand in a storage unit so as to produce the material strand assembly; wherein the extruded material strand is passed through a first strand accumulator between the extruder and the cutting arrangement and/or wherein the faultless material strand is passed through a second strand accumulator between the cutting arrangement and the storage unit.

[0010] This method allows to produce a faultless material strand which is stored in a storage unit, for example wound on a reel. Any faults that are produced during the extrusion process, are cut out before the material strand, which is faultless as a conse quence, is stored in the storage unit. The joints that are produced when re-joining the cutting end faces, have a uniform axial length.

[0011] In some embodiments, the joints may be produced with a quality so that such joint may be included in an applied material strand strip. In other cases such joints will have to be cut out before applying material strand strips at the application site, where in the detection and the cutting out of such joints can be simplified against the prior art due to the uniformity of the axial length of the joints.

[0012] The re-joining step of cutting end faces is preferably conducted at stand still, so that the first strand accumulator and/or the second strand accumulator are used in order to compensate for speed/velocity differences. Namely, the extrusion process cannot be stopped, so that the extruded material strand, which is fed into an input side of the first strand accumulator, is accumulated therein, while the output side of the accumulator may be at standstill (e.g. for conducting the joining process).

[0013] The faultless material strand that is stored in the storage unit may have an axial length of at least 500 m, preferably at least 800 m, in particular at least 1000 m. Typically, the maximum axial length of the faultless material strand is less than 2000 m, preferably less than 1800 m.

[0014] The faultless material strand that is stored in the storage unit of the ma terial strand assembly may, in the best case, include no joint at all. This would mean that the entire axial length has been produced without any faults in the extrusion process. On the other hand, depending on the fault level or fault standard set by an OEM, the faultless material strand which is stored in the storage unit may include 1 to 20 joints. In a worst case scenario, the number of joints may reach 40.

[0015] The minimum joint distance between any two adjacent joints is prefera bly in a range from 3 m to 10 m, and is preferably in a range from 5 m to 9 m. Further, it is preferred if the minimum joint distance is larger than two times the predefined strip length of a material strand strip.

[0016] The material of the material strand is preferably a plastics or elastomer material, which is preferably radially elastically compressible, for example TPE, EPDM, etc. The material strand may be a single component material strand, made from a single material, or may be a multi-component material strand including at least two components of different materials. Typically, the material strand is a two component-strand, including for example a relatively hard component for attaching the strand strip to a vehicle opening, and a relatively soft portion for providing sealing functions, e.g. an EPDM hose attached to a attachment socket strand.

[0017] In the above method, it is preferred that, if a joint is produced, the posi tion of the joint is neither recorded nor marked.

[0018] In other words, the manufacturing process does not include any addi tional step of marking a joint that is produced after cutting out a fault from the extruded material strand. Also, the position of such joint is not recorded. [0019] At the application site, an inspection device is adapted to inspect the un stored faultless material strand for joints. Such inspection device may be an image-based sensor, e.g. a camera-based sensor, that is able to detect joints, but may also be a sensor dedicated to the detection of joints. Namely, the joints may be produced by inserting a different type of material between the cutting end faces, in which case the inspection device is adapted to sense the different material. In addition, the joining step may include the use of a material that is detectable by such inspection device, e.g. a certain adhesive and/or the detection of a thread or a yarn that is used for stitching, particularly the material thereof, which may be or may include metal. In addition, any joint which uses a material different from the material of the extruded material strand, may include metallic particles or the like that can be easily detected by an inspection device at the application site. Preferably, however, the joint that is produced at the manufacturing site, is a standard joint, for example a joint produced by mirror-imaged cutting faces, optionally with a different material or an adhesive therebetween. In other cases, the standard joints can be produced from complementary, non-mirror-imaged, cutting end faces, either with a different material or an adhesive therebetween, or with a stitching or the like.

[0020] In the case of stepped complementary cutting end faces, an adhesive or the like may be arranged between cutting end face portions that are arranged parallel to the strand axis. In this case, certain gaps may be provided between those cutting end face portions that extend transversely to the strand axis.lt is the object of the invention to provide an improved method for detecting irregularities on a material strand, an improved apparatus for detecting irregularities on a material strand, as well as an improved method for applying a material strand strip on a body portion.

[0021] The above object is achieved by a method for detecting irregularities on a material strand according to claim 1, wherein the material strand is made of an elasto meric, i.e. radially elastically deformable material, such as TPE or EPDM, comprising the steps of: providing a material strand which defines a longitudinal axis along which the material strand is to be conveyed; bringing a detection element in contact with the material strand, wherein the detection element is movably mounted in a direction of deflection trans verse to the longitudinal axis and/or wherein a force can act on the detec tion element in a force direction, setting up a relative movement between the detection element and the material strand along the longitudinal axis; and detecting a deflection of the detection element in the deflection direction and/or a force acting on the detection element in the force direction, so as to detect irregularities in the material strand.

[0022] Further, the above object is achieved by an apparatus for detecting ir regularities on a material strand made of an elastomeric material according to claim 7, comprising a control device which is adapted to: providing a material strand which defines a longitudinal axis along which the material strand is to be conveyed; bringing a detection element in contact with the material strand, wherein the detection element is movably mounted in a direction of deflection transverse to the longitudinal axis and/or wherein a force can act on the detection element in a force direction, setting up a relative movement between the detection element and the material strand along the longitudinal axis; and detecting a deflection of the detection element in the deflection direction and/or a force acting on the detection element in the force direction, so as to detect irregularities in the material strand.

[0023] Finally, the above object is achieved by a method for applying a material strand strip on a body portion according to claim 6, comprising the steps of: providing a material strand assembly including a material strand which might have one or more irregularities, particularly joints, un-storing the material strand from the material strand assembly, where in a detection element is brought into contact with the material strand, wherein the detection element is movably mounted in a deflection direc tion transverse to a longitudinal axis and/or wherein a force acting on the detection element in a force direction can be detected, detecting a deflection of the detection element in the deflection direction and/or a force acting upon the detection element in the force direction, so as to detect irregularities in the material strand, particularly according to the detecting method of the invention, and cut off a material strand strip which has a predefined length, from an end of the material strand, if no irregularity has been detected between the end of the material strand and a cutting location determined by the pre determined length.

[0024] In practice, it is sometimes not easy to reliably detect joints in a faultless material strand by means of a camera-based system.

[0025] The present invention aims to overcome this problem by providing a de tection element which is in contact with the material strand, wherein a relative movement between the detection element and the material strand along the longitudinal axis is set up, and wherein a deflection of the detection element in a deflection direction transverse to the longitudinal axis, and/or a force acting on the detection element in a force direction is detected, so as to detect irregularities. The deflection direction and/or the force direction is preferably aligned transverse to the longitudinal axis ( the relative movement direction), particularly orthogonal thereto. [0026] It is preferred if the detection element is slightly pressed radially (for ex ample parallel to the deflection direction) into the elastically deformable material strand. Typically, joints have a uniform axial length and are harder than the material strand itself. Therefore, the joint, when passing along the detection element during the relative move ment, will lead to a radial deflection of the detection element and/or to a force on the detection element, which can be detected by a sensor, for example a travel sensor and/or a force sensor. The detection element is preferably mounted moveably in the deflection direction, particularly if the detection element is used to detect a deflection in a deflection direction. On the other hand, if the detection element is used to detect a force acting on the detection element, the detection element may be stationary ( immoveably mounted).

[0027] The sensor signal produced by such a travel sensor and/or a force sen sor is typically a relatively constant signal which exhibits a peak only when a joint is detected.

[0028] The peak can be detected by using a threshold value. Only in case that the detector signal exceeds the threshold value, a joint will be recognized. The threshold value is typically the basic value plus 10%. On the other hand, considering the speed of relative movement, the distance over which the peak appears should have a certain dimension which is in the range of the predetermined axial length that the joints typically have. The axial length of the joints is preferably in a range of 0.1 to 1.0 mm.

[0029] If the peak length in the longitudinal direction is considerably longer than such average axial joint length, the peak does not reflect a joint but any other unforeseea ble fault. On the other hand, if the axial length of the detected irregularity is considerably shorter than the axial joint length, the detected peak will also be discarded as not reflect ing a joint but another irregularity.

[0030] The method according to the invention can be used in combination with a camera based sensor for detecting joints, or can be used as an alternative thereto. [0031] The steps of applying the material strand strip to the body portion can be essentially the same as disclosed in document EP 3431 250 A1. The disclosure of this document is incorporated herein by reference.

[0032] The above object is therefore achieved in full.

[0033] Preferably, the detection element is mounted on a bearing block, where in a deflection of the bearing block in the deflection direction and/or a force exerted on the bearing block by the material strand is detected in order to detect irregularities in the material strand.

[0034] The detection element can be a element having a low friction coefficient surface, like a gliding element. Therefore, the relative movement between the deflection element and the material strand does not produce excessive heat.

[0035] In a preferred embodiment, the detection element is a roller element which is mounted on a bearing block, wherein the roller element is rotatable about a roller axis which is aligned transversely to both the longitudinal axis and the deflection direction or force direction, respectively.

[0036] In this embodiment, the roller element rolls on the material strand during the relative movement, so that no heat is produced thereby, even if the roller element is slightly pressed into the material strand in the radial direction.

[0037] In another preferred embodiment, the deflection and/or the force is con tinuously detected and compared with a previously stored characteristic.

[0038] As explained above, the previously stored characteristic preferably in cludes a certain threshold as well as a certain axial length of a detected peak.

[0039] In a preferred embodiment, the axial length of the detected irregularity may be in a range from 2 mm to 10 mm in order to be identified as a joint. [0040] In another preferred embodiment, the deflection and/or the force are stored in the form of a displacement profile and/or a force profile.

[0041] Such profiles may be used for monitoring and/or quality assessment purposes. The profiles may be profiles recorded over the relative movement travel and/or profiles recorded over the time (temporal profiles).

[0042] It will be understood that the features of the invention mentioned above and those yet to be explained below can be used not only in the respective combination indicated, but also in other combinations or in isolation, without leaving the scope of the present invention.

[0043] Exemplary embodiments of the invention are explained in more detail in the following description and are represented in the drawings, in which:

Fig. 1 is a schematic view of a prior art manufacturing apparatus for manufac turing a material strand assembly;

Figs. 2a to 2o are sequences of operation in a prior art method for manufacturing a material strand assembly;

Fig. 3 shows several schematic views of different types of joints in a faultless material strand;

Fig. 4 is a schematic view of an apparatus for applying a material strand strip to a vehicle part;

Fig. 5 is a schematic view of an apparatus for detecting irregularities on a ma terial strand and a portion of a profile of deflection and/or force over a relative travel between the material strand and the detection apparatus; and Fig. 6 an alternative embodiment of an apparatus for detecting irregularities.

[0044] In Fig. 1 , an embodiment of a manufacturing apparatus for manufactur ing a material strand assembly is schematically shown and given the reference numeral 10.

[0045] The manufacturing apparatus 10 includes an extruder 12, which is adapted to receive strand material 14. The extruder 12 may include a heater 16 and comprises a die 18. In operation, the extruder 12 produces a material strand 20 that moves at an extrusion speed v _E out of the die, along a moving direction 21.

[0046] Downstream of the extruder 12, the manufacturing apparatus 10 in cludes a first strand accumulator 22, a monitoring device 24, a first cutting device 26, a joining device 27, a second cutting device 28, wherein the first cutting device 26 and the second cutting device 28 form a cutting arrangement 29, a second strand accumulator 30 and a storing device 31.

[0047] The first strand accumulator 22 and the second strand accumulator 30 allow for movement speeds of the material strand between the accumulators 22, 30 that differ from the movement speed upstream of the first strand accumulator 22 and/or downstream of the second strand accumulator 30. Typically, the storing device 31 may be adapted to store a material strand at the same speed as the extrusion speed (v _E ).

[0048] The storing device 31 is adapted to store a material strand in a storage unit 32. The storage unit 32 may have a reel 34 which is supported rotatably in a reel carrier 36, e.g. a reel box.

[0049] The material strand that is stored in the storage unit 32 is a faultless ma terial strand 37, wherein any faults of the extruded material strand 20 have been cut out.

[0050] As soon as a predefined length of faultless material strand 37 is stored in the storage unit 32, thus forming a material strand assembly 38, the material strand assembly 38 can be transported to another site where the material strand of the material strand assembly 38 is processed, e.g. an application site at an OEM.

[0051] The material strand 20 is typically used for sealing, trimming or fastening body openings in vehicle bodies, typically in the automobile industry.

[0052] The first cutting device 26 may include a single cutter for preparing right- angled cutting end faces, as for example shown in Fig. 3, left side.

[0053] In the present case of Fig. 1 , the first cutting device 26 includes a first upstream cutter 42 and a second downstream cutter 44. The first cutter 42 and the second cutter 44 are provided so as to prepare complementary cutting edges, as for example shown in Fig. 3, middle or right side.

[0054] The first cutter 42 and the second cutter 44 are adapted to cut out any extrusion fault 48 that has been detected by the monitoring device 24, thus producing a scrap piece 50. The joining device 27 is adapted to re-join the remaining material strand at its opposite cutting end faces (not shown in Fig. 1). The joining process conducted by the joining device 27 leads to a joint 46, two of which are shown at 46 _! and 46 ₂ in Fig. 1. The faultless material strand 27 does not include any faults 48, but may include a number of joints 46.

[0055] A distance between the monitoring device 24 and the first cutting device 26 is shown at l_i. The distance l_i is chosen such that, at a typical maximum speed of the material strand 20, there is sufficient time for the first cutting device 26 to be operated when a fault 48 is detected by the monitoring device 24.

[0056] The axial distance between the first cutter 42 and the second cutter 44 is shown at l_ ₂ . [0057] The length l_ ₂ may, for example, correspond to an average axial fault length. In the present embodiment, l_ ₂ is chosen to be in a range from 50 cm to 150 cm, for example 1 m (100 cm).

[0058] An axial distance between the first cutter 42 and the second cutting de vice 28 (which may include a third cutter) is shown in Fig. 1 at L _c .

[0059] The length L _c (the cutting device distance) corresponds preferably to a minimum joint distance L _M IN, explained below.

[0060] The cutting device distance L _c is preferably shorter than L _M IN-

[0061] The ratio of L _c to l_ ₂ is preferably in a range from 7:1 to 3:1, preferably in a range from 4.5:1 to 6: 1.

[0062] If the movement speed of the material strand downstream of the first strand accumulator 22 is set to be smaller than the extrusion speed v _E , the first strand accumulator 22 can be loaded, as shown at 52. On the other hand, if the material strand speed downstream of the first strand accumulator 22 is set to be higher than the extrusion speed v _E , the first strand accumulator 22 can be unloaded as shown at 54.

[0063] Similarly, the second strand accumulator 22 can be loaded, as shown at 56, if the material strand speed upstream of the second strand accumulator 30 is higher than the material strand speed downstream of the second strand accumulator 30. On the other hand, if the speed relation is reversed, the second strand accumulator 30 can be unloaded, as shown at 58.

[0064] The cutters 42, 44 may include knifes or notching devices, and can be operated online, i.e. while the material strand moves along the first cutting device 26. On the other hand, it is also possible to stop the material strand when conducting the cutting- out step. [0065] When the scrap piece 50 is cut out from the material strand, two oppos ing cutting end faces 60, 62 are produced, which can be re-joined in the joining device 27, thus producing a joint 46.

[0066] The joining device 27 is preferably a stationary device. Similarly, the cut ters 42, 44 and the second cutting device 28 are stationary. In other embodiments, however, these elements can be axially movable devices, so that these devices can be moved synchronously with the material strand.

[0067] In Fig. 2a to 2o, a sequence of operation of a manufacturing apparatus 10 is shown, which corresponds with respect to construction and function to the manufac turing apparatus 10 of Fig. 1. Similar elements are given the same reference numerals. In the following, the operation is explained in detail.

[0068] In Fig. 2a, a situation is shown where the material strand 20 is moved in moving direction 21, wherein a fault 48 _! is detected by the monitoring device 24.

[0069] In Fig. 2b, the fault 48 _! has been moved into the area axially between the first cutter 42 and the second cutter 44.

[0070] In Fig. 2c, the first cutter 42 and the second cutter 44 are operated sim ultaneously, thus cutting out a scrap piece 50i on which the fault 48i is located, thus producing two opposing cutting end faces 60i, 62i in the area of the cutters 42, 44.

[0071] In Fig. 2d, the first strand accumulator 22 is unloaded (schematically shown at 54), so that the material strand downstream of the first strand accumulator 22 moves with a speed Vi which is larger than v _E , such that the two cutting end faces 60i, 62i are approaching each other.

[0072] In Fig. 2e, the cutting end faces 60i, 62i are close to each other and are located in the area of the joining device 27, which is stationary, so that the material strand is brought to a standstill, such that the material strand speed v ₂ = 0. In this case, the first strand accumulator 52 is loaded, as shown at 52 in Fig. 2e. The joining device 27 is operated so as to stitch overlapping ends of the cutting end phases 60i, 62 _! . In the joining device 27, therefore, a first joint 46 _! is produced.

[0073] In Fig. 2f, it is shown that the material strand is moving again at the ex trusion speed v _E , so that the accumulators 22, 30 are neither loaded nor unloaded. The first joint 46i has moved into the direction of the second cutting device 28.

[0074] In Fig. 2f, it is shown that the joint 46i has reached an axial distance from the monitoring device 24, which is L _M IN, which is a minimum joint distance. Namely, the faultless material strand 37 that is to be stored in the storage unit 32 may have joints, but any two adjacent joints must be at the minimum joint distance L _M IN from each other. The distance L _M IN is preferably in a range from 3 m to 10 m, particularly in a range from 4 m to 7 m, preferably in a range from 4.5 m to 6 m.

[0075] In Fig. 2f, it is shown that no further fault 48 has been detected within the minimum joint distance L _M IN, SO that the process can be continued by moving the material strand and storing the faultless material strand 37 in the storage unit 32.

[0076] Fig. 2g shows a different situation. Here, a second fault 48 ₂ has been detected by the monitoring device 24 at a distance from the first joint 46i, which is less than or equal to L _M IN- Here, a distance between the first joint and a second joint for the second fault 48 ₂ would be axially shorter than the minimum joint distance L _M IN-

[0077] Therefore, the process continues with the situation of Fig. 2h, where the second fault 48 ₂ is located between the first and the second cutter 42, 44. The first joint 46i is still located upstream of the second cutting device 28 in this case.

[0078] As shown in Fig. 2i, the first cutter 42 and the second cutting device 48 are operated simultaneously, so that a second scrap piece 50 ₂ is produced (as shown in Fig. 2k), which includes the first joint 46i and the second fault 48 ₂ . Further, two opposing cutting end faces 60 ₂ , 62 ₂ are produced at the locations of the first cutter 42 and the second cutting device 28, respectively.

[0079] In order to bring the opposing cutting end faces 60 ₂ , 62 ₂ into the area of the joining device 27, the first strand accumulator 22 is unloaded, as shown at 54, and, further, the second strand accumulator 30 is unloaded as shown at 58. The unloading of the first strand accumulator 22 has the effect that the material strand speed Vi down stream of the first strand accumulator 22 is higher than the extrusion speed v _E . The unloading 58 of the second strand accumulator 30 has the effect that the cutting end face 62 ₂ is moved in a direction opposite to the moving direction (extrusion direction), so that the material stand that is moved out of the second strand accumulator 30 is moved at a speed v ₂ which is smaller than zero (negative speed).

[0080] Therefore, as shown in Fig. 2m, the cutting end faces 60 ₂ , 62 ₂ meet at the joining device 27, so that, at a material strand speed of v = 0, a second joint 46 ₂ is produced. As shown in Fig. 2n, the second joint 46 ₂ has moved beyond the second cutting device 42, without that another fault having been detected in the monitoring device. Thus, the second joint 46 ₂ is at the minimum joint distance from any upstream joint, and the second joint 46 ₂ can be fed into the second strand accumulator 30 as shown at 56 in Fig. 2n. In Fig. 2n, the speed with which the faultless material strand 37 is stored in the storage unit 32 is preferably less than v _E . As shown in Fig. 2o, a third fault 48 ₃ is detected after the second joint 46 ₂ has passed the second joining device 28. The third fault 48 ₃ will be dealt with in a manner identical to what has been described with respect to Figs. 2a to 2f.

[0081] In Fig. 3, three different types of joints 46 are shown. On the left hand side in Fig. 3, a joint 46A of a faultless material strand 37A is shown, wherein a material dissimilar from the material of the material strand 37A is inserted between the cutting end faces 60, 62, wherein the joining material is for example a thermoplastic elastomer material or any other thermoplastic joining material which, by way of heating, produces a thermoplastic weld at the cutting end faces 60, 62. [0082] In the middle portion of Fig. 3, a joint 46B is shown, wherein the cutting end faces 60', 62', produced by special cutters 42, 44, have complementary shapes. For example, the cutters 42, 44 can be formed by L-shaped notching elements. Therefore, these L-shaped cutting end faces are complementary to each other and overlap axially, such that a stitching 63 can be produced in the joining device 27, so as to join the material strand portions of the faultless material strand 37B together. As an alternative to the stitching 63, the cutting end faces portions that are aligned parallel to the longitudinal direction, could be connected by adhesive or the like, so that the portions of the cutting end faces 60', 62', that are arranged transverse and at the outer border of the material strand 37B, could be distant from each other and present gaps that can be easily detect ed.

[0083] In Fig. 3, the joint 46C includes cutting end faces 60", 62", that are com plementary to each other by having complementary slopes, thus, again, producing a faultless material strand 37C.

[0084] As shown in the left hand part of Fig. 3, any joint 46A (or 46B, 46C or any other joint) can be marked by a marking 64, wherein an axial length L ₄ of the marking 64 is shorter than an axial length L ₃ of the joint. Further, the marking 64 may have an axial distance L ₅ from the joint 46A, wherein 0 < L ₅ < 20 cm, for example, either upstream or downstream of the joint.

[0085] On the other hand, the above joints 46A, 46B, 46C may not be marked at all.

[0086] As a third alternative, an axial position of each of the joints 46A, 46B, 46C may be recorded in a recording device, which is assigned to the material strand assembly 38. As explained later, at an assembly site, such recording device can be used in order to identify the positions of joints of the faultless material strand 37.

[0087] In Fig. 4, an apparatus for applying a material strand strip to a vehicle part is schematically shown and is given reference 66. The production apparatus 66 includes an inspection device 68. The inspection device 68 is designed to inspect the faultless material strand 37 that is un-stored from the material strand assembly 38, at a production speed v _P . The inspection device 68 is preferably a camera-based inspection device that is able to clearly identify joints, wherein the joints may have been produced by a mirror weld joining step, either with or without material between cutting end faces. The inspection device may, however, also be another type of inspection device, e.g. a metal detection device. Downstream of the inspection device 68, the production apparatus 66 includes a separation device 70 which is adapted to separate or cut the material strand.

[0088] Between the material strand assembly 38 and the inspection device 68, optionally, a production accumulator 71 can be provided which has a function similar to that of the first strand accumulator 22 of the manufacturing apparatus 10 of Fig. 1.

[0089] The separation device 70 is adapted to cut off strand strips 72 from the endless and faultless material strand 37, which strand strips 72 have an axial length l_ _D which is a predefined strip length adapted to the application purpose.

[0090] The production apparatus 66, further, includes an applying device 74. The applying device 74 is designed to apply a strand strip 72 to a vehicle part, in particular to a body opening of a vehicle body. As shown schematically in Fig. 4, the applying device 74 may be adapted to apply a strand strip 72 to a window opening 78 of a vehicle door 76.

[0091] The applying device 74 is preferably adapted to apply the strand strip 72 automatically, using at least one robot. In Fig. 1, two robots are shown at 80, 82. A first robot 80 may be used to handle the strand strips 72. A second robot 82 may be adapted to handle and three-dimensionally move the vehicle part (vehicle door 76).

[0092] In general, it is possible to provide an applying device 74, wherein the strand strip 72 is applied to the vehicle part while the strand strip 72 is still attached to the faultless material strand 37 (up until to the last portion). In Fig. 4, however, it is shown that strand strips 72 are cut off in advance before being applied to the vehicle part. [0093] Fig. 4 also shows that the faultless material strand 37, when un-stored from the storage unit 32, has a downstream end 86. When the downstream end 86 has reached the distance l_ _D from the separation device 70, the separation device 70 is operated, so as to cut off the strand strip 72, and producing a new downstream end of the material strand 37.

[0094] In Fig. 4, left hand side, a situation is shown where a joint 46 is located at a distance l_ _F from a downstream end 86^ which distance l_ _F is shorter than the prede fined strip length l_ _D .

[0095] Therefore, in a second step, the joint 46 is moved passed the separation device 70, and the separation device 70 is operated, so that a second downstream end 86 ₂ is produced. The strand portion 88 between the first downstream end 86 _! and the second downstream end 86 ₂ , including the joint 46, is discarded as waste.

[0096] Finally, it is shown that the second downstream end 86 has then again moved at the production speed v _P to a location, where it is located at the distance l_ _D from the cutting device 70 and wherein no joint is arranged within this distance, so that the separation device 70 can again be operated, so that another strand strip 72 can be cut off and used for applying it to the vehicle part, creating a third downstream end 86 ₃ .

[0097] Fig. 5 shows a situation similar to Fig. 4, wherein a material strand 37 is un-stored from a material strip assembly 38 at a certain speed V _P . In order to identify or detect joints, the production apparatus 66 of Fig. 4 may, in addition to the inspection device 68 shown in Fig. 4 or as an alternative thereto, include an apparatus 100 for detecting irregularities.

[0098] The apparatus 100 is preferably a stationary apparatus. The material strand 37 is conveyed along a longitudinal axis 102. The movement of the material strand 37 is also shown in Fig. 5 at s. [0099] The apparatus 100 includes a detection element 104 that is brought into contact with a surface of the material strand 37. Particularly, the detection element 104 is arranged at a bearing block 106. Here, the bearing block 106 is mounted movably in a deflection direction d on a housing 108. Further, the bearing block 106 is biased in a direction toward the material strand 37 by means of a spring 110.

[00100] The detection element 105 may be a low-friction surface element so that only little heat is produced during the relative movement between the detection element 104 and the material strand 37.

[00101] A deflection d of the bearing block 106 can be detected by means of a deflection sensor 112 which is typically an electro-mechanical travel sensor which is connected (via A) to a controller 114.

[00102] As an alternative and/or in addition to the deflection sensor 112, a force sensor 116 can be provided. In this case, the bearing block 106 does not need to be movable in a direction transverse to the longitudinal axis 102. In contrast, the bearing block 106 and the force sensor 116 may be stationary.

[00103] In any case, during the movement of the material strand 37, the deflec tion sensor 112 and/or the force sensor 116 will produce a sensor signal which essentially corresponds to a basic force by means of which the detection element 104 is pressed against the material strand 37.

[00104] Fig. 5 also shows a diagram of the deflection d and/or of the force F over the travel s.

[00105] Normally, if no irregularities are detected, the signal of the sensor(s) is at a basic value d ₀ . In case of detecting an irregularity, the deflection and/or force increases. If the deflection d and/or force F exceeds a certain threshold value T and if the axial length As of the peak is within a typical range of the axial joint length, an irregularity in the form of a joint in the faultless material strand is detected. The axial length As of the peak is preferably in a range of 0.5 to 80.0 mm, particularly 0.5 to 8.0 mm. A typical axial joint length is in a range of 0.1 to 1.0 mm. The threshold may be set on the basis of the basic value d _0. For example T = d ₀ + 0.1 x d ₀ , i.e. 10% above the basic value d ₀ .

[00106] The sensor signals can be detected and recorded. Preferably, the sen sor signals are output continuously and compared with a previously stored characteristic which reflects the shape of a peak when a joint is detected.

[00107] Joints 46a, 46b are for example shown in Fig. 5 as well in the material strand 37.

[00108] Fig. 6 shows an alternative embodiment, wherein the detection element is a roller element 104' which is mounted rotatably on a bearing block 106' about a roller axis 118 which is aligned transversely to both the longitudinal axis 102 and the deflection direction d.

[00109] In Fig. 6, it is further shown that the roller element 104', by means of a spring 110, is slightly pressed into the elastically deformable material strand 37 by a deflection amount D ₀ , which corresponds essentially to the basic value d ₀ in the diagram of Fig. 5.

[00110] The material strand which the detection element contacts, is preferably manufactured by a method and/or an apparatus according to any one of the following clauses, wherein reference is made in this context to document EP 3431 250 A1 the disclosure which is incorporated herein by reference:

Clauses

Clause 1. A method for manufacturing a material strand assembly (38) for a vehicle, particularly for sealing a body opening (78) of a vehicle part (76), including the steps of: extruding strand material (14) in an extruder (12) so that an extruded mate rial strand (20) is produced, monitoring the quality of the extruded material strand (20) so as to detect faults (48) of the extruded material strand (20), in case of a detection of a fault (48), cutting out the fault (48) from the mate rial strand (20), using a cutting arrangement (29), and re-joining cutting end faces (60, 62), thus producing a joint (46), so that a faultless material strand (37) is produced, wherein the cutting-out step is conducted such that any two adjacent joints (46) are at a minimum joint distance (L _MIN ) from each other, and storing the faultless material strand (37) in a storage unit (32) so as to pro duce the material strand assembly (38), wherein the extruded material strand (20) is passed through a first strand accumu lator (22) between the extruder (12) and the cutting arrangement (29) and/or wherein the faultless material strand (37) is passed through a second strand ac cumulator (30) between the cutting arrangement (29) and the storage unit (32).

Clause 2. The method of Clause 1 , wherein, if a joint (46) is produced, the position of the joint (46) is neither recorded nor marked.

Clause 3. The method of Clause 1 , wherein, if a joint (46) is produced, the position of the joint (46) is marked on the material strand (20; 37) by a single marking (64) which has an axial marking length (l_ ₄ ) that is shorter than an axial joint length (l_ ₃ ) of the joint (46).

Clause 4. The method of any of Clauses 1 or 3, wherein, if a joint (46) is produced, the position of the joint (46) is recorded by recording one single axial position that identifies the joint (46). Clause 5. The method of any of Clauses 1 - 4, wherein the cutting step includes the use of at least two cutters (42, 44) that are arranged at an axial cutter distance (l_ ₂ ) from each other, wherein the axial cutter distance (l_ ₂ ) is axially shorter than the minimum joint distance (L _M IN) and/or wherein the axial cutter distance (l_ ₂ ) is axially longer that an average axial fault length.

Clause 6. A manufacturing apparatus (10) for manufacturing a material strand as sembly (38), particularly for conducting a method for manufacturing a material strand assembly (38) according to any of Clauses 1 - 5, comprising: an extruder (12) for producing an extruded material strand (20), a monitoring device (24) for monitoring the quality of the extruded material strand (20), such that faults (48) of the extruded material strand (20) can be detected, a cutting arrangement (29) for cutting out detected faults (48) from the ex truded material strand (20), such that cutting end faces (60, 62) are creat ed, a joining device (27) for re-joining the cutting end faces (60, 62), thus pro ducing a joint (46), so that a faultless material strand (37) is produced, wherein the cutting arrangement (29) is adapted to conduct the cutting-out step such that any two adjacent joints (46) are at a minimum joint distance (L _M IN) from each other, and a storing device (31) for storing the faultless material strand (37) in a stor age unit (32).

Clause 7. The manufacturing apparatus of Clause 6, wherein the cutting arrangement (29) comprises a first cutting device (26) and a second cutting device (28), wherein the joining device (27) is arranged axially between the first cutting device (26) and the second cutting device (28).

Clause 8. The manufacturing apparatus of Clause 7, wherein a cutting device dis tance between the first cutting device (26) and the second cutting device (28) cor responds to the minimum joint distance (L _M IN)-

Clause 9. The manufacturing apparatus of Clause 7 or 8, wherein the first cutting device (26) comprises a first cutter (42) and a second cutter (44), which are ar ranged at an axial cutter distance (l_ ₂ ), wherein the axial cutter distance (l_ ₂ ) is axi ally longer than an average axial fault length and/or wherein the first cutter (42) and the second cutter (44) are operable independently from each other.

Clause 10. The manufacturing apparatus of Clause 9, wherein the first cutter (42) and the second cutter (44) are adapted to produce complimentary cutting end faces (60', 62'), wherein the second cutting device (28) comprises a third cutter which is adapted to produce the same cutting end face (62') as the second cutter (44).

Clause 11. The manufacturing apparatus of any of Clauses 6 - 10, wherein a second accumulator (30) is adapted to feed an accumulated faultless material strand to the joining device (27).