Patent Application
20220162033
The present application 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.
Further, the present application relates to a corresponding apparatus for detecting irregularities on a material strand. Finally, the present application relates to a method for applying a material strand strip on a body portion.
The material strand is preferably a sealing profile strand for sealing body openings of vehicle bodies.
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 (thermoplastic elastomer) and EPDM (ethylene propylene diene monomer rubber).
Other types of material strands can be used for trimming or fastening purposes in relation to body openings, particularly doors, windows, lids etc.
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 application site, typically an OEM.
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.
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.
From document EP 3 431 250 A1, there is known a method for manufacturing 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.
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 consequence, is stored in the storage unit. The joints that are produced when re-joining the cutting end faces, have a uniform axial length.
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, wherein 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.
The re-joining step of cutting end faces is preferably conducted at standstill, 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).
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.
The faultless material strand that is stored in the storage unit of the material 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.
The minimum joint distance between any two adjacent joints is preferably 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.
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.
In the above method, it is preferred that, if a joint is produced, the position of the joint is neither recorded nor marked.
In other words, the manufacturing process does not include any additional 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.
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.
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.
It is an object of the application 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.
The above object may be achieved by a method for detecting irregularities on a material strand according to claim 1, wherein the material strand is made of an elastomeric, i.e. radially elastically deformable material, such as TPE or EPDM, comprising the steps of:
Further, the above object may be achieved by an apparatus for detecting irregularities on a material strand made of an elastomeric material according to claim 7, comprising a control device which is adapted to:
Finally, the above object may be achieved by a method for applying a material strand strip on a body portion according to claim 6, comprising the steps of:
In practice, it is sometimes not easy to reliably detect joints in a faultless material strand by means of a camera-based system.
The present application aims to overcome this problem by providing a detection 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.
It is preferred if the detection element is slightly pressed radially (for example 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 movement, 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).
The sensor signal produced by such a travel sensor and/or a force sensor is typically a relatively constant signal which exhibits a peak only when a joint is detected.
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.
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 unforeseeable 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 reflecting a joint but another irregularity.
The method according to the application can be used in combination with a camera based sensor for detecting joints, or can be used as an alternative thereto.
The steps of applying the material strand strip to the body portion can be essentially the same as disclosed in document EP 3 431 250 A1. The disclosure of this document is incorporated herein by reference.
The above object is therefore achieved in full.
Preferably, the detection element is mounted on a bearing block, wherein 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.
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.
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.
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.
In another preferred embodiment, the deflection and/or the force is continuously detected and compared with a previously stored characteristic.
As explained above, the previously stored characteristic preferably includes a certain threshold as well as a certain axial length of a detected peak.
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.
In another preferred embodiment, the deflection and/or the force are stored in the form of a displacement profile and/or a force profile.
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).
It will be understood that the features of the application 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.
Exemplary embodiments of the application are explained in more detail in the following description and are represented in the drawings, in which:
In
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 vE out of the die, along a moving direction 21.
Downstream of the extruder 12, the manufacturing apparatus 10 includes 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.
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 (vE).
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.
The material strand that is stored in the storage unit 32 is a faultless material strand 37, wherein any faults of the extruded material strand 20 have been cut out.
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.
The material strand 20 is typically used for sealing, trimming or fastening body openings in vehicle bodies, typically in the automobile industry.
The first cutting device 26 may include a single cutter for preparing right-angled cutting end faces, as for example shown in
In the present case of
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
A distance between the monitoring device 24 and the first cutting device 26 is shown at L1. The distance L1 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.
The axial distance between the first cutter 42 and the second cutter 44 is shown at L2.
The length L2 may, for example, correspond to an average axial fault length. In the present embodiment, L2 is chosen to be in a range from 50 cm to 150 cm, for example 1 m (100 cm).
An axial distance between the first cutter 42 and the second cutting device 28 (which may include a third cutter) is shown in
The length LC (the cutting device distance) corresponds preferably to a minimum joint distance LMIN, explained below.
The cutting device distance LC is preferably shorter than LMIN.
The ratio of LC to L2 is preferably in a range from 7:1 to 3:1, preferably in a range from 4.5:1 to 6:1.
If the movement speed of the material strand downstream of the first strand accumulator 22 is set to be smaller than the extrusion speed vE, 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 vE, the first strand accumulator 22 can be unloaded as shown at 54.
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.
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.
When the scrap piece 50 is cut out from the material strand, two opposing cutting end faces 60, 62 are produced, which can be re-joined in the joining device 27, thus producing a joint 46.
The joining device 27 is preferably a stationary device. Similarly, the cutters 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.
In
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Therefore, the process continues with the situation of
As shown in
In order to bring the opposing cutting end faces 602, 622 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 v1 downstream of the first strand accumulator 22 is higher than the extrusion speed vE. The unloading 58 of the second strand accumulator 30 has the effect that the cutting end face 622 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 v2 which is smaller than zero (negative speed).
Therefore, as shown in
In
In the middle portion of
In
As shown in the left hand part of
On the other hand, the above joints 46A, 46B, 46C may not be marked at all.
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.
In
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
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 LD which is a predefined strip length adapted to the application purpose.
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
The applying device 74 is preferably adapted to apply the strand strip 72 automatically, using at least one robot. In
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
In
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 862 is produced. The strand portion 88 between the first downstream end 861 and the second downstream end 862, including the joint 46, is discarded as waste.
Finally, it is shown that the second downstream end 86 has then again moved at the production speed vP to a location, where it is located at the distance LD 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 863.
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
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.
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.
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.
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.
In any case, during the movement of the material strand 37, the deflection 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.
Normally, if no irregularities are detected, the signal of the sensor(s) is at a basic value d0. 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 Δs 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 Δs 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 d0. For example T=d0+0.1×d0, i.e. 10% above the basic value d0.
The sensor signals can be detected and recorded. Preferably, the sensor signals are output continuously and compared with a previously stored characteristic which reflects the shape of a peak when a joint is detected.
Joints 46a, 46b are for example shown in
In
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 3 431 250 A1 the disclosure which is incorporated herein by reference:
It is to be understood that the foregoing is a description of one or more preferred exemplary embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.
As used in this specification and claims, the terms “for example,” “e.g.,” “for instance,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.
| Number | Date | Country | Kind |
|---|---|---|---|
| 19 191 373.0 | Aug 2019 | EP | regional |
The present application is a continuation application of PCT application PCT/EP2020/071836, filed Aug. 3, 2020, which itself claims the priority of European patent application EP19191373.0, filed Aug. 13, 2019.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2020/071836 | Aug 2020 | US |
| Child | 17669957 | US |
