Thermal marking for object tracking

Abstract

The invention relates to thermal marking for object tracking. A non-destructive product marking system is presented that tracks the progress of a product in a manufacturing process based on the application of a thermal feature to the product and by detecting its thermal feature.

Description

Technical Field

[0001] The present disclosure relates to thermal marking of objects and, more particularly, to using thermal features that record tracking information on an object to enable tracking of the object's progress through a manufacturing process. The present disclosure also relates to tracking an object by thermally imaging the thermal features on the object at one or more locations along a manufacturing process path. Background Art

[0002] In a manufacturing environment, components can travel large distances at high speed along a specific process path. It is important to be able to track the position of a component as it progresses along such a path and to be able to classify the status of each particular component as part of a quality control process to verify that the manufacturing process is being correctly performed.

[0003] Components can be marked by simple mechanisms such as by color, imprinting, or engraving to enable tracking of the components in a manufacturing process, but such techniques typically involve physically altering the component, which can remain perceptible to a customer or user after the manufacturing process is complete. Additionally, it may be necessary to communicate the nature of such physical changes to the customer or user in a product specification report, especially if the structure or behavior of the product is to be correctly verified after the production process. This increases the complexity of the production process.

[0004] There is a need to be able to track components through a process in a manner that does not require altering the characteristics or appearance of the components to enable them to be tracked. Summary of the Invention

[0005] According to a first aspect, there is provided a method of recording tracking information on an object to track the object's progress through a manufacturing process, the method comprising the steps of: obtaining one or more temperature specifications associated with the manufacturing process; and applying to the object a thermal feature representing the tracking information, the thermal feature including one or more covered areas having a temperature greater than the one or more temperature specifications associated with the manufacturing process.

[0006] In this way, a non-destructive solution for marking objects is provided, enabling them to be tracked without changing their appearance or characteristics. The thermal feature can be easily applied using any of a variety of techniques, such that the product marking scheme can be easily configured or improved for existing product manufacturing processes.

[0007] In an embodiment, the temperature of the thermal feature is at least a predetermined incremental temperature greater than the maximum temperature specification of the manufacturing process. In this way, a margin can be ensured between the maximum temperature that the object may reach during the manufacturing process and the thermal feature, such that even when the temperature of the object deviates from the expected profile, the thermal feature can be clearly separated from the unmarked area of the object throughout the movement of the object through the process path.

[0008] In an embodiment, the temperature of the thermal feature has a temperature gradient such that after applying the thermal feature, the temperature of the thermal feature exceeds the maximum temperature specification of the manufacturing process for a period of time during which the manufacturing process is completed. In this way, the traceability of the object throughout the duration of the manufacturing process is ensured by using the thermal feature, and the thermal feature can still be detected despite active cooling associated with parts of the manufacturing process or heat dissipation that occurs when the object travels through the process path.

[0009] In an embodiment, applying the thermal feature includes heating each of one or more surfaces of the object using a direct contact heat source or a non-contact heat source. In an embodiment, the heat source is selected based on at least one of the geometric shape and heat absorption characteristics of the object and / or the information to be recorded. In this way, optimal heating of the product is achieved, which avoids product damage and maximizes the detection of the thermal feature while avoiding overheating.

[0010] In an embodiment, the heat source is a laser having a wavelength selected based on the wavelength absorption properties of the object. For a given heating power, this optimizes the heating efficiency of the product while enabling the generation of a high-resolution thermal feature.

[0011] In an embodiment, the information recorded includes object identification information. In this way, the progress of individual products or groups of products passing through the path can be tracked in order to support the analysis of the performance and efficiency of the manufacturing process.

[0012] In an embodiment, the object identification information is a binary string, wherein each of a plurality of positions on the object is associated with a digit in the binary string, and the coverage area of the thermal feature located at one of the plurality of positions on the object represents the corresponding digit of the binary string having one of the binary states. In this way, detailed traceability information can be easily encoded on the product using a flexible technique.

[0013] In an embodiment, the object is an automotive component and the manufacturing process is an automotive manufacturing process.

[0014] According to a second aspect, there is provided a method of tracking an object traveling through a manufacturing process path, the method comprising the steps of: thermally imaging a thermal feature located on the object at one or more locations along the manufacturing process path to identify one or more regions where the temperature of the object is higher than a threshold temperature; determining object information based on the identified one or more regions; and recording the progress of the object having the determined object identification along the manufacturing process path.

[0015] According to a third aspect, there is provided a manufacturing process comprising recording tracking information on an object according to the method of the first aspect; tracking the object according to the method of the second aspect; and recording a classification of the state of the object.

[0016] For each type of thermal feature, the shape, appearance or structural properties of the object to be marked do not change and the thermal feature is inherently transient. Thus, the manufacturing process providing the context of the thermal marking scheme is not impaired in any way in terms of the nature of the products produced or the methods of producing them. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Exemplary embodiments will now be described with reference to the drawings, in which:

[0018] Figure 1 A simplified representation of a manufacturing process in the context of describing an embodiment of the present invention is shown;

[0019] Figure 2 A thermal image of an object having a thermal feature produced according to a first embodiment is shown; and

[0020] Figure 3 A thermal image of an object having a thermal feature produced according to a second embodiment is shown. DETAILED DESCRIPTION

[0021] A first embodiment of the present disclosure is described with respect to Figure 1 the manufacturing process shown in, in which discs are conveyed through a painting system to be colored with paint. It will be clear from the remainder of the disclosure that the first embodiment is applicable to any manufacturing process applied to any product and the spraying of discs is an example chosen for simplicity of description.

[0022] In Figure 1 the structure shown, a plurality of unpainted discs 10 travel through a painting system 14 on a conveyor belt 12. The painted discs 16 are conveyed away from the painting system 14 to the output of the process or the input of a subsequent process.

[0023] It is desirable to be able to track one, several, or each individual disk 10 passing through the painting system 14 in order to verify that the disk 10 is not stuck to an object or surface in the painting system 14 or in the mechanism of the conveyor belt 12. Tracking one or more disks 10 in this way also enables the collection of information about the progress speed of the entire manufacturing process and the distribution of the disks throughout the process. In terms of space and time, the distribution herein refers to traveling through a process path, and tracking the travel through the process path enables the control or modification of the path to avoid bottlenecks and regulate the flow of objects along the path.

[0024] In a first embodiment, a thermal signature is applied to the disk 18 to be tracked. The thermal signature is shown in Figure 2 a thermal image and is the area of the disk 18 heated by a heat source 20 such that the area has a higher temperature than the rest of the disk 18. This area is referred to herein as the coverage area of the thermal signature. In the first embodiment, the thermal signature has a single coverage area that is approximately circular but does not have any particular shape.

[0025] In the first embodiment, the coverage area is identified as the area 22 where the temperature is approximately 10 - 15 K higher than the rest of the disk. In Figure 2 (a) in (no coverage area before applying the thermal signature), Figure 2 (b) in (coverage area 22 when the heat source 20 applies the thermal signature, shown here as T = 0), Figure 2 (c) in (cooler coverage area 24 at 10 seconds after applying the thermal signature) and Figure 2 (d) in (even cooler coverage area at 15 seconds after applying the heat signal) shows the evolution of the thermal signature over time, referred to herein as the 'thermal gradient'. It can be seen that although the thermal signature cools after being applied, it can still be identified 15 seconds later by its difference from the background temperature of the area 28 of the disk 18 without the thermal signature.

[0026] In the first embodiment, the disk is formed of silicone and a non - contact heat source such as any light or other thermal radiation source is used to apply the heat signal. The thermal signature is applied at the start of the process path, which corresponds to the position at the start of the conveyor belt (as Figure 1 shown), or the thermal signature is applied in a preliminary process from which the marked disk 10 is provided to the conveyor belt 12 to start the painting process.

[0027] Along the process path are one or more thermal detectors 30, 32 that perform thermal imaging on the objects traveling through the detectors. For the sake of illustration, Figure 1A pair of detectors 30, 32 are shown, with a thermal detection area 34 disposed therebetween. However, it should be understood that multiple individual detectors may be distributed along the conveyor belt 12 instead of being arranged in pairs.

[0028] For simplicity of illustration, the detectors are shown downstream of the painting process. This enables the path to be represented in Figure 1 discrete stages, including (a) a thermal marking stage 40, (b) a manufacturing process stage 50, and (c) a feature detection stage 60. It will of course be understood that stages (b) and (c) may overlap in terms of time and spatial configuration.

[0029] In a first embodiment, each detector 30, 32 is capable of tracking the number of objects passing through the detection area 34 in a detection window, thereby monitoring the capacity and throughput of the process. The number of objects is determined by counting the number of thermal features identified (by comparing the temperature of the detected objects with a threshold detection temperature and identifying the number of events where the threshold is exceeded). The outputs of the thermal detectors 30, 32 are provided to a control system (not shown), and using this output, the control system can determine, indicate, or control process diagnostics or adjustments.

[0030] In the case of thermally marking a disk, one or both surfaces of the disk may be marked such that if the disk is flipped during the manufacturing process, the thermal features remain visible to the detectors.

[0031] Figure 3 An example of a more detailed thermal feature applied to a disk in the context of the manufacturing process described in reference Figure 1 is shown in a second embodiment. The thermal feature has a plurality of coverage areas 36, shown as ten points spaced apart around a portion of the edge of the disk. The coverage areas are significantly smaller than Figure 2 the coverage areas shown, but have a thermal gradient similar to Figure 2 the thermal gradient shown.

[0032] Compared to the binary presence or absence of the coverage areas, the more detailed thermal feature allows richer information to be recorded on the object and identified by the detector. The thermal feature of the second embodiment has a predetermined pattern for identification by the detector. The pattern in this case may be a ten - bit binary string, where the coverage areas are heated or not heated to represent one of two thermal states. Based on the thermal detection of such a binary string, a unique disk identification (ID) or tracking information or code can be identified in the case where each disk is marked with a different thermal feature.

[0033] This process allows for a more refined monitoring of the performance and efficiency of the manufacturing process and is particularly applicable in cases where the products passing through the process have different sizes, thicknesses, materials or are otherwise different, such that tracking each product provides useful information. Even in cases where all products are identical to each other, tracking each product is useful in cases where it is necessary to classify which specific products have followed one or more branches of the process path to different manufacturing stages, for example in cases where it is necessary to record process information for the supply and verification of the manufactured products.

[0034] It should be understood that configurations can also be applied where groups of products are tracked according to an ID associated with each group of products rather than assigning a unique ID to each product. The groups can be defined according to product type, batch, date, etc.

[0035] In Figure 3 the example of, 10 points are shown, but some of the 10 points can be omitted to represent a binary low state at the corresponding position in the string. Thus, the product marking scheme is flexible and easy to control.

[0036] For a higher resolution thermal signature such as Figure 3 compared to a lower resolution thermal signature of Figure 2 a more precise heat source such as a laser is used. The specific material of the product affects the degree to which a laser of a particular wavelength is absorbed, and thus a laser with a wavelength having a maximum or high level of absorption at or near the wavelength absorption property of the product is selected to maximize the production efficiency of the signature.

[0037] The object to be tracked can have a variety of different regular and irregular three-dimensional shapes. Specific examples of the types of objects used in the embodiments of the present disclosure are automotive components formed or installed at specific processing stages of an automotive manufacturing process.

[0038] One or more surfaces of such a shape can be particularly suitable for thermal marking (for example if they are substantially flat) as this enhances compatibility with direct contact heat sources that can be used in the embodiments. Direct contact heat sources include contact with a heated conveyor belt, a heated roller, a stamp and other suitable devices. Thermal marking of each surface can enable the orientation of the product to be identified by tracking the configuration of the product from the relative positions of a plurality of different thermal signatures, and these signatures can be marked such that they identify a specific surface (e.g. 'top','side', etc.).

[0039] In embodiments where such a level of complexity of tracking is not required, it is more efficient to apply the thermal signature only to one or more selected surfaces, such as opposite surfaces of a cuboid-shaped product, where the selection is optimized to minimize the likelihood of the detector missing the thermal signature, but avoiding double-recording information or overheating the product.

[0040] More generally, the optimal heat source for thermally marking a particular product depends on the properties of the product itself (such as size, geometry, material) and the required thermal gradient and coverage area for tracking the thermal signature through a particular path. In this way, a heat source can be selected that can achieve the required temperature of the coverage area without deforming the product, maximizing the likelihood of detecting the thermal signature, and without unnecessarily wasting heating resources.

[0041] In embodiments based on Figure 3 With detailed information, depending on the number of coverage areas, their spacing, their positioning relative to the product as a whole, and the presence or nature of any scheme, any number of suitable marking schemes can be employed to enable the detector to identify the location of the thermal signature before extracting information from the thermal signature itself. Such a positioning scheme can include a pair of coverage areas at the start and end of the pattern, serving as "header" and "footer" markers for the disc information represented by the "payload" of the coverage areas between the markers. In embodiments, it may not be necessary to use any header or footer markers (especially in cases where a substantial reorientation of the object along the path is anticipated), such that the detector can be pre-aligned with the expected location of the thermal signature. Instead of a binary string, the coverage areas can be arranged to represent a particular two-dimensional image or pattern.

[0042] As described above, depending on the environment in which the thermal marking scheme will be used, a variety of different types of thermal signatures can be generated.

[0043] It should be understood that in order to optimize the traceability of an object through a long or complex manufacturing path with multiple different process stages, the thermal signature should be such that it remains visible to thermal detectors distributed throughout the path. In embodiments, prior to applying the thermal signature, the specifications of the manufacturing process are obtained and the thermal signature is configured according to those specifications such that the thermal signature can be isolated from the 'background temperature' of the unmarked areas of the object during the duration of the manufacturing process, or at least during the duration of the part of the process where the object is to be tracked.

[0044] Thus, the specification can include a plurality of different parameters characterizing the progression of an object, such as the expected speed of movement and the temperature applied to the object through various process stages (such as heating or cooling stages, or other processes expected to produce heating or cooling effects). The specification enables obtaining the thermal distribution of the manufacturing process, based on which the expected temperature of the object can be predicted as a function of time and position. In an embodiment, depending on the expected locations where product groups are to be separated from each other into different branches of the process flow, and / or the expected process bottleneck or perturbation regions, the specification can also include additional information characterizing specific areas of concern of the manufacturing process.

[0045] Figure 1 A representative information flow 70 from the paint spraying system 14 to the heat source 20 is shown to illustrate the configuration of the heat source 20 based on process parameters associated with the paint spraying system and the conveyor 12 through which the carrier tray 10 passes, but the entire process specification can be obtained from an external controller (not shown) or downloaded to the controller or driver of the heat source 20 from a remote computer or server.

[0046] In an embodiment, the thermal signature exceeds the maximum temperature defined by the process specification by a predetermined 'delta' temperature margin to allow for an actual deviation from the expected temperature of a particular object and / or to account for dissipation of heat from the thermal signature at a faster rate than predicted. Once applied to the product, the stability of the thermal gradient of the thermal signature depends both on the dimensions of the thermal signature itself (size and starting temperature) and on the nature of the object, in terms of surface-to-volume ratio and material, which affects its heat absorption characteristics. Based on this information, it can be predicted how quickly the thermal signature will cool after being applied, in order to compare the predicted cooling rate with the process specification. The mechanism by which the thermal signature is generated also affects the thermal gradient. For example, some heat sources apply high-intensity heating to the surface of the product, while other heat sources apply a more gradual heat to heat the product to a greater depth. For long manufacturing processes, a larger coverage area may be more appropriate, as a portion of the coverage area (such as the central area) can maintain the desired temperature of the thermal signature for longer than the peripheral area.

[0047] For example, for a silicone rubber object through a relatively low-intensity manufacturing process (from the perspective of the heating stage applied to the object), a thermal signature indicating heating of the coverage area of the object 15K greater than the rest of the object can be expected to have a detectable lifetime of 1 - 2 minutes. If the thermal signature indicates a temperature increase of 60K instead of 15K, the thermal signature can be detected for 3 - 4 minutes.

[0048] The object material is also considered when determining the upper temperature limit of the thermal gradient to be applied. If too high a temperature is used, the object may be damaged or deformed, so it is desirable to ensure that the thermal signature has as low a temperature as possible to ensure detectability during the manufacturing process. This also ensures that the embodiment is as efficient as possible in the use of its heating source.

[0049] It should be understood that the above-described embodiments are shown by way of example only for the purpose of illustration. In fact, many modifications to the illustrated embodiments are possible. These modifications take into account the nature of the manufacturing process for which the process is to be traced, the nature and quantity of the products passing through the manufacturing process, as well as the level of detection resolution required according to the information needed, and the number of times the information needs to be measured.

Claims

1. A method of recording tracking information on an object to track the progress of the object through a manufacturing process, the method comprising the steps of: Obtaining one or more temperature specifications associated with the manufacturing process; And Applying a thermal signature representing the tracking information to the object, the thermal signature including one or more covered areas having a temperature greater than the one or more temperature specifications associated with the manufacturing process.

2. The method according to claim 1, wherein, The temperature of the thermal signature is at least a predetermined incremental temperature greater than the maximum temperature specification of the manufacturing process.

3. The method according to claim 2, wherein, The temperature of the thermal signature has a temperature gradient such that after applying the thermal signature, the temperature gradient exceeds the maximum temperature specification of the manufacturing process within a period of time in which the manufacturing process will be completed.

4. The method according to claim 3, wherein Applying the thermal signature includes heating respective ones of one or more surfaces of the object using a direct contact heat source or a non-contact heat source.

5. The method according to claim 4, wherein The heat source is selected based on at least one of the geometric shape and heat absorption characteristics of the object and / or the information to be recorded.

6. The method according to claim 5, wherein The heat source is a laser having a wavelength selected based on the wavelength absorption characteristics of the object.

7. The method according to any one of claims 1 to 6, wherein The information recorded includes object identification information.

8. The method according to claim 7, wherein The object identification information is a binary string, wherein each of a plurality of positions on the object is associated with a digit in the binary string, and the covered area of the thermal signature at one of the plurality of positions on the object represents the corresponding digit of the binary string having one of the binary states.

9. The method according to any one of claims 1 to 8, wherein The object is an automotive component and the manufacturing process is an automotive manufacturing process.

10. A method of tracking an object traveling through a manufacturing process path, the method comprising the steps of: Thermally imaging a thermal signature located on the object at one or more positions along the manufacturing process path to identify one or more areas of the object having a temperature greater than a threshold temperature; Determining object information based on the identified one or more areas; And Recording the progress of the object having the determined object identification along the manufacturing process path.

11. A manufacturing process, the manufacturing process comprising: Recording tracking information on an object according to the method of any one of claims 1 to 9 ； Tracking the object according to the method of claim 10; and Recording a classification of the state of the object.

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