WO2008144717A1

WO2008144717A1 - Automated detection of leather hide and flexible material defects

Info

Publication number: WO2008144717A1
Application number: PCT/US2008/064333
Authority: WO
Inventors: Stephen Austin; Tim Vander Vos; Tom Gordon
Original assignee: Gerber Scientific International, Inc.
Priority date: 2007-05-21
Filing date: 2008-05-21
Publication date: 2008-11-27

Abstract

An apparatus for detecting defects in a work material includes a combination of inspection technologies in a novel fashion to enable automatic inspection of leather hides and other woven and non-woven flexible goods. The combination of one or more of the inspection technologies in cooperation with a CCD camera allows identification of front and back side defects, internal defects, and visual surface variations such as surface color, color regions and textural changes without operator intervention.

Description

Automated Detection of Leather Hide and Flexible Material Defects

FIELD OF INVENTION

[0002] The present invention relates in general to an apparatus for identifying defects or other defined properties on a work material, and, in particular, to an apparatus using one or more sources of energy such as but not limited to terahertz energy for identifying and marking defects on leather hides on one or both sides of the hides as well as identifying internal defects.

BACKGROUND

[0003] Traditionally, various work materials were hand inspected for defects and flaws prior to the work material being used. For example in the leather hide industry, leather hides used to produce parts for automobile upholstery, furniture upholstery, shoes and other leather articles were hand inspected for flaws and defects prior to having the hide cut. The surface area of the leather hide was then measured and templates would be arranged on the hide so as to minimize the amount of unused material. The hide would then be hand-cut according to the templates and the defects avoided. [0004] More recently, the hide cutting process has become automated, improving safety and increasing efficiency over traditional hand and die cutting processes. Automation reduces human error and promotes efficiency by using a computer to precisely place cuts within a hide or other substrate material. An accurate hide surface area is a necessary element required for maximizing hide yields.

[0005] Although the cutting process and precise surface area determination has become automated, it is still an inspector that manually inspects and marks the hides with special color coding so that the computer can read what defects are on the hide. Manual inspection of work material suffers from sub-optimum yields, high costs and inconsistent and unpredictable defect recognition errors.

[0006] Inspection of leather hides is a critical part of the hide manufacturing process and yet it remains totally manual, dependant upon the visual and tactile skills of highly trained technicians. It is possible to cut as many as 16 hides per hour on automated cutting systems such as Gerber Technology's Taurus. Typically an inspector can inspect, grade, and mark 3-10 hides per hour causing a bottleneck in production workflow. Therefore, hides are inspected offline, often by several different inspectors. [0007] The inspectors will typically mark hides with wax crayons noting defects which are unusable. Thin colored tape is used to grade flawed areas to be used in less obtrusive areas on the finished product. The marks are later used to align dies or templates for manual cutting operations, or they are scanned by cameras for computerized nesting and cutting for automated systems.

[0008] Accurate hide inspection is critical to efficient production of quality leather products. The manual inspection process is fraught with problems including; day to day variations in acceptance criteria due to operator fatigue making it difficult to see or feel subtle defects, uniformity of inspections from one operator to another, placement of flaw marking tapes resulting in variations in hide yield, damage to hide surface from marking tape adhesive, failure of tape adhesive to bond to hide surface initially and through movement and storage of hides prior to cutting resulting in additional subsequent re-placement of tape by inspector or machine personnel most likely not in the original position. These are just some of the limitations of current inspection process currently in use in the marketplace.

[0009] Current state of the art in the area of automated inspection of leather hides, for example, primarily attempt to identify flaws through the use of cameras to visualize the hide surface to denote flawed regions. These types of devices are limited in that they can not detect sub-surface flaws or flaws beneath the surface.

[0010] Yet there remains a need in the industry for an apparatus that not only identifies visual defects, but can identify sub surface flaws where the hide regions may or may not appear to be visually acceptable. In addition an apparatus is needed to accurately identify flaws such as variations in thickness, or natural and (tanning) process induced density changes that can have a marked impact on the final product.

BRIEF SUMMARY OF THE INVENTION

[0011] An object of the invention is to identify defects whether visual or not, sub surface or surface flaws without the aid of a visual or tactile human inspector. [0012] In addition it is an object of the invention to identify variations in thickness due to the butchering process, branding, or other causes, or natural and (tanning) process induced density changes that can have a marked impact on the final product.

[0013] The invention can be used with any work type material. Leather hides are given as an example. In addition, a combination of energy sources or single source of energy such as but not limited to Terahertz technology is described herein. There are several other technologies or sources of energy that can be used with the present invention as further described. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which: [0015] FIG. 1 is a perspective view of the apparatus being used on a cutting table

[0016] FIG. 2 is a block diagram of the apparatus in Figure 1.

[0017] FIG. 3 is an illustration of one embodiment of the apparatus shown in

Figure 2 showing the energy source and analyzer on opposite sides of the work sample. [0018] FIG. 4 is an illustration of one embodiment of the apparatus in Figure 2 showing the energy source and analyzer on the same side of the work sample.

DETAILED DESCRIPTION OF THE INVENTION

[0019] The apparatus disclosed can utilize several technologies in various ways that might be applied in novel fashions to the automated identification of flaws and defects in animal hide or other flexible materials. Identification of defects is usually prior to cutting or other material processing allowing the user to optimize the utilization of their material and thereby eliminate the variability and waste of the error prone manual processes currently in use. However, this invention can also be utilized as a post cutting or other material processing apparatus for the purpose of final inspection.

[0020] Screening experiments have been conducted on various leather samples in several technology areas. Technologies that have shown the most promise include; but are not limited to, x-ray, back scatter x-ray, IR thermography, terahertz laser, white light profilometry, ultrasound, and radar. These technologies an be used alone or more preferably in combination to achieve the result of the invention. [0021] Additionally, work with digital camera imagery has shown to be useful.

Depending on the embodiment, this technology will be a component in hide inspection necessary to recognize color variations within a single hide and color to color differences from hide to hide. The detection device or devices can be disposed about the sample to be inspected by placing one or more detectors above, below, parallel with or any combination thereof relative to the sample. In one example, one or more detectors can be placed in the table where the sample is placed. In another example, one or more detectors can be placed above the sample and below the sample. Below are further examples given to illustrate the invention. The invention is not limited to such examples, and these examples are given to merely illustrate some of the facets of the invention.

[0022] Example 1 : Backscatter X-ray -backscatter technology can be used to distinguish between good leather and brand marks & scars. This technology is used for personnel, parcel and cargo inspection systems. This technology has proven useful in penetrating cargo steel container walls, personnel airport security inspection and letter inspection. Production systems are in operation in Iraq and at the Whitehouse. This is a reflective technology.

[0023] Example 2: Terahertz laser (THz) -THz technology is capable of distinguishing between good leather and some defects. Terahertz experiments were in done in both transmission and reflection modes. Transmission scans discriminated between flaws and good areas in the leather, while reflection scan images were obscured somewhat suffering from echos bouncing back off the supporting surface causing interference with the primary images. [0024] Terahertz (THz) radiation penetrates paper and clothing, partially penetrates skin and other biological structures, and is deflected by metals. Different materials absorb different wavelengths of radiation, making it possible to identify void spaces in the interior of the foam.

[0025] Early THz spectroscopy focused on trying to detect ultra-short electrical transients propagating along an electrical transmission line (J. Phys. Chem. B 2002, 106, 7146-7159). The THz region, spanning about 3 to 600 cm-1, is potentially useful, but underused because the technology just hasn't been there to exploit it.

[0026] It is known in the art that time-domain THz spectroscopy creates pseudocolored images based on differences in the rays' rate of travel. A semiconductor crystal absorbs pulses of visible- wavelength laser light, and converts them to pulses with THz wavelengths. These THz pulses can be scanned across an object, which reflects them to a detector. The time the pulses take to reach the detector varies according to what the object is made of, and these varying times can be compiled into a three- dimensional image that illustrates the compositional variations in the object.

[0027] Example 3: Ultrasonic/ Acoustic -Acoustic sensors can be used for leather softness testing. Ultrasonic/ Acoustic energy has limited success testing leather sample flaws, but using different sensors may provide improved results.

[0028] Example 4: X-ray - High energy transmission x-ray has been shown to be able to distinguish many flaws in the sample leather in tests. While tests in lower energy "soft x-ray" have not yet been conducted, there are differing opinions in the art as to its viability as a scanning technology by industry experts. [0029] Example 5: Infrared Thermography - The premise with thermal imaging is that flawed areas of the hide have different thermal signatures from normal areas as they transition from hot to cold or visa versa. A FLIR thermal imaging camera was able to pick up the differences between scarred and non-scarred regions of a hide sample. Tests were conducted by rolling a hot tube over leather and imaging the surface as the leather cooled. Other tests, incorporating Thermal Wave Imaging company's IR cameras and utilizing a flash lamp to heat the sample leather, showed similar early results. IR thermography is a reflective technology.

[0030] Example 6: Radar (Microwave) - Leather is quite transparent to RF microwave signals. Early tests showed no discernable differences between scarred and non-scarred areas.

[0031] Example 7: White light diffraction scanning - This technology is a surface profiling technology that scans and displays the samples topology. Unlike all other technologies investigated, white light scanning does not attempt to penetrate the surface. Early tests conducted have shown that thickness variations and brand mark scars are very visible while density changes may not be recognizable. This is a fully developed technology currently in use in many industries for inspection and reverse engineering to determine the exact shape of 3-dimensional objects. This mature technology is capable of identifying and digitally measuring surface defects as small as 4 microns (.00016 in) and is available from several manufacturers.

[0032] Some flaw identification technologies operate by sending a signal through the leather hide, bouncing it back off of a reflective surface below the hide to a sensor located in close proximity to the emitter while others transmit the signal through the leather and receive it at a sensor at the back side of the hide. Technologies that operate on principals of transmission which incorporate an energy source on one side of the hide and a detector on the opposite side of the hide pose an additional challenge over those that reflect the signal due to the necessity of implementing a sensor under the cutting table which would track the source during hide scanning.

[0033] Terahertz laser appears to be the preferred technology for identifying internal defects such as density changes and gross thickness variations due to its prominent image quality and low (safe) energy levels. However, terahertz will not adequately identify all defects, including gradual thickness changes. Additionally, terahertz will produce an image which superimposes front side and back side defects plus internal defects and will not sufficiently differentiate front side flaws from back side flaws.

[0034] This issue with Terahertz might prove problematic as certain back side flaws may be acceptable in some situations for sub-grade applications where the same defect would be unacceptable on the front side. By merging the front and back side images, certain areas which might have been acceptable for some applications would be unnecessarily rejected.

[0035] Combination of one or more than one inspection technology to obtain sufficient breadth of defect identification would yield an apparatus with surprising results. Where technologies may be minimally useful or useless alone, combinations of several energies and detection technologies produce the desired result of detection. White light profilometry shows promise as an adjunct to terahertz's inspection capabilities with its surface discriminating capability. [0036] A combination of inspection technologies in a novel fashion to enable automatic inspection of leather hides and other woven and non- woven flexible goods is utilized. The combination of one or more of the listed inspection technologies in cooperation with a CCD camera will allow identification of front and back side defects, internal defects, and visual surface variations such as surface color, color regions and textural changes without operator intervention. The resulting data may be augmented with part nesting information and acted upon immediately by cutting or marking on a single hide, or stored and later recalled for one or more hides.

[0037] Automated defect identification will allow the machine control to grade regions of a hide according to end user definitions and use these regions across multiple hides to assemble large jobs. Users can define any number of grades (a significant advantage over the currently accepted practice) and which type and size of defect is acceptable (or not) for each grade.

[0038] For example, one user might define that a thickness difference over a part surface of x is acceptable for the back side of a seat cushion but not the front while the next user who has a much tighter tolerance and would not use any part with that same thickness variation at all. With knowledge of the grade rules, parts to be cut can be nested according to the unique requirements of a user to determine yield of a specific hide.

[0039] Digital representations for multiple hides can be stored in a scanned hide database. A job which might consist of any number of seats each consisting of numerous smaller elements (some elements require close color and texture matching if they are to be assemble adjacent to one another) is entered into the system. [0040] The scanned hide inventory is reviewed and a set of hides is selected which gives the optimal yield with the closest match for color, texture, thickness, etc. according to the customer requirements. Since pre-scanned hides will not retain their original positions and exact dimensions when moved from a scanning station to a cutting station, the system will have to identify key attributes of a given hide (either pre- identified defects, registration marks, or perimeter features) and modify the cut (or print) data appropriately for optimum utilization.

[0041] FIG. 1 illustrates a sample system embodying the invention. The system, generally designated 10, includes a controller 12 and an apparatus 14 driven by command signals from the controller for identifying flaws, cutting and performing related work operations on sheet material supported on the apparatus.

[0042] As shown in FIG. 1, the system 10 includes table end covers 16, beam end covers 18, beam 76, and container 20 that contains for example, but is not limited to, an energy source, an analyzer for analyzing resultant energy from a sample or work material, and a CCD camera, all which are further shown and explained in detailed herein and in the drawings. It is within the scope of the invention that these components may be placed outside of the container and do not necessarily need to be within the container. For example, the CCD camera may be disposed above the table in FIG. 1. Other permutations can be done by those so skilled in the art. Also included is a base enclosure 22.

[0043] Container 20, depending on the embodiment can be moved in the generally "Y" axis direction along beam 76. Beam 76 is allowed to travel in the generally "X" axis direction. Other permutations are also within the scope of this invention. For example, container 20 and/or beam 76 may be allowed to travel in the generally "Z" direction (not shown) to allow movement closer to or farther away from work material 36.

[0044] The energy source can transmit energy through the work material or have energy reflect off the work material as well as all permutations in between. The analyzer will be positioned accordingly depending upon what type of energy is used and its amount.

[0045] Depending on the implementation, the controller 12 includes a central processor linked to a pattern development system (not shown) for receiving digitized representations of the individual pattern pieces. Any known pattern development system may be employed to create the digitized representations of the pattern pieces.

[0046] Flexible material 36 includes , but is not limited to, commonly used material in garment making such as, for example, leather and suede.

[0047] The apparatus may also include a vacuum hold-down table 24. A generally horizontally disposed sheet material support surface 34 is also included for supporting a layer of sheet material 36, such as the illustrated layer in a spread condition.

[0048] A cutting device (no shown) may also be included in container 20 for movement relative to the support surface 34 in the illustrated X and Y coordinate directions along predetermined cutting paths to cut the illustrated garment parts 41. Any cutting device know in the art may be used. For example, the cutting device may be a cutting wheel 40 mounted on a tool head, which moves the cutting wheel into and out of cutting engagement with the material 36. [0049] Referring now to FIG. 2, the apparatus can identify flaws in sample 202 that represents flexible material 36 of FIG. 1. The sample 202 can be any flexible material as previously describe, and is preferably a leather hide. Container 22 may contain the energy source 201, CCD camera 203 and analyzer 204 or it is within the scope of the invention for these components to be separately mounted about the sample 202. For example, the CCD camera 203 may be above or below the sample and disposed outside the container 20. Furthermore, the analyzer 204 may be incorporated into table support 34 and outside container 20.

[0050] FIG. 3 illustrates a schematic when the energy source and analyzer are on opposite sides of the flexible material or sample. Energy source 301 transmits energy 305 through flexible material 302. Resultant energy 306 enters analyzer 303 for detection. An optional CCD camera 304 may be disposed to capture visual information from the sample, either exposed or unexposed by the energy source, which is denoted by arrow 307.

[0051] FIG. 4 illustrates a schematic when the energy source is at least reflected back. Energy source 401 transmits energy 405 to flexible material 402. Material 402 has resultant energy 406, 407 that is received by analyzer 403 and/or CCD camera 404. Again the CCD camera may be utilized at any stage of the operation. For example it may be utilized before, during and/or after exposure of the material by the energy source. Preferably, the CCD camera is used in conjunction with the energy source.

[0052] As previously described the energy source can be any one of the above mentioned sources or a combination of two or more such sources. Other sources not named that may be further developed are also within the purview of this invention. [0053] Although the invention has been described in conjunction with specific embodiments, many alternatives and variations can be apparent to those skilled in the art in light of this description and the annexed drawings. Accordingly, the invention is intended to embrace all of the alternatives and variations that fall within the spirit and the scope of the appended claims.

Claims

CLAIMSWhat is claimed is:

1. An apparatus for identifying a defect or defects in a work material, comprising: at least one energy source disposed about the work material for irradiating the material with energy; and one or more monitoring devices for detecting defects in the work material.

2. The apparatus in claim 1 wherein the energy is at least one of terahertz radiation, X-ray radiation, back scatter x-ray radiation, infra-red (IR) radiation, microwave radiation, ultrasonic radiation, light, ultra-violet radiation, or any combination thereof.

3. The apparatus in claim 1 wherein the defects detected are surface and subsurface defects in the work material.

4. The apparatus in claim 1 wherein the energy is a combination of different energy sources.

5. The apparatus in claim 1 wherein the energy is a combination of the same energy sources.

6. The apparatus in claim 1 wherein the one or more detectors is or are positioned above the work material, below the work material, approximately level to the work material or any positional combination thereof.

7. The apparatus in claim 1 further including a table for the work material to be disposed thereon, and the table having one or more detectors disposed therein.

8. The apparatus in claim 7 wherein the one or more detectors is or are positioned above the work material, below the work material, approximately level to the work material or any positional combination thereof.

9. The apparatus in claim 1 wherein the energy is transmitted through the part under inspection.

10. The apparatus in claim 1 wherein the energy is not transmitted through the part under inspection.

11. The apparatus in claim 1 further including a CCD camera.

12. An apparatus for identifying defects in a work material, comprising: a tabletop surface for supporting a work material; at least one energy source disposed about the tabletop surface for inducing a reflective property from at least a portion of the work material being irradiated by the energy; a detector for detecting reflective radiation and providing detection information; and a CCD-type camera for receiving the reflective energy emitted from the work material after being irradiated.

13. The apparatus of claim 12 further including a controller for directing a cutting tool to cut the work material using information derived from the detector.

14. The apparatus of claim 12 further including a signal processor for digitizing the detection information and relaying it to the controller.

15. The apparatus of claim 12 further including a display device for displaying the detection information

16. The apparatus of claim 12, wherein the work material is leather hide.

17. The apparatus of claim 16 wherein flaws in the leather hide are captured by the camera and displayed on the display device.

18 A method for automatic identification of physical flaws in a flexible material, comprising: exposing a flexible material to at least one energy source; and analyzing energy from the flexible material after the flexible material is exposed to the energy source.

19. The method of claim 18, wherein the energy is transmitted through the flexible material.

20. The method of claim 18, wherein at least some of the energy is transmitted completely through the flexible material.

21. The method of claim 18, wherein the energy is reflected off of the flexible material.

22. The method of claim 18, wherein the energy is reflected off and transmitted through the flexible material.

23. The method of claim 18 wherein the flexible material is leather.

24. A method for automatic grading of flaws in a flexible material, comprising: exposing a flexible material to at least one energy source; and analyzing energy from the flexible material after the flexible material is exposed to the energy source for automatic grading of flaws and identification of front and back side defects, internal defects, and visual surface variations such as surface color, color regions and textural changes without operator intervention.

25. The method of claim 24 further including assigning user assignment of flaw grading.

26. The method of claim 24 further including combining multiple hides for detection of flaws.

27. The method of claim 24 further including complying a database based on similar visual and physical attributes in later tested material.

28. The method of claim 24 further including correcting for scaling, skew, and stretch prior to cut or post processing.