Source: https://patents.google.com/patent/US9575013
Timestamp: 2018-02-21 19:34:23
Document Index: 45319136

Matched Legal Cases: ['arts 31', 'art 102', 'art 31', 'art 102', 'art 102', 'art 36', 'art.\n2', 'art.\n4', 'art.\n10', 'art.\n12', 'application No. 12786466', 'application No. 13757558']

US9575013B2 - Non-contact method and system for inspecting a manufactured part at an inspection station having a measurement axis - Google Patents
Non-contact method and system for inspecting a manufactured part at an inspection station having a measurement axis
US9575013B2
US9575013B2 US14629527 US201514629527A US9575013B2 US 9575013 B2 US9575013 B2 US 9575013B2 US 14629527 US14629527 US 14629527 US 201514629527 A US201514629527 A US 201514629527A US 9575013 B2 US9575013 B2 US 9575013B2
US14629527
US20150204798A1 (en )
A method and system for inspecting a manufactured part at an inspection station are provided. A supported part is rotated about a measurement axis so that the part moves at predetermined angular increments during at least one rotational scan. A backside beam of collimated radiation is directed at and is occluded by the supported part at each of a first plurality of consecutive increments of movement to create a stream of unobstructed portions of the backside beam in rapid succession passing by and not blocked by the supported part. A frontside beam of radiation is directed at and is reflected by the supported part at each of a second plurality of consecutive increments of movement to create a stream of reflected portions of the frontside beam in rapid succession. The streams of reflected and unobstructed portions are detected at the inspection station to obtain electrical signals which are processed.
This application is a continuation-in-part of U.S. patent application Ser. No. 14/050,907, filed Oct. 10, 2013, which is a continuation of U.S. patent application Ser. No. 13/109,369, filed on May 17, 2011, now U.S. Pat. No. 8,570,504. This application is also a continuation-in-part of U.S. patent application Ser. No. 13/414,081 filed on Mar. 7, 2012.
This application relates to non-contact methods and systems for inspecting manufactured parts such as ammunition cases and threaded fasteners.
Other U.S. patent documents related to the invention include: U.S. Pat. Nos. 3,411,009; 3,604,940; 4,280,624; 4,315,688; 4,598,998; 4,636,635; 4,644,394; 4,691,231; 4,852,983; 4,906,098; 4,912,318; 4,923,066; 4,969,746; 5,521,707; 5,608,530; 5,646,724; 5,291,272; 6,055,329; 4,983,043; 3,924,953; 5,164,995; 4,721,388; 4,969,746; 5,012,117; 6,038,521; 7,329,855; 7,738,121; 6,055,329; 7,065,242; 8,723,068; 7,684,054; 7,403,872; 7,633,635; 7,312,607, 7,777,900; 7,633,046; 7,633,634; 7,738,121; 7,755,754; 7,738,088; 7,796,278; 7,684,054; 8,054,460; 8,179,434 and U.S. published patent applications 2010/0245850, 2010/0201806, 2012/0293623; 2012/0105429; and 2012/0293789.
An object of at least one embodiment of the present invention is to provide a high-resolution, low-cost method and system for inspecting a manufactured part at an inspection station having a measurement axis by rotating the part.
In carrying out the above object and other objects of at least one embodiment of the present invention, a method of inspecting a manufactured part at an inspection station having a measurement axis is provided. The method includes the step of supporting a part having opposite ends, a length between the ends, a width and a part axis. The part has backside and frontside surfaces when supported. The method also includes rotating the supported part about the measurement axis so that the part moves at predetermined angular increments during at least one rotational scan. The steps further include directing a backside beam of collimated radiation at substantially the entire backside surface of the supported part at each of a first plurality of consecutive angular increments of movement. The backside beam is occluded by the supported part at each of the first plurality of consecutive increments of movement to create a stream of unobstructed portions of the backside beam in rapid succession passing by and not blocked by the supported part. The steps include directing a frontside beam of radiation at at least a portion of the entire frontside surface of the supported part at each of a second plurality of consecutive angular increments of movement. The frontside beam is reflected by the supported part at each of the second plurality of consecutive increments of movement to create a stream of reflected portions of the frontside beam in rapid succession. The steps further include detecting the streams of reflected and unobstructed portions at the inspection station to obtain electrical signals and processing the electrical signals to determine at least one geometric dimension and any visual defects of the part.
Substantially the entire backside surface may be completely enclosed by a beam profile of the backside beam.
The beam profile may be generally rectangular with a height greater than or equal to the length of the part and a width greater than or equal to the width of the part.
The streams of reflected and unobstructed portions may be detected at a single image plane.
The method may further include centering and aligning the part axis with the measurement axis.
The method may further include projecting focused lines of radiation at the frontside surface of the supported part during the at least one rotational scan to obtain reflected radiation and sensing the reflected radiation to obtain electrical signals.
The part may have a radially extending surface wherein the focused lines are angled with respect to the radially extending surface.
The focused lines of radiation at the frontside surface may be strobed.
The first and second plurality of consecutive angular increments may be coincident.
Further in carrying out the above object and other objects of at least one embodiment of the present invention, a system for inspecting a manufactured part at an inspection station having a measurement axis is provided. The system includes a fixture to support a part having opposite ends, a length between the ends, a width and a part axis. The part has backside and frontside surfaces when supported. The system also includes an actuator assembly to rotatably drive the fixture about the measurement axis at predetermined angular increments of movement during at least one rotational scan. A backside illumination assembly directs a backside beam of collimated radiation at substantially the entire backside surface of the supported part at each of a first plurality of consecutive angular increments of movement. The backside beam is occluded by the supported part at each of the first plurality of consecutive increments of movement to create a stream of unobstructed portions of the backside beam in rapid succession passing by and not blocked by the supported part. A frontside illumination device directs a frontside beam of radiation at at least a portion of the entire frontside surface of the supported part at each of a second plurality of consecutive angular increments of movement. The frontside beam is reflected by the supported part at each of the second plurality of consecutive angular increments of movement to create a stream of reflected portions of the frontside beam in rapid succession. A lens and detector assembly images and detects the streams of reflected and unobstructed portions at the inspection station to obtain electrical signals. At least one processor processes the electrical signals to determine at least one geometric dimension and any visual defects of the part.
The streams of reflected and unobstructed portions may be detected at a single image plane of the lens and detector assembly.
The system may further include a part centering and aligning subsystem to center and align the part axis with the measurement axis.
The system may further include a triangulation-based sensor configured to project focused lines of radiation at the frontside surface of the supported part during the at least one rotational scan and to sense corresponding reflected lines of radiation to obtain electrical signals.
The focused lines of radiation may be strobed.
The frontside illumination device may include an array of spaced light sources.
The actuator assembly may include a stepper motor.
FIGS. 2a-2e are schematic views, of various threaded fasteners having various symmetric and non-symmetric features which can be extracted and measured using at least one embodiment of the present invention;
FIG. 3 is a schematic perspective view of an example embodiment of a system of the invention;
FIG. 4 is a side elevational view, partially and broken away and in cross-section, of an upper tooling unit including an upper holding device of FIG. 3;
FIG. 5 is a front perspective view of cartridge case including an apertured top surface located at a mouth end of the case;
FIG. 6 is a bottom perspective view of an apertured bottom surface located at a primer end of the case;
FIG. 7 is a side perspective view of an upper holding device constructed in accordance with one embodiment of the present invention;
FIG. 8 is a side sectional view of the device of FIG. 7 taken along lines 8-8;
FIG. 9 is a side perspective view of a lower holding device also constructed in accordance with one embodiment of the present invention;
FIG. 10 is a side perspective view of an upper holding device constructed in accordance with another embodiment of the present invention;
FIG. 11 is a side sectional view of the device of FIG. 10 taken along lines 11-11;
FIG. 12 is a side view, partially broken away, of the system of FIG. 3 together with a block diagram of various electronics of the system and showing the height of the collimated beam of radiation;
FIG. 13 is a top plan schematic view, partially broken away, of parts of the system of FIGS. 3 and 12 and showing the width of the collimated beam of radiation;
FIG. 14 is a top plan schematic view, partially broken away and in cross section, of an illumination assembly and a telecentric lens and detector assembly of FIGS. 3, 12 and 13 with a threaded fastener at the inspection station with some radiation blocked by the threaded fastener and some radiation scattered by the edges of the threaded fastener and through a diaphragm of the telecentric lens;
FIG. 15 is an enlarged view, partially broken away and in cross section, of a portion of the telecentric lens of FIG. 14 with corresponding rays of the radiation either blocked or passing therethrough the diaphragm;
FIG. 16 is a schematic perspective view (partially broken away) of the various components of a sensor head of one embodiment of the system together with a threaded part;
FIG. 17 is a schematic view wherein a framework in the figure is applied to a part such as a cartridge case once it has been located;
FIG. 18 is a schematic view of a screen shot which describes a cartridge case or bullet to be inspection;
FIG. 19 is a schematic view, similar to the view of FIG. 17, wherein buffers are applied once the case regions have been identified;
FIG. 20 is a screen shot of a graph of data with external wires with respect to a view of a threaded fastener; and
FIG. 21 is a block diagram schematic view that illustrates yet another embodiment of a non-contact method and system for inspecting parts.
In general, and as described below, at least one embodiment of the present invention provides a non-contact method and system for inspecting a manufactured part at an inspection station having a measurement axis. A first embodiment of the system is generally indicated at 10 in FIG. 3. A second embodiment of the system is generally indicated at 10′ in FIG. 21. In general, parts of the two embodiments which are substantially the same in either structure or function have the same reference number but the parts of the second embodiment have a single prime designation. The part, such as a threaded fastener, has a length, a width, and a part axis which, preferably, is central to the part and parallel to its length.
Referring now to FIGS. 3, 12, 13, 14 and 16 a threaded bolt, generally indicated at 36, is held or supported by upper and lower parts 31 and 33, respectively, of a chuck or fixture, generally included at 32. In the second embodiment of FIG. 21 only a fixture 32′ including a lower part or recess bit 33′ is required. The lower part or recess bit 33 is mounted for rotary movement with a part stage 14 mounted above a top plate 42 of a base of the system 10. The part stage 14 is coupled via a coupler to the rotary output shaft 35 of an electric motor 28 supported below the plate 42. A head 37 of the bolt 36 is driven by the bit 33 which extends into the head 37 at one end surface thereof. This feature allows threads 38 as well as the entire exterior side surfaces of the bolt 36 to be optically inspected in an embodiment of the system 10 of the present invention. Other parts, such as the cases of FIGS. 1a-1c and a case generally indicated at 100 in FIG. 5 can be rotatably driven by the motor 28 via a motor driver controlled by a system controller (FIG. 12) while being held by upper and lower parts, generally indicated at 102 and 104, respectively, in FIGS. 4, and 7-9 and upper part 102 in FIGS. 10 and 11.
In like fashion and referring to FIG. 21, the bolt 36′ is rotatably driven by an actuator or motor 28′ such as a stepper motor via a motor driver or motor controller upon receiving control signals from a system controller. The motor 28′ either directly or via a transmission coupled to the output shaft of the motor 28′ may also alternatively raise or lower the fixture 32′ and the supported bolt 36′ via a second motor driver or controller.
Referring to FIGS. 3 and 4, there is shown a schematic, side elevational view of an upper tooling unit 16 for bolts 36 and ammunition cases 100, respectively. The tooling unit 16 includes a rod 32 which is manually movable along a central axis of the rod 32 in up and down directions by an operator of the system 10. The upper tooling unit 16 (as described in detail in U.S. Pat. No. 8,004,694) includes the upper part 31 (for bolts) or the upper part 102 (for cases) and comprises a spring-loaded, upper holding device or tooling assembly. The upper part 102 has a tip portion 103 which retains a part such as the ammunition case 100 to be inspected at an upper, apertured end surface 106 of the case 100 by extending into an opening 108 in the case 100 (FIG. 5). The tip portion 103 is frustum-shaped and has a sloped region and a cross-sectional shape substantially identical to the shape of opening 108 in the end surface 106 at a mouth end of the case 100. The sloped region of the tip portion 103 defines a range of sizes of the opening 108 that can be measured at the measurement station.
The holding device 102 has a first central bore 110 formed in a cylindrical housing portion 111 and in which a cylindrical, hollow bearing 112 is disposed. The holding device 102 also has a second central bore 114 concentric with the first central bore 110 and in which a compression spring 116 is disposed within the hollow bearing 112. A hole 118 extends through an upper portion of the housing portion 111 to receive a dowel (119 in FIG. 4) by which the holding device 102 is secured to the lower end of the rod 32. The lower end of the rod 32 has an elongated slot 120 extending therethrough which receives and retains the dowel 119. The lower end of the rod 32 is received within the bore 110 and engages the top end of the spring 116 to compress the spring 116 within the bore 114.
A threaded hole 122 is typically provided at a distal end of the tip portion 102 to threadably receive and retain one of a number of possible tips (not shown) that can contact a surface of a part or case to be inspected.
FIGS. 10 and 11 illustrate a second embodiment of an upper holding device, generally indicated at 102′. Parts of the upper holding device 102′ which have the same or similar structure or function as the parts of the first embodiment (i.e., upper holding device 102) have the same reference number but have a prime designation. The upper holding device 102′ generally is provided at the lower end of the rod 32 when measuring an opening in an ammunition case which is larger than opening that can be measured with the holding device 102.
A hexagonal base 130 (FIG. 9) of a lower holding device or tooling assembly, generally indicated at 132, is inserted into the part stage 14. The lower holding device 132 includes a pin 134 which extends upwardly from a top surface 136 of the base 130.
Much like the way the upper holding device 102 is secured to the rod 32, the pin 134 has an elongated aperture 138 which receives a dowel pin 140 which extends therethrough and through a hole 142 which extends through a cylindrical portion 144 of the lower holding device 132. A compression spring 146 extends between the top surface 136 and the lower surface of the cylindrical portion 144 to bias the cylindrical portion 144 away from the base 130.
A distal end portion 150 of the pin 134 extends through a central bore 152 which extends through a tip portion 154 of the lower holding device 132. The tip portion 154 is frustum-shaped and has a sloped region and a cross-sectional shape substantially identical to the shape of an opening 156 in an end surface 157 at a primer end of the case 100. The sloped region of the tip portion 154 defines a range of sizes of the opening 156 that can be measured at the measurement station. The distal end 150 of the pin 134 moves within the bore 152 after the sloped region of the tip portion 154 extends into the opening 156 of the case 100 and engages the side walls which define the opening 156. After engagement, further movement of the tip portion 154 downward against the biasing action of the spring 146 exposes the distal end 150 of the tip portion 154 which engages an inner end surface 158 of the opening 156. During this movement, the dowel pin 140 slides within the aperture 138 of the pin 134. As described herein, the depth of the primer pocket or opening 156 is determined after scanning the case 100 and the holding device 132. The depth that the pin 134 extends into the opening 156 and engages the end surface 158 is the depth of the opening 156.
In other words, the upper tooling for the case 100 incorporates a hollow cone (or frustrum) which lowers down inside the mouth of the case 100 and seats on the inner diameter of the mouth. This cone assembly is spring-loaded which provides a small preload to hold the part in place on the part stage 14 of the system 10. By defining a region that encompasses the point or line of contact between the cone and the case 100 and then measuring the minimum diameter in that region, the system 20 indirectly measures the inner diameter (ID) of the mouth.
If the ID on the part to be measured has a radius, the cone will seat deeper inside the mouth and the diameter measured will be larger than the actual ID of the part. In order to minimize this effect, the angle of the cone used in this fixture should be as shallow as possible. A cone with a shallow angle results in more accurate measurements.
Practically, a cone with a very shallow angle will tend to wedge itself inside the mouth of the part. The force of the spring 116 or 116′ in the upper tooling assembly can cause the cone to become stuck inside the case which can make unloading parts from the system challenging. Furthermore, a very shallow cone angle can be used only on parts with a very narrow range of mouth IDs. A cone with a steep angle is less likely to get stuck inside the mouth of the part and is usable on a wider variety of part sizes.
In light of these considerations, a relatively shallow cone angle of 10° is preferred with two different cone designs, one for small caliber ammunition (50 cal and smaller) and one for medium caliber ammunition (20 mm and larger). This is a convenient break point because it is rare that a single company manufacturers both small and medium caliber ammunition.
The wall thickness is calculated by subtracting the directly measured OD from the indirectly measured ID and dividing this result by two.
The lower tooling uses a similar concept, with the exception that this tooling configuration also allows the depth of the recess (primer pocket) to be determined. The basis of this assembly is a small post whose height has been pre-measured and is stored in memory of the system. Surrounding this post is a cone which slides up and down on the post. This cone is constrained from coming off the post with a through-pin which rides in a slot cut into the post. This cone is biased from underneath by the spring 146.
When an ammunition case with a primer pocket fixture in the system 10, the ID of the primer pocket seats on the angled surface of the cone. The upper tooling presses the case down which, being seated on the cone, causes the spring 146 to compress until the base of the primer pocket comes to rest on the top of the tooling post.
When the part is scanned in this configuration, the primer pocket diameter is determined by measuring the minimum diameter at the point where the cone contacts the head of the case in the same manner the mouth ID is indirectly measured as described above. The depth of the primer pocket is measured by measuring the height of the case head (above the base of the post) and subtracting this from the known height of the tooling post.
The choice of angle for the lower tooling cone (i.e., frustrum) requires consideration of all the same factors as the upper tooling cone. One additional detail is the available depth of the part recess. It is desirable to design this lower tooling assembly so that it can be used to measure a wide variety of recess depths and diameters. A shallow cone angle severely limits the range of recess aspect ratios (diameter vs depth) that can be measured with a single tooling design. In order to accommodate most of the small caliber range, a comprise angle of 18° is preferred. This allows measurement of common primer pockets machined into cases sized 7.62 mm and smaller.
Referring again to FIGS. 3 and 12 and as described in U.S. Pat. No. 8,550,444, the system 10 also preferably includes a part centering and aligning subsystem, generally indicated at 200. The subsystem or apparatus 200 ensures that a part is centered in the system 10 and that the part is aligned with the measurement axis (Z-axis) without the need to measure any distances or angles. In other words, the apparatus 200 ensures that the part is properly placed or positioned in the system 10 prior to the part being held, for example, between the upper tooling unit and the part stage 14. The part may be a threaded part such as the threaded fastener 36 or the ammunition case 100.
As described in U.S. Pat. No. 8,550,444, the apparatus 200 includes a carrier which defines a part receiving cavity. The apparatus 200 also has a central axis substantially parallel to a measurement axis or Z-axis and including a plurality of members or levers having open and closed positions. The members having holding faces which are substantially equidistant from the central axis during movement between the open and closed positions. At least one of the members applies a force on an exterior side surface of a part, disposed between the holding faces during movement between the positions to reposition the part. The repositioned part is centered and aligned with respect to the measurement axis. The holding faces releasably hold the repositioned part in the holding position between the open and closed positions of the members.
The system 10 also includes a movable stage subsystem, generally indicated at 202, coupled to the apparatus 200 for sliding the apparatus 200 relative to the repositioned part along the central axis in the open position of the members to allow the exterior side surface of the repositioned part to be measured. In turn, the slide/base unit moves the movable stage subsystem 202 up and down. A horizontal support member couples the subsystem 202 to the apparatus 200 to move the apparatus 200 along the central axis.
The system 10 further includes a mechanism which is coupled to one end of the support member for translating the support member and the apparatus 200 a limited extent relative to the subsystem 202 along the central axis. The mechanism includes a manually operable knob to operate the mechanism.
Referring again to FIGS. 3, 12, 13 and 14, the system 10 also includes a backside illumination assembly, generally included at 300. The system 10′ includes a backside illumination assembly, generally indicated at 300′ in FIG. 21.
The illumination assembly 300 (and the assembly 300′) directs a beam of collimated radiation at substantially the entire backside surface of the held part at predetermined angular increments of movement of the held part about the measurement axis of the system 10 (or system 10′) during the rotational scan. The beam is occluded by the held part at each increment of movement to create a stream of unobstructed portions of the beam in rapid succession passing by and not blocked by the held part.
Preferably, substantially the entire backside surface is completely enclosed by a beam profile of the beam. The beam profile is generally rectangular with a height greater than or equal to the length of the part and a width greater than or equal to the width of the part as show in FIGS. 12, 13 and 14.
Referring again to FIG. 21, the backside illumination assembly 300′ is substantially the same as the illumination assembly 300. The assembly 300′ may be movable up or down via a motor M driven or controlled by a driver/controller upon receiving a control signal from the system controller.
The illumination assembly or radiant source 300 (or assembly 300′) illuminates an object such as an ammunition case or threaded bolt to be imaged, and a telecentric optical lens 302 (or lens 302′ of FIG. 21) receives the radiation passing by and not blocked by the case or bolt and guides it towards an image plane 303 of the image acquisition device or detector, generally referred as 304 (or detector 304′ of FIG. 21). The illumination assembly 300 is provided for illustrative purposes in FIG. 14. Consequently, the radiation source 300 (and the source 300′) preferably comprises a LED emitter 311 including a plurality of LED emitter elements serving to emit radiation in either the visible or ultraviolet range. The LED emitter of the source 300 (or source 300′) is preferably high power, capable of generating 100 optical mW or more for each emitting element. A lens 308 (FIG. 14) collimates the radiation.
As shown in FIG. 21, the back light 300′ and the detector 304′ may be coupled together by a yoke 306′ to rotate together about the part 36′ via a motor via a driver/controller upon receiving a command signal from the system controller.
An optical or optoelectronic device for the acquisition of images (for example the camera or telecamera 304 or 304′) has the image plane 303 which can be, for example, an electronic sensor (CCD, CMOS). The case or bolt is received and retained at a predetermined position and orientation for optical inspection by the fixture 32 of the system 10 (or fixture 32′ of system 10′). Preferably the device 304 (and the device 304′) is a high resolution digital telecamera, having the electronic sensor 303 with individual pixels of lateral dimensions equal to or less than one or more microns.
Referring again to FIG. 21, the assembly 304′ can be driven up and/or down by a motor via a driver/controller upon receiving an appropriate control signal from the system controller. Typically, movement of the assembly 304′ and the backlight 300′ is coordinated by the system controller so that they move in unison.
The lens 302 (and the lens 302′) schematically comprises a forward set of optical elements 305 proximal to the bolt or case, a rear optical element 306 proximal to the acquisition device 304 and an aperture diaphragm 307 interposed between the forward and rear sets of optical elements 305 and 306, respectively. The aperture diaphragm 307 comprises a circular window 308 transparent to the radiation, which is referred to as a diaphragm aperture. For example, the aperture diaphragm 307 can comprise an opaque plate preferably of thickness of a few tenths of a millimeter, and the diaphragm aperture can be defined a simple hole in the plate.
The diaphragm aperture or window 308 is coaxial to the optical axis 309 of the forward set of optical elements 305, and positioned on the focal plane of the forward set 305 defined for the wavelength range of radiation emitted by the radiant source 300.
The lens 302 (and lens 302′) only accepts ray cones 301 exhibiting a main (barycentric) axis that is parallel to the optical axis 309 of the forward set 305. Thereby, the lens 302 is a telecentric lens configured for the particular radiation. The rear set of optical elements 306 serves to compensate and correct the residual chromatic dispersion generated by the forward set optical elements 305 for the wavelength in question.
The optical axis of the rear set 306 coincides with the optical axis 309 of the forward set 305 and the focal plane of the rear set 306 defined for the wavelength cited above, coincides with the plane on which the aperture diaphragm 307 is located. Consequently, rays of radiation 309 (FIG. 15) conveyed by the rear set 306 towards the image plane 303 form light cones, the main (barycentric) axis of which is parallel to the optical axis 309 of the lens 302 (and the lens 302′).
The forward set 305 preferably includes two positive lenses, 312 and 313, which can exhibit a flat-convex, bi-convex, or meniscus shape. The positive lenses 313 and 312 can both be made in common optical glass. For example, they can both be made in low chromatic dispersion crown glass, including, for example, Schott glass varieties classified with codes N-SK16, N-BK7, or B270.
The rear set of optical elements preferably comprises four lenses respectively numbered from 314 to 317. The lens 314 which is proximal to the diaphragm 307 can be a negative lens serving to partially or completely correct the chromatic aberrations generated by the forward set 305. The negative lens 314 can be bi-concave, flat-concave, or meniscus shaped, and can be made of common optical glass, for example it can be made of high chromatic dispersion flint glass, for example, Schott optical glass types classified with codes N-F2, LLF1, or N-SF1.
The rear lenses 315, 316 and 317 are positive lenses that can all be made of common optical glass, for example in low chromatic dispersion crown glass, including the hereinabove cited Schott optical glass types classified with codes N-SK16, N-BK7, or B270.
The lens 302 (and the lens 302′) is therefore both telecentric on the object side and telecentric on the image side, and overall the lens 302 is a bi-telecentric lens configured for light such as visible light or ultraviolet light.
Referring now to FIGS. 3, 12, 13 and 16, there is illustrated a triangulation-based sensor head, generally indicated at 400. The system 10′ includes a sensor head 400′ substantially the same as the sensor head 400. The sensor head 400 may comprise a high-speed, 2D/3D laser scanner (LJ-V7000 series) available from Keyence Corporation of Japan. Such a sensor head from Keyance generates a laser beam that has been expanded into a line and is reflected from the side surface of the part as well as any radially extending surfaces of the part, such as the threaded bolt 36. The reflected line of light 447 is formed on a HSE3-CMOS sensor 454 and by detecting changes in the position and shape of the reflection, it is possible to measure the position of various points along the surface of the part.
The sensor head 400′ of FIG. 21 may rotate and/or linearly move via a motor via a rotary driver/controller and/or a linear driver/controller, respectively, upon receiving command signals from the system controller. A transmission (not shown) may convert the rotary motion of the motor output shaft to linear motion.
The sensor head 400 typically includes (FIG. 16) a cylindrical lens 450, at least one and preferably two semiconductor laser diodes 451, a GP64-Processor 452, a 2D Ernostar lens 453 and the HSE3-CMOS Sensor 454. Preferably, the laser diodes 451 emit “blue” light beams which are polarized and combined by optical elements or components 455 to form the line of laser light 445.
Preferably, the beams from the pair of blue laser diodes 451 are combined such that the transmitted beam is polarized in both X and Y axes. The captured images at the sensor 454 in both polarizations are used to generate a resulting 2D profile signal wherein stray reflections are cancelled.
As the bolts or cases rotate corresponding sets of 2D profile signals are generated by the sensor head 400. At least one processor processes the sets of 2D profile signals to obtain a 3D view of the complete side surface and any radially extending surfaces of the part.
The system controller provides control signals based on the signals from rotary sensors or encoders. Alternatively, sensors and/or encoders are not required if stepper motor(s) are provided. Alternatively or additionally, the signals from the rotary encoders are directly utilized by the sensor heads 400 at the station to control the sensor head 400. The control signals are utilized to control the sensor head 400 which preferably have encoder inputs which allow precise control over the position of 2D profile signals samples.
At least one signal processor may process the sets of 2D profile signals to identify a defective part as described in greater detail hereinbelow. The at least one processor may process the sets of 2D profile signals to obtain one or more measurements of the part.
When using a 3D camera, the laser light source and receiver (camera) are independent of each other, greatly complicating on-site installation and adjustment. With such sensor heads 400, the laser light source and receiver are contained in a single body or enclosure 456, making transmitter-to-receiver mounting adjusting unnecessary. This also ensures that the transmitter and receiver maintain this alignment regardless of machine use.
The sensor heads 400 and the at least one processor can extract serrations (FIG. 2a ), knurls, twelve point aerospace (FIG. 2d ) or non-symmetric features of part like D-head (FIG. 2b ) or T-head (FIG. 2c ) bolts etc. The operator may tell the system controller (FIG. 12) via a display and user interface where the interesting parameters are located on the Z axis (height of the part). Then, the software tools extract and measure features from the images and resulting 2D profile signals created by the reflected lines of radiation.
The frontside illumination device of the first embodiment may include a ring LED illuminator 350 (FIGS. 3 and 12) and the frontside illumination device of the second embodiment may include a ring LED illuminator 350′. Each illuminator 350 and 350′ includes a curved array of LED light sources, groups of which are under control of the system controller to provide direct illumination of the front of the case or bolt and are used to enhance defects in the front surface of the case or bolt. Alternatively, the frontside illumination device may be side-mounted so that the front light comes from the side of the part and not from above the part, i.e., basically like painting a thin line along the length of the part.
S M = ( ∂ f ∂ x ) 2 + ⁢ ( ∂ f ∂ x ) 2
6. Fill in Holes: The image obtained after the completion of steps 1-5 appears as a series ofON-pixel rings. The final step is to fill in all enclosed contours with ONpixels.
1. Threshold: Apixel brightness threshold filter may be applied to pick out all saturated pixels (greyscale 255). A user-definable threshold may be provided so values lower than 255 can be detected.
Thread Signal/Data Processing Introduction
roughpos/neg crossinglocations
roughcrest locations
“Refinements” noted hereinmay make the crossings more accurate. The refinements also separate the crossings into positive crossings and negative crossings. The thread model is a lateral sequence of points that represent a best estimate of the outline of one cycle of the thread form.
The procedure avoids the non-linear regions near the left crest and central root. In addition, a “flank line valid” flag is computed, based on the RMS distance between the left flank line and the data within the left flank line data extraction region. If the RMS distance between the flank line and the data points in the flank line data extraction interval is larger than 10 pm per point (a configurable parameter), then the flag is set to invalid.
Major diameter is also corrected by a final end-to end calibration of the total system. The reported major diameter is often two low, with bias ranging from −20 μm to 0.
The functional diameter measurement method is an approximation of the fit gage method. We do not perform a full 3-D analog of the physical fit gage. Instead we have made an approximation that involves the use of lead deviation and the shape of the thread form
FD=PD+√{square root over (3)}(Lead Deviation)
1. A method of inspecting a manufactured part at an inspection station having a measurement axis, the method comprising the steps of:
supporting a part having opposite ends, a length between the ends, a width and a part axis wherein the part has backside and frontside surfaces when supported;
rotating the supported part about the measurement axis so that the part moves at predetermined angular increments during at least one rotational scan;
directing a backside beam of collimated radiation at substantially the entire backside surface of the supported part at each of a first plurality of consecutive angular increments of movement, wherein the backside beam is occluded by the supported part at each of the first plurality of consecutive increments of movement to create a stream of unobstructed portions of the backside beam in rapid succession passing by and not blocked by the supported part;
directing a frontside beam of radiation at at least a portion of the entire frontside surface of the supported part at each of a second plurality of consecutive angular increments of movement, wherein the frontside beam is reflected by the supported part at each of the second plurality of consecutive increments of movement to create a stream of reflected portions of the frontside beam in rapid succession;
detecting the streams of reflected and unobstructed portions at the inspection station to obtain electrical signals; and
processing the electrical signals to determine at least one geometric dimension and any visual defects of the part.
2. The method as claimed in claim 1, wherein substantially the entire backside surface is completely enclosed by a beam profile of the backside beam.
3. The method as claimed in claim 2, wherein the beam profile is rectangular with a height greater than or equal to the length of the part and a width greater than or equal to the width of the part.
4. The method as claimed in claim 1, wherein the streams of reflected and unobstructed portions are detected at a single image plane.
5. The method as claimed in claim 1, further comprising centering and aligning the part axis with the measurement axis.
6. The method as claimed in claim 1, further comprising projecting focused lines of radiation at the frontside surface of the supported part during the at least one rotational scan to obtain reflected radiation and sensing the reflected radiation to obtain electrical signals.
7. The method as claimed in claim 6, wherein the focused lines of radiation at the frontside surface are strobed.
8. The method as claimed in claim 1, wherein the first and second plurality of consecutive angular increments are coincident.
9. A system for inspecting a manufactured part at an inspection station having a measurement axis, the system comprising:
a fixture to support a part having opposite ends, a length between the ends, a width and a part axis, wherein the part has backside and frontside surfaces when supported;
a motor to rotatably drive the fixture about the measurement axis at predetermined angular increments of movement during at least one rotational scan;
a back light to direct a backside beam of collimated radiation at substantially the entire backside surface of the supported part at each of a first plurality of consecutive angular increments of movement wherein the backside beam is occluded by the supported part at each of the first plurality of consecutive increments of movement to create a stream of unobstructed portions of the backside beam in rapid succession passing by and not blocked by the supported part;
a front light to direct a frontside beam of radiation at at least a portion of the entire frontside surface of the supported part at each of a second plurality of consecutive angular increments of movement wherein the frontside beam is reflected by the supported part at each of the second plurality of consecutive angular increments of movement to create a stream of reflected portions of the frontside beam in rapid succession;
a lens and detector assembly to image and detect the streams of reflected and unobstructed portions at the inspection station to obtain electrical signals; and
at least one processor to process the electrical signals to determine at least one geometric dimension and any visual defects of the part.
10. The system as claimed in claim 9, wherein substantially the entire backside surface is completely enclosed by a beam profile of the backside beam.
11. The system as claimed in claim 10, wherein the beam profile is rectangular with a height greater than or equal to the length of the part and a width greater than or equal to the width of the part.
12. The system as claimed in claim 9, wherein the streams of reflected and unobstructed portions are detected at a single image plane of the lens and detector assembly.
13. The system as claimed in claim 9, further comprising a part centering and aligning subsystem to center and align the part axis with the measurement axis.
14. The system as claimed in claim 9, further comprising a triangulation-based sensor configured to project focused lines of radiation at the frontside surface of the supported part during the at least one rotational scan and to sense corresponding reflected lines of radiation to obtain electrical signals.
15. The system as claimed in claim 14, wherein the focused lines of radiation are strobed.
16. The system as claimed in claim 9, wherein the front light includes an array of spaced light sources.
17. The system as claimed in claim 16, wherein each of the light sources is a light emitting diode.
18. The system as claimed in claim 16, wherein the light sources are arranged in a curved arrangement.
19. The system as claimed in claim 9, wherein the motor is a stepper motor.
US14629527 2011-05-17 2015-02-24 Non-contact method and system for inspecting a manufactured part at an inspection station having a measurement axis Active US9575013B2 (en)
US13109369 US8570504B2 (en) 2011-05-17 2011-05-17 Method and system for optically inspecting parts
US13414081 US20130235371A1 (en) 2012-03-07 2012-03-07 High-speed, 3-d method and system for optically inspecting parts
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US14629527 US9575013B2 (en) 2011-05-17 2015-02-24 Non-contact method and system for inspecting a manufactured part at an inspection station having a measurement axis
US14876187 US9370799B2 (en) 2011-05-17 2015-10-06 Method and system for optically inspecting a manufactured part at a single inspection station having a measurement axis
US14876192 US9372160B2 (en) 2011-05-17 2015-10-06 Method and system for optically inspecting the ends of a manufactured part at a single inspection station having a measurement axis
US15132450 US9697596B2 (en) 2011-05-17 2016-04-19 Method and system for optically inspecting parts
US15398240 US20170118457A1 (en) 2011-05-17 2017-01-04 Non-contact method and system for inspecting a manufactured part at an inspection station having a measurement axis
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US13414081 Continuation-In-Part US20130235371A1 (en) 2012-03-07 2012-03-07 High-speed, 3-d method and system for optically inspecting parts
US14050907 Continuation-In-Part US9019489B2 (en) 2011-05-17 2013-10-10 Method and system for optically inspecting parts
US14050907 Continuation US9019489B2 (en) 2011-05-17 2013-10-10 Method and system for optically inspecting parts
US14876187 Continuation-In-Part US9370799B2 (en) 2011-05-17 2015-10-06 Method and system for optically inspecting a manufactured part at a single inspection station having a measurement axis
US14876192 Continuation-In-Part US9372160B2 (en) 2011-05-17 2015-10-06 Method and system for optically inspecting the ends of a manufactured part at a single inspection station having a measurement axis
US15132450 Continuation-In-Part US9697596B2 (en) 2011-05-17 2016-04-19 Method and system for optically inspecting parts
US15398240 Division US20170118457A1 (en) 2011-05-17 2017-01-04 Non-contact method and system for inspecting a manufactured part at an inspection station having a measurement axis
US20150204798A1 true US20150204798A1 (en) 2015-07-23
US9575013B2 true US9575013B2 (en) 2017-02-21
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US14629527 Active US9575013B2 (en) 2011-05-17 2015-02-24 Non-contact method and system for inspecting a manufactured part at an inspection station having a measurement axis
US15398240 Pending US20170118457A1 (en) 2011-05-17 2017-01-04 Non-contact method and system for inspecting a manufactured part at an inspection station having a measurement axis
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Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:NYGAARD, MICHAEL G.;KUJACZNSKI, NATHAN ANDREW-PAUL;REEL/FRAME:035016/0833