Source: http://www.google.com/patents/US5825017?dq=6978253
Timestamp: 2014-09-19 14:15:21
Document Index: 566839107

Matched Legal Cases: ['art 1350', 'art 1350', 'art 1542', 'art 1803', 'art 1803', 'art 1902']

Patent US5825017 - Apparatus for setting a tool in a correct position for work - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign in<nobr>Advanced Patent Search</nobr>PatentsThe invention primarily concerns improvements to turning, grinding milling and other machining processes using electro-optical sensors for analyzing images or patterns related to tools used to work objects. Also disclosed are unique electro-optical sensing methods and apparatus in their own right, capable...http://www.google.com/patents/US5825017?utm_source=gb-gplus-sharePatent US5825017 - Apparatus for setting a tool in a correct position for workAdvanced Patent SearchPublication numberUS5825017 APublication typeGrantApplication numberUS 08/463,098Publication dateOct 20, 1998Filing dateJun 5, 1995Priority dateMar 27, 1980Fee statusPaidPublication number08463098, 463098, US 5825017 A, US 5825017A, US-A-5825017, US5825017 A, US5825017AInventorsTimothy R. PryorOriginal AssigneeSensor Adaptive Machines Inc.Export CitationBiBTeX, EndNote, RefManPatent Citations (37), Non-Patent Citations (8), Referenced by (28), Classifications (46), Legal Events (6) External Links: USPTO, USPTO Assignment, EspacenetApparatus for setting a tool in a correct position for workUS 5825017 AAbstract The invention primarily concerns improvements to turning, grinding milling and other machining processes using electro-optical sensors for analyzing images or patterns related to tools used to work objects. Also disclosed are unique electro-optical sensing methods and apparatus in their own right, capable of high accuracy measurement required for modern industry. In a preferred embodiment of the invention, a two axis image analysis of the backlit tool edge is performed to determine tool position, damage, or wear, and where desired appropriate control steps taken to reposition or change the tool. In another preferred embodiment the tool itself is equipped with optically sensed contact members according to the invention to measure the part produced with the tool, or to determine the deflection of the tool.
What is claimed is: 1. A method for setting a tool in a correct position for work, said tool having a working portion, said method comprising the steps of:illuminating the working portion of said tool with light, forming an image of said working portion on a detector array, determining from the position of said image on said array, the location of said working portion of said tool, from said determination, providing a signal indicative of a correct position of said tool, and using said signal, setting said tool in said correct position. 2. Apparatus for setting a tool in a correct position for work, comprising:means for illuminating a working portion of a tool with light; a detector array; means for forming an image of said working portion on said detector array; means for determining from the position of said image on said array the location of said working portion of said tool; means for providing from said determination a signal indicative of a correct position of said tool; and means responsive to said signal for setting said tool in said correct position. Description
RELATED APPLICATIONS This application is a division of co-pending application Ser. No. 08/071,012, filed Jun. 2, 1993, which was: a continuation-in-part of application Ser. No. 07/884,331, filed May 18, 1992, now abandoned; and a continuation-in-part of co-pending application PCT/US93/04857, filed May 17, 1993; and a continuation-in-part of application Ser. No. 07/770,728, filed Oct. 4, 1991, now abandoned, which was a continuation of application Ser. No. 07/577,086, filed Aug. 28, 1990, now abandoned, which was a continuation of Ser. No. 07/346,284, filed May 1, 1989, now abandoned, which was a continuation of Ser. No. 07/230,675, filed Aug. 9, 1988, now abandoned, which was a continuation of Ser. No. 07/104,518, filed Sep. 28, 1987, now abandoned, which was a continuation of Ser. No. 06/799,548, filed Nov. 18, 1985, now abandoned, which was a continuation of Ser. No. 06/413,618, filed Sep. 1, 1982, now abandoned, which was a division of Ser. No. 06/134,465, filed Mar. 27, 1980, now U.S. Pat. No. 4,403,860; and a continuation-in-part of application Ser. No. 08/848,937, filed Mar. 10, 1992, now abandoned, which was a continuation of application Ser. No. 07/509,295, filed Apr. 16, 1990, now U.S. Pat. No. 5,112,131, which was a continuation of application Ser. No. 07/042,527, filed Apr. 27, 1987, now U.S. Pat. No. 5,012,574, which was a continuation of application Ser. No. 06/767,374, filed Aug. 20, 1985, now abandoned, which was a continuation of application Ser. No. 06/560,259, filed Dec. 12, 1983, now U.S. Pat. No. 4,559,684, which was a continuation of application Ser. No. 06/238,702, filed Feb. 21, 1981, now abandoned. The disclosures of the foregoing applications are hereby incorporated by reference.
FIGS. 18 (A, B) illustrates a method for inspecting rotating tools, for example boring tools, also from a plurality of angles.
FIGS. 19(A-C) illustrates a tool sensing trip wire confirmation embodiment of the invention.
FIGS. 22(A-C) illustrates a Contact optical sensor embodiment, also in a tool, and further illustrating a remote sensing configuration with no wires.
As shown in FIG. 2, (in which only gage member 18 is shown) each gage member is elongate and bears a flange 24 adjacent its rounded contact end and a flange 25 adjacent its edge end. At least one of flanges 24, 25 is removable to facilitate assembly. A spring 26 urges gage member 18 outwardly of tube 21 into a contact position in which contact portion 22 is in contact with a surface of a positioned object. Flange 25 acts as a stop to limit the outward motion of a gage member 18. Gage member 18 thus has an operable length, in the depicted embodiment, approximately equal to the distance between outer wail 27 (FIG. 2) of tube 21 and flange 24. Spring 26 is chosen so as to urge gage member 18 against the surface of a positioned object. A solenoid coil 28 surrounds gage member 18 and is provided with electrical energizing means not shown. Gage member 18 is magnetic, or bears a magnetic element, adjacent coil 28 and the magnet is arranged such that on energizing coil 28, gage member 18 is drawn inwardly into tube 21 to a withdrawn position in which contact portion 22 is out of contact with the surface of a positioned object with which it was previously in contact. Flange 24 limits the inward motion of gage member 18.
It is further noted that the gage members shown do not need to be in contact with the surface except for the brief instant required to take the reading with a high speed diode array scan. This means that the retractors can be utilized even though the probe is spinning without fear of substantial binding and shear wear on the probe tips. It is only necessary to read the diode array at the point at which the probe deceleration reaches zero as it is driven in against the bore wall, for example in the example of FIG. 1. Thus it is entirely within the invention to rotate the probe and diode array combination of FIG. 1 while the measurement is taken by simply firing the pins out, say every 30�, to obtain cylindricity data.
In addition to the optical magnification, electronic magnification of the diode array signal can be used to improve the resolution of the system beyond the simple number of elements in the array times the magnification. Such a circuit has been disclosed in my co-pending application Ser. No. 269,614, filed Jun. 2, 1981, which is a continuation of Ser. No. 073,226, filed Sep. 7, 1979, the disclosure of which is hereby incorporated by reference.
Another advantage of using the multiple line grid is that it improves resolution and/or range for any given size diode array, or allows a reduction in diode array cost or size. For example, if a system was comprised as in FIG. 4A, but only edge 101 were monitored, range would be 0.100" and resolution would be 0.0001" for lens magnification of lox and a 0.001" element to element spacing of the array. Appropriate multiple threshold circuitry can extend this resolution and, in the absence of same, one can extend resolution by going to higher lens magnification of say 20:1. In the present context, this would cut range to 0.050". However, if a dual edge system is used (e.g. edges 121 and 101) the range is extended to 0.1". Similarly, a 5 edge system could provide 0.50" range, etc. Quite obviously, the circuitry to handle which edge is that circuitry which could probably function up to at least 50 edges (on a 1000 element array). Thus, range could be 2.5" at 20x. The more closely spaced the lines, the smaller the light field has to be--a desirable feature at high magnification.
It is further noted that the pins shown in FIGS. 3 and 4 are, in this case, spring loaded by springs 140 and 141 against the part with no retractor mechanism such as illustrated in FIG. 2. As the probe is moved in the z direction into the part bore, the ball contact slide s into the bore due to its taper. Naturally the fully extended pin can be only slightly bigger than the part bore if such a lead-in is to b e effective.
Similarly, a pair of integral opposing pins can determine diameter as discussed previously. Alternatively, they can be located orthogonally at 900 in the circumferential direction and a separate diode array utilized but with the same lens and light source system.
This firing of the data can be done by either pulsing light source 406 with a very short pulse or by simply restrobing the readout of the diode array. The short pulse technique is preferred to "freeze", the motion if very high rotational speeds are utilized.
One of the other features of the gage is to monitor the position of the cutter or the bore diameter throughout the total 360� cycle not only in this particular embodiment, but in other embodiments that might be used to simply gage bores for cylindricity for example In this case an example is shown in which a dove prism 428 in housing 429 is driven by gear reducer 430 at half the rotational speed of the cutter such that the image of the cutter edge appears stationary on the diode array even though it is rotating throughout is 360�. Alternatively, a similar mirror arrangement to the dove prism can also be used to accomplish this image derogation. It is also possible to approximate a full 360� monitoring by having a diode array 408 comprised of radial lines of detector elements at circumferential increments, i.e. every 5�.
It is also of interest to note that being able to monitor the cutter position 360� through rotation allows the control unit 425 to sense the onset of chatter by detecting the minute high frequency movements of the cutter and therefore slow the rotational speed or the inward feed rate in the z direction such that the chatter is eliminated. By suitable finesse the control system can also control the cutter coolant flow and look for problems encountered due to poor metal conditions in the bore etc. This is particularly true if the control is also linked into a torque sensor such as 450 in the drive train from the motor 421.
It is also a part of this invention to provide useful means to monitor the edge of the cutter even if it is spinning as it is withdrawn from the part. This is done in order to achieve a calibration as to where the cutter is and the amount of tool damage. Tool wear is also determined using the invention to determine both the rear position and the front position of the cutting point.
Another possibility is to simply rotate the diode array unit with the boring tool. Obviously, however, this gets to be very difficult if the tool is in continuous 360� motion since it implies the use of slip rings, etc. which are costly and prone to so many noise problems that it is not considered to be a satisfactory solution.
FIG. 11 illustrates another version utilizing fiber based readout. In this case a bore probe or `plug` 900 comprises four contact pins 901-904, each contacting a bore wall 905 at 90# increments. An LED light source 910 is used and lens 911 images the inner edges of the contact members onto coherent fiber bundle 912 with about 10�magnification.
In this embodiment a microprocessor based controller (not shown) is used to monitor and control the tool position, feed and speed rates as a function of data obtained from pin 940 regarding the dimension of the part and changes therein (due to chatter, etc.) At this point it is of interest to discuss various circuits which can be used to determine image edge position of the contact members. The single edge per pin case is similar to that discussed in my copending U.S. application Ser. No. 269,614, the disclosure of which is hereby incorporated by reference is noted therein, a multiple threshold circuit can be used. This can yield up to 0�additional magnification--a very important point where high resolution is desired.
Now, the payoff in this is the resolution of defining where the pin is. Normally in a single threshold system, it would be 10�the lens magnification) times the array spacing or 0.00006". However, in this case, the pin edge is taken to be the average of all 20 edges for really 40 as each side of a bar can be counted). If the period of the grid as imaged by the lens (i.e. a line space 80.002 becomes 0.020" on the array at 10�) is a prime number insofar as the array inter-element spacing is concerned, then in general the resolution of the average is improved 40 times even with a single array threshold voltage vo. ##EQU1## This averaging procedure also tends to cancel out inter-element sensitivity differences.
For edge image detection, this embodiment discloses use of a matrix diode array which is canted slightly relative to the edge image cant angle φ. This angle is kept very small at such that at a fixed threshold detector voltage value of V0. The detected edge image moves down each line of the array, let us say line 1 through 128 on a 128 line array before it recirculates to trip the next detector in the first line. This creates a type of vernier for the array and vastly increases the resolution.
As shown in the figure, one mode of interrogating such a system is to count via counter 1135, the number of detectors which are `dark` (i.e. below the threshold voltage V0) in the matrix arrays This number is proportional to the value on all detectors at once in each column, for example a 100�100 element array has 10,000 detectors dark (ie. below V0). If at a first edge position one row has 11 where all the other rows have 10 dark. The count total is 1001. If however the point moves just slightly into the light field, i.e. in the positive x (vertical) direction, then the detector count in each of the first two rows goes to 11 with 10 in the rest. This ups the count total to 1002.
It is noted that larger offset angles φ can be used if suitable is additional calculation provided. However φ=l/n where n is the number of elements in the array row is preferred.
Consider FIG. 15. This shows in block form a typical machining center such as a Kerney & Trecker Miwaukee-Matic "Moduline" travelling table machine. This machine as is typical of many machining centers has a vertically moving spindle with a horizontally moving table. The whole column itself moves in and out in the z axis (out of the plane of the drawing).
In the version shown, the matrix diode array might typically have a 250�250 element array which would be imaged on a 1 to 1 basis roughly to look at a 1/4" square zone of the tooling. This is usually quite ample in order to totally define a cutter's radial location in space as well as the length of tooling, the contour of taps etc. The resolution nominally is 0.001 inch of this unit with a fixed threshold and for this reason resolution extension such as described relative to FIG. 13 and other circuits is highly desirable in order to improve the resolution to at least 0.0001 inch or better.
To further illustrate operation the tool edge measurement aspects of the invention, the basic lathe tool edge arrangement used to turn a part is illustrated in FIG. 16A. A cylindrical part 1350 is being cut by tool insert 1351, separated from tool holder 1352 typically by a spacer 1353. The tool is manufactured or mounted to have a relief angle φ to the tangent to the part OD and may also be relieved by an angle β with respect to its flank face and perpendicular to the part centerline (and the machine z axis).
The cutting action due to the rotation of the part (shown rotating in a counter clockwise direction), creates chip 1354, and an associated wearing of the tool face 1358 due to the chip, which is categorized in the literature as "crater wear".
FIG. 16B illustrates a top view of the FIG. 16A, showing part 1350 and insert 1351. An angle β exists between the flank face of the tool and the perpendicular to the centerline of the part.
As seen in the side view of FIG. 16C, the depth of cut being taken, 1360, creates as well wear on the tool flank 1359, the surface of which extends out of the plane of the paper. The rectangle 1365 delineates the imaged zone of the tool (and, optionally the part), used in the invention to determine location, wear and damage of the tool. A typical parallelogram shaped cutter insert used in finishing tools is shown, that in which the strictest control of size and wear is required.
FIG. 16D further illustrates a tool measuring embodiment of the invention similar to FIG. 8, in which the edge of a tool insert 1301, in lathe tool holder 1302 attached to turret 1303 in this case is illuminated by light 1304 at an angle to at least one tool face such as to clearly define the edge image 1310 formed on a solid state TV Camera 1315 such as an Elmo Brand EM 102BW. Light 1304 can be provided from an external source or projected and returned via a retroreflective mirror source, such as shown in FIG. 22 and other figures of the invention.
If we look now at a representative operator display of the zone 1368, shown in FIG. 16D, we see that such a display of the edge location and condition can be very useful. First the position of a new tool can be determined in memory, and the position of edge locations, either due to additional tools that are put in, or due to wear in the tool, can be compared. This also can be used to determine the accuracy of the machine to bring the tool back to a given position.
A close-up of the tool edge is shown in FIG. 17A, in which the nose radius region of the lathe tool insert 1368, is shown. It is typically this zone that is imaged by the camera system, for maximum resolution determination of tool wear. Where only an indication of gross breakage is desired, the camera of the invention can image a larger zone of the tool, allowing different types of tools, possibly different locations to be placed in front of the camera, used in this case to simply see if they were broken (such as broken tool image 1369). However, for the maximum resolution of breakage (for example of a 0.001" chip off of ceramic tools 1371), and particularly wear, one needs a higher magnification that often relatively limited field of view, of typically 5 mm square or less being taken, as shown.
As determined from the image measured with the Array of the tool edge sensor camera the line AA indicates the effective size the tool will cut, reduced from the original edge profile which can be stored for comparison. As shown, the flank surface of the tool has been worn, reducing the tool edge in that region. A tool edge from previous measurements at a time a complete break occurred is also stored for comparison to the instant image to see if this condition is being approached (signifying a tool change at an appropriate time).
FIGS. 17B and 17C
At this point, we need to consider the situation from the optical imaging and measurement point of view. A goal is to accurately measure the wear of the tool, and, as well, the position of the tool. Particularly in FIG. 16 above, and expanded here in FIGS. 17B and 17C, we see that where the tool is at a substantial angle with respect to a face of the tool, a distinct optical image can be formed of the cutting edge, with no appreciable confusing reflections from the face.
However, if this angle β or β is small (e.g. 0-10), as it often is for some tools, optical determination of the edge condition becomes more difficult unless the sensor is cocked at a larger angle.
I have found therefore, that it is desirable when measuring such tools, to measure at a larger angle with respect to a tool face, such as φ1 or β1. I have found that the best angles φ1 for tool edge mensuration in a dependable manner that corresponds to tool wear, are indeed between 20�-70�. Similar situation applies for the angle β1 with respect to the flank face where the maximum wear occurs.
Use of significant angle's φ1 and β1 creates a new form of reliable and accurate tool characterization, capable of use in machines proper, where the measured value is a composite of the effects caused by crater wear and flank wear. Unlike references in the literature, I feel the exact type of wear in this case is not of interest, only that it results in the wearing down of the edge. Typically too in many processes one type of wear or the other will predominate, and a choice of the angles used can tend to accentuate the sensitivity to one or the other. I have found, for example, that the angles that emphasize flank wear are typically of the most used. Indeed for certain type of ceramic tools, the crater wear is almost non-existent, but the tool breakage is manifested as a chipping of the edge.
Tests also indicate that the finish and size of the parts produced with a tool measured in this manner can be predicted, and these effects as well can be displayed to the operator in a data display, such as that shown in FIG. 17D. Such data can be overlaid with the image visual data of the part or tool, or both (as shown), including any profile changes occurring in either due to tool wear or other causes. Sensed data taken with other sensors can also be so displayed.
The NC control unit of the machine tool can be commanded by an intelligence module such as 1450 shown in FIG. 19 below, for example, to change the tool when a pre-determined finish value predicted by wear related erosion of the tool edge has been exceeded, or to offset the tool when a given size has been exceeded. The machine can check the tool, at a more frequent interval (e.g. after each cut, when it is reaching the end of its life, as predicted from the number of parts cut, if such data is available (as it often is in high production applications). In low production applications, the time of cutting, as opposed to the number of parts usually, becomes the criteria for more frequent inspection of the tool, for example.
FIG. 18(A, B)
FIG. 18(A, B) illustrates the measurement of breakage, wear, and position of a milling tool, or boring tool according to the invention, which can also be monitored at various angles, not only the tangential, but at angles other than tangential to the tool rotation. It is noted to that the tool edge can be sensed either continuously while rotating, or at discreet stopped positions. Indeed one can read tool edge data at various rotation angles, by simply taking different points along the rotation, such as A & B, as shown in FIG. 18. One can keep track of the positions, with encoders in the rotation of the tool, and even position the tools at a fixed point, or can read them on the fly, using pulsing techniques described in the references, or using high speed shutters on the camera unit. By using different angles, different tool wear/breakage characteristics can be monitored.
Another aspect of the invention is that it allows the machine, as noted above, to teach itself what is the correct response for the given tool force scenario. This aspect of the invention has 3 major advantages:
It is noted that in FIG. 19A, the tool turret, or FIG. 20 the spindle housing holding the tool, is secured to the moving portion of the machine by bolts. These bolts, generally 4 in number, clearly have to carry the load generated by the cutting forces in the lateral direction (shear) and in the direction that they are extensible. It is known to have up to 3 axis measurements of force in washers under such bolts, and piezoelectric load washers are provided by Kistler A. G.
Typical Inputs to Intelligence controller 1450 from Machine CNC
To ol in zone of cutting to be monitored.
Note that the light source and camera of the tool edge sensor can be built like 1420 in a "C" shape and used to look at a tool in the turret of a lathe for example when the turret is indexed to a tool checking position--e.g. at 10 O'clock as shown, where the sensor is optionally actuated out from behind one of the lathe splash guards to generally a fixed stop position to make the measurement. A programmable positioner can also be used such as FIG. 15.
It is noted that the tool sensor of the invention can qualify the tool for operation, and correlate the breakdown of the tool shape to wear and breaks via a "look back" and teach function. This allows one to analyze the tool shape history as a tool progressed to breakage. After a sufficient amount of such data is taken, this pattern can be used to look at a given tool and its history, and determine if, and when, it is likely to break in the future, or, if some other issue studied, such as surface finish history of parts produced as a function of the tool, when it would make a bad part.
FIG. 20 illustrates the use of a rotating tool in production application, with particular emphasis on a tool that not only can have the tool sensed as described in FIG. 18 above when it is retracted, but also that can actually have a built-in diameter probe for the part. This is shown in FIG. 20, wherein a boring bar 1545 rotating about axis 1540 is used to bore a hole 1541 in part 1542. The boring tool 1546 is typically actuatable in and out via an automatic mechanism, such as Sandvik's "AutoComp".
Determine bore size cut from edge location also if applicable in consideration of any knowledge of deflection of the tool either determined empirically over time, predicted theoretically, or measured during the cut, for example using the invention of FIG. 7).
If necessary, command the tool to index outward to account for wear determined and cut the next part on the next cycle. (or recut the instant part if desired, and if time is available).
The primary goal is to look at the tool position, and from that determine the corrections required to keep the diameter D at a constant determined value. Conversely, one can also look at the tool position to reset the tool to a different value d, for example in boring a step bore, or a bore on another part put in place of 1542, for example on a flexible line, where multiple holes are to be drilled. The optical tool monitoring also provides a method for setting the tool, insert at its correct radial location.
Also shown here however, is the possibility of measuring the part, having a built-in gage within the tool, to measure the part surface, for example on the retract cycle. This is shown with gage points 1570 & 1571, which are actuated outward (e.g. via air pressure) from protected areas within the housing of the boring tool, in order to effect the measurement at the proper time, as the part, for example, is retracted through the hole just made. This measurement can be done optically from the rear, as is shown, with lens 1580, imaging the points on detector 1581, and it is generally possible to stop the position of the boring tool, in a particular rotational location, so that this sensing can be made with the probe and detector lined up as desired to facilitate measurement (e.g. in the x,y axis of a matrix array for example). Two other members (not shown for clarity) located 90� to 1570 and 1571 can desirably also be monitored to allow a 4 pt bore characterization with respect to the centerline 1540 determined by the optical axis.
This particular approach is substantially less expensive than having a completely separate gage station occupying another portion on a transfer machine line, which can cost a great deal more money, such as $200,000-300,000 just for the gaging station on a transfer line, not including the space cost of the extra station. This can all be avoided by interacting the tool position to the size, as noted in the patent herein.
It is noted too that the contact optical sensing units herein also offer a chance to have a wide range of bore sizes, usable with such a system. And the tool sensors herein can also handle the large range. This means that a tool compensation system can actually be used for different bore sizes within a reasonable range. It is also noted that the measuring probe or probes used to located the part surface can be built into the rotating tool. To avoid the rotational problems of sweeping the spindle can actually be stopped, or slowly rotating, or as pointed out above, the measurements can be taken at high speeds if stroboscopic light sources or short integration times are used.
In this case, the bore probe simply actuates out of the spindle, and the measurement is taken. On retract the sensor unit goes into a master ring, which is used to verify function. Air blows, if necessary, are used to blow-off the edges of the context.
Confirmation of Tool Breakage
In the discussion relative to FIG. 19 above, it is mentioned that one can confirm the actions of a tool force sensor in giving out a collision, or breakage, or wear signal by looking at the tool with an optical tool sensor. This is proven to be a very important aspect of the invention. As noted above, the commercial force sensors by themselves have not been well received in the trade, because of the difficulty in determining valid force signals amongst all of the other noise created by the machine and cutting action.
FIG. 21A illustrates a contour milling embodiment of the invention in which a turbine blisk 1630 is being machined by milling machine 1631, using endmill 1632, known in the art.
A contact optical probe 1640 is shown, patterned after that above with the capability of interchangeable probe heads and landmark detection. It is based on the same concept shown in FIG. 22A. A sensor unit such as 1650 is utilized such that the light source and imaging optics and image position sensing chip (noted here as 1650, or alternatively 1650') can be located remotely from the working portion 1640. As noted previously, the light source can in some cases be provided in the probe (in place of the retroreflector) or externally. The image position sensing chip can be one axis or preferably two axis, and can be either a matrix array or a analog continuous device. The lens unit, as in FIG. 6, further provides an inviolate optical axis (1630) from which measurements can be made, even if the sensor probe 1640 is taken out to allow a tool to be used, or interchanged with another probe having a different length, diameter, point distribution or other characteristic. To facilitate such interchange the sensor has the same tapered morse coupling 1651 that the machine has. Other methods of changing sensors can also be used, such as bayonet mounts, screw thread mounts and the like. These mounts can also be used to add probe tips, say for different effective measuring diameters, at points toward the end of the probe (the right side as shown in the drawing).
In this case the sensor unit 1650 images via beam splitter 1656 and window 1657 and determines the position (desirably in both x and y axes) of the inner edge of ring member 1660 which ball shaped contact member 1666 which approximates the shape of the ball nose end mill used to cut the part. In this manner, one can drive the machine with the NC cutter program that made the part, and the ball nosed probe herein reads the deviation of the part surface from where the tool was previously directed to go. The effects of wear and tool or part deformation under load are thus discerned, and the part corrected in a subsequent machining operation. This data can be used to inspect the part, or to derive corrections to the NC program, or to the machine parameters, also in combination with force, finish and other sensing systems of the invention.
It is noted that the probe can also be constructed so one can just change the working end of the probe device, to accomplish different tasks. For example using a bayonet coupling 1684, the bore probe of FIG. 22C can be inter changed for accessory probe 1685 which provides high magnification microscopic viewing of small features. Other probe designs such as different bore sizes, touch probes, and a host of other such optical sections can be interchanged, as can wired probes, with more difficulty.
One problem of adding sensors such as tool force sensors, or part gages into the machining tool locations on the turrets is that present lathes are simply not set up for the wiring required. A way to accomplish a "wireless" transmission is by direct optical image transmission, as shown on FIG. 22A. While operable with numerous types of optical sensors for size and finish of parts, it is shown herein, relative to a contacting touch probe and tool location sensor. In this case, tool insert 1705 in tool holder 1706 is mounted to turret plate 1708, and is used to cut workpiece 1712. In an opening in the tool holder 1722 is a contact member 1725, urged by spring 1724 to contact the workpiece 1712.
It is noted that a retroreflective arrangement as shown is not necessarily required, one could have this edge self luminous or backlit with light even through a window from light sources mounted at the end of a lathe, or wherever. As an example point 172G can include a LED which is positioned relative to the surface of the member 1712, and whose position can be monitored by an analog spot position detector 1720, for example a UDT SC10. Generally however digital array based systems are more accurate in plant conditions, as they do not drift with temperature.
As shown in FIG. 22B, the contact member 1725 can be located either axially behind the tool (z Direction), or circumferentially behind the tool (y direction), and can be located either within the tool holder, attached to it on the outside, or positioned near it, either in the circumferential or axial direction.
It is also noted that the camera system can view the tool from the direction out of the plane of the paper (y direction), as opposed to along the axis of the part (z direction). In order to see tool location in the x & z plane, as opposed to in the x & y plane. This can be useful for monitoring deflection of the tool due to radial and longitudinal feed forces as opposed to, in the drawings shown, the radial and circumferential (and tangential) forces.
It is also noted that triangulation sensor, suitably miniaturized, can be attached to the tool holder, or built into same and used in place of contact member 1735 to monitor the part surface location in a non-contact manner.
Other techniques for monitoring, such as multiple edges, etc. of the Figures above can be used which can increase accuracy, range or both.
For use in the apparatus of FIG. 22A, the member with multiple edges, preferably grating lines (on glass substrate) can be short, such that all the lines are always in the field of the lens. However, shown in FIG. 22C, is an arrangement somewhat different than that referenced in the copending application, where the member with lines is long, such that lines move in and out of the field. Light source 1760 illuminates a grating of parallel edges 1761 which is imaged by lens 1762 to form magnified image 663 on the face of a DALSA 40 mhz linear diode array 1765 having 256 elements on 20 micron centers. If the line spacing is 200 microns, and magnifications 4:1, spacing on the array is 400 microns, or 40 elements per line--sufficient to resolve well the individual edges of the lines (256/40 of which are present at any one time on the average on the face of the array). The lines move in and out of the field of view, and if the array is fast enough, they can be tracked so as not to loose count. A 40 MHZ array with 256 elements can be operated at about 150,000 scans/second which gives the rate at which all edges can be sensed. Clearly if the lines move one line worth in this time, a tracking problem exists. however on 200 micron centers, this is 200�150,000 or 30 meters/second--much faster than most machines can move.
FIG. 23A illustrates another gage (besides that of FIG. 10) for round parts, typically made on grinders, as shown in the invention. This gage is typically meant to be used while grinding, but can be used before or after grinding as well. Typically the gage is utilized as shown, in which two sensor units, according to the invention, 1800 and 1801 are utilized to respectively check the opposite sides of the diameter of part 1803, either during grinding, or before or after grinding, for control purposes as disclosed here in the invention.
Measurement of part diameter is accomplished using probe tips 1810 and 1811 to contact part 1803, supported by tubular mounts 1812 and 1813, which are mounted to flexures 1815 and 1816, and are free to move in the plane of the drawing, and as will be discussed later, as well in an optional case, in the plane out of the drawing. The points, such as 1830 and 1831, are monitored this case, as opposed to FIG. 10 above, by individual camera systems, comprised of lens 1840 and 1850, which image the respective edge images 1830 and 1831, onto arrays 1845 and 1846. As described in the Figures above, the retro-reflective devices are used to send light from an on-axis light source (not shown), or other self-luminous sources, such as LEDs, can be located from the end of the tube 1813, for example, to illuminate the edge.
As in the measurement is made relative to the optical axis of the lens systems shown, which adds a degree of stability to the system, since the housings 1850 and 1860 can be particularly rugged, and themselves movable, using a motor driven, or manually actuated differential screw 1870, for example, to expand or contract the diameter Do between the sensor units. This allows the device to be used on a variety of different diameters in sequence, and with suitable encoding on the motor, the actual motor movements can attribute the accuracy.
Also shown is a novel method of calibrating the sensors individually, and any mechanical system (optional) to adjust them to different nominal diameters. In this case, an absolute reference plate 1880 is shown, having multiple landmark datums, such as illuminated lines 1881, which can be viewed by the same lens and camera systems of the sensors (if the retroreflector or other device used has a hole, or a separate viewing channel is used. The sensors can be moved to different locations in the diameter direction, in order to zero from the landmark settings at any given time. If one considers the grinding wheel to be located along the axis of the part displaced in a position out of the plane of the paper, the reference plate is off to the side, therefore of the grinding wheel, and the sensor unit is moved axial from its position in the plane of the wheel to the reference position for calibration. Alternatively the grinding wheel can be backed off, and the master plate brought in front of the grinding wheel.
The above sensor has significant advantages over conventional OD probes such as those of Marposs and Movomatic. Using simple apparatus, it measures absolutely to the very high accuracies described above over a large �0.2" range from a master setting. Operation is all digital, with no levers or other error prone mechanics. Using the positioning system such as 1870 shown, it can expand or contract to a wide range of diameters. The probe can also be used for IDs by reversing the direction of the contacts. A single probe can also be used for measurement of radial variation in parts, such as cam lobe lift profiles or base circle runouts.
FIGS. 23B and 23C
FIGS. 23B and 23C illustrate a use of a sensor somewhat similar to that of FIG. 23 for the purpose of sen sing i n a plurality of directions.
For example, if the probe of FIG. 23B is constructed in a manner similar to that of FIG. 20; namely to allow a ball contact at the end of the flexure responding probe barrel 1880 to move in position as the ball 1881 contacts the part (we assume this probe to be that of 1840 above), then it is clear that the lens will detect the image of the probe to be in a different x or z location, depending on whether the ball is moved in the x direction, or z direction as it comes into contact with the part. Or conversely, as the part is ground down at another point on the surface while the ball is in contact. Thus the probe can serve to both control the grinding of ODs (movement in x direction with change in ground size), and lands (movement in the z direction with change in ground size).
This, of course, requires that the diode array 1845 be of a type that can be responsive in two axes. Indeed, it may even be an analog sensor, such as UDT SC10, although these are not as digitally accurate as the drift free diode array systems, and are generally not as preferred. However, either one can sense the image of a self-luminous object, such as the small diode laser, or LED light source 1882, shown here being monitored for its position as a function of the location of ball 1881 (the move in the x direction as shown in 1885, or z direction).
The version of FIG. 23C is somewhat different. In this case, there are physically two probes at the end of the sensor arm, and these can be either monitored by linear diode arrays at 90�, or other means. Indeed this allows one to be grinding or otherwise machining two surfaces at once, and controlling the position of the ground surface.
FIG. 24 illustrates the use of the invention in the grinding of ID bores, such as those in bearing raceways, or fuel injectors. A good description of the problem associated with such grinding is described in U.S. Pat. No. 4,590,573 by Robert Hahn, particularly for example his FIG. 6. This patent discusses a computer control mechanism for the control of the grinding process, based on deflections and forces therein, particularly useful for rounding an other wise out of round bore (or other surface) in the shortest possible time via control of forces.
FIG. 24A illustrates ID grinding wheel 1900, grinding bore 1901 in part 1902, for example a fuel injector nozzle component.
The invention herein, using the optically sensed contact checking member, 1930, can sense the position in the x direction of the contact point 1930, whose member contacts the surface at point 1935, by sensing the back end of the contact 1940, and its position relative to the optical axis 1945 of the camera system 1920, as disclosed above. This system can use a linear array or linear analog position sensitive image detection element for measuring in one direction, or a combination of linear devices or area devices for measuring in multiple directions as required. Where today's analog devices are used, such as detectors by SITEK (Sweden) or a UDT SC10, the image formed on the detector is not of edges, but of spots or zones of luminous intensity. This requires the "edge" of the member 1940 to be a luminous point, or the use of an illuminated slot, disc or other defined zone of light such as shown in FIG. 24C below.
While the contact, for example, is depicted in the drawing of FIG. 24B, can be located at, let us say, the end of the probe tip, or toward the motor drive side, a novel arrangement shown in FIG. 24C in the side view illustrates a contact member, which if 360 degree response was needed, could be a thin round disc with a hole in it, (the inner edges of the hole being measured). The contact member is illuminated in this case, by an external light source 1941, rather than an retro reflective or self luminous versions noted above. For dry finish grinding this works well, but optical signals in the open can be interrupted by coolant, and light sources are generally inside the probe device, if the probe is to be used while grinding.
This disk is urged by spring pressure exerted by a flexure (not shown for clarity) against the surface of the Part ID, in order to make contact during the grinding operation or for checking purposes after or before grind. While the axial extension of wheel 1900 containing the contact member along the axis is not ground, a oscillatory motion of the wheel and sensor unit in the z direction (axial), allows this deficit to be overcome by averaging the grinding action along the z axis. This is accomplished using slideway 1960, on which the motor drive driving the grinding wheel 1970 is mounted. It also serves to move the wheel through the bore (if the wheel is not long enough to grind the whole axial length required at once) and to retract the system from the bore.
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KGMethod of measuring a tool of a machine toolWO2005005083A1 *Jul 3, 2004Jan 20, 2005Mtu Aero Engines GmbhMilling method for the production of componentsWO2007032681A1 *Sep 13, 2005Mar 22, 2007Gudmunn SlettemoenOpto-mechanical position finder* Cited by examinerClassifications U.S. Classification250/208.1, 250/559.33, 250/559.08International ClassificationG01S17/46, F02F1/24, G01B11/08, G01B11/24, G05B19/42, G01B11/12, G05B19/4065, G01S5/16Cooperative ClassificationG05B2219/50069, G01B11/2433, G05B2219/50026, G05B2219/37574, F02F1/24, G05B2219/37228, G01B11/24, G05B2219/36478, G01B11/08, G05B2219/37206, G01S17/48, G05B2219/35349, G05B2219/50276, G05B19/4065, G05B2219/50375, G01B11/12, G05B2219/37357, G05B2219/37559, G01S5/16, G05B2219/37008, G05B19/4207, G01S7/497, G05B2219/37575, G05B2219/37335, G05B2219/50203, G05B2219/50071European ClassificationG01S17/48, G05B19/4065, G05B19/42B2, F02F1/24, G01S5/16, G01B11/12, G01B11/24G, G01B11/24, G01B11/08Legal EventsDateCodeEventDescriptionApr 14, 2010FPAYFee paymentYear of fee payment: 12Mar 22, 2006FPAYFee paymentYear of fee payment: 8Mar 29, 2002FPAYFee paymentYear of fee payment: 4Jan 28, 2000ASAssignmentOwner name: LASER MEASUREMENT INTERNATIONAL INC., CANADAFree format text: SECURITY INTEREST;ASSIGNOR:SENSOR ADAPTIVE MACHINES INC.;REEL/FRAME:010547/0542Effective date: 19991004Owner name: LASER MEASUREMENT INTERNATIONAL INC. 2835 KEW DRIVAug 13, 1999ASAssignmentOwner name: LASER MEASUREMENT INTERNATIONAL, INC., BRITISH COLFree format text: SECURITY AGREEMENT;ASSIGNOR:SENSOR ADAPTIVE MACHINES, INC.;REEL/FRAME:010154/0802Effective date: 19990401Jan 28, 1999ASAssignmentOwner name: GREAT LAKES INTELLECTUAL PROPERTY LTD., CANADAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SENSOR ADAPTIVE MACHINES, INC.;REEL/FRAME:009711/0948Effective date: 19990114RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google