Temperature measurement of gears and other toothed articles

Abstract

Measurement of workpiece (gear or other toothed article) temperature prior to dimensional inspection of the workpiece wherein the workpiece (32, 34, 36, 38) is positioned on a temperature measurement station (20) and in contact with a temperature measurement sensor (24) and / or adjacent to a temperature measurement sensor (60).

Description

TEMPERATURE MEASUREMENT OF GEARS AND OTHER TOOTHED ARTICLESField of the Invention

[0001] The present invention is directed to temperature measurement of gears and other toothed articles, particularly the measurement of workpiece temperature prior to dimensional inspection of the gear or other toothed article.Background of the invention

[0002] For many years dimensional inspection (i.e. measurement) of gears and gearlike workpieces (e.g. cylindrical and bevel gears, worms) has mostly been carried out by two different methodologies, namely, (1 ) functional testing comprising meshing a gear or other toothed workpiece with a known master gear or mating gear, and (2) analytical testing using a coordinate measurement machine (CMM) or a gear measurement machine (GMM) such as the GMS line of gear measurement machines manufactured by, and commercially available from the Applicant, Gleason Metrology Systems Corporation.

[0003] Functional testing compares the measurement of a work piece against a master gear or a mating gear. Functional testing platforms for gears (i.e. roll testers) include those testers known as double flank testers and single flank testers. With single flank testing, mating gears roll together at their proper (fixed) center distance with backlash and with only one flank in contact. Gears can be tested in pairs or with a master gear. With double flank testing, mating gears are rolled together in tight mesh which produces contact on both flanks. A work gear is meshed with master gear. By providing various encoders on the platform, the relative movement of gears (i.e. center distance variation)making up a collection or summary of gear errors is captured. For example, on a typical double flank gear roll testing machine, a work piece (e.g. cylindrical gear) is meshed with a known master part (e.g. cylindrical gear) and rotated. One of the gears is mounted on a fixed axis and other is mounted on a floating axis. The linear displacement between the axes is measured when the two gears are rotated. Composite errors from this functional testing, such as center distance variation, are reported and compared against required tolerances. Such a roll tester is also capable of reporting characteristics related to the size of gear teeth such as tooth thickness and diameter-over-pins (DOP).

[0004] Analytical testing of gears may be done by either a GMM or CMM. These machines include a computer-controlled apparatus which includes a high-resolution touch sensor (e.g. tactile probe) and / or a non-contact probe. The machine of US Patent No. 11 ,092,430, the disclosure of which being hereby incorporated by reference, is an example of an analytical machine for inspecting a gear workpiece utilizing a touch sensor and / or a laser sensor for inspection. Both sensors require repeatable positioning of the sensor for reliable and accurate measurement at desired locations on the gear tooth surface. In metrology systems such as disclosed by U.S. Patent No. 11 ,262,190, the disclosure of which being hereby incorporated by reference, at least one non-contact sensor and preferably two non-contact sensors are utilized to measure gears or other toothed articles.

[0005] Analytical and / or functional dimensional inspection capabilities may also be utilized as a component of a gear manufacturing cell, such as the HFC Hard Finishing Cell commercially available from The Gleason Works, Rochester, New York. An example of a gear hard finishing cell is shown by the block diagram illustration of Figure 1 . In this example, a hard finishing cell 2 may comprise a gear processing machine 4 for finishing a previously cut workpiece such as by grinding (e.g. threaded-wheel and / or profile grinding), honing, power skiving, hard skiving, finish hobbing, and / or polishing, and a dimensional inspection machine 8 such as a GRSL (Gear Rolling System with Integrated Laser Technology) commercially available from Applicant (see previouslymentioned US 11 ,262,190 for example). The hard finishing cell 2 may further include an automation system 6, preferably a robotic system, for loading and unloading the gear processing machine and the dimensional inspection machine 8 and transferring workpieces between the machines, with the automation system 6 preferably being located between the gear processing machine 4 and the dimensional inspection machine 8. The automation system may also include additional devices 10 for performing auxiliary processes such as, for example, part washing and drying, laser marking, sorting and part handling in a stackable basket system. The gear hard finishing cell 2 may be an automated closed-loop cell wherein part measurement information, particularly out-of-tolerance measurements, obtained by the dimensional inspection machine 8 is communicated to the gear processing machine 4 and any process adjustments are automatically made to the operational settings of the gear processing machine to correct the detected deficiencies in the machined part. Preferably, 100 percent of parts processed by the gear processing machine are measured and / or tested by the dimensional inspection machine.

[0006] The thermal stability of the environment and workpiece has an effect on the accuracy of the measurement of workpieces (i.e. parts or gears), particularly production parts. A part exiting a drying cycle may be several degrees warmer (e.g. 5 degrees C) than the surrounding environment. Several studies have been conducted to show the influence of environment and part temperature on the accuracy of measurements. AGMA AISO 10064-5-A06, Annex A, is an industry standard that quantifies temperature effect of a gear (toothed part with involute geometry) on measurement characteristics including profile slope (fHa), helix slope (fH[3), and tooth thickness measurements of external gears.

[0007] Traditionally, workpiece temperature may be measured using a handheld device 12 comprising a contact sensor 14, shown in Figure 2 for example, on a CMM or GMM such as the machine disclosed in previously mentioned US 11 ,092,430, wherein the user (i.e. machine operator) measures workpiece temperature by manually placing the contact sensor on the workpiece in response to instructions from the machinecomputer control (e.g. utilizing GAMA inspection and analysis software commercially available from Applicant). The temperature of the gear is recorded and displayed. The machine operator removes the sensor and instructs the machine control to continue with part inspection. The temperature of the gear is used to correct measured characteristics such as in accordance with the previously mentioned AGMA standard.

[0008] During automated measurement of gears, particularly non-contact measurement such as by laser or other light, it is preferable to measure part temperature automatically as well. Traditional methods of manual temperature measurement of gears are not practical in an automated environment. Automated temperature measurement may be carried out via use of a non-contact temperature sensor. However, non-contact sensors have been shown to have accuracy limitations. Therefore, another approach is needed for accurately determining the temperature of a gear workpiece before the dimensional inspection cycle begins.Summary of the Invention

[0009] The invention is directed to the measurement of workpiece (part) temperature prior to dimensional inspection of a workpiece (e.g. gear or other toothed article) wherein the workpiece is positioned in a temperature measuring station and (a) in contact with a first temperature measurement sensor and / or (b) adjacent to a second temperature measurement sensor.

[0010] For subsequent dimensional inspection, the workpiece is transferred from the temperature measuring station to a dimensional inspection machine and the measured workpiece temperature is communicated to the dimensional inspection machine. The workpiece is dimensionally inspected to obtain measurement characteristics of the workpiece, and wherein the accuracy of the obtained measurement characteristics of the workpiece are corrected based on the obtained workpiece temperature.Brief Description of the Drawings

[0011] Figure 1 is a block diagram illustration of a gear manufacturing cell, such as a hard finishing cell.

[0012] Figure 2 shows a handheld temperature measuring device comprising a contact sensor.

[0013] Figure 3 illustrates a temperature measurement station in accordance with a first embodiment of the invention.

[0014] Figure 4 illustrates a block diagram illustration of a gear manufacturing cell, such as a hard finishing cell, including a temperature measuring station.

[0015] Figure 5 shows an example of a robot for placement of parts onto a temperature measurement station and for removing parts from the temperature measurement station.

[0016] Figure 6 illustrates an example of gears positioned on a temperature measurement station.

[0017] Figure 7 illustrates an example of a shaft and pinion positioned on a temperature measurement station.

[0018] Figure 8 illustrates another example of gears positioned on a temperature measurement station.

[0019] Figure 9 illustrates yet another example of gears positioned on a temperature measurement station.

[0020] Figure 10 shows another embodiment of the invention wherein a temperature measurement sensor is located in a contact surface of a workholding fixture.

[0021] Figure 11 shows the workholding fixture of Figure 10 with a part located thereon.

[0022] Figure 12 shows an alternative embodiment comprising a non-contact temperature sensor located adjacent to workpiece placement surface.

[0023] Figure 13 shows an alternative embodiment for non-contact temperature sensing wherein the workpiece placement surface is rotatable.Detailed Description of the Preferred Embodiment

[0024] The terms “invention,” “the invention,” and “the present invention” used in this specification are intended to refer broadly to all of the subject matter of this specification and any patent claims below. Statements containing these terms should not be understood to limit the subject matter described herein or to limit the meaning or scope of any patent claims below. Furthermore, this specification does not seek to describe or limit the subject matter covered by any claims in any particular part, paragraph, statement or drawing of the application. The subject matter should be understood by reference to the entire specification, all drawings and any claim below. The invention is capable of other constructions and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for the purposes of description and should not be regarded as limiting.

[0025] The details of the invention will now be discussed with reference to the accompanying drawings which illustrate the invention by way of example only. In the drawings, similar features or components will be referred to by like reference numbers. The size and relative sizes of certain aspects or elements may be exaggerated for clarity or detailed explanation purposes. For a better understanding of the invention and ease of viewing, doors, casings, internal or external guarding, etc. may have been omitted from the drawings.

[0026] The use of “including”, “having” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The use of letters to identify elements of a method or process is simply for identification and is not meant to indicate that the elements should be performed in a particular order. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise and the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0027] Although references may be made below to directions such as upper, lower, upward, downward, rearward, bottom, top, front, rear, etc., in describing the drawings, these references are made relative to the drawings (as normally viewed) for convenience. These directions are not intended to be taken literally or limit the present invention in any form. In addition, terms such as “first”, “second”, “third”, etc., are used to herein for purposes of description and are not intended to indicate or imply importance or significance unless explicitly stated. In the following discussion and claims, the terms “part’, “workpiece”, “gear” and “toothed workpiece” are intended to be synonymous.

[0028] In a first embodiment, a temperature measurement station 20 as shown in Figure 3 is preferably positioned near to, most preferably next to, a dimensional inspection machine 8 for gears and other toothed articles in hard finishing cell 30 as shown in Figure 4 for example. The temperature measurement station 20 is designedfor placement of a gear on it (or in it), preferably via a robot 31 (Figure 5), in such a way whereby a temperature measurement sensor 24 contacts the gear automatically once a part is placed on the temperature measurement sensor. The temperature measurement station 20 preferably comprises a base 21 , preferably plate-like in shape, having an upper or top side, preferably planar, on which at least one part (workpiece) placement surface or “nest” 23 is arranged. The length of base 21 is designated “I” and the width of base 21 is designated “w”. If desired, part placement surface 23 may include one or more part size and position indicators, or guides, thereon such as circular lines or circular machined indentations representing part diameter, for example, to show the proper position of a particular or predetermined part relevant to a temperature sensor 24. In Figure 3, for example, part placement nest 23 includes part size and position indicators 22 (e.g., for a larger diameter gear) and 25 (e.g., for a smaller diameter gear).

[0029] It is to be understood that part placement surfaces located “on” base 21 is intended to include part placement surfaces located on or above the surface of base 21 as well as part placement surfaces located in a recessed area of base 21 . If a gear has a center hub or other element protruding from the face thereof, an opening 27 may be included in the part placement nest 23 to allow the hub to pass through, thereby enabling at least a portion of the face of the gear to contact the part placement nest 23 and temperature sensor 24.

[0030] At least one temperature measurement sensor 24 (such as a thermocouple commercially available from Watlow Electric Manufacturing Co., for example) is positioned in part placement nest 23 so that it preferably contacts either a radial or axial face of a gear (i.e. part or workpiece) when the gear is placed on the part placement nest 23 so as to maximize contact and obtain a stable and accurate reading. If desired, a light curtain 26 may be included so as to confirm the presence of a part on the part placement nest 23. Temperature measurement sensor 24 may be located in a fixed position in part placement nest 23 or the position of the sensor 24 may be adjustable within part placement nest 23 so as to enable the part placement nest 23 to accommodate parts of different sizes (e.g. different diameters) or configurations.Temperature measurement sensor 24 is in communication with the dimensional inspection machine.

[0031] Although the drawings show one temperature sensor 24 located in a part placement surface, the invention also contemplates more than one sensor spaced about a part placement surface to provide a plurality of temperature readings from which an average or median temperature can be obtained. For example, sensors may be spaced equidistantly about a part placement nest 23 so as to obtain readings at different locations on the face of a gear.

[0032] Figures 6-9 illustrate various examples of parts that can be accommodated by a temperature measurement station 20. Figure 6 shows a helical gear 32. Figure 7 shows a shaft with pinion 34. Figure 8 shows the inner gear 36 of a stepped gear and Figure 9 shows a stepped gear with inner gear 36 and outer gear 38.

[0033] An example of a workflow of an automated part inspection subsequent to hard finishing (e.g. grinding) and workpiece (i.e. , a part, such as a gear or other toother article) wash / dry utilizing an automated temperature compensation is shown below:• Robot moves to inspection machine temperature nest.• Robot exchanges a part at the temperature nest (picks part that has been sitting in the nest from previous cycle being measured and places a newly dried part from wash / dry).• Temperature of the part is recorded by reading an engaged part temperature sensor immediately before the part is picked up by the robot for inspection and the measured temperature data is used for determination of correction.• Robot enters the inspection machine and exchanges parts (picks a measured part out of inspection machine and places the part from the temperature nest for inspection measurement).• Dimensional inspection machine inspects the part and uses the measured part temperature for correcting the results (explained above).• In parallel, the robot continues through hard finishing cell (back to basket to deposit finished part and pick up new (next) part, moving the next part to the grinder, moving ground part to wash / dry station and picking up a washed / dried part).• Robot moves to temperature nests and exchanges a part at the temperature nest.• Process repeats above steps.

[0034] The inventive temperature measurement station eliminates the need for manual measurement of workpieces thereby enabling the entire inspection operation to be fully automatic while maintaining an accurate measurement of part temperature.

[0035] The temperature measurement station can also be utilized with a stand-alone dimensional inspection machine having manual or automated loading and unloading.

[0036] In another embodiment as shown in Figures 10 and 11 , a contact temperature measurement sensor 40 is positioned in a part contacting surface 42 of a workholding fixture 44 having a gripping mechanism 46 (in this case, an arbor). Effectively, the part contacting surface 42 is a temperature measurement station. The workholding fixture is attached to a machine spindle (not shown) such as a spindle of a measuring and / or inspection machine. When a part 50 is mounted on the workholding fixture 44 (Figure 11 ), the temperature measurement sensor 40 contacts an axial surface or a radial surface of the part (gear). The temperature of the gear is measured automatically before the start of an inspection cycle. The recorded temperature of the gear is then used to correct measured characteristics as discussed above. While the workholding fixture 44 having a gripping mechanism 46 is preferably located on the spindle of a measuring and / or inspection machine, the workholding fixture 44 having a gripping mechanism 46 could also be located on the spindle of a gear grinding machine, or other gear finishing machine, thereby enabling the gear to be transferred directly to a measuring and / or inspection machine.

[0037] While the invention has been discussed with reference to a contact-type temperature measurement sensor, the invention also contemplates, alternatively or inclusively, a non-contact type temperature measurement sensor located in the temperature measurement station 20 or in the workholding fixture. The non-contact type temperature measurement sensor is arranged adjacent to the edge of workpiece placement surface 23 thereby enabling the measurement sensor to obtain the temperature of a workpiece at the outer periphery (i. e. , the teeth) of the workpiece.

[0038] Figure 12 shows an alternative embodiment comprising a non-contact temperature sensor 60 located adjacent to workpiece placement surface 23 and workpiece (gear) 32. Temperature sensor 60 may be any type of suitable temperature sensor such as an infrared temperature sensor / transmitter from, for example, Omega Engineering, OS130A Series, Model OS137A. The position of temperature sensor 60 is preferably adjustable on base 21 so as to be locatable near to a workpiece.

[0039] Figure 13 shows an alternative embodiment for non-contact temperature sensing wherein the workpiece placement surface 23, and therefore workpiece 32, is rotatable, in either direction, about a workpiece axis of rotation, Aw, via a motor 62. Workpiece placement surface 23 is spaced above the upper surface of table 21 and non-contact temperature sensor 60 is positioned in a mounting bracket 64 such that the periphery of the workpiece 32 is appropriately located in the scanning field of the temperature sensor 60. The position of bracket 64 on the table 21 may be changed by repositioning the bracket 64 in any of a plurality of screw holes 66 depending on the size (e.g. diameter) of a workpiece. The rotation of workpiece 32 enables continuous temperature sensing over the entire workpiece periphery (e.g., one complete workpiece rotation), or temperature readings may be recorded at predetermined intervals (e.g., every 90 degrees of workpiece rotation or every 5thworkpiece tooth).

[0040] Temperature measurement station 20 may include both a temperature measurement sensor 60 and a temperature measurement sensor 24 at the same workpiece placement surface, or a temperature measurement station 20 may comprisea first workpiece placement surface with an associated temperature measurement sensor 24 and a second workpiece measurement surface with an associated temperature measurement sensor 60.

[0041] Alternatively, the position of temperature sensor 60 may be adjustable on table 21 in up to three directions, preferably mutually perpendicular to one another, either manually or via computer control. Such flexibility for positioning enables the accommodation of a variety of workpiece dimensions (e.g. diameter, face width) on measurement station 20. Additionally, workpiece placement surface 23 and motor 62 may be movable along the length and / or width of table 21 if additional clearance is needed for loading and / or unloading of a workpiece onto and / or from workpiece placement surface 23. Such movement may be necessary to avoid interference between, for example, a robot part gripper and the temperature measurement sensor 60 or any other element that may be located near to a workpiece in the scanning position, such as a bar code reader for part identification. Also, the previously discussed one or more part size and position indicators, or guides, may also be utilized with respect to temperature measurement sensor 60. Although less preferred, temperature measurement sensor 60 may be a contact-type sensor, for example, incorporating a retractable stylus-type temperature sensor.

[0042] Operation of measurement station 20 is preferably controlled by the computer control of an adjacent dimensional inspection machine or by the computer control of a hard finishing cell of which measurement station 20 is one element thereof. Of course, measurement station 20 may have its own computer control.

[0043] Placement of a temperature sensor in, or on, a robot (e.g. robot 31 in Figure 5) is also contemplated by the present invention. For example, a contact-type temperature measurement sensor could be included as part of the gripping mechanism of a robot, or a non-contact type temperature measurement sensor could be placed on the robot in a position near to the gripped part.

[0044] While the invention has been described with reference to preferred embodiments it is to be understood that the invention is not limited to the particulars thereof. The present invention is intended to include modifications which would be apparent to those skilled in the art to which the subject matter pertains without deviating from the spirit and scope of the appended claims.

Claims

CLAIMS1 . A method of measuring the temperature of a toothed workpiece, said method comprising: providing a temperature measuring station, said temperature measuring station having one or more part placement surfaces with each of said one or more part placement surfaces comprising (a) at least one first temperature measurement sensor being arranged therein and / or (b) at least one second temperature measurement sensor being adjacent thereto, whereby upon placement of a toothed workpiece on the part placement surface, a portion of the workpiece contacts said at least one first temperature measurement sensor and / or a portion of the workpiece is located adjacent to said at least one second temperature sensor, placing the toothed workpiece on the part placement surface in contact with said at least one first temperature measurement sensor and / or adjacent to said at least one second temperature measurement sensor, obtaining a toothed workpiece temperature measured by said at least one first temperature measurement sensor and / or by said at least one second temperature measurement sensor.

2. The method of claim 1 wherein said toothed workpiece comprises a gear and the method further comprises: transferring the gear from the temperature measuring station to a dimensional inspection machine, communicating the obtained workpiece temperature to said dimensional inspection machine, anddimensionally inspecting the gear to obtain measurement characteristics of the gear, wherein the obtained measurement characteristics of the gear are corrected based on the obtained workpiece temperature thereby resulting in enhanced measurement characteristics.

3. The method of claim 2 wherein said transferring is carried out via a robot.

4. The method of claim 2 wherein said toothed workpiece temperature is obtained immediately before said transferring.

5. The method of claim 1 wherein said one or more part placement surfaces is rotatable.

6. The method of claim 5 wherein the placed toothed workpiece is rotated and a temperature is recorded at each of a plurality of locations on said toothed workpiece by said at least one second temperature measurement sensor.

7. The method of claim 1 wherein said at least one second temperature measurement sensor is a non-contact temperature measurement sensor.

8. The method of claim 1 wherein said at least one first temperature measurement sensor is positionable in said one or more part placement surfaces.

9. The method of claim 1 wherein said temperature measuring station comprises a base portion having an upper side and wherein said one or more part placement surfaces are located on said upper side.

10. The method of claim 9 wherein said at least one second temperature measurement sensor is located on said upper side.11 . The method of claim 10 wherein said at least one second temperature sensor is positionable on said upper side.

12. A toothed workpiece temperature measuring station for measuring the temperature of a toothed workpiece, said temperature measuring station comprising: a base having an upper side, at least one part placement surface arranged on said upper side, at least one first temperature measurement sensor positioned in said at least one part placement surface and / or at least one second temperature measurement sensor adjacent to said at least one part placement surface.

13. The toothed workpiece temperature measuring station of claim 12 wherein said at least one first temperature measurement sensor is a contact temperature measurement sensor.

14. The toothed workpiece temperature measuring station of claim 12 wherein said at least one second temperature measurement sensor is a non-contact temperature measurement sensor.

15. The toothed workpiece temperature measuring station of claim 12 wherein said at least one part placement surface is rotatable.

16. The toothed workpiece temperature measuring station of claim 12 wherein said at least one second temperature measurement sensor is located on said upper side.

17. The toothed workpiece temperature measuring station of claim 16 wherein the location of said at least one second temperature measurement sensor is adjustable on said upper side.

18. The toothed workpiece temperature measuring station of claim 12 wherein said at least one part placement surface comprises one or more part size and position indicators thereon so as to show a proper placement location for a predetermined part relevant to said at least one first temperature measurement sensor and / or said at least one second temperature measurement sensor.

19. The toothed workpiece temperature measuring station of claim 12 wherein said at least one part placement surface is positionable.

20. The toothed workpiece temperature measuring station of claim 14 wherein said non-contact temperature measurement sensor is an infrared temperature sensor.

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