Abstract
A three-roll thread gauge for measuring interior threads includes a fixed gauge roll and two movable gauge rolls. The motion of the two movable gauge rolls is constrained so that the interior angles of a triangle defined by the three gauge rolls are equal for each position of the first and second gauge rolls when the three gauge rolls are in engagement with an interior thread. The motion is constrained by reverse sine bars that limit the motion of first and second tables to which the first and second gauge rolls are attached.
Claims
1. An apparatus for measuring an interior thread having any of a plurality of diameters, the apparatus comprising: a. a base; b. a fixed gauge roll, a first gauge roll and a second gauge roll, said fixed gauge roll being attached to said base, said fixed gauge roll, said first gauge roll and said second gauge roll in combination defining a triangle, said triangle having included angles; c. a carriage, said carriage being movable in a direction away from said fixed gauge roll; d. a first table, said first gauge roll being attached to said first table, said first table being in slidable engagement with said carriage, said carriage being configured to urge said first table away from said fixed gauge roll and into engagement with the interior thread when said carriage is moved in said direction away from said fixed gauge roll; e. a second table, said second gauge roll being attached to said second table, said second table being in slidable engagement with said carriage, said carriage being configured to urge said second table away from said fixed gauge roll and into engagement with the interior thread when said carriage is moved in said direction away from said fixed gauge roll; f. a first reverse sine bar and a second reverse sine bar, said first reverse sine bar constraining a motion of said first table away from said fixed gauge roll, said second reverse sine bar constraining said motion of said second table away from said fixed gauge roll, said first and second reverse sine bars limiting said motion of said first and second tables when said carriage is urging said first and second tables away from said fixed gauge roll so that said included angles of said triangle are equal when said fixed gauge roll, said first gauge roll and said second gauge roll are urged into said engagement with the interior thread for each of the plurality of diameters of the interior thread.
Description
IV. BRIEF DESCRIPTION OF THE FIGURES
[0038] FIG. 1 is a perspective view of the gauge having reverse sine bars.
[0039] FIG. 2 is a plan view of the gauge having reverse sine bars.
[0040] FIG. 3 is a plan view of the gauge having reverse sine bars.
[0041] FIG. 4 is a detail section view of a spring-loaded contact ball.
[0042] FIG. 5 is a cutaway view of the spring loaded contact balls.
[0043] FIG. 6 is a section view of a gauge roll with a wear coating.
[0044] FIG. 7 is a magnified detail of a gauge roll with a wear coating.
[0045] FIG. 8 is a top view of a gauge roll.
[0046] FIG. 9 is a top view of a gauge roll.
[0047] FIG. 10 is a flow chart of a method of functional value measurement.
[0048] FIG. 11 is a flow chart of a method of use of the functional value reference.
[0049] FIG. 12 is a plan view of the thread gauge advancing to measure an internal thread.
[0050] FIG. 13 is a plan view of the thread gauge measuring an internal thread.
V. DESCRIPTION OF AN EMBODIMENT
[0051] FIGS. 1-3 and 12-13 illustrate a three-roll gauge 2 having reverse sine bars 4 and capable of measuring a female thread, such as a ring gauge, by holding one gauge roll stationary and simultaneously moving two movable gauge rolls until all three gauge rolls contact the object to be measured.
[0052] FIG. 1 is a perspective view of an example gauge 2 and FIGS. 2 and 3 are plan views of the gauge 2. The gauge 2 includes a base 6. A fixed gauge roll 8 is attached to the base 6 and is stationary with respect to the base 6. A carriage 10 is configured to move in a longitudinal direction 12 both toward and away from the fixed gauge roll 8. The motion of carriage 10 is constrained so that carriage 10 does not move laterally with respect to the base 10. The carriage 10 defines a slide 14. The slide 14 defines a first advancing contact surface 16 and a second advancing contact surface 18. The slide also defines a first retreating contact surface 20 and a second retreating contact surface 22.
[0053] A first table 24 is supported by the base 6. The first table is configured to move with respect to the base 6 in the first direction 26, both toward and away from the fixed gauge roll 8. The first table 24 defines a first table advancing contact surface 28 that engages the carriage first advancing contact surface 16 when the carriage 10 moves toward the fixed gauge roll 8. The first table 24 defines a first table retreating carriage contact surface 30 that engages the carriage first retreating contact surface 20 when the carriage is moving away from the fixed gauge roll 8.
[0054] When the carriage 10 is advancing toward the fixed gauge roll 8, the engagement between the first table advancing contact surface 28 and the carriage first advancing contact surface 16 causes the first table 24 also to move in the longitudinal direction 12. The motion of the first table 24 is constrained laterally when the first table 24 is advancing by the first sine bar 32. The first sine bar contact surface 34 engages the first table 24 when the carriage 10 and the first table 24 are advancing, forcing the first table 24 to move laterally with respect to the longitudinal axis 12 as the first table 24 advances. The first movable gauge roll 36 is attached to the first table 24 and moves with the first table 24.
[0055] When the carriage 10 moves in the longitudinal direction 12 away from the fixed gauge roll 8, the carriage first retreating contact surface 20 engages the first table retreating contact surface 30, forcing the first table 24 also to move in the longitudinal direction 12. When retreating from the fixed gauge roll 8, the lateral motion of the first table 24 is constrained by the first reverse sine bar 38. The first reverse sine bar contact surface 40 contacts the first table 24, forcing the first table 24 to move laterally as the first table 24 retreats in the longitudinal direction 12 away from the fixed gauge roll 12.
[0056] The second table 42 is a mirror image of the first table 24 and the second table 42 moves in a manner identical to the first table 24. When the carriage 10 is advancing toward the fixed gauge roll 8, the engagement between the second table advancing contact surface 44 and the carriage second advancing contact surface 20 causes the second table 26 also to move in longitudinal direction 12. The motion of the second table 42 is constrained laterally when the second table 42 is advancing by the second sine bar 48. The second sine bar contact surface 50 engages the second table 42 when the carriage 10 and the second table 42 are advancing, forcing the second table 42 to move laterally with respect to the longitudinal axis 12 as the second table 42 advances. The second movable gauge roll 52 is attached to the second table 42 and moves with the second table 42.
[0057] When the carriage 10 is moving in the longitudinal direction 12 away from the fixed gauge roll 8, the carriage second retreating contact surface 22 engages the second table retreating contact surface 46, forcing the second table 42 also to move in the longitudinal direction 12. When retreating from the fixed gauge roll 8, the lateral motion of the second table 42 is constrained by the second reverse sine bar 54. The second reverse sine bar contact surface 56 contacts the second table 42, forcing the second table 42 to move laterally as the second table 42 retreats in the longitudinal direction 12 away from the fixed gauge roll 12.
[0058] In use, and as shown by FIG. 2, an object to be measured 58 that defines a male thread, such as a plug gauge, is placed between the three gauge rolls 8, 36, 52 and the carriage 10 is advanced toward the fixed gauge roll 8 until all three gauge rolls 8, 36, 52 contact the object to be measured 58. The position of the carriage 10 in the longitudinal direction 12 defines the measurement. To measure an object that defines a female thread, such as a ring gauge, the object is placed over the three gauge rolls 8, 36, 52 and the carriage 10 is moved in the longitudinal direction 12 away from the fixed gauge roll 8 until all three gauge rolls 8, 36, 52 engage the interior of the female thread. The longitudinal location of the carriage 10 defines the measurement. Where the gauge rolls 8, 36, 52 are full-form threads, the measurement will be the functional value of the measured object 58.
[0059] FIG. 3 illustrates that the first and second sine bars 32, 48, the first and second reverse sine bars 38, 54 and the first and second tables 24, 54 are configured so that the first and second movable gauge rolls 36, 52 in cooperation with the fixed gauge roll 8 define a triangle 60, preferably an equilateral triangle 60 have equal included angles , for every location of the first and second movable gauge rolls 36, 52, both when the first and second movable gauge rolls 36, 52 are advancing against a male object to be measured 58 and when the first and second movable gauge rolls 36, 52 are retreating against a female object to be measured.
[0060] The gauge 2 may dispense with the first and second sine bars 32, 48 while retaining the first and second reverse sine bars 38, 54, in which event the gauge 2 is suitable for measurement only of female threads, such as a ring gauge.
[0061] FIGS. 4 and 5 illustrate the use of spring-loaded contact balls 62. The spring loaded contact balls 62 include a housing 64 and a spring 66. The contact balls 62 may be composed of a resilient material, such as nylon, or may be composed of a hard material, such as stainless steel. As shown by FIG. 5, the spring-loaded contact balls 62 may be inset into one or more of the contact surfaces of the gauge 2. For example, the contact balls 62 may be inset into the carriage first advancing contact surface 16 or the corresponding first table advancing contact surface 28. The contact balls 62 may be inserted into the carriage first retreating contact surface 20 or the corresponding first table retreating contact surface 30. The contact balls may be inset into any of the surfaces of the gauge 2 that make contact, as described above, other than the contact between a gauge roll 8, 36, 52 and an object to be measured 58. The spring loaded contact balls 62 may roll when surfaces make a sliding contact, such as the surfaces of the carriage 10 and the corresponding surfaces of the tables 24, 42, or such as the surfaces of the tables 24, 42 and the corresponding surfaces of the sine bars 32, 48 or reverse sine bars 38, 54.
[0062] The spring-loaded contact balls 62 provide a perception of high-quality to the metrologist because the spring-loaded contact balls extend beyond the surface to which the contact ball 62 is inset, cushioning the blow when one contact surface collides with another and reducing any sound caused by the impact.
[0063] FIGS. 6 through 9 illustrate a gauge roll 8, 36, 52 having a wear-indicating coating 68. FIG. 6 illustrates that the gauge roll 8, 36, 52 is secured to the gauge 2 by a bolt 70 and is movable and replaceable. FIG. 7 is a magnified detail of FIG. 6, showing that a uniform layer of the coating 68 appears on the surface of the gauge roll 8, 36, 52. The coating may be a thin layer of titanium nitride or any suitable material that has a contrasting color to the color of the material defining the remainder of the gauge roll 8, 36, 52. The coating 68 may be composed of a plurality of layers, each having a contrasting color. As the gauge roll 8, 36, 52 is used, the coating 68 will wear until the color of the material underlying the coating 68 is visible to a user.
[0064] FIGS. 8 and 9 are end views of the gauge roll 8, 36, 52. The gauge roll 8, 36, 52 may indicate a plurality of locations around the circumference of the gauge roll 8, 36, 52 that may be used for thread measurement. When one location becomes worn, the user will loosen the bolt 70 securing the gauge roll 8, 36, 52 and rotate the gauge roll 8, 36, 52 until an un-worn location on the gauge roll 8, 36, 52 is exposed. The user then would tighten the bolt 70 and calibrate the gauge 2. As shown by FIG. 9, the gauge roll 8, 36, 52 may include grooves 72, fillets or other physical features limiting the locations on the gauge roll 8, 36, 52 available for use. The possible locations may be numbered or otherwise indicated by a mark on the gauge roll 8, 36, 52. In the examples of FIGS. 8 and 9, eight locations are provided, but any number of locations may be indicated. The permissible locations on the gauge roll 8, 36, 52 may be indicated by color; for example, by having the coating 68 appear only on specified portions of the gauge roll 8, 36, 52.
[0065] The possible orientations of the gauge roll 8, 36, 52 on the gauge 2 may be limited by the physical characteristics of the gauge roll 8, 36, 52 and of the mounting location for the gauge roll 8, 36, 52 or both. For example, the mounting location may include one or more upright pins that engage slots 72 and, in the example of FIG. 9, prevent the gauge roll 8, 36, 52 from being mounted to the gauge 2 in any other than the eight prescribed orientations. Alternatively, the gauge roll 8, 46, 52 and mounting location may include mating keys and slots or any other physical features such as mating pins and holes that limit the possible orientations of the gauge roll 8, 36, 52 on the gauge 2.
[0066] FIGS. 10 and 11 illustrate methods of using a functional value to evaluate threaded objects, such as fasteners. FIG. 10 provides the steps to be followed by a service provider. In step 74, the service provider receives a gauge to be measured, such as a set plug or ring gauge, from a user. In step 76, the service provider measures the functional value, as defined above, for the set plug or ring gauge to be measured. In step 78, the service provider marks the set plug or ring gauge with the measured functional value. In alternative step 80, the service provider provides a certificate to the user of the functional value of the set plug or ring gauge.
[0067] FIG. 11 illustrates the use of the set plug or ring gauge measured for functional value. In step 82 the user of the set plug or ring gauge receives a set plug or ring gauge that has been measured for functional value. The user calibrates a tri-roll gauge, the Navarro '618 gauge or the improved gauge described above to the functional value of the measured set plug or ring gauge in step 84. From step 86, the user will use the calibrated tri-roll gauge Navarro '618 gauge or improved gauge described above to measure the functional value of a thread. For step 88, the user compares the measured functional value of the thread with the measured pitch diameter for the same thread to determine an accuracy of the thread. With the pitch diameter and functional diameter, the user has enough information to make a determination as to whether the thread is of an acceptable dimensional quality. The user can compare the results to the measurement of functional value and thread accuracy, as indicated by step 90, to the results of other measurements made by other person, on other thread gauges and at other times. The user may make meaningful statistical evaluations of the functional value and accuracy of different threads, of threads measured using different tools, of threads measured by different metrologists and at different locations.
[0068] FIGS. 12 and 13 illustrate the thread gauge 2 where the object to be measured 58 is an internal thread, such as a ring gauge. As shown by FIG. 12, the object to be measured 58 is placed where the gauge rolls 8, 36, 52 will contact the internal threads. The carriage 10 is urged away from the fixed gauge roll 8 in the longitudinal direction indicated by arrow 92. The carriage 10 is in a sliding engagement with the first and second tables 24, 42. The motion of the carriage 10 causes the tables 24, 42 to move in the direction indicated by arrows 94. The motion of the first table 24, and hence the motion of the first gauge roll 36, away from the fixed gauge roll 8 is constrained by the first reverse sine bar 38. The motion of the second table 42 away from the fixed gauge roll 8 is constrained by the second reverse sine bar 54. The carriage 10 is moved in the longitudinal direction 92 away from the fixed gauge roll 8 until the first, second and fixed gauge rolls 8, 36, 52 engage the internal threads of the object to be measured 58.
[0069] FIG. 13 shows the gauge rolls 8, 36, 52 in engagement with the internal threads of the object to be measured 58. The gauge rolls 8, 36, 52 define a triangle 60 for which the included angles are equal for any diameter of the object to be measured 58 within the range of measurement of the thread gauge. Although FIG. 13 shows the triangle 60 as defined by the center of the gauge rolls 8, 36, 52, the locations on the gauge rolls 8, 36, 52 that contact the internal threads of the object to be measured 58 also define the triangle 60 with equal included angles .
[0070] As shown by FIGS. 12 and 13 and unlike the Navarro '618 patent, a single motion of the carriage 10 in the direction 92 of FIG. 12 will move both tables 24, 42 into engagement with an interior thread of the object to be measured 58 while maintaining equal included angles for the triangle 60 defined by the three gauge rolls 8, 36, 52.
LIST OF NUMBERED ELEMENTS FROM THE DRAWINGS AND SPECIFICATION
[0071] 2 gauge [0072] 4 reverse sine bars [0073] 6 base [0074] 8 fixed gauge roll [0075] 10 carriage [0076] 12 longitudinal direction [0077] 14 slide of the carriage [0078] 16 carriage first advancing contact surface [0079] 18 carriage second advancing contact surface [0080] 20 carriage first retreating contact surface [0081] 22 carriage second retreating contact surface [0082] 24 first table [0083] 26 first direction [0084] 28 first table advancing contact surface [0085] 30 first table retreating contact surface [0086] 32 first sine bar [0087] 34 first sine bar contact surface [0088] 36 first movable gauge roll [0089] 38 first reverse sine bar [0090] 40 first reverse sine bar contact surface [0091] 42 second table [0092] 44 second table advancing contact surface [0093] 46 second table retreating contact surface [0094] 48 second sine bar [0095] 50 second sine bar contact surface [0096] 52 second movable gauge roll [0097] 54 second reverse sine bar [0098] 56 second reverse sine bar contact surface [0099] 58 object to be measured [0100] 60 triangle [0101] 62 spring-loaded contact ball [0102] 64 housing 64 [0103] 66 spring [0104] 68 coating [0105] 70 bolt [0106] 72 groove [0107] 74 receive plug or ring gauge [0108] 76 measure functional value [0109] 78 mark plug or ring gauge with functional value [0110] 80 provide certificate of functional value [0111] 82 receive measured gauge [0112] 84 use measured gauge to calibrate thread gauge [0113] 86 measure functional value of a thread [0114] 88 compare measured functional value to pitch diameter of the thread to determine accuracy [0115] 90 compare accuracy of the thread to the accuracy of other threads measured [0116] 92 using different equipment [0117] 94 direction of motion of the carriage [0118] 94 direction of motion of the first and second tables
