1、Printed copies are uncontrolled. Page 1 of 14 GLOBAL MANUFACTURING STANDARDS STANDARD NUMBER: w-GG1 ISSUE DATE: 19991201 REV: MASTER GEAR DESIGN STANDARD 1. Purpose This standard has been established to ensure that the design of master gears which are used for the inspection of the part gear composi
2、te action will be consistent and perform these evaluation to the design intent. The master gears described in this standard are used for the inspection of cylindrical spur and helical involute gears with parallel axes. Values and tolerances in this standard are expressed in mm unless otherwise speci
3、fied. 2. Related References ISO 1328-1:1995 Cylindrical gears ISO system of accuracy Part 1: Definitions and allowable values of deviations relevant to corresponding flanks of gear teeth. ISO. 1328-1:1995 Cylindrical gears ISO system of accuracy Part 1: Definitions and allowable values of deviations
4、 relevant to radial composite deviations and runout information. 3. Definitions 3.1. Master Gear A master gear is a high quality cylindrical involute gear with known characteristics which is used for the inspection of other gears or racks. 3.1.1. Rolling Master Gear A rolling master gear is designed
5、 to evaluate or inspect the total and tooth-to-tooth composite action of a part gear or rack. 3.1.2. Rolling and Sizing Master Gear A rolling and sizing master gear is a rolling master gear used to also determine the functional tooth thickness of a part gear or rack. This type of master gear has bee
6、n used in some places at Ford in the past. It has been replaced by a separate gauge that checks the over ball or over pin dimension which is more accurate and more economic. Therefore, sizing master gears and the corresponding setting master gears are not subject of this standard any more. 3.1.3. Ma
7、ster Gear for Interference Control A master gear for interference control is a special rolling master gear that is designed to control the interference conditions when rolling in tight mesh with the part gear, and to ensure that the mating gear does not interfere with the part gear. 3.1.4. In-Proces
8、s Master Gear An in-process master gear, sometimes called a Green Master Gear, is a rolling master gear gear that is designed for a specific operation (e.g. precutting, rolling, shaving, etc.). 3.2. Composite Action Composite action is the variation in centre distance when two gears are rolled in ti
9、ght mesh (no backlash). This is sometimes referred to as the double flank contact method. Printed copies are uncontrolled. Page 2 of 14 GLOBAL MANUFACTURING STANDARDS STANDARD NUMBER: w-GG1 ISSUE DATE: 19991201 REV: 3.2.1. Total Composite Action Tolerance The total composite action tolerance is the
10、centre distance variation allowed during one complete revolution of the gear being inspected This includes the effect of variations in the profile, lead, pitch, tooth thickness, axial runout and radial runout. 3.2.1. Tooth-to-Tooth Composite Action Tolerance The tooth-to-tooth composite action toler
11、ance is the centre distance variation allowed when the gear is rotated through any increment of 360/Z ( with Z = number of teeth of the gear being inspected). This includes the effect of variations in the profile, lead and pitch. 3.3. Controlled Profile The controlled profile is in that area of the
12、tooth face bounded by the form diameter, the tooth tip or start of tooth tip chamfer and the limits of the active face width. 3.4. Form Diameter The form diameter is that diameter at which the true involute profile of a gear originates. It is in the area near the base of the tooth and along with the
13、 tooth tip or start of tooth tip chamfer defines the controlled profile depth. 3.5. Active Face Width The active face width of a gear is that portion of its face width which can come into contact with a mating gear. If a specific active face width is not specified on the part gear drawing, the entir
14、e face width shall be considered as the active face width. 3.6. Checking Pressure The checking pressure is the specified pressure applied when rolling gears in tight mesh for composite action inspection. For recommended values for this pressure see the Appendix A. 3.7. Master Gear Inspection 3.7.1.
15、Total Profile Error ffThe total profile error is the distance, measured along their common normal, between two reference profiles which enclose the actual profile (Fig. 1). The total profile error is the resultant of the angle error and the form error of the profile. The zone of inspection will be l
16、imited towards the root of the tooth by the form diameter. Printed copies are uncontrolled. Page 3 of 14 GLOBAL MANUFACTURING STANDARDS STANDARD NUMBER: w-GG1 ISSUE DATE: 19991201 REV: An intentional alteration of the profile, such as a profile angle deviation or a barrel, should not be regarded as
17、a profile error. Fig. 2a through 2c show examples for the evaluation of a profile chart without any correction, with an intended profile angle deviation and with a barrel condition. 3.7.2. Total Alignment Error FThe total alignment error is the resultant of the deviation of the toth trace on a cylin
18、der coaxial to the reference cylinder, and of the longitudinal shape error. The error is determined by enclosing the actual trace of a flank between two reference traces. It is determined over the effective width of the teeth and in a plane perpendicular to the axis. An intentional alteration of the
19、 lead, such as a lead angle deviation or a crowning, should not be regarded as a lead error. Fig. 3a through 3c show examples for the evaluation of a lead chart without any correction, with an intended lead angle deviation and with a crowning condition. 3.7.2. Adjacent Pitch Error fpThe adjacent pit
20、ch error, sometimes called the individual pich error, is the difference between the actual circular pitch and the theoretical circular pitch. The theoretical circular pitch is the mean value of all the actual circular pitches. 3.7.3. Total Cumulative Pitch Error FpThe total cumulative pitch error is
21、 the total amplitude of the displacement curve that is constituted by the algebraic sum of the individual pitch errors. It is the maximum cumulative error over any sector of one half circumference. TheoreticalprofileIntended profileangle deviationIntended profilebarrelOutside diameter ortip chamfer
22、diameterForm diameterFig. 2bffffForm diameterOutside diameter ortip chamfer diameterControlledtooth heightffFig. 1ffFig. 2a Fig. 2cTheoreticalleadIntended leadangle deviationIntended leadcrowningActive face widthFig. 3bActive face width Active face widthFFFFig. 3a Fig. 3cPrinted copies are uncontrol
23、led. Page 4 of 14 GLOBAL MANUFACTURING STANDARDS STANDARD NUMBER: w-GG1 ISSUE DATE: 19991201 REV: 3.7.5. Radial Runout FrThe radial runout is the maximum radial deviation in position if a probe inserted successively in all tooth spaces, approximately in the centre of the face width of a gear. The ge
24、ar being inspected is mounted so as to be rotated in its functional axis. 3.8. Symbols Used in this Standard 3.8.1. Symbols for Geometrical Data z number of teeth m Module Pressure angle wPressure angle at the operating pitch diameter Helix angle wHelix angle at the operating pitch diameter aHelix a
25、ngle at the outside diameter a Centre distance awTight mesh centre distance d Reference diameter dwOperating pitch diameter dbBase diameter daOutside diameter dNaTip chamfer diameter dNfForm diameter dfRoot diameter s Tooth thicknesssaTooth thickness at the outside diameterswTooth thickness at the o
26、perating pitch diametereNfSapace width at the form diameter c Tip clearance cos Trigonometric cosine tan Trigonometric tangent inv Involutes of an angle (inv = tan - ) 3.8.2. Symbols for Tolerances ffTotal profile error FTotal alignment error FpTotal cumulative pitch error fpAdjacent pitch error FrR
27、adial runout Printed copies are uncontrolled. Page 5 of 14 GLOBAL MANUFACTURING STANDARDS STANDARD NUMBER: w-GG1 ISSUE DATE: 19991201 REV: 3.8.2. Additional Suffixes 0 Master gear 1 Part gear 2 Mating gear n Normal plane t Transverse plane w Operating max Maximum value min Minimum value e Upper limi
28、t i Lower limit 4. Technical Content 4.1 Use of the Master Gear The master gear and the gear to be inspected are mounted on a variable centre distance fixture which allows the part gear and the master gear to rotate while in tight mesh. Variations in the centre distance are observed or recorded and
29、may be processed by an appropriate SPC system. The determination of the part gear composite action and the interference control may be obtained simultaneously with a single master gear, provided the master gear tooth thickness, outside diameter and form diameter are calibrated correctly. The use of
30、in-process master gears (green masters) is determined by production requirements. Their design depends on the necessary gear element specifications. In most cases, the master gear that has been designed for the final part may also be used as an inprocess master gear to evaluate the composite action.
31、 In order to assure the least possible loss of production gear tolerance, the master gears shall be within the tolerances specified in this standard. 4.2. Master Gear Design Considerations 4.2.1. Number of teeth The number of teeth of the master gear shall satisfy the following: It is recommended to
32、 have the least possible number of common factors with the number of teeth in the part gear. It shall provide for a centre distance when meshed with the part gear that is within the range of the rolling fixture to be used. It shall provide for a tip land that is of reasonable width consistent with t
33、he module A minimum tip land width of 0.1*module is recommended. 4.2.2. Module and Pressure Angle The module and the pressure angle of the master gear are identical with those of the part gear. Printed copies are uncontrolled. Page 6 of 14 GLOBAL MANUFACTURING STANDARDS STANDARD NUMBER: w-GG 1 ISSUE
34、 DATE: 19991201 REV: 4.2.3. Helix Angle The helix angle of the master gear is identical with that of the part gear, but the hand of helix is opposite. 4.2.4. Tooth Thickness and Outside Diameter (a). Rolling Master Gear The tooth thickness of a rolling master gear shall be preferably designed so as
35、the master gear to operate at the main pressure angle of the part gear (or the operating pressure angle if available). Sometimes one or more derivatives of a part gear are inspected on the same rolling fixture. In that case it is recommended to design the correspondent master gears all to the same c
36、enter distance to minimize the time required to adjust the fixture. The outside diameter of the master gear shall be calculated to correspond to the part gears form diameter. If the outside diameter does not provide for a minimum clearance of 0.15*module to the part gear root or a minimum tip land o
37、f 0.1*module, then the tooth thickness has to be reduced to guarantee the minimum limits of clearance and tip land. (b). Master Gear for interference control When designing a master gear for interference control it is important that the trochoid of the master gear lies between the trochoid of the ma
38、ting gear having maximum outside diameter or tip chamfer diameter, and all the trochoids of the finishing tool between its new condition and its end of life. This can be accomplished by adjusting the master gear tooth thickness and outside diameter accordingly and visualizing the trochoids by means
39、of a computer program. However, the design of the master gear outside diameter shall guarantee to contact a diameter equal or lower than the part gear form diameter (see sample in Appendix B). 4.2.5. Form Diameter The master gear form diameter shall be equal or lower than the diameter that correspon
40、ds to the part gear maximum outside diameter or tip chamfer diameter of the part gear when in tight mesh and both having minimum tooth thickness. 4.2.6. Root Diameter The master gear root diameter shall provide for minimum clearance of 0.15*module to the part gear outside diameter. Printed copies ar
41、e uncontrolled. Page 7 of 14 GLOBAL MANUFACTURING STANDARDS STANDARD NUMBER: w-GG 1 ISSUE DATE: 19991201 REV: 4.2.7. Bore Diameter The bore diameter of the master gear shall be in line with the following table: Pitch Diameter mm over to Bore Size mm 25 38 38 50 50 63 63 150 150 200 12 20 25 32 50 4.
42、2.8. Face Width The master gear face width shall provide for a minimum of 2 mm overlap on each side of the active face width as specified on the part gear drawing. 4.2.9. Concentricity Band The diameter of the concentricity band shall be 15 mm smaller than the root diameter of the master gear in ord
43、er to allow proper deburring of the master gear tooth faces. 4.2.10. Inscription The master gear shall be marked with: its drawing number the part gear drawing number the module, pressure angle, helix angle 4.2.11.Other Design Considerations: The master gear design must be finalized against the foll
44、owing data: latest part print release rolling fixture design and its centre distance range available arbors that will suit the fixture to be used tolerance and format conformance to this standard 4.3. Regrinding of Master Gears For cost saving reasons, master gears may be reground repeatedly if they
45、 are worn-out or damaged to the extent that they are not performing an acceptable inspection function. Regrinding of a master gear reduces the tooth thickness which makes a recalibration of the outside diameter necessary. It also reduces the operating pressure angle when meshing with the part gear a
46、nd increases the error value indicated on the rolling device. This again means a reduction of the part print tolerance on total composite action which restricts the amount of regrinding to certain limits. Printed copies are uncontrolled. Page 8 of 14 GLOBAL MANUFACTURING STANDARDS STANDARD NUMBER: w
47、-GG 1 ISSUE DATE: 19991201 REV: The master gear has reached its end of life when the error indicated exceeds the error indicated in the new condition by more than 10%. In order to properly control the regrinding process, a chart shall be established giving the new condition of the master gear and it
48、s end of life condition and within these limits the relationship between the over ball dimension and the outside diameter, the form diameter and the root diameter (see Appendix C for a sample chart). 4.4. Master Gear Tolerances and Inspection All master gear elements shall be inspected with the mast
49、er gear mounted on an axis established by its bore. 4.4.1. Tooth Thickness The tooth thickness tolerance of the master gear shall be 0.02 for the new condition. The outside diameter shall be calibrated accordingly. 4.4.2. Outside Diameter The master gear outside diameter tolerance shall always be plus and shall not exceed the following values: Outside Diameter mm over to Tolerance mm 50 80 80 120 120 180 180 250 250 320 + 0.019 + 0.022 + 0.025 + 0.029 + 0.032 4.4.2. Root
