Abstract
The aim of this study is the manufacturing analysis of five spur gear pairs where the initial geometric parameters are the same only the pressure angle is different. Firstly, the gears must be designed and modelled. After that, I analyse the modification of this geometric parameter for the manufacturing parameters of the pinion and the gear in the case of gear cutting by module disc milling cutter. Using this technology the one tooth cutting can repeat from tooth to tooth in the function of the number of teeth. I would like to find correlations between the pressure angle and the manufacturing parameters. For this purpose, I define the initial technological parameters and calculate necessary technological parameters for the manufacturing process in a general way. I also define the manufacturing parameters for the given gear geometries. This analysis is practical and theoretical at the same time since the results and the process can help the manufacturing engineers to develop the gear manufacturing processes and applying my results for similar manufacturing problems.
1 Introduction
The involute profile is selected based on experience of geometric, tooth connection and load transmission. It can be generated by constructive and mathematical way. The involute curve is always generated from the base circle of the gear [10, 11, 19, 21].
The generation of the involute curve by mathematical way
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
The common normal line, which is the common tangent line of the base circles, has to go through on the C main point (Fig. 2) [10, 11, 19, 21]. The connection always takes place on this line. This line is called line of action. This line and the common tangent line of the rolling circles (r w1 , r w2 ) always include an α w angle [21]. This angle is called pressure angle. If the centre distance is modified from a to a′ the α w will be also modified to α′ w . The pressure angle that belongs to the pitch circle radius (r p ) is called base profile angle (α p ).
Connection of the involute curves in the case of different centre distances
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
1.1 The properties of spur gear having normal teeth
The basic rack gear tooth profile contains the base parameters of the normal section (circular pitch, whole depth, basic rack gear tooth profile angle and clearance). This profile has infinite number of teeth along a line. The basic rack gear tooth profile of an involute gear is standardized (Fig. 3) [10, 11, 19, 21].
Tool basic rack gear tooth profile in the case of involute gear having normal teeth
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
The x is positive when the basic profile is moved from the gear axis (Fig. 4b). The x is negative when the basic profile is moved to the gear axis (Fig. 4a). If x=0, the tool centre line and the tool reference line are the same. This type of gear pair is called x-zero gear drive [10, 11, 21].
The connection possibilities of the tool basic rack gear tooth profile and the gear profile
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
1.2 Determination of the tooth thickness in general way
The correlation between the addendum modification and the tooth thickness on the pitch circle on the basic rack gear tooth profile
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
The correlations of the tooth thicknesses on the pitch circle (r p ) and an arbitrary (r) circle
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
1.3 Manufacturing of spur gear by module disc milling cutter
Spur and helical gears could be manufactured by plain milling technology on a horizontal knee type milling machine (Figs 8 and 9) or a CNC milling machine (Fig. 9) [1, 3–5, 8, 9, 12, 15, 16]. The profile of the module disc milling cutter is the same as that of the tooth space [1, 2, 4, 7–9, 11, 12]. The tool is doing rotation (
Manufacturing of spur gear by module disc milling cutter [3, with permission from Debrecen University Press]
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
The structure of the dividing head
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
Spur gear manufacturing by a CNC milling machine
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
The geometric shape of the module disc milling cutter can be seen in Fig. 10. The geometry of the tool depends on the number of teeth and the module of the gear [1, 2, 9, 12, 15, 16].
The geometry of the module disc milling cutter
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
2 Geometric design and modelling of spur gears having normal teeth
Knowing the references' recommendations [10, 11, 13, 19, 20, 21] and the initial gear parameters all of the other geometric parameters can be calculated by MATLAB software, which was created by me. The formulas for the gear design were programmed into this software. The output parameters of this program are the calculated geometric parameters, the profile curves of the elements and a txt file that contains the point coordinates of the profile points. The involute profile curves on the pinion and the gear in the case of
The profiles of the gear pairs (
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
Geometrically, the shape of the involute curves is similar to both gear pairs since the base circle diameters are the same for each gear pair. The differences are the arc length between the root and the outside circles. The tooth connections take place on different d w rolling circle diameters [10, 11, 21]. The calculated geometric parameters of the designed gear pairs can be seen in Table 1.
The calculated geometric parameters of the gear pairs
Geometric parameters | Gear drive I | Gear drive II | Gear drive III | Gear drive IV | Gear drive V |
m ax [mm] | 6 | ||||
z 1 | 20 | ||||
z 2 | 30 | ||||
|
20 | ||||
|
0.2 | ||||
u | 1.5 | ||||
l m [mm] | 50 | ||||
|
20 | 21 | 22 | 23 | 24 |
d p1 [mm] | 120 | ||||
d p2 [mm] | 180 | ||||
d b1 [mm] | 112.763 | ||||
d b2 [mm] | 169.144 | ||||
d w1 [mm] | 120 | 120.785 | 121.618 | 122.501 | 123.434 |
d w2 [mm] | 180 | 181.178 | 182.428 | 183.752 | 185.151 |
|
0 | 0.167 | 0.353 | 0.559 | 0.786 |
a [mm] | 150 | 150.982 | 152.023 | 153.126 | 154.293 |
a 0 [mm] | 150 | ||||
y | 0 | 0.163 | 0.337 | 0.521 | 0.715 |
h’ [mm] | 12 | 11.976 | 11.901 | 11.770 | 11.576 |
h a [mm] | 6 | 5.988 | 5.950 | 5.885 | 5.788 |
c [mm] | 1.2 | ||||
p p [mm] | 18.849 | ||||
p w [mm] | 18.849 | 18.973 | 19.103 | 19.242 | 19.389 |
h f [mm] | 7.2 | 7.188 | 7.150 | 7.085 | 6.988 |
h [mm] | 13.2 | 13.176 | 13.101 | 12.970 | 12.776 |
d a1 [mm] | 132 | 132.761 | 133.520 | 134.271 | 135.011 |
d a2 [mm] | 192 | 193.154 | 194.329 | 195.522 | 196.728 |
d f1 [mm] | 105.6 | 106.409 | 107.317 | 108.331 | 109.458 |
d f2 [mm] | 165.6 | 166.802 | 168.126 | 169.582 | 171.175 |
j s [mm] | 0.942 | 0.948 | 0.955 | 0.962 | 0.969 |
x 1 | 0 | 0.065 | 0.134 | 0.208 | 0.286 |
x 2 | 0 | 0.102 | 0.218 | 0.351 | 0.499 |
s p1 [mm] | 9.424 | 9.710 | 10.014 | 10.335 | 10.674 |
s p2 [mm] | 9.424 | 9.871 | 10.380 | 10.957 | 11.608 |
s w1 [mm] | 8.953 | 9.005 | 9.045 | 9.071 | 9.082 |
s w2 [mm] | 8.953 | 9.019 | 9.103 | 9.208 | 9.336 |
Knowing the geometric parameters of the gear pairs the CAD models and the assembly can be done by SolidWorks software. These models are important for the manufacturing simulations (CAM) [3, 17, 18] and the tooth contact analysis (TCA) [10]. The CAD models of a gear pair (
The CAD model of a gear pair (z
1
=20, z
2
=30, max=6 mm,
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
The effect of the pressure angle on the geometric parameters can be seen in the diagrams of Fig. 13.
The effect of the modification of the pressure angle on the geometric parameters
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
3 Analysis of the manufacturing parameters
3.1 Determination of the technological parameters by general way
The gear cutting process by module disc milling cutter is applicable in a conventional way (gear cutting on horizontal knee type milling machine) or in a modern way (application of CNC machine) too [1, 3–5, 8, 9, 12, 15, 16]. Since the basis of the modern way is the conventional way, I analyse this gear cutting technology in the conventional way. The gear parameters are changing (tooth thickness, diameters, pressure angle, etc.), consequently the tool geometry must be also changed [1, 2, 7–9, 11, 12, 15, 16]. Gears having different geometries need different cutting tools in geometric aspects.
The cutting process for one tooth can be seen in Fig. 14. This process must be repeated in the function of the number of teeth. The gear is fixed into a clamping device. After the cutting of one tooth the gear has to be divided according to the circular pitch. The tool has two motions: rotation (
The cutting process for one tooth
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
The separated chip volume can be seen in Fig. 15. The widest distance is the w a tooth space on the outside circle of the gear.
The approximation by volume constancy
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
Determination of the w a tooth space on the outside circle
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
3.2 Manufacturing design and analysis for the designed gear pairs
Knowing the geometric parameters of the gear pairs, the geometric and manufacturing formulas I tried to find correlations between the geometric formulas and the manufacturing parameters for the concrete cases and analyse the results. The geometric parameters are found in Table 1. The initial manufacturing parameters are found in Table 2. According to the subchapter 3.1., I made an Excel table to determine the manufacturing parameters for each gear pair. The results can be seen in Tables 3 and 4 for the pinions and the gears.
The initial manufacturing parameters
Manufacturing parameters | Value |
D [mm] | 120 |
z t | 18 |
f z [mm] | 0.06 |
l m [mm] | 50 |
k c [N mm−2] | 5,000 |
x 1o , x 2o [mm] | 3 |
Manufacturing parameters for the pinions
Manufacturing parameters | Pressure angles ( |
||||
20 | 21 | 22 | 23 | 24 | |
v c [m min−1] | 45.216 | ||||
m [mm] | 37.546 | 37.516 | 37.423 | 37.258 | 37.012 |
|
38.759 | 38.722 | 38.608 | 38.407 | 38.107 |
i [mm] | 40.568 | 40.529 | 40.409 | 40.199 | 39.885 |
h m [mm] | 0.019522 | 0.019505 | 0.019452 | 0.019358 | 0.019219 |
w a [mm] | 17.037 | 17.288 | 17.527 | 17.750 | 17.951 |
F c1 [N] | 1663.068 | 1686.138 | 1704.787 | 1718.105 | 1725.060 |
|
2.028 | 2.026 | 2.020 | 2.010 | 1.994 |
F c [N] | 3373.353 | 3416.913 | 3444.468 | 3453.295 | 3440.237 |
P c [W] | 2542.159 | 2574.985 | 2595.751 | 2602.403 | 2592.562 |
v f [mm min−1] | 129.6 | ||||
T [min] | 20.230 | 20.221 | 20.192 | 20.141 | 20.065 |
Manufacturing parameters for the gears
Manufacturing parameters | Pressure angles ( |
||||
20 | 21 | 22 | 23 | 24 | |
v c [m min−1] | 45.216 | ||||
m [mm] | 37.546 | 37.516 | 37.423 | 37.258 | 37.012 |
|
38.759 | 38.722 | 38.608 | 38.407 | 38.107 |
i [mm] | 40.568 | 40.529 | 40.409 | 40.199 | 39.885 |
h m [mm] | 0.019522 | 0.019505 | 0.019452 | 0.019358 | 0.019219 |
w a [mm] | 16.144 | 16.392 | 16.601 | 16.762 | 16.864 |
F c1 [N] | 1575.952 | 1598.717 | 1614.679 | 1622.500 | 1620.632 |
|
2.028 | 2.026 | 2.020 | 2.010 | 1.994 |
F c [N] | 3196.647 | 3239.757 | 3262.407 | 3261.133 | 3231.980 |
P c [W] | 2408.993 | 2441.481 | 2458.550 | 2457.590 | 2435.620 |
v f [mm min−1] | 129.6 | ||||
T [min] | 30.346 | 30.332 | 30.288 | 30.212 | 30.098 |
The correlation between the pressure angle (
The correlation between the pressure angle and the angle of contact
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
The correlation between the pressure angle (
The correlation between the pressure angle and the arc of contact
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
The correlation between the pressure angle (
The correlation between the pressure angle and the cutting force for one edge on the tool
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
The highest result is received in the case of
The correlation between the pressure angle (
The correlation between the pressure angle and the total cutting force on the tool
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
The correlation between the pressure angle (
The correlation between the pressure angle and the switch number
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
The correlation between the pressure angle (
The correlation between the pressure angle and the cutting power
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
The correlation between the pressure angle (
The correlation between the pressure angle and the machining time
Citation: International Review of Applied Sciences and Engineering 13, 3; 10.1556/1848.2022.00418
4 Consclusion
The aim of this study is to find correlations between the modified geometric parameter, that is the pressure angle and the manufacturing parameters in the case of gear cutting by module disc milling cutter for the pinion and the gear. This technology can be executed in a conventional way (using a horizontal knee type milling cutter) or a computer numerical controlled way (using of a CNC milling machine). In this work, I determined the necessary technological parameters for both cases in a general way.
Firstly, I designed five types of connecting gear pairs where the difference between the initial parameters was the pressure angle beside the constancy of the other initial geometric parameters. I made a computer program in MATLAB language to enhance the design time and process for the output geometric parameters and the involute profile points. The received geometric results can be imported into the SolidWorks designer software where the CAD models can be generated for the tooth contact analysis (TCA) and the computer aided manufacturing (CAM) analysis. The CAM analysis is important for making CNC programs for CNC machines among other things if we choose CNC manufacturing for the gears.
I selected the conventional manufacturing process for the gears since this is the oldest way for which the newest methods are built up. I determined all of the necessary technological parameters for the manufacturing design in a general way. After that, I chose initial parameters with concrete values for the manufacturing design. I made an Excel table to determine the manufacturing parameters for the pinion and the gear. Considering the results, I made diagrams for the possible correlations of the analysed technological parameters and the pressure angle. I determined the consequences.
This study is theoretical and practical at the same time. In a theoretical way, there are a lot of ways to continue this research. In a practical way, this study can help the manufacturing engineers to design such manufacturing technologies for spur gears since my developed process is general. The received formulas are useable for the manufacturing of different types of spur gears by module disc milling cutter in a conventional or CNC way.
Obviously, changing the tooth space geometrically a different type of module disc type milling cutter is needed. It is another field how it is possible to design the tool for these manufacturing problems.
Acknowledgement
The work is supported by the EFOP-3.6.1-16-2016-00022 project. The project is co-financed by the European Union and the European Social Fund.
I would like to thank Mr. Zoltán Géresi manufacturing engineer (University of Debrecen, Department of Mechanical Engineering) for the experimental manufacturings.
References
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Nominations
Symbol | Unit | Parameter |
|
[°] | The sum of the involute angle and the angle between the arbitrary radius and the base circle radius |
|
[°] | Angle between the arbitrary radius and the base circle radius |
|
[mm] | Curvature radius of the involute curve |
|
[°] | Angle between the basic circle radius and the tooth centre line |
|
Switch number | |
|
[°] | Angle between the outside circle radius and the base circle radius |
|
[°] | Angle of contact |
|
[m min−1] | Real cutting speed |
|
[mm min−1] | Feed speed |
|
Clearence factor ( |
|
a | [mm] | Normal centre distance |
a 0 | [mm] | Elementary centre distance |
c | [mm] | Clearance |
C | Main point | |
CAD | Computer Aided Design | |
CAM | Computer Aided Manufacturing | |
CNC | Computer Numerical Control | |
D | [mm] | Diameter of the module disc milling cutter |
d a1 | [mm] | Outside circle diameter of the pinion |
d a2 | [mm] | Outside circle diameter of the gear |
d b1 | [mm] | Base circle diameter of the pinion |
d b2 | [mm] | Base circle diameter of the gear |
d f1 | [mm] | Root circle diameter of the pinion |
d f2 | [mm] | Root circle diameter of the gear |
d p1 | [mm] | Pitch circle diameter of the pinion |
d p2 | [mm] | Pitch circle diameter of the gear |
d w1 | [mm] | Rolling circle diameter of the pinion |
d w2 | [mm] | Rolling circle diameter of the gear |
F c | [N] | Total cutting force |
F c1 | [N] | Cutting force for one edge |
f z | [mm] | Feed for one edge |
h | [mm] | Whole depth |
h’ | [mm] | Working depth |
h a | [mm] | Addendum |
h f | [mm] | Dedendum |
h m | [mm] | Medium chip thickness |
i | [mm] | Arc of contact |
inv
|
[°] | Arbitrary involute angle (polar angle) |
inv
|
[°] | Involute angle of the outside circle |
inv
|
[°] | Involute angle of the pitch circle |
inv
|
[°] | Involute angle of the rolling circle |
j s | [mm] | Backlash |
k c | [N mm−2] | Specific cutting force |
l m | [mm] | Tooth length |
m ax | [mm] | Transverse module |
m | [mm] | Distance between the tool centre line and the corner point of the workpiece |
n | [min−1] | Adjustable number of revolution |
O 1 , O 2 | Middle points of the pinon and the gear | |
P c | [W] | Cutting power |
p p | [mm] | Circular pitch on the pitch circle |
p w | [mm] | Circular pitch on the rolling circle |
r | [mm] | Arbitrary radius of the involute curve |
r b | [mm] | Base circle radius |
r p1 | [mm] | Pitch circle radius of the pinion |
r p2 | [mm] | Pitch circle radius of the gear |
r w1 | [mm] | Rolling circle radius of the pinion |
r w2 | [mm] | Rolling circle radius of the gear |
s a | [mm] | Tooth (arc) thickness on the outside circle |
s p1 | [mm] | Tooth (arc) thickness of the pinion on the pitch circle |
s p2 | [mm] | Tooth (arc) thickness of the gear on the pitch circle |
s w1 | [mm] | Tooth (arc) thickness of the pinion on the rolling circle |
s w2 | [mm] | Tooth (arc) thickness of the gear on the rolling circle |
t | [mm] | Tooth pitch on the module disc milling cutter |
T | [min] | Machining time |
t a | [mm] | Tooth pitch on the outside circle |
TCA | Tooth Contact Analysis | |
t p | [mm] | Tooth pitch on the pitch circle |
u | Tooth ratio | |
V 1 , V 2 | [mm3] | Approximate chip volumes |
V h | [mm3] | Separated chip volume |
w a | [mm] | Tooth space on the outside circle |
x c | Addendum modification coefficient | |
x, y | Coordinates of the given point on the involute curve | |
x 1, x 2 | Addendum modification coefficient of the pinion and the gear | |
x 1o , x 2o | [mm] | Overruns |
y | Centre distance increment | |
z 1 | Number of teeth of the pinion | |
z 2 | Number of teeth of the gear | |
z t | Number of teeth around the perimeter of the module disc milling cutter | |
|
[°] | Base profile angle |
|
[°] | Pressure angle |
|
Sum of the addendum modification coefficients |