Modification

Profile modifications are actually variations of the involute and are known as height corrections. The following sections describe which profile modifications are included in the KISSsoft system.

•     Tip / Root Relief, Linear

Tip relief on the driven gear reduces the impact on the entry, while tip relief on the driving gear reduces the impact on the exit. Tip reliefs are therefore usually applied to both gears.

Below figure illustrates Tip Relief. The constantly increasing amount of material removed in the transverse section, starting at , up to the tip circle, refers to the theoretical involute. The same applies to the Root Relief.

Figure 1  Linear Tip/Root Relief

The KISSsoft input the size value  in the Value input field, for tip relief. The Coefficient 1 input field defines the quotient from the calculated tip relief length  and normal module . Similarly, to represent root reliefs, input the values for  and the quotient from  and .

•     Tip / Root Relief, Arc-like

The method used here is similar to the one used for a linear profile modification. The difference is that this method involves approximating an arc of circle which starts at the point where diameter  intersects with the unchanged tooth profile. The tangents of the arc of circle are identical to the tangent of the unchanged tooth profile at this point. The benefit of this modification is that the tangents do not change abruptly in the unchanged tooth form - circular pitch approximation transition point.

Figure 2  Arc-like Tip/Root Relief

•     Tip / Root Relief, Progressive

The procedure used here is similar to the one used for a linear profile modification. The progressive profile modification is also detailed in the description of tooth form options.

Figure 3  Progressive Tip/Root Relief

Tip:

In a progressive profile modification, the tooth thickness is reduced from a starting diameter to the tip (relief  on each flank as a tooth thickness modification) in accordance with

The coefficient controls the course of the relief. A coefficient of 5 represents a linear relief. For more information, see also Figure below. If a coefficient greater than 5 is used, the progressive profile modification moves tangentially into the unmodified tooth flank.

This is the preferred option if larger reliefs are to be achieved. We do not recommend you use a coefficient of less than 5 (some of these lower values are simply ignored by the program). Coefficients greater than 20 are also ignored. In this case, a coefficient of 20 is used.

•     Tip / Root Relief, with Transition Radius

Below figure shows tip and root relief with transition radii. The constantly increasing amount of material removed in the transverse section, starting at , up to the tip circle, refers to the theoretical involute. The same applies to the root relief.

Figure 4  Tip/Root Relief with Transition Radius

Enter a Value for  in the input field. In the Factor 1 input field, enter the quotient from the calculated tip relief length  and normal module . In the Factor 2, input the quotient from the transition radius in the tip area  and normal module . If coefficient 2 = 0, then  is calculated in such a way that  = 0.8 *  applies. The corresponding coefficient 2 is calculated and applied. If coefficient 2 is so large that  < 0.75 *  applies, then   is calculated in such a way that  = 0.75 *  applies. The corresponding coefficient 2 is calculated and applied. Similarly, to represent root reliefs, input the values for  and the quotient from  and , and the quotient from  and .

•     Profile Crowning(Barreling)

Profile crowning (barreling) is where a constantly increasing amount of material is removed in the transverse section in the direction of the tip and root circle, starting at the middle of the calculated tooth flank length. Points A, E and the value  define the arc-like progression.

Figure 5  Profile Crowning (Barraling)

•     Eccentric Profile Crowning

The definition of eccentric profile crowning is the same as for eccentric crowning, but Factor 1 corresponds to the diameter ratio ()/(). Here, you should note that the modification is defined by the diameter, not by the length of path of contact. Therefore, if you input a value of 0.5 for Factor 1, this will not correspond to the profile crowning, which is symmetric to the center point of the path of contact ().

Factor 2 is used to define the root relief from the tip relief. You can use Factor 2 to set a different value for  and .  = 'Value';  =  * 'Factor 2' then applies.

Figure 6  Eccentric Profile Crowning

•     Pressure Angle Modification (value)

You define the pressure angle modification in a similar way to tip/root relief. However, the difference here is that the value  applies over the entire tooth depth.

Figure 7  Pressure Angle Modification

Enter the value  in the Value input field.

A minute of arc is equal to 1/60 of one degree. In the Arc Minute Type, enter the arc minute value in the Factor 1 input field.

•     End relief, linear I, II

A linear end relief is the constantly increasing removal of material from the tooth trace, starting from particular points, in the direction of the front and rear face surface. In this case, the numbers for I and II relate to both face surfaces.

Figure 8  Linear End Relief I, II

This is why the KISSsoft system, go to the Value input field and enter the value , in the Coefficient 1 input field, enter the quotient  where  is the facewidth minus chamfer.

•     End relief, Arc-like I, II

An arc-like end relief is the constantly increasing removal of material from the tooth trace, starting from particular points, in the direction of the front and rear face surface. In this case, the numbers for I and II relate to both face surfaces

Figure 9  Arc-like End Relief I, II

This is why the KISSsoft system, go to the Value input field and enter the value , in the Coefficient 1 input field, enter the quotient   where  is the facewidth minus chamfer.

•     Helix Angle Modification, tapered or conical

You define the helix angle correction in a similar way as end relief. However, the difference here is that the mass  applies over the entire facewidth.

This is why the KISSsoft enter the value  in the Value input field.

Figure 10  Helix Angle Modification, Tapered or Conical

If Conical Type removes material towards  from  as  on both side of gear tooth, Parallel Type removes material towards opposite side of gear tooth as (I-II) and (II-I).

•     Crowning

Crowning is where material is removed constantly and symmetrically in the direction of the face surfaces, starting from a common point and where the tooth trace remains constant. The material is removed in an arc-like progression with the maximum at the /2.

Figure 11  Crowning

In KISSsoft, go to the Value input field and enter the value .

•     Eccentric Crowning

For eccentric crowning, the Value defines the amount of modification and the Factor 1 defines the modification position from the side I divided by the facewidth. The modification is defined as a part of arc that the center is located along the vertical line defined by the Factor 1. The radii are shown in the Information field according to your input. If you define the Factor 1 as 0.5, the modification is equivalent with general Crowning.

You can use Factor 2 to set a different value for the modification on side II ( =  * Factor 2).

Figure 12  Eccentric Crowning

•     Triangular End Relief I, II

The corners are broken.

Figure 13  Triangular End Relief I, II

This is why the KISSsoft enter the Value  in the input field. Then go to the Coefficient 1 input field and enter the quotient of . Then go to the Coefficient 2 input field and enter the quotient of  and facewidth b.

•     Twist

Twist is the torsion of the transverse section profile along a helix. Usually, the angle increases in a linear progression from the start of the effective flank to its end. A positive directional torsion moves clockwise away from the observer. Modification C can be input as either a positive or negative value.

Figure 14  Twist