A method for measuring the span of variable tooth thickness gears

Abstract

The present invention belongs to the field of gear detection technology and relates to a method for measuring the span of a variable tooth thickness gear. The method utilizes the characteristic that the displacement coefficient in the variable tooth thickness gear changes proportionally according to the pitch cone angle, and uses a taper rod to measure the span. During measurement, the large end of the taper rod is aligned with the small end face of the gear, or the small end of the taper rod is aligned with the large end face of the gear, so that the span value at each cross section of the gear is equal. The present invention uses a taper rod that matches the variable tooth thickness gear for measurement, and the span value at each cross section of the gear is equal. The measurement operation is simple, and no special measuring instrument is required, which reduces the measurement difficulty and improves the measurement efficiency. The method is also highly practical, and a corresponding taper rod can be designed according to a variable tooth thickness gear of any module.

Description

Technical Field

[0001] The invention belongs to the technical field of gear detection and relates to a method for measuring the span of a gear with variable tooth thickness. Background Art

[0002] A gear with variable tooth thickness is one whose tooth thickness continuously changes along the axial direction. By adjusting the axial play when the two gears mesh, gapless meshing can be achieved, which can greatly improve the backlash and transmission accuracy of the transmission device and achieve precision transmission. However, there are difficulties in measuring variable tooth thickness gears. Traditional tooth thickness measurement methods use a measuring rod to measure the cross-rod distance or a normal micrometer to measure the normal value. However, the tooth thickness of each axial section of a gear with variable tooth thickness is different. Using traditional measurement methods, one can only use a measuring ball to measure the cross-ball distance of a fixed section or measure the normal value of the end face. This requires the use of instruments and the production of specialized tooling, making measurement difficult and the results less than accurate. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to solve the measurement problem of variable tooth thickness gears and provide a method for measuring the span of variable tooth thickness gears.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A method for measuring the span of a variable tooth thickness gear utilizes the characteristic that the displacement coefficient in the variable tooth thickness gear changes proportionally with the pitch cone angle. A taper rod is used to measure the span. During measurement, the large end of the taper rod is aligned with the small end face of the gear, or the small end of the taper rod is aligned with the large end face of the gear, so that the span value in each cross section of the gear is equal.

[0006] Furthermore, when designing the size of the tapered measuring rod, first take a measuring rod diameter according to the module of the variable tooth thickness gear, and then calculate the span value of the section under the taken measuring rod diameter according to the modification coefficient value of one end face of the variable tooth thickness gear tooth; then, according to the modification coefficient of the other end face of the gear and the calculated span value, reversely calculate the measuring rod diameter corresponding to the other section, where the measuring rod length is the same as the tooth width, that is, the large end diameter, small end diameter and length of the tapered measuring rod are obtained.

[0007] Furthermore, the variable tooth thickness gear is an external gear or an internal gear.

[0008] Furthermore, the diameter tolerance of the tapered measuring rod is controlled within ±0.001 mm.

[0009] The beneficial effects of the present invention are as follows: the present invention uses a tapered measuring rod that matches the variable tooth thickness gear for measurement, the span value of each cross section of the gear is equal, the measurement operation is simple, no special measuring instrument is required, the measurement difficulty is reduced, the measurement efficiency is improved, and at the same time, the present invention is highly practical, and a corresponding tapered measuring rod can be designed according to a variable tooth thickness gear of any module.

[0010] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0012] Figure 1 Schematic diagram of measuring the span of a variable tooth thickness gear in the present invention;

[0013] Figure 2 Schematic diagram of a gear with variable tooth thickness in the present invention;

[0014] Figure 3 Schematic diagram of the tapered measuring rod in the present invention.

[0015] Reference numerals: 1 - variable tooth thickness gear; 2 - taper measuring rod. DETAILED DESCRIPTION

[0016] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0017] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0018] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0019] A method for measuring the span of a variable tooth thickness gear utilizes the characteristic that the displacement coefficient in the variable tooth thickness gear changes proportionally with the pitch cone angle. A taper rod is used to measure the span. During measurement, the large end of the taper rod is aligned with the small end face of the gear, or the small end of the taper rod is aligned with the large end face of the gear, so that the span value in each cross section of the gear is equal.

[0020] When designing a tapered measuring rod, first determine a measuring rod diameter based on the module of the variable tooth thickness gear. Then, calculate the span of the cross-section at that diameter based on the modification coefficient of one end face of the variable tooth thickness gear tooth. Then, calculate the corresponding measuring rod diameter for the other cross-section based on the modification coefficient of the other end face of the gear and the calculated span of the cross-section. The measuring rod length is the same as the tooth width, thus obtaining the large and small end diameters and length of the tapered measuring rod. The diameter tolerance of the tapered measuring rod is controlled within ±0.001mm.

[0021] The design of the tapered measuring rod includes the following steps:

[0022] Assume that the module of the variable tooth thickness gear is m, the number of teeth is z, the pressure angle is α, the pitch angle is θ, the tooth width is H, the large end modification coefficient is X1, and the small end modification coefficient is X2; the diameters of the two ends of the tapered measuring rod are dp1 and dp2 respectively, the measuring rod cone angle is β, and the length is equal to the tooth width H; then the calculation formula for the span between the two end faces of the variable tooth thickness gear is:

[0023]

[0024]

[0025] If the span of each section is equal, then M1 = M2. Subtracting formula 1 from formula 2 yields:

[0026]

[0027] where α M is the pressure angle of the measuring rod center on the involute, and its calculation formula is:

[0028]

[0029]

[0030] Subtracting formula 4 from formula 5 yields:

[0031]

[0032] Simplified:

[0033]

[0034] The module m, the number of teeth z, the pressure angle α, and the displacement coefficients X1 and X2 are all determined when designing the variable tooth thickness gear, so they can be regarded as constants in the formula;

[0035] When designing a tapered measuring rod, the diameter of the measuring rod at one end must be determined first. That is, the diameter of the measuring rod at one end can also be a constant. Assuming dp1 is known, α can be obtained from formula 4. M1 Also a constant.

[0036] Therefore, Equation 6 can be regarded as the variable α M2 An equation can be solved by mathematical calculation, and then the measuring rod diameter dp2 can be calculated by formula 5. According to the initially determined measuring rod diameter dp1 and the calculated measuring rod diameter dp2 and the tooth width,

[0037] The cone angle of the measuring rod can be calculated as: tanβ=(dp1-dp2) / H;

[0038] According to the calculated pitch cone angle, the diameter of the measuring rod can be fine-tuned to make the selection of the measuring rod diameter more reasonable.

[0039] See also Figures 1 to 3 In this embodiment, the variable tooth thickness gear 1 is an external gear, and its parameters are m = 1, z = 50, α = 20°, pitch cone angle θ = 2°, tooth width H = 10, large end modification coefficient X1 = 0.5, small end modification coefficient X2 = 0.1508, and the diameter of one end of the taper measuring rod 2 dp1 = 1.732 (measuring the large end of the variable tooth thickness) is substituted into the above formula to obtain dp2 = 1.9016 and M1 = 53.31008;

[0040] Verify whether the measuring rod is correct by calculating the span value of the middle section of the tooth width of the variable tooth thickness gear: because the end face of the tapered measuring rod is aligned with the end face of the variable tooth thickness gear during measurement, the measuring rod diameter dp of the middle section of the tooth width of the variable tooth thickness gear is =(1.9016+1.732) / 2=1.8168, and the displacement coefficient X of the middle section of the tooth width of the variable tooth thickness gear is =(0.5+0.1508) / 2=0.3254;

[0041]

[0042] αΜ =24.1561°;

[0043]

[0044] By comparing M and M1, it can be concluded that there is an error of about 0.0005 in the two calculated spans. This error is completely acceptable in actual processing measurement, so this taper measuring rod can be used to measure the span of variable tooth thickness gears.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for measuring the span of a variable tooth thickness gear, characterized by: Taking advantage of the fact that the displacement coefficient in variable tooth thickness gears changes proportionally with the pitch cone angle, a taper rod is used to measure the span. During measurement, the large end of the taper rod is aligned with the small end face of the gear, or the small end of the taper rod is aligned with the large end face of the gear, so that the span value is equal in each section of the gear. When designing the size of the tapered measuring rod, first take a measuring rod diameter based on the module of the variable tooth thickness gear, and then calculate the span value of the section under the taken measuring rod diameter based on the modification coefficient value of one end face of the variable tooth thickness gear tooth; then, based on the modification coefficient of the other end face of the gear and the calculated span value, reversely calculate the measuring rod diameter corresponding to the other section, where the measuring rod length is the same as the tooth width, that is, the large end diameter, small end diameter and length of the tapered measuring rod are obtained.

2. The method for measuring the span of a variable tooth thickness gear according to claim 1, characterized in that: The variable tooth thickness gear is an external gear or an internal gear.

3. The method for measuring the span of a variable tooth thickness gear according to claim 1, characterized in that: The diameter tolerance of the tapered measuring rod is controlled within ±0.001 mm.

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