Direct online measurement method and system for gear meshing contact trace

Abstract

The invention discloses a direct online measurement method and system for a gear meshing contact trace, and the method comprises the steps: S1, obtaining a resistance change condition in an electric loop formed by the connection of meshed gear pairs according to the continuity characteristic of an electric signal; and S2, obtaining the contact trace area according to the resistance change condition in the electric loop. By means of the technical scheme, real-time online quantitative measurement of the contact performance can be achieved, and high-precision and high-bearing-capacity gear design can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of gear transmission, and in particular relates to a direct online measurement method and system for gear meshing contact traces. Background Art

[0002] The traces left on the tooth surface during gear meshing include contact traces and contact spots. Among them, the contact trace is the contact trace at each instant of gear meshing, which is dynamically changing; while the contact spot is the total trace formed by the dynamically changing contact trace, which is the total collection of contact traces and is static. Both the contact trace and the contact spot comprehensively reflect the contact performance, load distribution, load-bearing capacity, shaping effect and wear condition of the gear. By controlling the position and shape of the contact trace and its influence by speed, load, etc., the contact spot that meets the design requirements can be obtained naturally.

[0003] At present, the evaluation and measurement of contact marks are mainly based on GB / Z18620.4 to measure contact spots, using qualitative static observation methods such as rolling test and coloring method. There are mainly two types. One is to apply red lead powder on the tooth surface of a gear, observe and calculate the coloring area, position and shape on the tooth surface of the gear meshing with it after rotation, and compare it with the design requirements to determine whether the contact spot meets the requirements. This method generally does not add load or the load is extremely small during the experiment. Another method is to apply blue imprint paint on the gear tooth surface, apply a certain load in the meshing of a pair of gears, and adjust the speed within a certain range. It can be regarded as a measurement and observation method for variable speed and variable load. The contact spot can effectively reflect the influence of load on the position, shape and size of the contact spot, but it cannot meet the high-speed, heavy-load and high-quality requirements of gear transmission. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a direct online measurement method and system for gear meshing contact trace, which can realize real-time online quantitative measurement of contact performance and help to realize high-precision and high-load capacity gear design.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A direct online measurement method for gear meshing contact trace, comprising:

[0007] Step S1, obtaining the resistance change in the electrical circuit formed by the meshing gear pair according to the continuity characteristics of the electrical signal;

[0008] Step S2: Obtain the contact trace area according to the resistance change in the electrical circuit.

[0009] Preferably, in step S2, the contact resistance in the electrical circuit is measured online in real time, combined with the theoretical calculated value of the gear meshing contact trace, and the real-time contact trace area at each moment is obtained through comparative calculation.

[0010] Preferably, a gear pair is composed of a small gear and a large gear, and the gear pair forms a closed electrical circuit, and the closed electrical circuit is the shortest closed electrical circuit.

[0011] Preferably, the shortest closed electrical circuit is composed of wires connected to the large and small gears, the large and small gears, and a resistance measuring instrument in the electrical circuit, and the large and small gears are insulated from the conductors in contact with them.

[0012] The present invention also provides a direct online measurement system for gear meshing contact traces, comprising:

[0013] A measuring device for obtaining the resistance change in an electrical circuit composed of meshing gear pairs according to the continuity characteristics of the electrical signal;

[0014] The calculating device is used to obtain the contact trace area according to the resistance change in the electric circuit.

[0015] Preferably, the computing device measures the contact resistance in the electrical circuit in real time online, combines the theoretical calculated value of the gear meshing contact trace, and obtains the real-time contact trace area at each moment through comparative calculation.

[0016] Preferably, a gear pair is composed of a small gear and a large gear, and the gear pair forms a closed electrical circuit, and the closed electrical circuit is the shortest closed electrical circuit.

[0017] Preferably, the shortest closed electrical circuit is composed of wires connected to the large and small gears, the large and small gears, and a resistance measuring instrument in the electrical circuit, and the large and small gears are insulated from the conductors in contact with them.

[0018] The present invention obtains the resistance change in the electrical circuit composed of meshing gear pairs according to the continuity characteristics of the electrical signal; and obtains the contact trace area according to the resistance change in the electrical circuit. The technical solution of the present invention can realize real-time online quantitative measurement of contact performance, which is helpful to realize high-precision and high-load capacity gear design. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0020] Figure 1This is a flow chart of a direct online measurement method according to an embodiment of the present invention;

[0021] Figure 2 It is a schematic diagram of RND(εr)+1 encoding of spiral bevel gear;

[0022] Figure 3 A schematic diagram of a gear pair composed of an insulating coating on a driving wheel;

[0023] Figure 4 Equivalent circuit diagram formed for a single contact trace;

[0024] Figure 5 It is a schematic diagram of the meshing relationship between two contact traces in a spiral bevel gear pair;

[0025] Figure 6 Equivalent circuit diagram formed for two contact traces;

[0026] Figure 7 It is a schematic diagram of the meshing relationship of the three contact traces in the spiral bevel gear pair;

[0027] Figure 8 Equivalent circuit diagram formed by three contact traces. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Embodiment 1:

[0031] like Figure 1 As shown, an embodiment of the present invention provides a direct online measurement method of a gear meshing contact trace, comprising:

[0032] According to the continuity characteristics of the electrical signal, the resistance change in the electrical circuit composed of meshing gear pairs is obtained;

[0033] The contact trace area is obtained based on the resistance change in the electrical circuit.

[0034] Furthermore, a gear pair is formed by a pinion and a large gear, in which the pinion is called a driving wheel according to the actual usage habits, and the large gear is called a driven wheel according to the actual usage habits. One of the driving wheel or the driven wheel can be the gear to be measured, and the other is the accompanying test gear. This situation is mainly applicable to the measurement stage; if both gears are measuring gears, it should be the measurement of the application stage. The gear pair should form a closed electrical circuit, and the circuit should ensure that it is the shortest closed electrical circuit.

[0035] Furthermore, the shortest closed electrical circuit is composed of a wire connected to two gears, two gears and a resistance measuring instrument in the circuit. The two gears must be effectively insulated from other conductors in contact with them, such as shafts, fastening nuts, etc., so as to form the shortest closed electrical circuit.

[0036] The overlap of gear pairs is generally greater than 1. For example, the overlap of gear pairs formed by straight-tooth gears is generally between 1 and 2, while gear pairs with helical angles will form a larger overlap, such as an overlap greater than 2 or even 3. This means that more than one pair of gear teeth will be involved in meshing at any moment, and the meshing of the gear pairs will have two or more contact traces connected to the measurement electrical circuit. At this time, the electrical circuit should be treated equivalently according to different scenarios and needs.

[0037] If it is a theoretical study of gears or a need to test the performance of new gears, it should start with the uniqueness and accuracy of the contact trace, and adopt a method of coating the teeth of one gear in the gear pair with an insulating layer according to a certain rule to ensure that when the gears are meshing, only the contact trace of one pair of teeth is connected to the electrical circuit, forming a unique circuit.

[0038] To ensure that only one contact trace connects the electrical circuit, the gear teeth can be insulated according to a certain rule based on the calculated overlap. r represents the calculated overlap of the gear pair, then the gear teeth of the gear can be calculated according to RND(ε r )+1 binary code, where "RND()" indicates rounding operation. For example, if the overlap of a pair of helical gears (which can be helical cylindrical gears or helical bevel gears) is ε r =2.345, then rounded to RND(ε r )=2, that is, the gear teeth can be coded in ternary system. That is to say, each gear tooth is numbered 0, 1, 2, 0, 1, 2…, and the gear teeth with non-0 codes are coated with insulating material, so that only the gear teeth with number 0 are not insulated, so that only one contact trace can connect the electrical circuit during the meshing process of the gear pair. The coding rules are as follows Figure 2 If Figure 2 The coated gear shown is used as a test gear for the driving wheel and can be used to test the driven wheel. The meshing relationship between the two is as follows: Figure 3As shown in the figure, A and B indicate the wire access points on the gear end face. Similarly, if the companion gear is a driven wheel, the teeth of the driven wheel should be as follows: Figure 2 If there is no companion gear in the driving wheel and the driven wheel, the gear teeth should be treated with insulation coating from the cost point of view. At the same time, the inner hole and end face of the gear can be coated with an insulating material layer, or an insulating pad can be installed on the end face.

[0039] Figure 3 The gear pair shown in the figure has at most one contact trace connected to the measuring circuit. The equivalent circuit formed by the single contact trace is as follows: Figure 4 As shown. j is the measured resistance value (Ω); I j is the current (A); U v is the voltage meter reading (V); R w1 and R w2 are the resistance of the wire (Ω) respectively. Based on the measured current and voltage values, the resistance generated by the contact trace at this time can be calculated by formula 1:

[0040] R j =U V / I g -R w1 -R w2 (1)

[0041] According to the resistance law, the area of ​​the contact trace can be calculated by formula (2). Then the contact resistance directly measured is converted into the contact trace area. Since the electrical signal is an analog signal with continuity, as long as the electrical circuit is connected, the corresponding contact trace area value can be obtained.

[0042] S=ρ / R j (2)

[0043] Where ρ is the resistivity and S is the area of ​​the contact trace.

[0044] A pair of gears with certain materials and dimensions forms a certain measuring circuit, corresponding to a nominal contact resistance [R j ], nominal contact resistance [R j ] and the actual contact resistance R j The relationship between the gear surface quality Ra, the machining accuracy IT and the meshing position M during meshing ik 、Load F i , load distribution rate L ik Influenced by factors such as the actual contact resistance R j With nominal contact resistance [R j ] satisfy the relationship of formula (3)

[0045] R j =Fun(Ra,IT,Mik ,F i )×L ik ×[R j ] (3)

[0046] Among them, Fun() represents the functional relationship, and the subscript i takes RND(ε r ) or RND(ε r )+1, represents the number of meshing gear tooth pairs currently, that is, the number of contact traces formed; k=1, 2, ..., i, represents the contact traces on different meshing gear tooth pairs in the current situation.

[0047] If the method of the embodiment of the present invention is used for the detection of the gear pair after assembly, the gear teeth may not be subjected to the insulating coating. In this case, the actual number, shape and position of the contact spots are distributed on different tooth surfaces and different positions of the gear teeth involved in the meshing according to the meaning of the overlap, thus forming a graph containing RND(ε r ) or RND(ε r )+1 circuit branches, these circuit branches form a parallel circuit, and their contact resistance can be calculated and determined according to the current resistance law in the parallel circuit, and the contact spots on each branch circuit can be obtained by conversion.

[0048] Still Figure 3 Taking the spiral bevel gear pair shown in the figure as an example, due to the overlap of the spiral bevel gear pair ε r =2.345, then rounded to RND(ε r )=2, then the relationship between the two pairs of teeth in the gear pair when they are engaged at the same time is as follows Figure 5 The black part in the enlarged image in the upper left corner indicates the range of change of the contact trace formed by the two pairs of gear teeth involved in the meshing.

[0049] The equivalent circuit diagram corresponding to the two contact traces is as follows Figure 6 As shown in the figure. j21 and R j22 They represent the contact resistances corresponding to the two contact traces formed on the two pairs of tooth surfaces. According to the rules of parallel circuits, the total contact resistance at this time satisfies the relationship shown in formula (4). And the corresponding contact area can be calculated based on the relationship shown in formula (3) combined with the gear meshing principle.

[0050] 1 / R j =1 / R j21 +1 / R j22 (4)

[0051] The relationship between the three pairs of teeth in the spiral bevel gear pair when they are engaged at the same time is as follows: Figure 7 The black part in the enlarged image in the upper left corner indicates the range of change of the contact traces formed by the three pairs of gear teeth involved in the meshing.

[0052] The equivalent circuit diagram corresponding to the three contact traces is as follows Figure 8 As shown in the figure. j31 , R j32 and R j33 They represent the contact resistances corresponding to the three contact traces formed on the three pairs of tooth surfaces. According to the rules of parallel circuits, the total contact resistance at this time satisfies the relationship shown in formula (5). And the corresponding contact area can be calculated based on the relationship shown in formula (3) combined with the gear meshing principle.

[0053] 1 / R j =1 / R j31 +1 / R j32 +1 / R j33 (5)

[0054] In engineering practice, the shortest closed electrical circuit is achieved by insulating the gears from other non-transmission contact parts. For example, insulating materials are applied to the gear holes or insulating paint is sprayed on them, insulating materials are applied to the gear end faces or insulating pads are installed, etc. This ensures that a pair of gear pairs are in contact only at the meshing position and can be connected to form a closed electrical circuit. At this time, the circuit is the shortest.

[0055] Lead out the wires at the appropriate positions of the two gears and connect them to the resistance measuring components. At this time, it is necessary to consider preventing the wires from getting tangled during the gear rotation, which can be solved by adding slip rings.

[0056] The embodiment of the present invention connects the meshing gear pairs to form a measuring electrical circuit, measures the contact resistance online in real time, combines the theoretical calculated value of the gear meshing contact trace, and obtains the online measurement of the real-time contact trace area at each moment through comparative calculation. During implementation, it is ensured that the gear pair forms the shortest closed electrical circuit, that is, the gear is insulated relative to other contact parts. The contact trace on the gear tooth surface eventually forms a contact spot, which is used to evaluate the contact performance and load-bearing capacity of the gear transmission. This contact trace measurement method makes up for the current static qualitative evaluation method of observing the size and position of the contact spot, and can realize real-time online quantitative measurement of contact performance, which is helpful to realize high-precision and high-load-bearing capacity gear design.

[0057] Embodiment 2:

[0058] The embodiment of the present invention further provides a direct online measurement device, comprising:

[0059] A measuring device for obtaining the resistance change in an electrical circuit composed of meshing gear pairs according to the continuity characteristics of the electrical signal;

[0060] The calculating device is used to obtain the contact trace area according to the resistance change in the electric circuit.

[0061] As an implementation mode of an embodiment of the present invention, the computing device measures the contact resistance in the electrical circuit in real time online, combines the theoretical calculated value of the gear meshing contact trace, and obtains the real-time contact trace area at each moment through comparative calculation.

[0062] As an implementation mode of the embodiment of the present invention, a gear pair is composed of a small gear and a large gear, and the gear pair forms a closed electrical circuit, and the closed electrical circuit is the shortest closed electrical circuit.

[0063] As an implementation method of the embodiment of the present invention, the shortest closed electrical circuit consists of wires connected to large and small gears, large and small gears and a resistance measuring instrument in the electrical circuit, and the large and small gears are insulated from the conductors in contact with them.

[0064] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A direct online measurement method for gear meshing contact trace, characterized in that: include: Step S1, obtaining the resistance change in the electrical circuit formed by the meshing gear pair according to the continuity characteristics of the electrical signal; Step S2: Obtain the contact trace area according to the resistance change in the electrical circuit.

2. The direct online measurement method of gear meshing contact trace according to claim 1, characterized in that: In step S2, the contact resistance in the electric circuit is measured online in real time, and the real-time contact trace area at each moment is obtained by comparison and calculation in combination with the theoretical calculated value of the gear meshing contact trace.

3. The direct online measurement method of gear meshing contact trace according to claim 2, characterized in that: A gear pair is composed of a small gear and a large gear, and the gear pair forms a closed electrical circuit, and the closed electrical circuit is the shortest closed electrical circuit.

4. The direct online measurement method of gear meshing contact trace according to claim 3, characterized in that: The shortest closed electric circuit is composed of wires connected to the large and small gears, the large and small gears and a resistance measuring instrument in the electric circuit, and the large and small gears are insulated from the conductors in contact with them.

5. A direct online measurement system for gear meshing contact trace, characterized in that: include: A measuring device for obtaining the resistance change in an electrical circuit composed of meshing gear pairs according to the continuity characteristics of the electrical signal; The calculating device is used to obtain the contact trace area according to the resistance change in the electric circuit.

6. The direct online measurement system for gear meshing contact trace according to claim 5, characterized in that: The calculation device measures the contact resistance in the electric circuit in real time online, combines it with the theoretical calculated value of the gear meshing contact trace, and obtains the real-time contact trace area at each moment through comparative calculation.

7. The direct online measurement system for gear meshing contact trace according to claim 6, characterized in that: A gear pair is composed of a small gear and a large gear, and the gear pair forms a closed electrical circuit, and the closed electrical circuit is the shortest closed electrical circuit.

8. The direct online measurement system for gear meshing contact trace according to claim 7, characterized in that: The shortest closed electric circuit is composed of wires connected to the large and small gears, the large and small gears and a resistance measuring instrument in the electric circuit, and the large and small gears are insulated from the conductors in contact with them.

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