Method and equipment for determining reference teeth of seven-tooth chain wheel

Abstract

A method and device for determining reference teeth of a seven-tooth chain wheel relates to the technical field of chain wheel repair, and comprises the following steps: determining a mapping position of a symmetric center line of outer teeth of the seven-tooth chain wheel on an inner spline; one outer tooth is used as a candidate tooth, and the other outer teeth are used as judgment teeth; determining a reference line based on the symmetric center line of the candidate teeth; determining whether the mapping positions corresponding to the judgment teeth on the two sides of the reference line are consistent or not, and if yes, determining the candidate teeth as reference teeth; according to the method, the reference teeth of the seven-tooth chain wheel are judged according to the geometrical relationship that the mapping positions corresponding to the outer teeth on the two sides of the reference teeth of the seven-tooth chain wheel are consistent, whether the candidate teeth are the reference teeth or not is determined by determining whether the mapping positions corresponding to the judgment teeth on the two sides of the candidate teeth are consistent or not, the operation process is greatly simplified, and the judgment efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of sprocket repair technology, specifically a method and apparatus for determining the reference tooth of a seven-tooth sprocket. Background Technology

[0002] As a core component of chain drive systems, sprockets are widely used in industries such as mining, metallurgy, and ports. After a period of use, sprockets will experience varying degrees of wear and corrosion, thus requiring repair. In sprocket repair production lines, each type of sprocket relies on corresponding tooling for transfer, machining, and welding. Fixed tooling ensures that the same type of sprocket is consistently mounted on the boring and milling machine and in the welding room, thereby ensuring the universality of boring, milling, and welding procedures. This requires that different sprockets of the same type maintain the same assembly method when assembled with the corresponding tooling.

[0003] To ensure consistent assembly between the sprocket and tooling, a reference tooth assembly method is currently used. Only one external tooth of the sprocket aligns with the internal spline; this tooth is the reference tooth. The reference tooth assembly method involves the tooling's reference spline meshing with the internal spline corresponding to the sprocket's reference tooth during assembly. Reference tooth markings are typically marked on the sprocket during manufacturing, allowing the identification of the sprocket's reference tooth. However, wear during use causes these markings to disappear, making it impossible to determine the sprocket's reference tooth based on them.

[0004] A seven-tooth sprocket is a type of sprocket. When the reference tooth marking line fails, the traditional method for determining the reference tooth of a seven-tooth sprocket is to visually inspect it or use tools to assist in traction. This method utilizes the geometric relationship within the seven-tooth sprocket, namely, that the reference tooth is aligned with the internal spline. However, in actual operation, multiple external teeth may be approximately aligned with the internal spline, making them difficult to distinguish. Furthermore, the external teeth of a seven-tooth sprocket often exhibit asymmetrical wear, further complicating the identification of the reference tooth in actual production. Summary of the Invention

[0005] This invention provides a method and apparatus for determining the reference teeth of a seven-tooth sprocket. The reference teeth of the seven-tooth sprocket are determined by utilizing the geometric relationship between the external teeth and the internal splines in the seven-tooth sprocket, which can quickly and accurately find the reference teeth of the seven-tooth sprocket.

[0006] To achieve the above objectives, the specific solution adopted by the present invention is as follows: a method for determining the reference tooth of a seven-tooth sprocket, comprising the following steps: Determine the mapping position of the symmetrical center line of the external teeth of the seven-tooth sprocket on the internal spline; Select one of the external teeth as the candidate teeth and the remaining external teeth as the judgment teeth; The reference line is determined based on the symmetry center line of the candidate tooth; Determine whether the mapping positions of the teeth on both sides of the reference line are consistent. If they are consistent, the candidate tooth is the reference tooth.

[0007] As an optimized solution to the above method for determining the reference tooth of a seven-tooth sprocket: the mapping position is the tooth groove, tooth tip, or sidewall.

[0008] As an optimization of the above-mentioned method for determining the reference tooth of a seven-tooth sprocket, the method for determining the mapping position of the symmetry center line of the outer tooth of the seven-tooth sprocket on the internal spline includes: The first reference line is obtained by projecting the symmetrical center line of the external tooth onto the end face of the seven-tooth sprocket, and the second reference line is obtained by projecting the outline of the internal spline onto the end face of the seven-tooth sprocket. Determine the intersection of the first and second baselines. If the intersection is located in the recess of the second baseline, the mapped position is the tooth groove. If the intersection is located in the protrusion of the second baseline, the mapped position is the tooth tip. If the intersection is located in the transition between the recess and the protrusion of the second baseline, the mapped position is the sidewall.

[0009] As an alternative optimization to the method for determining the reference tooth of a seven-tooth sprocket, if the corresponding mapping position of the external tooth is the sidewall after considering the external tooth as a candidate external tooth, then the candidate tooth is skipped.

[0010] As an optimization of the above method for determining the reference tooth of a seven-tooth sprocket, the method for determining the symmetry center line of the external tooth includes: Select multiple sets of symmetrical points on the edge of the external tooth, with two symmetrical points in each set; Create alternative lines based on two symmetrical points in the same group; The center line of symmetry is obtained by merging all the candidate lines.

[0011] As an alternative optimization to the method described above for determining the reference tooth of a seven-tooth sprocket, the specific methods for determining whether the mapping position corresponding to the tooth is symmetrical about the reference line include: The judgment teeth are grouped based on the distance between the candidate teeth and the judgment teeth, and two judgment teeth that are equidistant from the candidate teeth are grouped together. If any two sets of judgment teeth are selected, and the mapping positions of the two judgment teeth in each of the two selected sets are consistent, then the candidate tooth is the reference tooth.

[0012] A device for determining the reference tooth of a seven-tooth sprocket includes a vision acquisition module, a data processing module, and a result output module; The vision acquisition module is used to capture images of the seven-tooth sprocket to be inspected; The data processing module is used to analyze and process the image to be detected using any of the methods described above for determining the reference teeth of the seven-tooth sprocket, and obtain the reference teeth. The results output module marks the reference teeth in the image to be detected.

[0013] As an optimized solution for the aforementioned device for determining the reference teeth of a seven-tooth sprocket: the device includes a fixed platform for supporting the seven-tooth sprocket, and a frustum protrusion is provided on the fixed platform. When the seven-tooth sprocket is placed on the fixed platform, the frustum protrusion is inserted into the inner hole of the seven-tooth sprocket.

[0014] As an alternative optimization of the aforementioned device for determining the reference tooth of a seven-tooth sprocket: the vision acquisition module includes an industrial camera for photographing the seven-tooth sprocket, the industrial camera being located above the truncated cone protrusion.

[0015] As an alternative optimization of the aforementioned device for determining the reference tooth of a seven-tooth sprocket: the result output module includes a display for displaying the image to be detected with the reference tooth marked.

[0016] Compared with the prior art, the present invention has the following advantages: The present invention uses the geometric relationship that the corresponding mapping positions of the outer teeth on both sides of the reference tooth of the seven-tooth sprocket are consistent to determine the reference tooth of the seven-tooth sprocket. By determining whether the corresponding mapping positions of the judgment teeth on both sides of the candidate tooth are consistent, it is determined whether the candidate tooth is the reference tooth. This method greatly simplifies the operation process and improves the determination efficiency. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the method for determining the reference tooth of a seven-tooth sprocket in an embodiment of the present invention. Figure 2 This is a flowchart illustrating the method for determining the symmetry centerline of the external teeth in an embodiment of the present invention. Figure 3 This is a schematic diagram of a seven-tooth sprocket structure with 38 internal splines in an embodiment of the present invention; Figure 4 This is a schematic diagram of a seven-tooth sprocket structure with 47 internal splines in an embodiment of the present invention; Figure 5 This is a schematic diagram of a seven-tooth sprocket structure with 55 internal splines in an embodiment of the present invention; Figure 6 This is a schematic diagram of the device for determining the reference tooth of the seven-tooth sprocket in an embodiment of the present invention.

[0018] Reference numerals: 1. First baseline; 2. Protrusion; 3. Recess; 4. Transition; 5. Second baseline; 6. Fixed platform; 601. Frustum protrusion; 7. Industrial camera; 8. Vision acquisition module; 9. Data processing module; 10. Result output module. Detailed Implementation

[0019] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. Parts not described or disclosed in detail in the following embodiments of the present invention should be understood as prior art known or should be known by those skilled in the art.

[0020] like Figure 1 As shown, the present invention provides a method for determining the reference tooth of a seven-tooth sprocket, including steps S1 to S4.

[0021] S1. Determine the mapping position of the symmetrical center line of the outer teeth of the seven-tooth sprocket on the internal spline.

[0022] like Figure 3 As shown, in this embodiment, the outer teeth of the seven-tooth sprocket are numbered sequentially in a clockwise direction, from 1 to 7, where tooth 4 is the reference tooth, and teeth 1, 2, 3, 5, 6, and 7 are ordinary teeth. The symmetrical center line of the outer teeth is projected onto the end face of the seven-tooth sprocket to obtain the first reference line 1, and the outline of the internal spline is projected onto the end face of the seven-tooth sprocket to obtain the second reference line 5. The intersection point of the first reference line 1 and the second reference line 5 is determined. Based on the intersection point of the first reference line 1 and the second reference line 5, the mapping position of the symmetrical center line of the outer teeth of the seven-tooth sprocket on the internal spline is determined. If the intersection point is located in the recess 3 of the second reference line 5, the mapping position is the tooth groove; if the intersection point is located in the protrusion 2 of the second reference line 5, the mapping position is the tooth tip; if the intersection point is located in the transition 4 between the recess 3 and the protrusion 2 of the second reference line 5, the mapping position is the sidewall.

[0023] There are two types of alignment between the reference tooth and the internal spline: 1. The reference tooth and the tooth groove of the internal spline are aligned, meaning the center line of symmetry of the reference tooth is mapped onto the internal spline at the center of the tooth groove; 2. The reference tooth and the tooth tip of the internal spline are aligned, meaning the center line of symmetry of the reference tooth is mapped onto the internal spline at the center of the tooth tip. In this embodiment, the reference tooth and the tooth groove of the internal spline are aligned, meaning the center line of symmetry of tooth number 4 is mapped onto the internal spline at the center of the tooth groove.

[0024] The symmetrical center lines of the external teeth on both sides of the reference tooth of the seven-tooth sprocket are mapped to the same position on the internal spline. Specifically: tooth 4 is the reference tooth, the symmetrical center line of tooth 3 is mapped to the same position as the symmetrical center line of tooth 5 on the internal spline, the symmetrical center line of tooth 2 is mapped to the same position as the symmetrical center line of tooth 6 on the internal spline, and the symmetrical center line of tooth 1 is mapped to the same position as the symmetrical center line of tooth 7 on the internal spline.

[0025] like Figure 2 As shown, in step S1, the method for determining the symmetrical center line of the outer teeth of the seven-tooth sprocket includes steps S11 to S13.

[0026] S11. Select multiple sets of symmetrical points on the edge of the external tooth, with two points in each set.

[0027] In this embodiment, three sets of symmetrical points are selected on both sides of the outer tooth. Each set of symmetrical points consists of two points, and the two symmetrical points in the same set are at the same height. The three sets of symmetrical points are located at the upper, middle and lower parts of the outer tooth, respectively. This can cover the complete outline of the outer tooth and avoid excessive error due to the concentration of points.

[0028] S12. Create alternative lines based on two symmetrical points in the same group.

[0029] In this embodiment, two symmetrical points in the same group are connected to obtain three connecting lines. The perpendicular bisectors of the three connecting lines are then drawn, and the resulting three perpendicular bisectors are three candidate lines.

[0030] S13. Merge all candidate lines to obtain the symmetrical center line.

[0031] In this embodiment, the two outermost candidate lines are selected. The two outermost candidate lines define the reasonable range of the symmetry center line of the external tooth. The symmetry line of the two outermost candidate lines is drawn, and the symmetry line of the two outermost candidate lines is the symmetry center line of the external tooth.

[0032] S2. Select one of the external teeth as the candidate teeth and the remaining external teeth as the judgment teeth.

[0033] In this embodiment, one of the seven external teeth of the seven-tooth sprocket is used as a candidate tooth, and the remaining six external teeth are used as judgment teeth. For example, tooth 3 is used as a candidate tooth, and teeth 1, 2, 4, 5, 6, and 7 are used as judgment teeth.

[0034] S3. Determine the reference line based on the symmetry center line of the candidate tooth.

[0035] In this embodiment, the center line of symmetry of tooth number 3 is marked as the reference line.

[0036] S4. Determine whether the mapping positions of the teeth on both sides of the reference line are consistent. If they are consistent, the candidate tooth is the reference tooth.

[0037] In this embodiment, the judgment teeth are grouped based on the distance between the candidate teeth and the judgment teeth, with two judgment teeth equidistant from the candidate teeth grouped together. Specifically, the two judgment teeth closest to the candidate teeth are in the same group, the two judgment teeth farther from the candidate teeth are in the same group, and the two judgment teeth furthest from the candidate teeth are in the same group. That is, teeth 2 and 4 are in the same group, teeth 1 and 5 are in the same group, and teeth 7 and 6 are in the same group, resulting in three groups of judgment teeth. Two groups of judgment teeth are randomly selected from these three groups, and it is determined whether the mapping positions of the two judgment teeth in the same group are consistent. If the mapping positions of the two judgment teeth in each of the two selected groups are consistent, then the candidate tooth is the reference tooth. If the mapping positions of the two judgment teeth in the same group are inconsistent, steps S2 to S4 are repeated. In step S2, when reselecting candidate teeth, the seven outer teeth are used as candidate teeth in turn until the reference tooth is determined.

[0038] In this embodiment, only the symmetrical center lines of the external teeth on both sides of tooth 4 have consistent mapping positions on the internal spline. When tooth 3 is selected as a candidate tooth, the mapping positions of two teeth in the same group will be inconsistent, so a new candidate tooth needs to be selected. When tooth 4 is selected as a candidate tooth, teeth 3 and 5 are in the same group of judgment teeth, teeth 2 and 6 are in the same group of judgment teeth, and teeth 1 and 7 are in the same group of judgment teeth. The seven-tooth sprocket has the following geometric relationships: the mapping position of the symmetrical center line of tooth 3 on the internal spline is consistent with the mapping position of the symmetrical center line of tooth 5 on the internal spline, the mapping position of the symmetrical center line of tooth 2 on the internal spline is consistent with the mapping position of the symmetrical center line of tooth 6 on the internal spline, and the mapping position of the symmetrical center line of tooth 1 on the internal spline is consistent with the mapping position of the symmetrical center line of tooth 7 on the internal spline. If any two groups of judgment teeth are randomly selected from the three groups of judgment teeth, then the mapping positions of the two judgment teeth in each of the two selected groups of judgment teeth are consistent. At this time, the selected candidate tooth is the reference tooth, that is, tooth No. 4 is the reference tooth.

[0039] The mapping position corresponding to the reference tooth is the tooth groove or tooth tip. Therefore, in step S2, if the mapping position of the symmetry center line of the selected candidate pool on the internal spline is the side wall, then the candidate tooth is skipped.

[0040] like Figure 6 As shown, the present invention further provides a device for determining the reference tooth of a seven-tooth sprocket, including a vision acquisition module 8, a data processing module 9, and a result output module 10. The vision acquisition module 8 is used to capture an image of the seven-tooth sprocket to be inspected; the data processing module 9 is used to analyze and process the image to be inspected using methods S1 to S4 to obtain the reference tooth; the result output module 10 marks the reference tooth in the image to be inspected.

[0041] The device for determining the reference teeth of a seven-tooth sprocket includes a fixed platform 6 for supporting the sprocket. A frustum-shaped protrusion 601 is positioned in the center of the fixed platform 6. The cross-section of the frustum-shaped protrusion 601 is rectangular or trapezoidal, and its diameter is smaller than the diameter of the inner hole of the seven-tooth sprocket. When the seven-tooth sprocket is placed horizontally on the fixed platform 6, the frustum-shaped protrusion 601 is inserted into the inner hole of the sprocket. The vision acquisition module 8 includes an industrial camera 7 for capturing an image of the seven-tooth sprocket to be inspected. The industrial camera 7 is located above the frustum-shaped protrusion 601, which confines the seven-tooth sprocket within the field of view of the industrial camera 7, thus ensuring that the image captured by the industrial camera 7 covers the entire seven-tooth sprocket. The result output module 10 includes a display for displaying the image of the seven-tooth sprocket marked with reference teeth. The reference teeth are marked with different colors in the image. The operator determines the position of the reference teeth in the seven-tooth sprocket based on the position of the reference teeth in the image.

[0042] This invention utilizes the geometric relationship that the corresponding mapping positions of the outer teeth on both sides of the reference tooth of a seven-tooth sprocket are consistent to determine the reference tooth of the seven-tooth sprocket. By determining whether the mapping positions of the judgment teeth on both sides of the candidate tooth are consistent, it is determined whether the candidate tooth is the reference tooth. This method greatly simplifies the operation process and improves the efficiency of determining the reference tooth.

[0043] This invention further clarifies the geometric relationship that the corresponding mapping positions of the external teeth on both sides of the reference tooth of the seven-tooth sprocket are consistent.

[0044] Seven-tooth sprockets are classified into three categories based on the remainder when the number of internal splines is divided by 7. The first category of seven-tooth sprockets has a remainder of 1 or 6 when the number of internal splines is divided by 7; the second category has a remainder of 2 or 5 when the number of internal splines is divided by 7; and the third category has a remainder of 3 or 4 when the number of internal splines is divided by 7.

[0045] Of the seven external teeth of a seven-tooth sprocket, there is one reference tooth and six ordinary teeth. The external teeth and internal splines of the seven-tooth sprocket are evenly distributed around the circumference, and only the reference tooth and the internal spline are directly opposite each other among the seven external teeth. This is the basic structural relationship of the seven-tooth sprocket, which will not be elaborated further.

[0046] like Figure 3 As shown, the number of internal splines of the seven-tooth sprocket is 38. 38 divided by 7 leaves a remainder of 3, which belongs to the third type of seven-tooth sprocket. The external teeth of the seven-tooth sprocket are numbered sequentially in a clockwise direction, from 1 to 7. Tooth 4 is the reference tooth, and teeth 1, 2, 3, 5, 6, and 7 are all ordinary teeth.

[0047] The center line of symmetry of the external tooth divides the internal splines into seven equal parts. The difference in the number of internal splines between the ordinary tooth and the reference tooth is calculated. This difference in the number of internal splines between the ordinary tooth and the reference tooth is represented by the number of internal splines between the center lines of symmetry of the ordinary tooth and the center lines of symmetry of the reference tooth. The number of internal splines between tooth 5 and tooth 4 is 38 / 7, approximately 5.429. The number of internal splines between tooth 6 and tooth 4 is twice that between tooth 5 and tooth 4, approximately 10.857. The number of internal splines between tooth 7 and tooth 4 is three times that between tooth 5 and tooth 4, approximately 16.286. The external teeth are evenly distributed on the circumference, and the external teeth on both sides of the reference tooth are symmetrically distributed. Therefore, the number of internal splines between teeth 3 and 4 is equal to the number of internal splines between teeth 5 and 4, which is approximately 5.429. The number of internal splines between teeth 2 and 4 is equal to the number of internal splines between teeth 6 and 4, which is approximately 10.857. The number of internal splines between teeth 1 and 4 is equal to the number of internal splines between teeth 7 and 4, which is approximately 16.286.

[0048] An internal spline consists of three parts: a tooth tip, a tooth groove, and two sidewalls. The ratio of the tooth tip, tooth groove, and sidewalls is the ratio between the corresponding arcs of each part on the circumference. The ratio between the parts of the internal spline varies depending on the model of the seven-tooth sprocket. This invention provides a simplified ratio, specifically: the ratio of tooth tip, tooth groove, and sidewalls is 3:3:4. Taking the symmetrical center line of tooth 4 as the starting point, looking clockwise, there are five parts in the first internal spline: the first part, half a tooth groove; the second part, one sidewall; the third part, one tooth tip; the fourth part, one sidewall; and the fifth part, half a tooth groove. In the first internal spline, the arc corresponding to the first part on the circumference of the seven-tooth sprocket accounts for 15% of the total arc corresponding to the seven-tooth sprocket circumference of the internal spline; the arc corresponding to the second part on the circumference of the seven-tooth sprocket accounts for 20% of the total arc corresponding to the seven-tooth sprocket circumference of the internal spline; the arc corresponding to the third part on the circumference of the seven-tooth sprocket circumference accounts for 30% of the total arc corresponding to the seven-tooth sprocket circumference of the internal spline; the arc corresponding to the fourth part on the circumference of the seven-tooth sprocket circumference accounts for 20% of the total arc corresponding to the seven-tooth sprocket circumference of the internal spline; and the arc corresponding to the fifth part on the circumference of the seven-tooth sprocket circumference accounts for 15% of the total arc corresponding to the seven-tooth sprocket circumference of the internal spline. Based on the proportional relationship, the relationship between the number of internal splines and the position of the internal splines can be obtained, as shown in Table 1.

[0049] Table 1. Relationship between the number and position of the first internal spline Number of internal splines 0-0.15 0.15-0.35 0.35-0.65 0.65-0.85 0.85-1 0.5 1 Position of internal spline tooth groove sidewall Tooth tip sidewall tooth groove Tooth tip center Tooth center Furthermore, the relationship between the number and position of the second internal spline can be obtained, as shown in Table 2.

[0050] Table 2. Relationship between the number and position of the second internal spline Number of internal splines 1-1.15 1.15-1.35 1.35-1.65 1.65-1.85 1.85-2 1.5 2 Position of internal spline tooth groove sidewall Tooth tip sidewall tooth groove Tooth tip center Tooth center Similarly, a table showing the relationship between the number and position of the third, fourth, fifth, and so on internal splines can be derived. From the above analysis, it can be concluded that when the number of internal splines is 0.5, 1.5, 2.5, 3.5, etc., the position of the internal spline is at the center of the tooth tip; when the number of internal splines is 0, 1, 2, 3, 4, etc., the position of the internal spline is at the center of the tooth groove.

[0051] The difference between tooth #5 and tooth #4 is 5.429 internal splines. This means the number of internal splines between the symmetrical center lines of tooth #5 and tooth #4 is 5.429. The mapping position of the symmetrical center line of tooth #5 on the internal splines can be determined using the table of the number and position of the sixth internal spline. This invention provides a simple method for determining this: judging by the number of internal splines after the decimal point. Taking 5.429 internal splines as an example, the positions of the internal splines corresponding to 0.429 and 5.429 internal splines are the same—the tooth apex. Therefore, the position of the internal splines can be determined by the number of internal splines after the decimal point. 0.429 is between 0.35 and 0.65, so the position corresponding to 0.429 internal splines is the tooth apex, and consequently, the position corresponding to 5.429 internal splines is also the tooth apex. Based on the above judgment method, the mapping position of the symmetrical center line of tooth 5 on the internal spline is the tooth tip. Tooth 6 differs from tooth 4 by 10.857 internal splines, so the mapping position of the symmetrical center line of tooth 6 on the internal spline is the tooth groove. Tooth 7 differs from tooth 4 by 16.286 internal splines, so the mapping position of the symmetrical center line of tooth 7 on the internal spline is the sidewall. Based on the symmetrical relationship of the external teeth, tooth 3 differs from tooth 4 by 5.429 internal splines, so the mapping position of the symmetrical center line of tooth 3 on the internal spline is the tooth tip. Tooth 2 differs from tooth 4 by 10.857 internal splines, so the mapping position of the symmetrical center line of tooth 2 on the internal spline is the tooth groove. Tooth 1 differs from tooth 4 by 16.286 internal splines, so the mapping position of the symmetrical center line of tooth 1 on the internal spline is the sidewall. The results are shown in Table 3.

[0052] Table 3. Relationship between external teeth and internal splines of a seven-tooth sprocket with 38 internal splines. External tooth number 1 2 3 4 5 6 7 Number of internal splines between standard teeth and reference teeth (per spline) 16.286 10.857 5.429 0 5.429 10.857 16.286 The mapping position of the symmetry center line of the external tooth and the internal spline. sidewall tooth groove Tooth tip tooth groove Tooth tip tooth groove sidewall The number of internal splines on the 7-foot sprocket is increased to 39. 39 divided by 7 leaves a remainder of 4, classifying it as a third-category 7-tooth sprocket. The external teeth of the sprocket are numbered sequentially clockwise from 1 to 7, with tooth 4 as the reference tooth, and teeth 1, 2, 3, 5, 6, and 7 as standard teeth. The proportional relationships of the internal splines remain unchanged. The symmetrical center line of the external teeth divides the 39 internal splines into seven equal parts. The difference in the number of internal splines between the standard teeth and the reference tooth is calculated. The number of internal splines between tooth 5 and tooth 4 is 39 / 7, approximately 5.571. The number of internal splines between tooth 6 and tooth 4 is twice that between tooth 5 and tooth 4, approximately 11.143. The number of internal splines between tooth 7 and tooth 4 is three times that between tooth 5 and tooth 4, approximately 16.714. The number of internal splines between teeth 3 and 4 is equal to the number of internal splines between teeth 5 and 4, approximately 5.571. The number of internal splines between teeth 2 and 4 is equal to the number of internal splines between teeth 6 and 4, approximately 11.143. The number of internal splines between teeth 1 and 4 is equal to the number of internal splines between teeth 7 and 4, approximately 16.714.

[0053] Since the proportional relationship of each part of the internal spline remains unchanged, the number and positional relationship of the internal splines also remain unchanged. We can apply the number and positional relationship of the first internal spline in Table 1 to determine the mapping position of the symmetry center line of the external tooth on the internal spline. Tooth #5 differs from tooth #4 by 5.571 internal splines, so the mapping position of the symmetry center line of tooth #5 on the internal spline is the tooth tip. Tooth #6 differs from tooth #4 by 11.143 internal splines, so the mapping position of the symmetry center line of tooth #6 on the internal spline is the tooth groove. Tooth #7 differs from tooth #4 by 16.714 internal splines, so the mapping position of the symmetry center line of tooth #7 on the internal spline is the sidewall. Tooth #3 and... The difference between teeth 4 and 4 is 5.571 internal splines, so the mapping position of the center line of symmetry of tooth 3 on the internal spline is the tooth tip. The difference between teeth 2 and 4 is 11.143 internal splines, so the mapping position of the center line of symmetry of tooth 2 on the internal spline is the tooth groove. The difference between teeth 1 and 4 is 16.714 internal splines, so the mapping position of the center line of symmetry of tooth 1 on the internal spline is the sidewall. The results are shown in Table 4.

[0054] Table 4. Relationship between external teeth and internal splines of a seven-tooth sprocket with 39 internal splines. External tooth number 1 2 3 4 5 6 7 Number of internal splines between standard teeth and reference teeth (per spline) 16.714 11.143 5.571 0 5.571 11.143 16.714 The mapping position of the symmetry center line of the external tooth and the internal spline. sidewall tooth groove Tooth tip tooth groove Tooth tip tooth groove sidewall Comparing Tables 3 and 4 reveals that for the same external tooth number, the mapping position of the center line of symmetry on the internal spline is consistent. Specifically: the mapping position of the center line of symmetry of tooth 1 in Table 3 is consistent with that of tooth 1 in Table 4; the mapping position of the center line of symmetry of tooth 2 in Table 3 is consistent with that of tooth 2 in Table 4; and the mapping position of the center line of symmetry of tooth 3 in Table 3 is consistent with that of tooth 3 in Table 4. The mapping position of the center line of symmetry of tooth 4 on the internal spline in Table 3 is consistent with the mapping position of the center line of symmetry of tooth 4 on the internal spline in Table 4. The mapping position of the center line of symmetry of tooth 5 on the internal spline in Table 3 is consistent with the mapping position of the center line of symmetry of tooth 5 on the internal spline in Table 4. The mapping position of the center line of symmetry of tooth 6 on the internal spline in Table 3 is consistent with the mapping position of the center line of symmetry of tooth 6 on the internal spline in Table 4. The mapping position of the center line of symmetry of tooth 7 on the internal spline in Table 3 is consistent with the mapping position of the center line of symmetry of tooth 7 on the internal spline in Table 4.

[0055] The mapping position of the center line of symmetry of the external teeth with the same number on the internal spline is consistent. This can be explained mathematically. Taking tooth number 5 as an example, in Table 3, there is a gap of 5.429 internal splines between tooth number 5 and tooth number 4, and in Table 4, there is a gap of 5.571 internal splines between tooth number 5 and tooth number 4. The numbers 5.429 and 5.571 are symmetrical about 5.5 on the number line. Reflected on the internal spline, the mapping position of the center line of symmetry of tooth number 5 in Table 3 on the internal spline is symmetrical about the center of the tooth tip of the fifth internal spline in Table 4. Therefore, the mapping position of the center line of symmetry of tooth number 5 on the internal spline in Table 3 is consistent with the mapping position of the center line of symmetry of tooth number 5 on the internal spline in Table 4.

[0056] The above relationship applies to other seven-tooth sprockets whose number of internal splines leaves a remainder of 3 or 4 when divided by 7. When the remainder is 3, taking tooth 5 as an example, the number of internal splines between tooth 5 and tooth 4 is shown in Table 5.

[0057] Table 5. Mathematical and geometric relationships of tooth #5 when the remainder is 3. Number of internal splines on a 7-tooth sprocket 10 17 24 31 38 45 52 Number of internal splines between tooth #5 and tooth #4 1.429 2.429 3.429 4.429 5.429 6.429 7.429 The mapping position of the symmetry center line of tooth #5 on the internal spline Tooth tip Tooth tip Tooth tip Tooth tip Tooth tip Tooth tip Tooth tip When the remainder is 4, the number of internal splines between tooth 5 and tooth 4 is shown in Table 6.

[0058] Table 6. Mathematical and geometric relationships of tooth #5 when the remainder is 4 Number of internal splines on a 7-tooth sprocket 11 18 25 32 39 46 53 Number of internal splines between tooth #5 and tooth #4 1.571 2.571 3.571 4.571 5.571 6.571 7.571 The mapping position of the symmetry center line of tooth #5 and the internal spline Tooth tip Tooth tip Tooth tip Tooth tip Tooth tip Tooth tip Tooth tip Based on Tables 5 and 6, it can be analyzed that for seven-tooth sprockets with a remainder of 3 or 4 when the number of internal splines is divided by 7, the symmetrical center lines of the same-numbered external teeth are mapped to the same position on the internal splines.

[0059] The mapping positions of the external teeth of the third type of seven-tooth sprocket can be represented by Table 7.

[0060] Table 7. Mapping position relationship of the symmetrical center line of the external teeth of the third type of seven-tooth sprocket on the internal spline. External tooth number 1 2 3 4 5 6 7 The mapping position of the symmetry center line of the external tooth and the internal spline. sidewall tooth groove Tooth tip Tooth center Tooth tip tooth groove sidewall From Table 7, the following geometric relationships can be obtained: The mapping positions of the center lines of symmetry of the outer teeth on both sides of the reference tooth of the third type of seven-tooth sprocket on the internal spline are consistent. Specifically, the mapping position of the center line of symmetry of tooth 3 on the internal spline is consistent with the mapping position of the center line of symmetry of tooth 5 on the internal spline, the mapping position of the center line of symmetry of tooth 2 on the internal spline is consistent with the mapping position of the center line of symmetry of tooth 6 on the internal spline, and the mapping position of the center line of symmetry of tooth 1 on the internal spline is consistent with the mapping position of the center line of symmetry of tooth 7 on the internal spline.

[0061] like Figure 5 As shown, the same method can be used to analyze the first type of seven-tooth sprocket. The number of internal splines is 55, and 55 divided by 7 leaves a remainder of 6. Calculate the difference in the number of internal splines between the ordinary teeth and the reference teeth. The number of internal splines between teeth 5 and 4 is 55 / 7, approximately 7.857. The number of internal splines between teeth 6 and 4 is twice that between teeth 5 and 4, approximately 15.714. The number of internal splines between teeth 7 and 4 is three times that between teeth 5 and 4, approximately 23.571. The external teeth are evenly distributed on the circumference, and the external teeth on both sides of the reference tooth are symmetrically distributed. Therefore, the number of internal splines between teeth 3 and 4 is equal to the number of internal splines between teeth 5 and 4, which is approximately 7.857. The number of internal splines between teeth 2 and 4 is equal to the number of internal splines between teeth 6 and 4, which is approximately 15.714. The number of internal splines between teeth 1 and 4 is equal to the number of internal splines between teeth 7 and 4, which is approximately 23.571.

[0062] By applying the relationships in Table 1 to determine the mapping position between the symmetrical center line of the external tooth and the internal spline, we obtain Table 8.

[0063] Table 8. Relationship between external teeth and internal splines of a seven-tooth sprocket with 55 internal splines. External tooth number 1 2 3 4 5 6 7 Number of internal splines between standard teeth and reference teeth (per spline) 23.571 15.714 7.857 0 7.857 15.714 23.571 The mapping position of the symmetry center line of the external tooth and the internal spline. Tooth tip sidewall tooth groove tooth groove tooth groove sidewall Tooth tip Taking 50 internal splines as an example, 50 divided by 7 leaves a remainder of 1. Calculate the difference in the number of internal splines between the standard tooth and the reference tooth. The number of internal splines between tooth 5 and tooth 4 is 50 / 7, approximately 7.143. The number of internal splines between tooth 6 and tooth 4 is twice that between tooth 5 and tooth 4, approximately 14.286. The number of internal splines between tooth 7 and tooth 4 is three times that between tooth 5 and tooth 4, approximately 21.429. The external teeth are evenly distributed on the circumference, and the external teeth on both sides of the reference tooth are symmetrically distributed. Therefore, the number of internal splines between teeth 3 and 4 is equal to the number of internal splines between teeth 5 and 4, which is approximately 7.143. The number of internal splines between teeth 2 and 4 is equal to the number of internal splines between teeth 6 and 4, which is approximately 14.286. The number of internal splines between teeth 1 and 4 is equal to the number of internal splines between teeth 7 and 4, which is approximately 21.429.

[0064] By applying the relationships in Table 1 to determine the mapping position between the symmetrical center line of the external tooth and the internal spline, we obtain Table 9.

[0065] Table 9. Relationship between external teeth and internal splines of a seven-tooth sprocket with 50 internal splines. External tooth number 1 2 3 4 5 6 7 Number of internal splines between standard teeth and reference teeth (per spline) 21.429 14.286 7.143 0 7.143 14.286 21.429 The mapping position of the symmetry center line of the external tooth and the internal spline. Tooth tip sidewall tooth groove tooth groove tooth groove sidewall Tooth tip The above relationship holds for other cases where the number of internal splines divided by 7 leaves a remainder of 1 or 6. When the remainder is 6, taking tooth 5 as an example, the number of internal splines between tooth 5 and tooth 4 is shown in Table 10.

[0066] Table 10 Mathematical and geometric relationships of tooth #5 when the remainder is 6 Number of internal splines on a 7-tooth sprocket 13 20 27 34 41 48 55 Number of internal splines between tooth #5 and tooth #4 1.857 2.857 3.857 4.857 5.857 6.857 7.857 The mapping position of the symmetry center line of tooth #5 and the internal spline tooth groove tooth groove tooth groove tooth groove tooth groove tooth groove tooth groove When the remainder is 1, the number of internal splines between tooth 5 and tooth 4 is shown in Table 11.

[0067] Table 11 Mathematical and geometric relationships of tooth #5 when the remainder is 1 Number of internal splines on a 7-tooth sprocket 8 15 22 29 36 43 50 Number of internal splines between tooth #5 and tooth #4 1.143 2.143 3.143 4.143 5.143 6.143 7.143 The mapping position of the symmetry center line of tooth #5 and the internal spline tooth groove tooth groove tooth groove tooth groove tooth groove tooth groove tooth groove Based on Tables 10 and 11, it can be analyzed that for seven-tooth sprockets with a remainder of 1 or 6 when the number of internal splines is divided by 7, the symmetrical center line of the same numbered external teeth is consistent with the mapping position of the internal splines.

[0068] The mapping position of the symmetrical center line of the external teeth and the internal spline of the first type of seven-tooth sprocket can be represented by Table 12.

[0069] Table 12. Mapping position relationship of the center line of symmetry of the external teeth of the first type of seven-tooth sprocket on the internal spline. External tooth number 1 2 3 4 5 6 7 The mapping position of the symmetry center line of the external tooth and the internal spline. Tooth tip sidewall tooth groove Tooth center tooth groove sidewall Tooth tip From Table 12, the following geometric relationships can be obtained: The mapping positions of the symmetrical center lines of the external teeth on both sides of the reference tooth of the first type of seven-tooth sprocket on the internal spline are consistent. Specifically, the mapping position of the symmetrical center line of tooth 3 on the internal spline is consistent with the mapping position of the symmetrical center line of tooth 5 on the internal spline, the mapping position of the symmetrical center line of tooth 2 on the internal spline is consistent with the mapping position of the symmetrical center line of tooth 6 on the internal spline, and the mapping position of the symmetrical center line of tooth 1 on the internal spline is consistent with the mapping position of the symmetrical center line of tooth 7 on the internal spline.

[0070] like Figure 4 As shown, the same method can be used to analyze the second type of seven-tooth sprocket. The number of internal splines is 47, and 47 divided by 7 leaves a remainder of 5. Calculate the difference in the number of internal splines between the ordinary teeth and the reference teeth. The number of internal splines between teeth 5 and 4 is 47 / 7, approximately 6.714. The number of internal splines between teeth 6 and 4 is twice that between teeth 5 and 4, approximately 13.429. The number of internal splines between teeth 7 and 4 is three times that between teeth 5 and 4, approximately 20.143. The external teeth are evenly distributed on the circumference, and the external teeth on both sides of the reference tooth are symmetrically distributed. Therefore, the number of internal splines between teeth 3 and 4 is equal to the number of internal splines between teeth 5 and 4, which is approximately 6.714. The number of internal splines between teeth 2 and 4 is equal to the number of internal splines between teeth 6 and 4, which is approximately 13.429. The number of internal splines between teeth 1 and 4 is equal to the number of internal splines between teeth 7 and 4, which is approximately 20.143.

[0071] By applying the relationships in Table 1 to determine the mapping position between the symmetry center line of the external tooth and the internal spline, we obtain Table 13.

[0072] Table 13 Relationship between external teeth and internal splines of a seven-tooth sprocket with 47 internal splines External tooth number 1 2 3 4 5 6 7 Number of internal splines between standard teeth and reference teeth (per spline) 20.143 13.429 6.714 0 6.714 13.429 20.143 The mapping position of the symmetry center line of the external tooth and the internal spline. tooth groove Tooth tip sidewall tooth groove sidewall Tooth tip tooth groove Taking a tooth with 44 internal splines as an example, 44 divided by 7 leaves a remainder of 2. Calculate the difference in the number of internal splines between the standard tooth and the reference tooth. The number of internal splines between tooth 5 and tooth 4 is 44 / 7, approximately 6.286. The number of internal splines between tooth 6 and tooth 4 is twice that between tooth 5 and tooth 4, approximately 12.571. The number of internal splines between tooth 7 and tooth 4 is three times that between tooth 5 and tooth 4, approximately 18.857. The external teeth are evenly distributed on the circumference, and the external teeth on both sides of the reference tooth are symmetrically distributed. Therefore, the number of internal splines between teeth 3 and 4 is equal to the number of internal splines between teeth 5 and 4, which is approximately 6.286. The number of internal splines between teeth 2 and 4 is equal to the number of internal splines between teeth 6 and 4, which is approximately 12.571. The number of internal splines between teeth 1 and 4 is equal to the number of internal splines between teeth 7 and 4, which is approximately 18.857.

[0073] By applying the relationships in Table 1 to determine the mapping position between the symmetry center line of the external tooth and the internal spline, we obtain Table 14.

[0074] Table 14 Relationship between external teeth and internal splines of a seven-tooth sprocket with 44 internal splines External tooth number 1 2 3 4 5 6 7 Number of internal splines between standard teeth and reference teeth (per spline) 18.857 12.571 6.286 0 6.286 12.571 18.857 The mapping position of the symmetry center line of the external tooth and the internal spline. tooth groove Tooth tip sidewall tooth groove sidewall Tooth tip tooth groove The above relationship holds true for other cases where the number of internal splines divided by 7 leaves a remainder of 2 or 5. When the remainder is 5, taking tooth 5 as an example, the number of internal splines between tooth 5 and tooth 4 is shown in Table 15.

[0075] Table 15 Mathematical and geometric relationships of tooth #5 when the remainder is 5 Number of internal splines on a 7-tooth sprocket 12 19 26 33 40 47 54 Number of internal splines between tooth #5 and tooth #4 1.714 2.714 3.714 4.714 5.714 6.714 7.714 The mapping position of the symmetry center line of tooth #5 and the internal spline sidewall sidewall sidewall sidewall sidewall sidewall sidewall When the remainder is 2, the number of internal splines between tooth 5 and tooth 4 is shown in Table 16.

[0076] Table 16 Mathematical and geometric relationships of tooth #5 when the remainder is 2 Number of internal splines on a 7-tooth sprocket 9 16 23 30 37 44 51 Number of internal splines between tooth #5 and tooth #4 1.286 2.286 3.286 4.286 5.286 6.286 7.286 The mapping position of the symmetry center line of tooth #5 and the internal spline sidewall sidewall sidewall sidewall sidewall sidewall sidewall Based on Tables 15 and 16, it can be analyzed that for seven-tooth sprockets with a remainder of 2 or 5 when the number of internal splines is divided by 7, the symmetrical center line of the same numbered external teeth is consistent with the mapping position of the internal splines.

[0077] The mapping position of the symmetrical center line of the external teeth and the internal spline of the second type of seven-tooth sprocket can be represented by Table 17.

[0078] Table 17. Mapping position relationship of the symmetry center line of the external teeth of the second type of seven-tooth sprocket on the internal spline. External tooth number 1 2 3 4 5 6 7 The mapping position of the symmetry center line of the external tooth and the internal spline. tooth groove Tooth tip sidewall Tooth center sidewall Tooth tip tooth groove From Table 17, the following geometric relationships can be obtained: The mapping positions of the center lines of symmetry of the outer teeth on both sides of the reference tooth of the second type of seven-tooth sprocket on the internal spline are consistent. Specifically, the mapping position of the center line of symmetry of tooth 3 on the internal spline is consistent with the mapping position of the center line of symmetry of tooth 5 on the internal spline, the mapping position of the center line of symmetry of tooth 2 on the internal spline is consistent with the mapping position of the center line of symmetry of tooth 6 on the internal spline, and the mapping position of the center line of symmetry of tooth 1 on the internal spline is consistent with the mapping position of the center line of symmetry of tooth 7 on the internal spline.

[0079] In summary, based on Tables 7, 12, and 17, it can be concluded that the mapping positions of the symmetrical center lines of the external teeth on both sides of the reference tooth of the seven-tooth sprocket on the internal spline are consistent. Specifically, the mapping position of the symmetrical center line of tooth 3 on the internal spline is consistent with that of tooth 5; the mapping position of the symmetrical center line of tooth 2 on the internal spline is consistent with that of tooth 6; and the mapping position of the symmetrical center line of tooth 1 on the internal spline is consistent with that of tooth 7.

[0080] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for determining the reference tooth of a seven-tooth sprocket, characterized in that: Includes the following steps: Determine the mapping position of the symmetrical center line of the external teeth of the seven-tooth sprocket on the internal spline; Select one of the external teeth as the candidate teeth and the remaining external teeth as the judgment teeth; The reference line is determined based on the symmetry center line of the candidate tooth; Determine whether the mapping positions of the teeth on both sides of the reference line are consistent. If they are consistent, the candidate tooth is the reference tooth.

2. The method for determining the reference tooth of a seven-tooth sprocket according to claim 1, characterized in that: The mapped location is the tooth groove, tooth tip, or sidewall.

3. The method for determining the reference tooth of a seven-tooth sprocket according to claim 2, characterized in that: Methods for determining the mapping position of the center line of symmetry of the external teeth of a seven-tooth sprocket on the internal spline include: The first reference line (1) is obtained by projecting the symmetrical center line of the external tooth onto the end face of the seven-tooth sprocket, and the second reference line (5) is obtained by projecting the outline of the internal spline onto the end face of the seven-tooth sprocket. Determine the intersection of the first baseline (1) and the second baseline (5). If the intersection is located in the recess (3) of the second baseline (5), the mapping position is the tooth groove. If the intersection is located in the protrusion (2) of the second baseline (5), the mapping position is the tooth tip. If the intersection is located in the transition (4) between the recess (3) and the protrusion (2) of the second baseline (5), the mapping position is the sidewall.

4. The method for determining the reference tooth of a seven-tooth sprocket according to claim 3, characterized in that: If the external tooth is selected as a candidate external tooth, and the corresponding mapping position of the candidate tooth is the sidewall, then the candidate tooth is skipped.

5. The method for determining the reference tooth of a seven-tooth sprocket according to claim 1, characterized in that: Methods for determining the center line of symmetry of external teeth include: Select multiple sets of symmetrical points on the edge of the external tooth, with two symmetrical points in each set; Create alternative lines based on two symmetrical points in the same group; The center line of symmetry is obtained by merging all the candidate lines.

6. The method for determining the reference tooth of a seven-tooth sprocket according to claim 1, characterized in that: Specific methods for determining whether the mapping position corresponding to the tooth is symmetrical about the reference line include: The judgment teeth are grouped based on the distance between the candidate teeth and the judgment teeth, and two judgment teeth that are equidistant from the candidate teeth are grouped together. If any two sets of judgment teeth are selected, and the mapping positions of the two judgment teeth in each of the two selected sets are consistent, then the candidate tooth is the reference tooth.

7. A device for determining the reference tooth of a seven-tooth sprocket, characterized in that: It includes a visual acquisition module (8), a data processing module (9), and a result output module (10); The visual acquisition module (8) is used to capture the image of the seven-tooth sprocket to be inspected; The data processing module (9) is used to analyze and process the image to be detected using the method for determining the reference tooth of a seven-tooth sprocket as described in any one of claims 1 to 6, so as to obtain the reference tooth; The result output module (10) marks the reference teeth in the image to be detected.

8. The device for determining the reference tooth of a seven-tooth sprocket according to claim 7, characterized in that: The device includes a fixed platform (6) for supporting a seven-tooth sprocket. A frustum protrusion (601) is provided on the fixed platform (6). When the seven-tooth sprocket is placed on the fixed platform (6), the frustum protrusion (601) is inserted into the inner hole of the seven-tooth sprocket.

9. The device for determining the reference tooth of a seven-tooth sprocket according to claim 8, characterized in that: The vision acquisition module (8) includes an industrial camera (7) for photographing the seven-tooth sprocket, the industrial camera (7) being located above the frustum protrusion (601).

10. The device for determining the reference tooth of a seven-tooth sprocket according to claim 7, characterized in that: The result output module (10) includes a display for displaying the image to be detected of the marked reference teeth.

Images