A device for measuring the meshing center distance of a worm and gear and a method for measuring backlash error

Abstract

The application relates to a measuring device and a measuring method of a worm and gear assembly, in particular to a meshing center distance measuring device of a worm and gear and an empty return error measuring method, which are used for solving the problems that the existing measuring device and measuring method cannot realize the accurate measurement of the meshing center distance of the worm and gear and are difficult to measure the meshing empty return error of the worm and gear under different center distances. The meshing center distance measuring device of the worm and gear comprises a base, a grating ruler, a linear guide rail, a worm assembly and a gear assembly. The application can be used for measuring the meshing center distance of the worm and gear before the worm and gear are assembled and measuring the size of the empty return error under different meshing conditions. The application has the advantages of high measuring precision, short measuring period and low measuring cost.

Description

Technical Field

[0001] This invention relates to a measuring device and method for worm gear assemblies, specifically to a measuring device for the meshing center distance of a worm gear and a method for measuring backlash error. Background Technology

[0002] In recent years, spaceborne optoelectronic imaging and measurement technology has developed rapidly. Scanning mechanisms, as the mechanisms that provide motion and support to space optical imaging payloads, play a crucial role. Worm gear drives, due to their advantages such as reverse self-locking and large transmission ratio, are increasingly widely used in scanning mechanisms. However, worm gears require a certain amount of clearance during operation; otherwise, jamming will occur. Excessive clearance, however, will produce excessive backlash, affecting the pointing accuracy of the scanning mechanism. Therefore, before assembling the worm gear, it is necessary to measure whether its center distance meets the design requirements and the magnitude of its backlash error under different meshing conditions.

[0003] Currently, there are two methods for measuring the center distance of worm gears. The first method involves installing two worms in parallel and then installing a worm wheel between them for meshing. The center distance (d / 2 - half the worm height) is calculated by measuring the assembly formed by these three components. However, this method has a relatively large measurement error, typically 2-3 microns. The second method uses a high-precision worm gear measuring instrument to measure the worm gear dimensions from all angles. This method offers high accuracy but is time-consuming and costly. Furthermore, while the above methods can measure the center distance of worm gears, they cannot determine whether the worm gear will jam at that center distance, or the extent of the meshing backlash error. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing measuring devices and methods in accurately measuring the meshing center distance of worm gears and the difficulty in measuring the meshing backlash error of worm gears under different center distances. Therefore, this invention provides a device for measuring the meshing center distance of worm gears and a method for measuring backlash error.

[0005] To address the shortcomings of the existing technology, the present invention provides the following technical solution:

[0006] A worm gear meshing center distance measuring device, characterized in that it includes a base, and a grating ruler, a linear guide, a worm gear assembly, and a worm assembly mounted on the base;

[0007] The extension direction of the grating ruler is parallel to the extension direction of the linear guide rail;

[0008] The worm gear assembly includes a first bracket mounted on a base, a first bearing assembly mounted on the first bracket, a measuring hexahedron, and a first plane mirror. The worm gear to be measured is placed on the first bracket, and the first bearing assembly is coaxially mounted on the worm gear to be measured. The measuring hexahedron and the first plane mirror are used to be mounted on the top surface of the worm gear to be measured. The measuring hexahedron is used in conjunction with an autocollimator to measure the backlash error between the worm gear and the worm shaft to be measured, and the first plane mirror is used to measure the parallelism error between the worm gear and the worm shaft to be measured.

[0009] The worm gear assembly includes a second bracket, a second plane mirror, two second bearing assemblies, a worm gear drive manual wheel, and an angular displacement encoder. The second bracket is mounted on a linear guide rail and has a groove adapted to the middle of the worm gear to be measured. The second plane mirror is mounted on the top surface of the second bracket, and the plane of the second plane mirror is parallel to the axis of the second bearing assembly. The second plane mirror is used to measure the parallelism error between the worm gear and the worm gear to be measured. The two second bearing assemblies are respectively located at both ends of the worm gear to be measured, where they pass through the second bracket. The worm gear drive manual wheel and the angular displacement encoder are respectively located at both ends of the worm gear to be measured. The angular displacement encoder is used to measure the running angle of the worm gear to be measured.

[0010] The measuring hexahedron, the first plane mirror, and the second plane mirror are on a straight line, and the straight line is parallel to the extension direction of the grating ruler, with the first plane mirror positioned close to the second plane mirror;

[0011] The base has a zero-position line on its top surface, which passes through the zero position of the grating ruler and intersects with the axis of the worm gear (01) to be measured; the zero-position line is perpendicular to the extension direction of the grating ruler.

[0012] Furthermore, the first bearing assembly includes a first back-to-back angular contact bearing disposed in the middle of the worm gear to be measured, a first inner pressure ring disposed on the inner ring of the first back-to-back angular contact bearing, and a first outer pressure plate disposed on the outer ring of the first back-to-back angular contact bearing.

[0013] Furthermore, the second bearing assembly includes a second back-to-back angular contact bearing disposed between the worm gear to be measured and the second bracket, and a second outer pressure plate disposed on the outer ring of the second back-to-back angular contact bearing.

[0014] Furthermore, adjustment pads are provided at the four corners of the bottom of the first bracket to adjust the parallelism of the worm gear assembly and the worm assembly.

[0015] Furthermore, the parallelism between the plane containing the second plane mirror and the axis of the second bearing assembly is less than or equal to 0.01 mm; the parallelism between the extension direction of the grating ruler and the extension direction of the linear guide rail is less than or equal to 0.01 mm.

[0016] Meanwhile, this invention provides a method for measuring the backlash error of a worm gear, characterized in that it employs the aforementioned worm gear meshing center distance measuring device, and includes the following steps:

[0017] Step 1: Install the worm gear to be measured and the worm to be measured onto the worm gear assembly and the worm assembly, respectively;

[0018] Step 2: Use a theodolite to level the worm gear assembly and worm shaft assembly using a first plane mirror and a second plane mirror; the diameter of the theodolite is larger than the maximum distance between the first and second plane mirrors.

[0019] Step 3: Place the worm gear assembly and the worm assembly close together and fix the position of the worm assembly on the linear guide; place the grating ruler probe at the axis of the worm to be measured and read the data from the grating ruler probe to obtain the meshing center distance d of the worm gear and worm.

[0020] Step 4: Drive the manual wheel to rotate the worm gear to be measured one revolution in the forward direction. The angular displacement encoder will provide feedback that the rotation angle of the worm gear to be measured is 360°. At this time, the angle of the hexahedron to be measured based on the preset reference is obtained by the autocollimating theodolite and recorded as θ1.

[0021] The worm gear drives the manual wheel to continue rotating the worm gear to be measured one revolution in the same direction. The angular displacement encoder feeds back the rotation angle of the worm gear to be measured as 360°. At this time, the angle of the hexahedron based on the preset reference is obtained by the autocollimating theodolite and recorded as θ2.

[0022] Then the worm gear backlash error θ = A - (θ2 - θ1) is obtained, where A is the degree of rotation of the worm gear to be measured when the worm gear to be measured rotates 1 revolution;

[0023] End of measurement.

[0024] Further, step 2 specifically involves adjusting the parallelism of the first plane mirror and the second plane mirror by adjusting the adjusting pads at the four corners of the bottom of the first bracket, so that the parallelism of the worm gear and the worm to be measured is less than or equal to 1 mil.

[0025] Furthermore, in step 3, the perpendicularity between the zero-position line and the extension direction of the grating ruler is required to be less than or equal to 0.01 mm.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] (1) The present invention provides a worm gear meshing center distance measuring device, comprising a base, a grating ruler, a linear guide rail, a worm gear assembly, and a worm assembly; the present invention can be used to measure the worm gear meshing center distance before worm gear assembly, and to measure the magnitude of its backlash error under different meshing conditions; the present invention has the advantages of high measurement accuracy, short measurement cycle, and low measurement cost.

[0028] (2) The present invention provides a method for measuring the backlash error of a worm gear. By using the worm gear meshing center distance measuring device in conjunction with a theodolite and an autocollimating theodolite, the method achieves the measurement of the worm gear meshing center distance. It can also measure whether the worm gear will jam under the given meshing center distance and the amount of the meshing backlash error. This avoids the jamming phenomenon caused by the worm gear having too small a clearance during operation and the problem of the scanning mechanism's pointing accuracy being affected by the clearance being too large. Compared with existing measurement methods, the present invention has higher measurement efficiency and measurement accuracy. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of an embodiment of a worm gear meshing center distance measuring device according to the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of the base, grating ruler, and linear guide rail in an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the worm gear assembly in an embodiment of the present invention;

[0032] Figure 4 This is a cross-sectional view of the worm gear assembly in an embodiment of the present invention;

[0033] Figure 5 This is a schematic diagram of the worm gear assembly in an embodiment of the present invention;

[0034] Figure 6 This is a cross-sectional view of the worm gear assembly in an embodiment of the present invention;

[0035] Figure 7 This is a schematic diagram illustrating the principle of step 2 in an embodiment of the backlash error measurement method for a worm gear according to the present invention;

[0036] Figure 8 This is a schematic diagram illustrating the principle of obtaining the worm gear meshing center distance by reading the grating ruler probe data in step 3 of this embodiment of the invention.

[0037] Figure 9 This is a schematic diagram illustrating the principle of step 4 in an embodiment of the present invention.

[0038] The markings on the attached diagram are explained as follows: 01-worm gear to be measured; 02-worm to be measured; 03-theodolite; 04-autocollimating theodolite;

[0039] 1-Base; 2-Grating ruler, 21-Grating ruler zero position, 22-Grating ruler probe; 3-Linear guide rail, 31-Fixing set screw; 4-Worm gear assembly, 41-First bracket, 42-First bearing assembly, 43-Measuring hexahedron, 44-First plane mirror, 45-First back-to-back angular contact bearing, 46-First inner pressure ring, 47-First outer pressure plate, 48-Adjusting shim; 5-Worm gear assembly, 51-Second bracket, 52-Second plane mirror, 53-Second bearing assembly, 54-Worm gear drive manual wheel, 55-Angular displacement encoder, 56-Second back-to-back angular contact bearing, 57-Second outer pressure plate; 6-Zero position line. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and exemplary embodiments.

[0041] Reference Figures 1 to 6 A worm gear meshing center distance measuring device includes a base 1, and a grating ruler 2, a linear guide rail 3, a worm gear assembly 4, and a worm assembly 5 disposed on the base 1.

[0042] Reference Figure 2 The extension direction of the grating ruler 2 is parallel to the extension direction of the linear guide rail 3, and the parallelism between the extension direction of the grating ruler 2 and the extension direction of the linear guide rail 3 is less than or equal to 0.01 mm.

[0043] Reference Figure 3 , Figure 4 The worm gear assembly 4 includes a first bracket 41 mounted on a base 1, a first bearing assembly 42 mounted on the first bracket 41, a measuring hexahedron 43, and a first plane mirror 44. Adjusting pads 48 for adjusting the parallelism between the worm gear assembly 4 and the worm gear assembly 5 are provided at the four corners of the bottom of the first bracket 41. The worm gear 01 to be measured is placed on the first bracket 41, and the first bearing assembly 42 is coaxially mounted on the worm gear 01. The measuring hexahedron 43 and the first plane mirror 44 are symmetrically arranged along the first bearing assembly 42 on the top surface of the worm gear 01 to be measured. The measuring hexahedron 43 is used in conjunction with an autocollimator to measure the backlash error between the worm gear 01 and the worm gear 02 to be measured, and the first plane mirror 44 is used to measure the parallelism error between the worm gear 01 and the worm gear 02 to be measured.

[0044] The first bearing assembly 42 includes a first back-to-back angular contact bearing 45 disposed in the middle of the worm gear 01 to be measured, a first inner pressure ring 46 disposed on the inner ring of the first back-to-back angular contact bearing 45, and a first outer pressure plate 47 disposed on the outer ring of the first back-to-back angular contact bearing 45.

[0045] Reference Figure 5 , Figure 6The worm gear assembly 5 includes a second bracket 51, a second plane mirror 52, two second bearing assemblies 53, a worm gear drive manual wheel 54, and an angle displacement encoder 55. The second bracket 51 is mounted on the linear guide rail 3 and has a groove adapted to the middle of the worm gear 02 to be measured. The second plane mirror 52 is mounted on the top surface of the second bracket 51. The plane of the second plane mirror 52 is parallel to the axis of the second bearing assembly 53, and the parallelism between the plane of the second plane mirror 52 and the axis of the second bearing assembly 53 is less than or equal to 0.01 mm. The second plane mirror 52 is used to measure the parallelism error between the worm wheel 01 to be measured and the worm gear 02 to be measured. The two second bearing assemblies 53 are respectively located at both ends of the worm gear 02 to be measured, where they pass through the second bracket 51. The worm gear drive manual wheel 54 and the angle displacement encoder 55 are respectively located at both ends of the worm gear 02 to be measured. The angle displacement encoder 55 is used to measure the running angle of the worm gear 02 to be measured.

[0046] The second bearing assembly 53 includes a second back-to-back angular contact bearing 56 disposed between the worm gear 02 to be measured and the second bracket 51, and a second outer pressure plate 57 disposed on the outer ring of the second back-to-back angular contact bearing 56.

[0047] The measuring hexahedron 43, the first plane mirror 44, and the second plane mirror 52 are on a straight line, and the straight line is parallel to the extension direction of the grating ruler 2, and the second plane mirror 52 is set close to the first plane mirror 44.

[0048] The base 1 has a zero-position line 6 on its top surface. The zero-position line 6 passes through the zero position 21 of the grating ruler and intersects with the axis of the worm gear 01 to be measured. The perpendicularity of the zero-position line 6 to the extension direction of the grating ruler 2 is required to be less than or equal to 0.01 mm.

[0049] Using the aforementioned worm gear meshing center distance measuring device, this invention discloses a method for measuring the backlash error of a worm gear, comprising the following steps:

[0050] Step 1: Install the worm gear 01 to be measured and the worm 02 to be measured onto the worm gear assembly 4 and the worm assembly 5, respectively;

[0051] Step 2, refer to Figure 7 A theodolite 03 is used to level the worm gear assembly 4 and the worm shaft assembly 5 through the first plane mirror 44 and the second plane mirror 52. Specifically, the parallelism of the first plane mirror 44 and the second plane mirror 52 is adjusted by adjusting the adjusting pads 48 at the four corners of the bottom of the first bracket 41, so that the parallelism between the worm gear 01 to be measured and the worm shaft 02 to be measured is less than or equal to 1 mil; the diameter of the theodolite 03 is greater than the maximum distance between the first plane mirror 44 and the second plane mirror 52.

[0052] Step 3, refer to Figure 8The worm gear assembly 4 and the worm assembly 5 are brought close together, and the position of the worm assembly 5 on the linear guide 3 is fixed by the fixing set screw 31 on the linear guide 3; the grating ruler probe 22 is located at the axis position of the worm 02 to be measured, and the data of the grating ruler probe 22 is read to obtain the meshing center distance d of the worm gear and worm.

[0053] Step 4, refer to Figure 9 The worm gear drives the manual wheel 54 to rotate the worm gear 02 to be measured one revolution. The angular displacement encoder 55 feeds back the rotation angle of the worm gear 02 to be measured as 360°. At this time, the angle of the hexahedron 43 based on the preset reference is obtained by the autocollimating theodolite 04 and recorded as θ1.

[0054] The worm gear drives the manual wheel 54 to continue rotating the worm gear 02 to be measured one revolution in the same direction. The angular displacement encoder 55 feeds back the rotation angle of the worm gear 02 to be measured as 360°. At this time, the angle of the hexahedron 43 based on the preset reference is obtained by the autocollimating theodolite 04 and recorded as θ2.

[0055] The worm gear backlash error θ is obtained as θ = A - (θ1 - θ2), where A is the degree of rotation of the worm gear to be measured for 1 revolution of the worm gear to be measured; in this embodiment, the number of heads of the worm gear to be measured 02 is 1, and the number of teeth of the worm gear to be measured 01 is 60. Therefore, when the worm gear to be measured 02 rotates for 1 revolution, the worm gear to be measured 01 rotates for 1 tooth, and A is 6°.

[0056] End of measurement.

[0057] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. For those skilled in the art, modifications can be made to the specific technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions protected by the present invention.

Claims

1. A device for measuring the meshing center distance of a worm gear, characterized in that: It includes a base (1), and a grating ruler (2), a linear guide (3), a worm gear assembly (4), and a worm assembly (5) mounted on the base (1); The extension direction of the grating ruler (2) is parallel to the extension direction of the linear guide rail (3), and the parallelism is less than or equal to 0.01 mm. The worm gear assembly (4) includes a first bracket (41) mounted on a base (1), a first bearing assembly (42) mounted on the first bracket (41), a measuring hexahedron (43), and a first plane mirror (44); the worm gear (01) to be measured is placed on the first bracket (41), and adjustment pads (48) are provided at the four corners of the bottom of the first bracket (41) for adjusting the parallelism of the worm gear assembly (4) and the worm assembly (5); the first bearing assembly (42) is coaxially mounted on the worm gear (01) to be measured; the measuring hexahedron (43) and the first plane mirror (44) are mounted on the top surface of the worm gear (01) to be measured; the measuring hexahedron (43) is used in conjunction with an autocollimator to measure the backlash error between the worm gear (01) to be measured and the worm (02) to be measured, and the first plane mirror (44) is used to measure the parallelism error between the worm gear (01) to be measured and the worm (02) to be measured; The worm gear assembly (5) includes a second bracket (51), a second plane mirror (52), two second bearing assemblies (53), a worm gear drive manual wheel (54), and an angular displacement encoder (55). The second bracket (51) is mounted on a linear guide rail (3), and a groove adapted to the middle of the worm gear (02) to be measured is provided on the second bracket (51) for placing the worm gear (02) to be measured. The second plane mirror (52) is mounted on the top surface of the second bracket (51), and the plane on which the second plane mirror (52) is located is parallel to the second axis. The axis of the bearing assembly (53) is parallel to the axis of the worm gear (01) to be measured, and the parallelism is less than or equal to 0.01 mm. The two second bearing assemblies (53) are respectively set at the two ends of the worm gear (02) to be measured, where they pass through the second bracket (51). The worm drive manual wheel (54) and the angular displacement encoder (55) are respectively set at the two ends of the worm gear (02) to be measured. The angular displacement encoder (55) is used to measure the running angle of the worm gear (02) to be measured. The measuring hexahedron (43), the first plane mirror (44), and the second plane mirror (52) are on a straight line, and the straight line is parallel to the extension direction of the grating ruler (2), and the first plane mirror (44) is set close to the second plane mirror (52). The base (1) has a zero line (6) on its top surface, which passes through the zero position (21) of the grating ruler and intersects with the axis of the worm gear (01) to be measured. The zero-position line (6) is perpendicular to the extension direction of the grating ruler (2).

2. The worm gear meshing center distance measuring device according to claim 1, characterized in that: The first bearing assembly (42) includes a first back-to-back angular contact bearing (45) disposed in the middle of the worm gear (01) to be measured, a first inner pressure ring (46) disposed on the inner ring of the first back-to-back angular contact bearing (45), and a first outer pressure plate (47) disposed on the outer ring of the first back-to-back angular contact bearing (45).

3. The worm gear meshing center distance measuring device according to claim 1, characterized in that: The second bearing assembly (53) includes a second back-to-back angular contact bearing (56) disposed between the worm gear (02) to be measured and the second bracket (51), and a second outer pressure plate (57) disposed on the outer ring of the second back-to-back angular contact bearing (56).

4. A method for measuring the backlash error of a worm gear, characterized in that, The worm gear meshing center distance measuring device according to claim 1 includes the following steps: Step 1: Install the worm gear (01) to be measured and the worm (02) to be measured onto the worm gear assembly (4) and the worm assembly (5) respectively; Step 2: Use a theodolite (03) to level the worm gear assembly (4) and worm assembly (5) through the first plane mirror (44) and the second plane mirror (52); adjust the parallelism of the first plane mirror (44) and the second plane mirror (52) by adjusting the adjustment pads (48) at the four corners of the bottom of the first bracket (41) so that the parallelism of the worm gear (01) to be measured and the worm (02) to be measured is less than or equal to 1 mil; the diameter of the theodolite (03) is greater than the maximum distance between the first plane mirror (44) and the second plane mirror (52); Step 3: Place the worm gear assembly (4) and the worm assembly (5) close together and fix the position of the worm assembly (5) on the linear guide (3); place the grating ruler probe (22) at the axis position of the worm (02) to be measured, and read the data of the grating ruler probe (22) to obtain the meshing center distance d of the worm gear and worm. Step 4: Rotate the worm gear (02) to be measured one revolution by driving the manual wheel (54) through the worm gear. The angle displacement encoder (55) feeds back the rotation angle of the worm gear (02) to be measured as 360°. At this time, the angle of the hexahedron (43) based on the preset reference is obtained by the autocollimating theodolite (04), and recorded as θ1. The worm gear is driven by the manual wheel (54) to continue rotating the worm gear to be measured one revolution in the same direction. The angular displacement encoder (55) feeds back the rotation angle of the worm gear to be measured as 360°. At this time, the angle of the hexahedron based on the preset reference is obtained by the autocollimating theodolite (04), which is recorded as θ2. Then the worm gear backlash error θ = A - (θ2 - θ1) is obtained, where A is the degree of rotation of the worm gear to be measured after one revolution of the worm gear to be measured; End of measurement.

5. The method for measuring the backlash error of a worm gear according to claim 4, characterized in that: In step 3, the perpendicularity of the zero-position line (6) to the extension direction of the grating ruler (2) is required to be less than or equal to 0.01 mm.

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