Flexspline expansion sleeve jig for harmonic reducer

Abstract

The present invention discloses a parameterized harmonic reducer flexspline expansion sleeve jig, comprising an expansion sleeve and a mandrel, the mandrel is coaxially mounted inside the expansion sleeve, the flexspline is mounted outside the expansion sleeve, the mandrel and the expansion sleeve are connected through a number of balls, when the mandrel is displaced under the action of an axial force, the balls are driven to roll in the same direction as the force is received, the inner diameter of the expansion sleeve is expanded, and the flexspline is tensioned. The present invention accurately describes the inner contour of the grooved expansion sleeve and the outer contour of the mandrel by a parameterized equation, improving the precision of the jig design, and the balls are disposed between the grooved expansion sleeve and the mandrel, reducing friction due to the rolling of the balls, and extending the service life of the jig, and employing two different diameter balls, which cause different deformations at different axial positions of the grooved expansion sleeve, reducing damage to the connection between the cup bottom and the cup body of the flexspline, and improving the clamping precision of the jig.

Description

[Technical Field]

[0001] The present invention relates to an expansion sleeve jig for a flexspline, and more particularly to an expansion sleeve jig for a parameterized harmonic reducer flexspline. [Background technology]

[0002] The cup-shaped flexspline is one of the core components of a harmonic reducer for a robot joint. Because the harmonic reducer is a device with a large reduction ratio and high transmission accuracy, the cup-shaped flexspline requires high processing accuracy and surface quality. The cup-shaped flexspline is a thin-walled part, and requires tensioning and support from the inside by a high-precision jig during the precision finishing and gear cutting processes.

[0003] As shown in Figure 1, conventional conical expansion sleeve jigs use an internal conical mandrel to move and tension the external expansion sleeve. However, conical expansion sleeves have the following problems. First, after the conical expansion sleeve jig is tensioned, the end surface of the internal expansion sleeve becomes warped, damaging the connection between the cup bottom and the cup body of the flexspline. Furthermore, during operation, friction occurs between the outer surface of the mandrel of the conical expansion sleeve and the inner surface of the expansion sleeve. Over time, this can lead to wear, reducing the taper angle and resulting in reduced clamping accuracy and reduced flexspline processing accuracy. Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention aims to provide a parameterized expansion sleeve jig for a flexspline of a harmonic reducer that employs a parameterized profile description to improve the clamping accuracy and maintainability of the expansion sleeve jig. [Means for solving the problem]

[0005] The technical solution is as follows: the present invention comprises an expansion sleeve and a mandrel, the mandrel is coaxially mounted inside the expansion sleeve, a flexspline is mounted on the outside of the expansion sleeve, and the mandrel and the expansion sleeve are connected via a number of balls, and when the mandrel is displaced under the action of an axial force, the balls are driven to roll in the same direction as the force, expanding the inner diameter of the expansion sleeve and tensioning the flexspline.

[0006] The expansion sleeve includes a tension ring having a plurality of open grooves spaced apart along its circumferential direction on its outer wall, and the inner wall of the tension ring between any two adjacent open grooves has a plurality of recessed grooves spaced apart along the axial direction of the tension ring.

[0007] The grooves include a first large ball groove and a first small ball groove.

[0008] A plurality of grooves, including a second large ball groove and a second small ball groove, are spaced apart on the circumferential surface of the mandrel that fits the tension ring, with a large ball disposed between the second large ball groove and the first large ball groove, and a small ball disposed between the second small ball groove and the first small ball groove, reducing friction through ball rolling and extending the service life of the jig.

[0009] The inner contour of the expansion sleeve and the outer contour of the mandrel are both continuous parameterized equations, and the parameterized equations accurately describe the inner contour of the grooved expansion sleeve and the outer contour of the mandrel, thereby improving the accuracy of the jig design.

[0010] The inner contour of the expansion sleeve includes a large arc portion AB of the expansion sleeve, a transition straight portion BC of the expansion sleeve, and a small arc portion CD of the expansion sleeve.

[0011] The large arc portion AB of the expansion sleeve has a curve equation as follows:

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[0012] The outer contour of the mandrel includes a large arc left portion EF of the mandrel, a large arc transition straight portion FG of the mandrel, a large arc right portion GH of the mandrel, an arc transition straight portion HI of the mandrel, a small arc left portion IJ of the mandrel, a small arc transition straight portion JK of the mandrel, and a small arc left portion KL of the mandrel.

[0013] The left large circular arc portion EF of the mandrel has a curve equation as follows:

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[0014] A flange is connected to one end of the tension ring, and an opening is provided at one end of each opening groove close to the flange, and the flange is used to fix the grooved expansion sleeve to a connecting member of a machine tool. [Effects of the Invention]

[0015] The beneficial effects of the present invention are as follows: the present invention uses parameterized equations to accurately describe the inner contour of the grooved expansion sleeve and the outer contour of the mandrel, improving the accuracy of the jig design; balls are placed between the grooved expansion sleeve and the mandrel, reducing friction through ball rolling and extending the service life of the jig; and balls with two different diameters are used, causing different deformations at different axial positions of the grooved expansion sleeve, reducing damage to the connection between the cup bottom and cup body of the flexspline and improving the accuracy of clamping by the jig. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view of a conventional conical expansion sleeve. [Figure 2] 1 is a schematic diagram of the overall structure of the present invention; [Figure 3] FIG. 3 is a cross-sectional view of FIG. 2. [Figure 4] 1 is a schematic diagram of a cup-shaped flexspline of the present invention. [Figure 5] 1 is a structural schematic diagram of a grooved expansion sleeve of the present invention; [Figure 6] 1 is a structural schematic diagram of a mandrel of the present invention. [Figure 7] 1 is a structural diagram of the parameterized inner contour of the grooved expansion sleeve and the outer contour of the mandrel of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be further explained below in connection with the drawings.

[0018] As shown in Figures 2 to 6, the present invention includes an expansion sleeve 1, a flexspline 2, and a mandrel 3. The mandrel 3 is attached inside the expansion sleeve 1 and the flexspline 2 is attached outside it. The flexspline 2 is a cup-shaped flexspline as shown in Figure 4. The mandrel 3 is attached coaxially to the expansion sleeve 1, with a coaxiality error of less than 5 μm. The mandrel 3 and the expansion sleeve 1 are connected via a number of balls, including large balls 5 and small balls 4. The balls roll to reduce friction and extend the service life of the jig. The balls have two different diameters, which reduces deformation at different axial positions on the grooved expansion sleeve, reducing damage to the connection between the cup bottom of the flexspline and the cup body and improving the clamping accuracy of the jig. When the mandrel 3 is displaced to the left under the action of a horizontal axial force in the left direction, it drives the balls to roll to the left, expanding the inner diameter of the expansion sleeve 1 and tensioning the flexspline 2, thereby achieving the purpose of clamping.

[0019] As shown in Figure 5, the expansion sleeve 1 is a grooved expansion sleeve and includes a tension ring 14. The outer wall of the tension ring 14 has a plurality of opening grooves 13 uniformly spaced along its circumferential direction, each opening groove 13 being distributed along the axial direction of the tension ring 14. One end of the tension ring 14 is connected to a flange 11, and each opening groove 13 has an opening 12 at one end near the flange 11, which is used to fasten the grooved expansion sleeve to a connector of a machine tool. Between two adjacent opening grooves 13, the inner wall of the tension ring 14 has a plurality of grooves, each groove being distributed along the axial direction of the tension ring 14 at intervals, including a first large ball groove 15 and a first small ball groove 16. The inner contour of the expansion sleeve 1 is a continuous parameterized equation.

[0020] As shown in FIG. 6 , the mandrel 3 has a plurality of uniformly spaced grooves on its circumferential surface that mates with the tensioning ring 14. The grooves include a second large ball groove 32 and a second small ball groove 33. The second large ball groove 32 mates with the first large ball groove 15 of the tensioning ring 14 in a one-to-one correspondence, and the second small ball groove 33 mates with the first small ball groove 16 of the tensioning ring 14 in a one-to-one correspondence. A large ball 5 is disposed between the second large ball groove 32 and the first large ball groove 15, and a small ball 4 is disposed between the second small ball groove 33 and the first small ball groove 16. The mandrel 3 further includes a tensioning shaft 31 and a needle shaft 34. The tensioning shaft 31 is formed with a male thread that is connected to a tension bar of a machine tool to achieve axial displacement, and the needle shaft 34 has a tapered hole on its end face for connection to a needle of the machine tool's spindle. To achieve the rotational accuracy, the tightening shaft 31 and the needle shaft 34 are mounted coaxially, and the coaxiality is within 5 μm. The outer contour of the mandrel 3 is a continuous parameterized equation.

[0021] As shown in Figure 7, a Cartesian coordinate system XOY is created with the central axes of the expansion sleeve 1 and mandrel 3 as the horizontal axis and the flange end face of the expansion sleeve 1 as the vertical axis, and is used to describe the inner contour of the expansion sleeve 1 and the outer contour of the mandrel 3.

[0022] The inner contour of the expansion sleeve 1 includes a large circular arc portion AB of the expansion sleeve, a transition straight portion BC of the expansion sleeve, and a small circular arc portion CD of the expansion sleeve.

[0023] 1) The large arc portion AB of the expansion sleeve has the following curve equation:

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[0024] 2) The linear transition section BC of the expansion sleeve has the following linear equation:

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[0025] 3) The small arc portion CD of the expansion sleeve has the following curve equation:

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[0026] The outer contour of the mandrel 3 includes a large arc left portion EF of the mandrel, a large arc transition straight portion FG of the mandrel, a large arc right portion GH of the mandrel, an arc transition straight portion HI of the mandrel, a small arc left portion IJ of the mandrel, a small arc transition straight portion JK of the mandrel, and a small arc left portion KL of the mandrel.

[0027] 1) The left part EF of the great arc of the mandrel has the following curve equation:

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[0028] 2) The linear equation of the mandrel's large arc transition straight line section FG is as follows:

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[0029] 3) The curve equation of the right large circular arc GH of the mandrel is as follows:

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[0030] 4) The linear equation of the mandrel's arc transition straight line section HI is as follows:

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[0031] 5) The curve equation of the small circular arc left part IJ of the mandrel is as follows:

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[0032] 6) The linear equation of the small arc transition straight line portion JK of the mandrel is as follows:

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[0033] 7) The curve equation of the small circular arc left part KL of the mandrel is as follows:

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[0034] The inner contour of the grooved expansion sleeve and the outer contour of the mandrel formed by the above-mentioned parameterized equations can effectively improve the design precision of the expansion sleeve jig. The use of balls improves the ability of the expansion sleeve jig to maintain precision, and the different diameters of the large and small balls reduce damage to the connection between the cup bottom and the cup body of the flex spline. Furthermore, by describing the parameterized equations, only the axial length of the expansion sleeve and the inner diameter of the cup-shaped flex spline need to be determined for design, providing a theoretical model for the design and inspection of similar products.

Claims

1. The invention comprises an expansion sleeve and a mandrel, the mandrel being coaxially attached inside the expansion sleeve and the flexspline being attached outside the expansion sleeve, the mandrel and the expansion sleeve being connected via a plurality of balls, and when the mandrel is displaced by the action of an axial force, the balls are driven to roll in the same direction as the direction in which the force is received, thereby expanding the inner diameter of the expansion sleeve and tensioning the flexspline; The expansion sleeve jig for a flexspline of a harmonic reducer is characterized in that the expansion sleeve includes a tension ring having a plurality of open grooves spaced apart along its circumferential direction on its outer wall, and the inner wall of the tension ring between any two adjacent open grooves has a plurality of recessed grooves spaced apart along the axial direction of the tension ring.

2. 2. The expansion sleeve jig for a flexspline of a harmonic reducer according to claim 1, wherein the grooves include a first large ball groove and a first small ball groove.

3. 3. The expansion sleeve jig for a flexspline of a harmonic reducer according to claim 2, wherein a plurality of grooves, including a second large ball groove and a second small ball groove, are spaced apart on a circumferential surface of the mandrel that fits with the tension ring, with large balls being provided between the second large ball groove and the first large ball groove, and small balls being provided between the second small ball groove and the first small ball groove.

4. 2. The expansion sleeve jig for a flexspline of a harmonic reducer as claimed in claim 1, wherein the inner contour of the expansion sleeve and the outer contour of the mandrel are both continuous parameterized equations.

5. 5. The expansion sleeve jig for a flexspline of a harmonic reducer according to claim 1 or 4, characterized in that the inner contour of the expansion sleeve includes a large arc portion AB of the expansion sleeve, a transition straight line portion BC of the expansion sleeve, and a small arc portion CD of the expansion sleeve.

6. The large arc portion AB of the expansion sleeve has a curve equation as follows: [Equation 21] In the formula, x ＡＢ is the abscissa value of an arbitrary point on the curve AB in the Cartesian coordinate system XOY, and y ＡＢ is the ordinate value in the Cartesian coordinate system of any point on the curve AB, n is the axial length of the expansion sleeve, and D Ｒ is the inner diameter of the cup-shaped flexspline, The linear transition section BC of the expansion sleeve has a linear equation as follows: [Equation 22] In the formula, y ＢＣ is the ordinate value of an arbitrary point on the line BC in the Cartesian coordinate system XOY, and x ＢＣ is the abscissa value of an arbitrary point on the line BC in the Cartesian coordinate system XOY, The small circular arc portion CD of the expansion sleeve has a curve equation as follows: [Equation 23] In the formula, x ＣＤ is the abscissa value of an arbitrary point on the curve CD in the Cartesian coordinate system XOY, and y ＣＤ is a vertical coordinate value of an arbitrary point on the curve CD in the orthogonal coordinate system XOY.

7. 5. The expansion sleeve jig for a flexspline of a harmonic reducer according to claim 1 or 4, characterized in that the outer contour of the mandrel includes a large arc left portion EF of the mandrel, a large arc transition straight portion FG of the mandrel, a large arc right portion GH of the mandrel, an arc transition straight portion HI of the mandrel, a small arc left portion IJ of the mandrel, a small arc transition straight portion JK of the mandrel, and a small arc left portion KL of the mandrel.

8. The curve equation of the left great circular arc portion EF of the mandrel is as follows: [0000] In the formula, y ＥＦ is the ordinate value of an arbitrary point on the curve EF in the Cartesian coordinate system XOY, and x ＥＦ is the abscissa value of any point on the curve EF in the Cartesian coordinate system XOY, The linear equation of the large circular arc transition straight line portion FG of the mandrel is as follows: [Equation 25] In the formula, y ＦＧ is the ordinate value of an arbitrary point on the line FG in the Cartesian coordinate system XOY, and x ＦＧ is the abscissa value of an arbitrary point on the line FG in the Cartesian coordinate system XOY, The curve equation of the right large circular arc portion GH of the mandrel is as follows: [Equation 26] In the formula, x ＧＨ is the abscissa value of an arbitrary point on the curve GH in the Cartesian coordinate system XOY, and y ＧＨ is the ordinate value of an arbitrary point on the curve GH in the Cartesian coordinate system XOY, The arc transition straight line portion HI of the mandrel has a straight line equation as follows: [0000] In the formula, y ＨＩ is the ordinate value of an arbitrary point on the line HI in the Cartesian coordinate system XOY, and x ＨＩ is the abscissa value of an arbitrary point on the line HI in the Cartesian coordinate system XOY, The curve equation of the small circular arc left portion IJ of the mandrel is as follows: [0000] In the formula, y ＩＪ is the ordinate value of an arbitrary point on the curve IJ in the Cartesian coordinate system XOY, and x ＩＪ is the abscissa value of an arbitrary point on the curve IJ in the Cartesian coordinate system XOY, The linear equation of the small arc transition straight line portion JK of the mandrel is as follows: [0000] In the formula, y ＪＫ is the ordinate value of an arbitrary point on the curve JK in the Cartesian coordinate system XOY, and x ＪＫ is the abscissa value of an arbitrary point on the curve JK in the Cartesian coordinate system XOY, The left small circular arc portion KL of the mandrel, the curve equation of which is as follows: [Equation 30] In the formula, y ＫＬ is the ordinate value of an arbitrary point on the curve KL in the Cartesian coordinate system XOY, and x ＫＬ 8. The expansion sleeve jig for a flexspline of a harmonic reducer according to claim 7, wherein is the abscissa value of an arbitrary point on the curve KL in the Cartesian coordinate system XOY.

9. 2. The expansion sleeve jig for a flexspline of a harmonic reducer according to claim 1, wherein a flange is connected to one end of the tension ring, and an opening is provided at one end of each opening groove close to the flange.

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