A device for measuring the relative motion speed of the contact point position of a planetary roller screw

Abstract

The present invention discloses a device for measuring the relative motion speed of the contact point position of a planetary roller screw, comprising: a motor, a motor seat, a rigid coupling, a speed sensor, a speed sensor seat, a bearing and a support, a movable slide, a screw to be measured, a guide rail and a grating ruler; wherein the motor is arranged on the motor seat; the speed sensor is arranged on the speed sensor seat; the output shaft of the motor is connected to one end of the rigid coupling, and the other end of the rigid coupling is connected to the speed sensor; the speed sensor is connected to one end of the screw to be measured; the other end of the screw to be measured passes through the bearing and the support and the movable slide in sequence; the movable slide is connected to the guide rail through a slider; the grating ruler is arranged on the guide rail. The present invention can directly measure the relative speed, and improves the accuracy of measuring the relative speed.

Description

Technical Field

[0001] The invention belongs to the technical field of planetary roller screw pairs, and in particular relates to a device for measuring the relative motion speed of a planetary roller screw contact point position. Background Art

[0002] In a planetary roller screw pair, the relative motion speed of the main screw and the roller affects the motion performance of the planetary roller screw pair, and the direction of the relative motion speed affects whether the thread profiles of the main screw and the roller will have curvature interference. Due to the coupling of the axial speed and the thread speed, the relative motion speed of the main screw and the roller at the contact point is neither parallel nor perpendicular, and is affected by the meshing of the gears composed of the roller and the inner ring. It is difficult to directly obtain the direction and magnitude of the relative motion speed at the contact point between the main screw and the roller through a mathematical model. Summary of the invention

[0003] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art and provide a device for measuring the relative motion speed of the contact point position of a planetary roller screw, which can directly measure the relative rotation speed and improve the accuracy of measuring the relative rotation speed.

[0004] The object of the present invention is achieved through the following technical solutions: A device for measuring the relative motion speed of the contact point position of a planetary roller screw, comprising: a motor, a motor seat, a rigid coupling, a speed sensor, a speed sensor seat, a bearing and a support, a movable slide, a screw to be measured, a guide rail and a grating ruler; wherein the motor is arranged on the motor seat; the speed sensor is arranged on the speed sensor seat;

[0005] The output shaft of the motor is connected to one end of the rigid coupling, and the other end of the rigid coupling is connected to the speed sensor; the speed sensor is connected to one end of the lead screw to be tested; the other end of the lead screw to be tested passes through the bearing, support and movable slide in sequence; the movable slide is connected to the guide rail through a slider; the grating ruler is arranged on the guide rail.

[0006] In the above-mentioned planetary roller screw contact point position relative motion speed measuring device, the bearing and support include a bearing and a bearing support; wherein the bearing is arranged on the bearing support; and the other end of the screw to be measured is passed through the bearing.

[0007] In the above-mentioned planetary roller screw contact point position relative motion speed measuring device, the screw to be measured includes a main screw, a circular grating sensor, a first inner gear ring, a second inner gear ring, a roller, a first retaining frame, a second retaining frame, a first bearing, a second bearing and a nut; wherein the inner ring of the first bearing is connected to the outer side of the first retaining frame, and the inner ring of the second bearing is connected to the outer side of the second retaining frame; the outer ring of the first bearing and the outer ring of the second bearing are both connected to the ascending and moving slide; the other end of the main screw passes through the second retaining frame and the first retaining frame in sequence; one end of the roller is connected to the first retaining frame, and the other end of the roller is connected to the second retaining frame; the nut is sleeved on the outer surface of the roller; the inner surface of the nut, the surface of the roller and the surface of the main screw all have external threads of the same rotation direction, and the nut, the roller and the main screw constitute a planetary thread transmission;

[0008] The circular grating sensor is sleeved on one end of the second retaining frame; the inner teeth of the first inner gear ring are meshed with the outer gear at one end of the roller, and the inner teeth of the second inner gear ring are meshed with the outer gear at the other end of the roller; one end of the main screw passes through the bearing and the support and is connected to the speed sensor.

[0009] In the above-mentioned planetary roller screw contact point position relative motion speed measuring device, the speed sensor can measure the rotation speed of the main screw; the circular grating sensor can measure the revolution speed of the roller, and the grating ruler can measure the displacement of the moving slide.

[0010] In the above-mentioned planetary roller screw contact point position relative motion speed measuring device, the expression of the surface external thread of the main screw is:

[0011]

[0012] Among them, r s is the radius vector of the screw surface, θ s is the rotation angle of the screw helical surface, f xs (u s ) is the expression of the x component of the screw helical normal section, u s is the independent variable of the normal section of the screw helix, α s is the lead angle of the screw, f z's (u s ) is the expression of the z component of the screw helical normal section, P 0s is the screw thread parameter.

[0013] In the above-mentioned planetary roller screw contact point position relative motion speed measuring device, the expression of the surface external thread of the roller is:

[0014]

[0015] Among them, r r is the roller surface radius vector, θ r is the rotation angle of the roller helical surface, f xr (u r ) is the expression of the x-component of the roller screw method section, f z'r (u r ) is the expression of the z component of the roller screw method section, u r is the independent variable of the normal section of the roller screw, α r is the roller helix angle, P 0r is the roller screw parameter, and a is the center distance.

[0016] In the above-mentioned planetary roller screw contact point position relative motion speed measuring device, the relative motion speed v between the main screw and the roller at the contact point is:

[0017] v=v s1 -v r1 -v r2

[0018] =r θs ·ω s -r θr ·ω r -ω e a;

[0019] Among them, v s1 is the instantaneous linear velocity of the main screw along the spiral line where the contact point is located, v r1 is the instantaneous linear velocity of the roller along the spiral line where the contact point is located, v r2 is the instantaneous linear velocity of the roller during its revolution, ω s is the main screw angular velocity, ω r is the roller angular velocity, ω e is the roller revolution angular velocity, r θs is the partial derivative of the screw surface radius vector to the rotation angle of the roller helical surface, r θr is the partial derivative of the roller surface radius vector to the rotation angle of the roller helical surface, and a is the center distance.

[0020] In the above-mentioned planetary roller screw contact point position relative motion speed measuring device, the central axis of the screw to be measured coincides with the central axis of the bearing.

[0021] In the above-mentioned planetary roller screw contact point position relative motion speed measuring device, the number of the rollers is multiple, and the multiple rollers are evenly distributed along the circumferential direction of the nut.

[0022] In the above-mentioned planetary roller screw contact point position relative motion speed measuring device, the central axis of the first bearing and the central axis of the second bearing coincide with each other.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The present invention directly measures the relative rotation speed, and the magnitude and direction of the relative motion speed are relatively accurate;

[0025] (2) The present invention achieves the increase or decrease of gear transmission by changing the structure without introducing external variables. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0027] Figure 1 is a schematic structural diagram of a device for measuring the relative motion speed of a planetary roller screw contact point position provided by an embodiment of the present invention;

[0028] Figure 2 is a schematic diagram of a lead screw to be tested provided by an embodiment of the present invention;

[0029] Figure 3 This is a diagram of the lead screw to be tested after the inner gear ring is removed provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0030] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to be able to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0031] Figure 1 Schematic diagram of the structure of the device for measuring the relative motion speed of the contact point position of a planetary roller screw provided by an embodiment of the present invention. Figure 1 As shown, the device for measuring the relative motion speed of the contact point position of the planetary roller screw comprises: a motor 1, a motor seat 2, a rigid coupling 3, a speed sensor 4, a speed sensor seat 5, a bearing and a support 6, a movable slide 7, a screw to be measured 8, a guide rail 9 and a grating ruler; wherein,

[0032] The motor 1 is arranged on the motor seat 2; the speed sensor 4 is arranged on the speed sensor seat 5; the output shaft of the motor 1 is connected to one end of the rigid coupling 3, and the other end of the rigid coupling 3 is connected to the speed sensor 4; the speed sensor 4 is connected to one end of the lead screw 8 to be tested; the other end of the lead screw 8 to be tested passes through the bearing and support 6 and the movable slide 7 in sequence; the movable slide 7 is connected to the guide rail 9 through the slider; the grating ruler is arranged on the guide rail 9. The movable slide 7 forms a moving pair with the guide rail 9 through the slider, and the displacement of the movable slide is measured by the grating ruler.

[0033] like Figure 1 As shown, the bearing and support 6 include a bearing and a bearing support; wherein the bearing is arranged on the bearing support; and the other end of the lead screw 8 to be measured passes through the bearing.

[0034] like Figure 2 As shown, the lead screw 8 to be tested includes a main lead screw 8-1, a circular grating sensor 8-2, a first inner gear ring 8-3, a second inner gear ring 8-10, a roller 8-4, a first retaining frame 8-5, a second retaining frame 8-6, a first bearing 8-7, a second bearing 8-8 and a nut 8-9.

[0035] The inner ring of the first bearing 8-7 is connected to the outer side of the first retaining frame 8-5, and the inner ring of the second bearing 8-8 is connected to the outer side of the second retaining frame 8-6; the outer ring of the first bearing 8-7 and the outer ring of the second bearing 8-8 are both connected to the ascending movable slide 7; the other end of the main screw 8-1 passes through the second retaining frame 8-6 and the first retaining frame 8-5 in sequence; one end of the roller 8-4 is connected to the first retaining frame 8-5, and the other end of the roller 8-4 is connected to the second retaining frame 8-6; the nut 8-9 is sleeved on the outer surface of the roller 8-4 ; The inner surface of the nut 8-9, the surface of the roller 8-4 and the surface of the main screw 8-1 all have external threads of the same rotation direction, and the nut 8-9, the roller 8-4 and the main screw 8-1 constitute a planetary thread transmission; the circular grating sensor 8-2 is sleeved on one end of the second retaining frame 8-6; the inner teeth of the first inner gear ring 8-3 are meshed with the external gear at one end of the roller 8-4, and the inner teeth of the second inner gear ring 8-10 are meshed with the external gear at the other end of the roller 8-4; one end of the main screw 8-1 passes through the bearing and the support 6 and is connected to the speed sensor 4.

[0036] Specifically, the inner sides of the first inner gear ring 8-3 and the second inner gear ring 8-10 are provided with inner teeth, and there are 8 rollers 8-4, each of which has outer teeth at both ends, which are gear-engaged with the inner gear ring; at the same time, there are external threads with the same rotation direction on the surfaces of the rollers 8-4 and the main screw 8-1, and there are internal threads with the same rotation direction on the inner side of the nut, and these three constitute a planetary thread transmission; the inner rings of the first bearing 8-7 and the second bearing 8-8 are respectively connected to the outer sides of the first retaining frame 8-5 and the second retaining frame 8-6, the outer rings of the first bearing 8-7 and the second bearing 8-8 are connected to the movable slide 7, the second retaining frame 8-6 is fixed to the circular grating sensor 8-2 by screws, the second retaining frame 8-6, the inner gear ring 8-3, the nut 8-9, and the first retaining frame 8-5 are axially connected in sequence and a single key is used to prevent circumferential movement, and the two ends of the 8 rollers 8-4 are respectively connected to the 8 blind holes on the inner sides of the first retaining frame 8-5 and the second retaining frame 8-6 to limit the relative positions between the rollers.

[0037] The speed sensor 4 can measure the rotation speed of the main screw 8 - 1 ; the circular grating sensor 8 - 2 can measure the revolution speed of the roller 8 - 4 ; and the grating ruler 9 can measure the displacement of the movable slide 7 .

[0038] like Figure 3 As shown, since the inner ring gear 8-3 and the roller 8-4 are fixed in relative position by the first retaining frame 8-5 and the second retaining frame 8-6, the inner ring gear only provides gear transmission constraints. After removing them, the roller 8-4 can still form a planetary thread transmission with the main screw 8-1 and the nut 8-9, and the inner ring gear 8-3 is not fixedly connected to the remaining parts, which facilitates disassembly and assembly while reducing the generation of other variables.

[0039] It can be known from the composition structure of the test bench that the speed sensor 4 can directly measure the rotation speed of the main screw, the circular grating sensor 8-2 can directly measure the revolution speed of the roller, and the grating ruler 9 can directly measure the displacement of the movable slide.

[0040] Relative motion speed test method

[0041] 1. Find the actual contact point p between the main screw and the roller, and obtain the common normal line n of the main screw and the roller at the contact point through differential geometry. Since both the main screw and the roller move along their own spiral lines, the absolute velocity direction at the contact point must be in the cotangent plane, that is, perpendicular to the common normal line. Therefore, the expression of the main screw and roller thread surface is set as:

[0042]

[0043]

[0044] Where u is the independent variable of the helical normal section, θ is the rotation angle of the helical surface, (u, θ) constitutes the helical surface, the subscript s represents the main screw, r represents the roller, and fx is the x-component expression of the helical section, f z’ is the expression of the z component of the helical normal section, P0 is the rotation parameter, a is the center distance, and α is the helix angle.

[0045] Taking partial derivatives of equations (1) and (2) with respect to u and θ respectively, we obtain:

[0046]

[0047]

[0048]

[0049]

[0050] Among them, the subscript s represents the main screw, r represents the roller; u s is the independent variable of the normal section of the screw helix, θ s is the rotation angle of the screw helical surface, r us is the radius vector of the screw surface u s The partial derivative, r θs θ is the radial vector of the screw surface s The partial derivative, P 0s is the screw rotation parameter, α s f is the lead angle of the screw; xs (u s ) is the expression of the x component of the screw helical normal section, f z's (u s ) is the expression of the z component of the screw helical normal section, f xs '(u s ) is the expression of the x component of the screw helical section with respect to u s The derivative of z's '(u s ) is the z component expression of the screw helical normal section with respect to u s The derivative of .

[0051] u r is the independent variable of the normal section of the roller screw, θ r is the rotation angle of the roller helical surface, r ur is the radius vector of the roller surface u s The partial derivative, r θr is the roller surface radius vector θ r The partial derivative, P 0r is the roller rotation parameter, α r is the roller helix angle; f xr (u r ) is the expression of the x-component of the roller screw method section, f z'r (u r) is the expression of the z component of the roller screw method section, f xr '(u r ) is the expression of the x-component of the roller screw method section with respect to u r The derivative of z'r '(u r ) is the expression of the z component of the roller screw method section with respect to u r The derivative of .

[0052] Then the common normal n can be expressed as:

[0053]

[0054] 2. Calculate the instantaneous linear velocity v of the main screw and roller along the spiral line where the contact point is located s1 With v r1 , assuming the main screw angular velocity is ω s , the roller angular velocity is ω r ,but:

[0055] v s1 =r θs ·ω s

[0056] v r1 = rθ r ·ω r ;

[0057] In addition to its own rotation, the roller also revolves around the main screw axis, and is constrained by the meshing of the inner gear ring and the roller, so that the angular velocity ratio of rotation to revolution is 4:1. Suppose the roller's orbital angular velocity is ω e , then ω r =4ω e , the instantaneous linear velocity v of the roller during revolution r2 for:

[0058] v r2 =ω e a;

[0059] Therefore, the relative motion speed v between the main screw and the roller at the contact point is:

[0060] v=v s1 -v r1 -v r2

[0061] =r θs ·ω s -r θr ·ω r -ω e a;

[0062] Combining the measured data, the size and direction of v can be calculated.

[0063] 3. After the inner gear ring 8-3 is removed, the friction phenomenon exists at the contact position, so that the angular velocity of the roller rotation and revolution no longer maintains a fixed ratio, resulting in a change in the lead of the screw pair. In the previous test, the value of the grating scale 9 on the guide rail can be recorded and compared with the test after the inner gear ring 8-3 is removed to obtain the friction ratio of the screw pair. At the same time, the relative motion speed is calculated according to the above method to obtain the influence of the gear constraint on the relative motion speed.

[0064] The present invention directly measures the relative rotation speed, and the magnitude and direction of the relative motion speed are relatively accurate; the present invention realizes the increase and decrease of gear transmission by changing the structure, and does not introduce external variables.

[0065] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A device for measuring the relative motion speed of the contact point position of a planetary roller screw, characterized in that include: A motor (1), a motor seat (2), a rigid coupling (3), a speed sensor (4), a speed sensor seat (5), a bearing and a support (6), a movable slide (7), a lead screw to be measured (8), a guide rail (9) and a grating ruler; wherein: The motor (1) is arranged on the motor base (2); The rotation speed sensor (4) is arranged on the rotation speed sensor seat (5); The output shaft of the motor (1) is connected to one end of the rigid coupling (3), and the other end of the rigid coupling (3) is connected to the rotation speed sensor (4); The rotation speed sensor (4) is connected to one end of the lead screw (8) to be measured; The other end of the lead screw (8) to be tested passes through the bearing and support (6) and the movable slide (7) in sequence; The movable slide (7) is connected to the guide rail (9) via a slider; The grating ruler is arranged on the guide rail (9); The lead screw (8) to be tested comprises a main lead screw (8-1), a circular grating sensor (8-2), a first inner gear ring (8-3), a second inner gear ring (8-10), a roller (8-4), a first retaining frame (8-5), a second retaining frame (8-6), a first bearing (8-7), a second bearing (8-8) and a nut (8-9); wherein: The inner ring of the first bearing (8-7) is connected to the outer side of the first retaining frame (8-5), and the inner ring of the second bearing (8-8) is connected to the outer side of the second retaining frame (8-6); The outer ring of the first bearing (8-7) and the outer ring of the second bearing (8-8) are both connected to the movable slide (7); The other end of the main screw (8-1) passes through the second retaining frame (8-6) and the first retaining frame (8-5) in sequence; One end of the roller (8-4) is connected to the first retaining frame (8-5), and the other end of the roller (8-4) is connected to the second retaining frame (8-6); The nut (8-9) is sleeved on the outer surface of the roller (8-4); The inner surface of the nut (8-9), the surface of the roller (8-4) and the surface of the main screw (8-1) all have external threads with the same rotation direction, and the nut (8-9), the roller (8-4) and the main screw (8-1) form a planetary thread transmission; The circular grating sensor (8-2) is sleeved on one end of the second retaining frame (8-6); The internal teeth of the first internal gear ring (8-3) mesh with the external gear at one end of the roller (8-4), and the internal teeth of the second internal gear ring (8-10) mesh with the external gear at the other end of the roller (8-4); One end of the main screw (8-1) passes through the bearing and the support (6) and is connected to the rotation speed sensor (4).

2. The device for measuring the relative motion speed of the contact point position of a planetary roller screw according to claim 1, characterized in that: The bearing and support (6) comprises a bearing and a bearing support; wherein: The bearing is arranged on the bearing support; The other end of the lead screw (8) to be tested is inserted into the bearing.

3. The device for measuring the relative motion speed of the contact point position of a planetary roller screw according to claim 1, characterized in that: The rotation speed sensor (4) can measure the rotation speed of the main screw (8-1); the circular grating sensor (8-2) can measure the revolution speed of the roller (8-4); and the grating ruler can measure the displacement of the movable slide (7).

4. The device for measuring the relative motion speed of the contact point position of a planetary roller screw according to claim 1, characterized in that: The expression of the surface external thread of the main screw (8-1) is: Among them, r s is the radius vector of the screw surface, θ s is the rotation angle of the screw helical surface, f xs (u s ) is the expression of the x component of the screw helical normal section, u s is the independent variable of the normal section of the screw helix, α s is the lead screw helix angle, f z's (u s ) is the expression of the z component of the screw helical normal section, P 0s is the screw thread parameter.

5. The device for measuring the relative motion speed of the contact point position of a planetary roller screw according to claim 1, characterized in that: The expression of the surface external thread of the roller (8-4) is: Among them, r r is the roller surface radius vector, θ r is the rotation angle of the roller helical surface, f xr (u r ) is the expression of the x-component of the roller screw method section, f z'r (u r ) is the expression of the z component of the roller screw method section, u r is the independent variable of the normal section of the roller screw, α r is the roller helix angle, P 0r is the roller screw parameter and a is the center distance.

6. The device for measuring the relative motion speed of the contact point position of a planetary roller screw according to claim 1, characterized in that: The relative motion speed v between the main screw (8-1) and the roller (8-4) at the contact point is: v=v s1 -v r1 -v r2 =r θs ·oh s -r θr ·oh r -oh e ·a; Among them, v s1 is the instantaneous linear velocity of the main screw along the spiral line where the contact point is located, v r1 is the instantaneous linear velocity of the roller along the spiral line where the contact point is located, v r2 is the instantaneous linear velocity of the roller during its revolution, ω s is the main screw angular velocity, ω r is the roller angular velocity, ω e is the roller revolution angular velocity, r θs is the partial derivative of the screw surface radius vector to the rotation angle of the roller helical surface, r θr is the partial derivative of the roller surface radius vector to the rotation angle of the roller helical surface, and a is the center distance.

7. The device for measuring the relative motion speed of the contact point position of a planetary roller screw according to claim 2, characterized in that: The central axis of the lead screw (8) to be measured coincides with the central axis of the bearing.

8. The device for measuring the relative motion speed of the contact point position of a planetary roller screw according to claim 1, characterized in that: The number of the rollers (8-4) is multiple, wherein the multiple rollers (8-4) are evenly distributed along the circumferential direction of the nut (8-9).

9. The device for measuring the relative motion speed of the contact point position of a planetary roller screw according to claim 1, characterized in that: The central axis of the first bearing (8-7) coincides with the central axis of the second bearing (8-8).

Images