Non-contact gas film axial loading device and method for main shaft rigidity test

Abstract

The invention provides a non-contact gas film axial loading device and method for a main shaft rigidity test, and relates to the field of machine tool dynamic performance detection. Comprising a bottom plate, an electric spindle supporting frame and a longitudinal adjusting mechanism are installed on the bottom plate, and an electric spindle is arranged on the electric spindle supporting frame; a frame is installed on the longitudinal adjusting mechanism, a vertical direction adjusting mechanism is arranged in the frame, a swing mechanism is installed on the vertical direction adjusting mechanism, and the O-shaped frame is connected with a transverse adjusting mechanism. The air-floating guide rail is arranged in the fixing block through an air-floating guide rail sleeve, a pressure sensor is installed at the end, away from the electric spindle, of the air-floating guide rail, the end, away from the electric spindle, of the air-floating guide rail communicates with a first air inlet head, an axial loading block is installed at the end, close to the electric spindle, of the air-floating guide rail, and the air-floating guide rail generates an air film through the axial loading block. The gas film generates an axial loading force on the electric spindle; the rigidity of the motorized spindle can be precisely measured, potential problems and abrasion are detected in advance, and the service life of the motorized spindle is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of machine tool dynamic performance detection, and particularly to a non-contact air film axial loading device and method for spindle stiffness testing. Background Art

[0002] In the application scenarios of high-speed cutting and precision machining, the motorized spindle must maintain excellent stiffness and stability under high-speed operation conditions to ensure that the manufacturing accuracy and surface quality of parts reach the best standards.

[0003] During the machining process of the machine tool, the spindle bears complex cutting forces from multiple directions, including radial, axial, and tangential forces. The changes and interactions of these forces need to be accurately simulated and measured, so it is crucial to test the stiffness of the motorized spindle. Especially in the case of high-speed machining, the stiffness of the spindle not only directly affects the cutting quality but also has a profound impact on the tool life and the overall stability of the machine tool.

[0004] In the stiffness testing of the motorized spindle, traditional contact loading methods face significant limitations in high-speed situations. These methods may cause contact loss, wear, and thermal effects, thereby reducing the accuracy of the test and affecting the reliability of the final results. To overcome these problems, modern research and practice tend to adopt non-contact electromagnetic loading technology. Although existing gas stiffness loading schemes have solved the above problems to a certain extent, due to the influence of guide rail friction during the loading process, this may lead to inaccurate measurement results, further reducing the reliability of the measurement results. Summary of the Invention

[0005] To solve the technical problems existing in the prior art, an embodiment of the present invention provides a non-contact air film axial loading device and method for spindle stiffness testing. The technical solution is as follows:

[0006] A non-contact air film axial loading device for spindle stiffness testing, comprising: a bottom plate, on which an electric spindle support frame and a longitudinal adjustment mechanism are installed, and an electric spindle is arranged on the electric spindle support frame;

[0007] A frame is installed on the longitudinal adjustment mechanism, a vertical direction adjustment mechanism is arranged inside the frame, a swing mechanism is installed on the vertical direction adjustment mechanism, the swing mechanism includes an O-shaped frame, and the O-shaped frame is connected to a transverse adjustment mechanism;

[0008] The lateral adjustment mechanism includes a fixed block. The air floating guide rail is arranged in the fixed block through an air floating guide rail sleeve. A pressure sensor is installed at one end of the air floating guide rail away from the electric spindle. One end of the air floating guide rail away from the electric spindle is communicated with a first air inlet head. An axial loading block is installed at one end of the air floating guide rail close to the electric spindle. The air floating guide rail generates an air film through the axial loading block, and the air film generates an axial loading force on the electric spindle. A first displacement sensor and a second displacement sensor are arranged on the electric spindle;

[0009] The longitudinal adjustment mechanism is used to adjust the longitudinal position of the air floating guide rail. The vertical direction adjustment mechanism is used to adjust the position of the air floating guide rail in the vertical direction. The swing mechanism is used to adjust the angle of the air floating guide rail. The lateral adjustment mechanism is used to adjust the lateral position of the air floating guide rail.

[0010] Optionally, grooves are uniformly arranged on the bottom plate along the width direction of the bottom plate. The length of the grooves is equal to the length of the bottom plate, and the extending direction of the grooves is the same as the length direction of the bottom plate. The longitudinal adjustment mechanism includes a positioning plate longitudinally arranged on the bottom plate. A positioning groove is formed in the positioning plate, and the extending direction of the positioning groove is the same as the width direction of the bottom plate. A positioning member passes through the positioning groove and is installed in the groove to install the positioning plate on the bottom plate. By connecting the positioning member with different grooves, the longitudinal position of the positioning plate on the bottom plate is changed.

[0011] Optionally, a first through hole is arranged in the bottom plate of the frame. A first fixed flange is installed at the bottom of the first through hole through a fixing member. A second through hole is arranged at the center of the first fixed flange, and the second through hole penetrates the first fixed flange in the vertical direction. The first knob is inserted into and penetrates the second through hole. Threads are arranged in the middle of the first knob and are threadedly connected with the first fixed flange;

[0012] A third through hole is arranged on the first fixed flange, and the third through hole penetrates the first fixed flange in the horizontal direction. The third through hole is communicated with the second through hole. Thrust screws are detachably installed at both ends in the third through hole, and the thrust screws are used to fix the first knob; A first bearing is rotatably installed in the first through hole, and the first bearing is installed on the top of the first fixed flange. The top end of the first knob extends into the first bearing, and the top end of the first knob is abutted against the bottom end of the first linear guide rail through a top ball. The bottom end of the first linear guide rail is inserted into the first bearing, and the bottom end of the first linear guide rail has a clearance fit with the first bearing. The first bearing can drive the first linear guide rail to rotate. The top end of the first linear guide rail is connected to the bottom end of the O-shaped frame. When the first linear guide rail rotates, it drives the O-shaped frame to swing around the axis of the first linear guide rail;

[0013] A fourth through hole is provided in the top plate of the frame. A second fixed flange is installed at the top in the fourth through hole through a fixing member. A fifth through hole is provided at the center of the second fixed flange. The fifth through hole vertically penetrates the second fixed flange. The second knob is inserted into and penetrates the fifth through hole. Threads are arranged in the middle of the second knob and are threadedly connected to the second fixed flange;

[0014] A sixth through hole is provided on the second fixed flange. The sixth through hole horizontally penetrates the second fixed flange. The sixth through hole communicates with the fifth through hole. Thrust screws are detachably installed at both ends in the sixth through hole. The thrust screws are used to fix the second knob; A second bearing is rotatably installed in the fourth through hole. The second bearing is installed at the bottom of the second fixed flange. The bottom end of the second knob extends into the second bearing. The bottom end of the second knob abuts against the top end of the second linear guide through a top bead. The top end of the second linear guide is inserted into the second bearing. The top end of the second linear guide has a clearance fit with the second bearing. The second bearing supports and drives the second linear guide to rotate. The bottom end of the second linear guide is connected to the top end of the O-shaped frame. When the second linear guide rotates, it drives the O-shaped frame to swing around the axis of the second linear guide;

[0015] When the first knob is rotated, the first linear guide moves in the vertical direction. When the second knob is rotated, the second linear guide moves in the vertical direction, driving the O-shaped frame to move in the vertical direction.

[0016] Optionally, the fixed block is installed between the two side walls of the O-shaped frame. A through cavity is provided inside the fixed block. An air floating guide rail sleeve is provided in the through cavity of the fixed block. The outer side wall of the air floating guide rail sleeve has a clearance fit with the inner side wall of the fixed block. The air floating guide rail sleeve is sleeved on the outer wall of the air floating guide rail; A seventh through hole is opened at the top of the fixed block. A second air inlet head is provided on the seventh through hole. The second air inlet head communicates with the air floating guide rail sleeve; The air floating guide rail has a through cavity inside. The through cavity of the air floating guide rail communicates with the first air inlet head. The axial loading block communicates with the through cavity of the air floating guide rail. Second air holes are evenly arranged at the center of the axial loading block. The axial loading block generates an air film through the second air holes. The axial loading block is arranged opposite to the core shaft of the electric spindle; A fixing plate is sleeved on the core shaft. The first displacement sensor and the second displacement sensor are provided on the fixing plate; The axial loading force causes the electric spindle to have horizontal displacement and vertical displacement. The first displacement sensor is used to measure the horizontal displacement of the electric spindle. The second displacement sensor is used to measure the vertical displacement of the electric spindle.

[0017] Optionally, a through cavity is provided inside the air-floating guide rail sleeve for wrapping the air-floating guide rail. Circumferential grooves are evenly arranged on the outer periphery of the air-floating guide rail sleeve along the length direction of the air-floating guide rail sleeve. First air holes are opened on the four walls of two of the circumferential grooves. The first air holes are communicated with the through cavity of the air-floating guide rail sleeve to provide air buoyancy for the air-floating guide rail and reduce the friction force of the air-floating guide rail. An axial groove is communicated between the two first air holes on the two side walls of the air-floating guide rail sleeve for air flow.

[0018] Optionally, a bracket is installed on the frame. The axis of the bracket is perpendicular to the axis of the frame. The bracket faces the pressure sensor. A pressure sensor connector is installed on the pressure sensor. An axially loaded screw rod is threadedly connected to the bracket. One end of the axially loaded screw rod abuts against the sensor connector through a top bead. The axis of the axially loaded screw rod coincides with the axis of the bracket. The other end of the axially loaded screw rod is connected with a hand wheel. Rotating the hand wheel drives the axially loaded screw rod to move in the axial direction, and pushes the air-floating guide rail to move in the axial direction.

[0019] Optionally, an eighth through hole is provided on one side wall of the O-shaped frame, and a ninth through hole is provided on the other side wall. A first ball bearing is arranged in the eighth through hole, and a second ball bearing is arranged in the ninth through hole. A first follower shaft is arranged in the first ball bearing, and a second follower shaft is arranged in the second ball bearing. One side wall of the first follower shaft is connected to one side wall of the fixed block, and the other side wall of the second follower shaft is connected to the other side wall of the fixed block. The first ball bearing drives the fixed block to swing around the first follower shaft through the first follower shaft, and the second ball bearing drives the fixed block to swing around the second follower shaft through the second follower shaft, so that the air-floating guide rail swings in the vertical direction.

[0020] Optionally, two first pin shaft fixing holes are opened on one side wall of the O-shaped frame, and two second pin shaft fixing holes are opened on one side wall of the fixed block. The two first pin shaft fixing holes and the two second pin shaft fixing holes correspond and match respectively. A pin shaft is detachably penetrated through the corresponding first pin shaft fixing hole and the second pin shaft fixing hole for fixing the fixed block.

[0021] A non-contact air film axial loading method for spindle stiffness testing, which is applied to the non-contact air film axial loading device for spindle stiffness testing, the method includes:

[0022] S1. Install the motorized spindle on the motorized spindle support frame;

[0023] S2. Adjust the position of the air-floating guide rail so that the axially loaded block faces the core shaft of the motorized spindle;

[0024] S3. Ventilate the first air inlet head and the second air inlet head to cause the axial loading block to generate an air film to exert an axial loading force on the motorized spindle and push the motorized spindle;

[0025] S4. Obtain the axial loading force through the pressure sensor, and obtain the horizontal displacement and vertical displacement of the motorized spindle through the first displacement sensor and the second sensor;

[0026] S5. Measure the stiffness of the motorized spindle according to the axial loading force, horizontal displacement and vertical displacement.

[0027] Optionally,

[0028] In S2, adjusting the position of the air bearing guide rail to make the axial loading block directly face the spindle of the motorized spindle includes:

[0029] Pass the positioning member through the positioning groove and install it in the groove of the bottom plate, install the positioning plate on the bottom plate, make the axis of the air bearing guide rail and the axis of the motorized spindle in the same vertical plane, rotate the first knob and the second knob to make the axis of the air bearing guide rail in the O-shaped frame and the axis of the motorized spindle at the same height, rotate the handwheel to make the axial loading block close to the spindle of the motorized spindle, drive the fixed block in the O-shaped frame to swing by rotating the first bearing and the second bearing and make the fixed block swing by rotating the first ball bearing and the second ball bearing. When the angle of the air bearing guide rail is aligned with the spindle of the motorized spindle, pass the pin through the first pin fixing hole and the second pin fixing hole to fix the fixed block;

[0030] In S5, measuring the stiffness of the motorized spindle according to the axial loading force, horizontal displacement and vertical displacement includes:

[0031] The calculation formula for the horizontal stiffness of the motorized spindle is formula (1)

[0032] (1)

[0033] is the horizontal stiffness of the motorized spindle, F is the axial loading force, is the horizontal displacement of the motorized spindle;

[0034] The calculation formula for the vertical stiffness of the motorized spindle is formula (2)

[0035] (2)

[0036] is the vertical stiffness of the motorized spindle, F is the axial loading force, is the vertical displacement of the electric spindle.

[0037] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0038] The technical solution of the present invention has a simple structure and can realize the precise measurement of the stiffness of the high-speed electric spindle. Regular testing of the stiffness of the electric spindle helps to detect potential problems and wear in advance, thereby reducing downtime, so that preventive maintenance can be carried out and the service life of the electric spindle can be extended. Product quality can be ensured and scrap and rework caused by processing errors can be reduced.

[0039] This solution uses an air-floating guide sleeve in conjunction with an air-floating guide to apply an axial loading force to the electric spindle, which can effectively reduce friction, reduce errors, wear and thermal effects, make the measured axial loading force more accurate and thus the calculated stiffness more accurate. In addition, this solution can adjust the position of the axial loading block from five degrees of freedom so that it can be accurately aligned with the electric spindle to apply force, making the results more accurate and the use process more convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 A lateral view of a non-contact air film axial loading device for spindle stiffness testing provided by the present invention;

[0042] Figure 2 A schematic structural diagram of a non-contact air film axial loading device for spindle stiffness testing provided by the present invention;

[0043] Figure 3 A lateral view of a non-contact air film axial loading device for spindle stiffness testing provided by the present invention after removing a side plate on one side of the frame;

[0044] Figure 4 for Figure 3 A magnified image of point A;

[0045] Figure 5 A first cross-sectional view of a non-contact air film axial loading device for spindle stiffness testing provided by the present invention;

[0046] Figure 6 A second cross-sectional view of a non-contact air film axial loading device for spindle stiffness testing provided by the present invention;

[0047] Figure 7 forFigure 6 Enlarged view at position B;

[0048] Figure 8 This is a schematic structural view of the air-floating guide sleeve of a non-contact air film axial loading device for spindle stiffness testing provided by the present invention.

[0049] Reference numerals:

[0050] 1. Base plate; 11. Groove; 2. Electric spindle support frame; 3. Electric spindle; 31. First displacement sensor; 32. Second displacement sensor; 33. Core shaft; 34. Axial loading block; 35. Fixed plate; 4. Handwheel; 41. Axial loading screw rod; 42. Pressure sensor; 43. Pressure sensor connector; 51. Frame; 52. Bracket; 6. O-shaped frame; 61. First ball bearing; 62. Pin shaft; 63. Second ball bearing; 64. First follower shaft; 65. Second follower shaft; 7. Positioning plate; 71. Positioning groove; 72. Positioning member; 81. First air inlet head; 82. Second air inlet head; 9. Air-floating guide; 91. Air-floating guide sleeve; 911. First air hole; 92. Fixed block; 10. Set screw; 101. First bearing; 102. First linear guide; 103. First knob; 104. First fixed flange; 105. Second linear guide; 106. Second bearing; 107. Second fixed flange; 108. Second knob. Detailed implementation manners

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0052] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those of ordinary skill in the art to which the present invention pertains. The "first", "second", and similar terms used in the present invention do not denote any order, quantity, or importance, but are only used to distinguish different components. Similarly, the terms such as "a", "an", or "the" do not denote a quantity limitation, but mean that there is at least one. The terms such as "comprising" or "including" mean that the elements or items appearing before this term cover the elements or items listed after this term and their equivalents, without excluding other elements or items. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0053] It should be noted that the terms "upper", "lower", "left", "right", "front", "rear", etc. used in the present invention are only used to represent relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0054] As shown in Figures 1 - 8 , a non-contact air film axial loading device for spindle stiffness testing is provided, including a bottom plate 1. Grooves 11 are uniformly arranged on the bottom plate 1 along the width direction of the bottom plate 1. The extending direction of the grooves 11 is the same as the length direction of the bottom plate 1, and the length of the grooves 11 is equal to the length of the bottom plate 1. A longitudinal adjustment mechanism is provided on the bottom plate 1. The longitudinal adjustment mechanism includes a positioning plate 7. The positioning plate 7 is longitudinally arranged on the bottom plate 1, that is, the length direction of the positioning plate 7 is the same as the width direction of the bottom plate 1. Two positioning slots 71 are opened on the positioning plate 7. The two positioning slots 71 are opposite and symmetrically arranged. The extending direction of the positioning slots 71 is the same as the width direction of the bottom plate 1. A positioning member 72 (the positioning member 72 can be a screw) passes through the positioning slot 71 and is installed in the groove 11 to install the positioning plate 7 on the bottom plate 1. The positioning member 72 passes through the positioning slot 71 and is connected to different grooves 11 to install the positioning plate 7 at different positions on the bottom plate 1, that is, to change the longitudinal position of the positioning plate 7 on the bottom plate 1. Here, the longitudinal position refers to the position of the positioning plate 7 in the width direction of the bottom plate 1.

[0055] As shown in Figures 1 - 2 , an electric spindle support frame 2 is installed on the bottom plate 1. The electric spindle support frame 2 is longitudinally arranged on the bottom plate 1. The electric spindle support frame 2 is opposite and parallel to the positioning plate 7. The axis of the positioning plate 7 and the axis of the electric spindle support frame 2 are located in the same vertical plane. The electric spindle support frame 2 includes two concave blocks. The two concave blocks are opposite and symmetrically arranged. The two concave blocks are parallel to the positioning plate 7. An electric spindle 3 is arranged in the recess of the two concave blocks. The electric spindle 3 is arranged in the center of the electric spindle support frame 2. Specifically, the inner side walls of the protruding parts of the two concave blocks are provided with slopes. The slopes face the center of the recessed block and slope downward. The electric spindle 3 is placed between the two opposite slopes. The electric spindle 3 under external force can displace in the vertical direction and can also displace in the horizontal direction (here, the horizontal direction refers to the length direction of the bottom plate 1).

[0056] As shown in Figures 2 to 5 , a frame 51 is installed on the positioning plate 7. A bracket 52 is connected between the center of the top plate side wall of the frame 51 and the center of the bottom plate side wall of the frame 5. The axis of the bracket 52 is perpendicular to the axis of the frame 51. A vertical direction adjustment mechanism is arranged in the frame 51. The vertical direction adjustment mechanism includes a first fixed flange 104. The bracket 52 is arranged on the side of the frame 51 away from the electric spindle 3.

[0057] The bottom plate of the frame 51 is provided with a first through hole. At the bottom inside the first through hole, a first fixing flange 104 is installed through a fixing member. A second through hole is provided at the center of the first fixing flange 104. The second through hole penetrates the first fixing flange 104 in the vertical direction. The first knob 103 is inserted into and penetrates the second through hole. Threads are arranged in the middle of the first knob 103 and it is threadedly connected to the first fixing flange 104;

[0058] A third through hole is provided on the first fixing flange 104. The third through hole penetrates the first fixing flange 104 in the horizontal direction. The third through hole communicates with the second through hole. At both ends inside the third through hole, set screws 10 are detachably installed. The set screws 10 are used to fix the first knob 103; A first bearing 101 is rotatably installed in the first through hole. The first bearing 101 is installed at the top of the first fixing flange 104. The top end of the first knob 103 extends into the first bearing 101. The top end of the first knob 103 is in contact with the bottom end of the first linear guide 102 through a top bead. The bottom end of the first linear guide 102 is inserted into the first bearing 101. The bottom end of the first linear guide 102 has a clearance fit with the first bearing 101. The first bearing 101 can drive the first linear guide 102 to rotate. The top end of the first linear guide 102 is connected to the bottom end of the O-shaped frame 6. When the first linear guide 102 rotates, it drives the O-shaped frame 6 to swing around the axis of the first linear guide 102;

[0059] The top plate of the frame 51 is provided with a fourth through hole. At the top inside the fourth through hole, a second fixing flange 107 is installed through a fixing member. A fifth through hole is provided at the center of the second fixing flange 107. The fifth through hole penetrates the second fixing flange 107 in the vertical direction. The second knob 108 is inserted into and penetrates the fifth through hole. Threads are arranged in the middle of the second knob 108 and it is threadedly connected to the second fixing flange 107;

[0060] A sixth through hole is provided on the second fixing flange 107. The sixth through hole penetrates the second fixing flange 107 in the horizontal direction. The sixth through hole communicates with the fifth through hole. At both ends inside the sixth through hole, set screws 10 are detachably installed. The set screws 10 are used to fix the second knob 108; A second bearing 106 is rotatably installed in the fourth through hole. The second bearing 106 is installed at the bottom of the second fixing flange 107. The bottom end of the second knob 108 extends into the second bearing 106. The bottom end of the second knob 108 is in contact with the top end of the second linear guide 105 through a top bead. The top end of the second linear guide 108 is inserted into the second bearing 106. The top end of the second linear guide 105 has a clearance fit with the second bearing 106. The second bearing 106 supports and drives the second linear guide 105 to rotate. The bottom end of the second linear guide 105 is connected to the top end of the O-shaped frame 6. When the second linear guide 105 rotates, it drives the O-shaped frame 6 to swing around the axis of the second linear guide 105; The axis of the second linear guide 105 coincides with the axis of the first linear guide 102.

[0061] When the first knob 103 is rotated, the first linear guide 102 moves in the vertical direction. When the second knob 108 is rotated, the second linear guide 105 moves in the vertical direction, driving the O-shaped frame 6 to move in the vertical direction.

[0062] A swing mechanism is installed on the vertical adjustment mechanism. The swing mechanism includes an O-shaped frame 6, and the O-shaped frame 6 is connected to the lateral adjustment mechanism; here, the lateral direction refers to the length direction of the bottom plate 1; the lateral adjustment mechanism includes a fixed block 92 and an air floating guide 9. A fixed block 92 is installed between the two inner side walls of the O-shaped frame 6. The fixed block 92 has a through cavity inside. An air floating guide sleeve 91 is arranged in the through cavity of the fixed block 92. The outer side wall of the air floating guide sleeve 91 is in clearance fit with the inner side wall of the fixed block 92. The air floating guide sleeve 91 is sleeved on the outer wall of the air floating guide 9; a seventh through hole is opened at the top of the fixed block 92, and a second air inlet head 82 is arranged on the seventh through hole. The second air inlet head 82 is communicated with the air floating guide sleeve 91 and supplies air to it.

[0063] As Figure 8 shown, a through cavity is arranged in the air floating guide sleeve 91 for wrapping the air floating guide 9. Along the length direction of the air floating guide sleeve 91, circumferential grooves are evenly arranged around the outer circumference of the air floating guide sleeve 91. First air holes 911 are opened on the four walls of two of the circumferential grooves (preferably, the two first air holes 911 on the same side wall of the air floating guide sleeve 91 are located at both ends of this side wall). The first air holes 911 are communicated with the through cavity of the air floating guide sleeve 91 to provide air buoyancy for the air floating guide 9 and reduce the friction of the air floating guide 9. An axial groove is communicated between the two first air holes 911 on the two side walls of the air floating guide sleeve 91 for air flow.

[0064] As Figures 2 - 5 shown, a through cavity is arranged inside the air floating guide 9. The through cavity of the air floating guide 9 is communicated with the first air inlet head 81. The first air inlet head 81 is arranged at one end of the air floating guide 9 away from the electric spindle 3. Both ends of the air floating guide 9 extend out of the air floating guide sleeve 91 and are exposed outside the fixed block 92. An axial loading block 34 is installed at one end of the air floating guide 9 close to the electric spindle 3. The axial loading block 34 is communicated with the through cavity of the air floating guide 9. Second air holes are evenly arranged at the center of the axial loading block 34. The air floating guide 9 supplies air to the axial loading block 34 through the first air inlet head 81. The axial loading block generates an air film through the second air holes, and the air film generates an axial loading force on the electric spindle 3.

[0065] Specifically, the axial loading block 34 is disposed opposite to and adjacent to the spindle 33 of the motorized spindle 3. A fixing plate 35 is sleeved on the spindle 33, and a first displacement sensor 31 and a second displacement sensor 32 are arranged on the fixing plate 35. The first displacement sensor 31 and the second displacement sensor 32 are electrically connected to the host computer, and the measured displacements are displayed through the host computer. The axial loading force causes the motorized spindle 3 to have horizontal and vertical displacements. The first displacement sensor 31 is used to measure the horizontal displacement of the motorized spindle 3, and the second displacement sensor 32 is used to measure the vertical displacement of the motorized spindle 3.

[0066] As Figures 2 - 5 shown, a pressure sensor 42 is installed at the end of the air bearing guide 9 away from the motorized spindle 3. The pressure sensor 42 is electrically connected to the host computer, and the measured data is displayed through the host computer. The pressure sensor 42 is used to display and measure the axial loading force. A bracket 52 is opposite to the pressure sensor 42. A pressure sensor connector 43 is installed on the pressure sensor 42. An axial loading screw rod 41 is threadedly connected to the bracket 52. One end of the axial loading screw rod 41 abuts against the sensor connector 43 through a ball. The axis of the axial loading screw rod 41 coincides with the axis of the bracket 52. The other end of the axial loading screw rod 41 is connected to a handwheel 4. Rotating the handwheel 4 drives the axial loading screw rod 41 to move in the axial direction, pushing the air bearing guide 9 to move in the axial direction (move horizontally).

[0067] The longitudinal adjustment mechanism is used to adjust the longitudinal position of the air bearing guide 9, the vertical adjustment mechanism is used to adjust the position of the air bearing guide 9 in the vertical direction, the swing mechanism is used to adjust the angle of the axial loading block 34 on the air bearing guide 9 so as to align it with the spindle 33, and the lateral adjustment mechanism is used to adjust the lateral position (horizontal position) of the air bearing guide 9.

[0068] As Figures 6 - 7 shown, an eighth through hole is provided on one side wall of the O-shaped frame 6, and a ninth through hole is provided on the other side wall. A first ball bearing 61 is arranged in the eighth through hole, and a second ball bearing 63 is arranged in the ninth through hole. A first follower shaft 64 is arranged in the first ball bearing 61, and a second follower shaft 65 is arranged in the second ball bearing 63. The first follower shaft 64 is connected to one side wall of the fixing block 92, and the second follower shaft 65 is connected to the other side wall of the fixing block 92. The first ball bearing 61 drives the fixing block 92 to swing around the first follower shaft 64 through the first follower shaft 64, and the second ball bearing 63 drives the fixing block 92 to swing around the second follower shaft 65 through the second follower shaft 65, causing the air bearing guide 9 to swing in the vertical direction. The axis of the first follower shaft 64 coincides with the axis of the second follower shaft 65.

[0069] On one side wall of the O-shaped frame 6, two first pin shaft fixing holes are provided. On one side wall of the fixing block 92, two second pin shaft fixing holes are provided. The two first pin shaft fixing holes and the two second pin shaft fixing holes correspond to and match each other. A pin shaft 62 is detachably penetrated through the corresponding first pin shaft fixing hole and the second pin shaft fixing hole. The pin shaft 62 is used to fix the fixing block 92.

[0070] A non-contact air film axial loading method for spindle stiffness testing, the method comprising:

[0071] S1. Install the motorized spindle 3 on the motorized spindle support frame 2;

[0072] S2. Adjust the position of the air bearing guide 9 so that the axial loading block 34 is directly opposite to the core shaft 33 of the motorized spindle 3;

[0073] Pass the positioning member 72 through the positioning groove 71 and install it in the groove 11 of the bottom plate 1. Install the positioning plate 7 on the bottom plate 1 so that the axis of the air bearing guide 9 and the axis of the motorized spindle 3 are in the same vertical plane. Rotate the first knob 103 and the second knob 108 so that the axis of the air bearing guide 9 in the O-shaped frame 6 and the axis of the motorized spindle 3 are at the same height. Rotate the handwheel 4 to make the axial loading block 34 close to the core shaft 33 of the motorized spindle 3 through the air bearing guide 9. Drive the fixing block 92 in the O-shaped frame 6 to swing by rotating the first bearing 101 and the second bearing 106 and drive the fixing block 92 to swing by rotating the first ball bearing 61 and the second ball bearing 63. When the angle of the air bearing guide 9 is aligned with the core shaft 33 of the motorized spindle 3, pass the pin shaft 62 through the first pin shaft fixing hole and the second pin shaft fixing hole to fix the fixing block 92;

[0074] S3. Ventilate the first air inlet head 81 and the second air inlet head 82 so that the axial loading block 34 generates an air film to generate an axial loading force on the motorized spindle 3 and push the motorized spindle 3;

[0075] S4. Obtain the axial loading force through the pressure sensor 42, and obtain the horizontal displacement and vertical displacement of the motorized spindle 3 through the first displacement sensor 31 and the second sensor 32;

[0076] S5. Measure the stiffness of the motorized spindle according to the axial loading force, horizontal displacement and vertical displacement:

[0077] The calculation formula for the horizontal stiffness of the motorized spindle 3 is formula (1)

[0078] (1)

[0079] is the horizontal stiffness of the motorized spindle 3, F is the axial loading force, is the horizontal displacement of the motorized spindle 3;

[0080] The calculation formula of the vertical stiffness of the electric spindle 3 is formula (2):

[0081] (2)

[0082] is the vertical stiffness of the electric spindle 3, F is the axial loading force, is the vertical displacement of the electric spindle 3.

[0083] This solution has a simple structure and can achieve precise measurement of the stiffness of high-speed electric spindles. Regular testing of the stiffness of the electric spindle helps to detect potential problems and wear in advance, thereby reducing downtime, so that preventive maintenance can be carried out and the service life of the electric spindle can be extended. Product quality can be ensured and scrap and rework caused by processing errors can be reduced.

[0084] This solution uses an air-floating guide sleeve in conjunction with an air-floating guide to apply an axial loading force to the electric spindle, which can effectively reduce friction, reduce errors, wear and thermal effects, make the measured axial loading force more accurate and thus the calculated stiffness more accurate. In addition, this solution can adjust the position of the axial loading block from five degrees of freedom so that it can be accurately aligned with the electric spindle to apply force, making the results more accurate and the use process more convenient.

[0085] The following points need to be explained:

[0086] (1) The drawings of the embodiments of the present invention only involve structures related to the embodiments of the present invention. Other structures may refer to conventional designs.

[0087] (2) For the sake of clarity, in the drawings used to describe the embodiments of the present invention, the thickness of layers or regions is exaggerated or reduced, that is, these drawings are not drawn according to the actual scale. It is understood that when an element such as a layer, film, region or substrate is referred to as being "on" or "under" another element, the element may be "directly" "on" or "under" the other element or there may be intermediate elements.

[0088] (3) In the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other to obtain new embodiments.

[0089] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A non-contact air film axial loading device for spindle stiffness testing, characterized in that: include: A bottom plate, on which an electric spindle support frame and a longitudinal adjustment mechanism are mounted, and on which an electric spindle is arranged; A frame is installed on the longitudinal adjustment mechanism, a vertical adjustment mechanism is arranged inside the frame, a swing mechanism is installed on the vertical adjustment mechanism, the swing mechanism includes an O-shaped frame, and the O-shaped frame is connected to the lateral adjustment mechanism; The lateral adjustment mechanism comprises a fixed block, an air-floating guide rail is arranged in the fixed block through an air-floating guide rail sleeve, a pressure sensor is installed at one end of the air-floating guide rail away from the electric spindle, the end of the air-floating guide rail away from the electric spindle is connected to a first air inlet head, an axial loading block is installed at one end of the air-floating guide rail close to the electric spindle, the air-floating guide rail generates an air film through the axial loading block, the air film generates an axial loading force on the electric spindle, and a first displacement sensor and a second displacement sensor are arranged on the electric spindle; The longitudinal adjustment mechanism is used to adjust the longitudinal position of the air-floating guide rail, the vertical adjustment mechanism is used to adjust the vertical position of the air-floating guide rail, the swing mechanism is used to adjust the angle of the air-floating guide rail, and the lateral adjustment mechanism is used to adjust the lateral position of the air-floating guide rail.

2. The non-contact air film axial loading device for spindle stiffness testing according to claim 1 is characterized in that: Grooves are evenly arranged on the base plate and along the width direction of the base plate, and the length of the grooves is equal to the length of the base plate. The longitudinal adjustment mechanism includes a positioning plate, and the positioning plate is longitudinally arranged on the base plate. A positioning groove is provided on the positioning plate, and the extension direction of the positioning groove is the same as the width direction of the base plate. A positioning member passes through the positioning groove and is installed in the groove to install the positioning plate on the base plate. The longitudinal position of the positioning plate on the base plate is changed by connecting the positioning member with different grooves.

3. The non-contact air film axial loading device for spindle stiffness testing according to claim 1 is characterized in that: A first through hole is arranged in the bottom plate of the frame, a first fixing flange is installed at the bottom of the first through hole through a fixing member, a second through hole is arranged at the center of the first fixing flange, the second through hole passes through the first fixing flange in a vertical direction, the first knob is inserted into and passes through the second through hole, a thread is arranged in the middle of the first knob and is threadedly connected with the first fixing flange; A third through hole is provided on the first fixing flange, the third through hole passes through the first fixing flange in the horizontal direction, the third through hole is communicated with the second through hole, and top screws are detachably installed at both ends of the third through hole, and the top screws are used to fix the first knob; a first bearing is rotatably installed in the first through hole, the first bearing is installed on the top of the first fixing flange, the top end of the first knob extends into the first bearing, the top end of the first knob abuts against the bottom end of the first linear guide through a top ball, the bottom end of the first linear guide is inserted into the first bearing, the bottom end of the first linear guide is loosely matched with the first bearing, the first bearing can drive the first linear guide to rotate, the top end of the first linear guide is connected to the bottom end of the O-shaped frame, and the first linear guide drives the O-shaped frame to swing around the axis of the first linear guide when rotating; A fourth through hole is provided in the top plate of the frame, a second fixing flange is installed on the top of the fourth through hole through a fixing member, a fifth through hole is provided at the center of the second fixing flange, the fifth through hole passes through the second fixing flange in a vertical direction, the second knob is inserted into and passes through the fifth through hole, a thread is arranged in the middle of the second knob and is threadedly connected with the second fixing flange; A sixth through hole is provided on the second fixing flange, the sixth through hole passes through the second fixing flange in the horizontal direction, the sixth through hole is communicated with the fifth through hole, and top screws are detachably installed at both ends of the sixth through hole, and the top screws are used to fix the second knob; a second bearing is rotatably installed in the fourth through hole, the second bearing is installed at the bottom of the second fixing flange, the bottom end of the second knob extends into the second bearing, the bottom end of the second knob abuts against the top end of the second linear guide rail through a top ball, the top end of the second linear guide rail is inserted into the second bearing, the top end of the second linear guide rail is clearance-matched with the second bearing, the second bearing supports and drives the second linear guide rail to rotate, the bottom end of the second linear guide rail is connected to the top end of the O-shaped frame, and the second linear guide rail drives the O-shaped frame to swing around the axis of the second linear guide rail when rotating; When the first knob is turned, the first linear guide rail moves in the vertical direction, and when the second knob is turned, the second linear guide rail moves in the vertical direction, driving the O-shaped frame to move in the vertical direction.

4. The non-contact air film axial loading device for spindle stiffness testing according to claim 1 is characterized in that: The fixed block is installed between the two side walls of the O-shaped frame, and the fixed block has a built-in through cavity. The air-floating guide rail sleeve is arranged in the through cavity of the fixed block, and the air-floating guide rail sleeve is sleeved on the outer wall of the air-floating guide rail; a seventh through hole is opened on the top of the fixed block, and a second air inlet head is arranged on the seventh through hole, and the second air inlet head is communicated with the air-floating guide rail sleeve; the air-floating guide rail has a built-in through cavity, and the through cavity of the air-floating guide rail is communicated with the first air inlet head, and the axial loading block is communicated with the through cavity of the air-floating guide rail, and second air holes are evenly arranged at the center of the axial loading block, and the axial loading block generates an air film through the second air holes, and the axial loading block is arranged opposite to the core shaft of the electric spindle; a fixed plate is sleeved on the core shaft, and the first displacement sensor and the second displacement sensor are arranged on the fixed plate; the axial loading force causes the electric spindle to displace horizontally and vertically, and the first displacement sensor is used to measure the horizontal displacement of the electric spindle, and the second displacement sensor is used to measure the vertical displacement of the electric spindle.

5. The non-contact air film axial loading device for spindle stiffness testing according to claim 1, characterized in that: A through cavity is provided in the air-floating guide rail sleeve for wrapping the air-floating guide rail, and circumferential grooves are evenly arranged on the air-floating guide rail sleeve and along the length direction of the air-floating guide rail sleeve around the outer circumference of the air-floating guide rail sleeve, and first air holes are provided on the four walls of two of the circumferential grooves. The first air holes are connected with the through cavity of the air-floating guide rail sleeve to provide air buoyancy for the air-floating guide rail and reduce the friction of the air-floating guide rail. An axial groove is connected between the two first air holes on the side walls of the air-floating guide rail sleeve for circulating airflow.

6. The non-contact air film axial loading device for spindle stiffness testing according to claim 1 is characterized in that: A bracket is installed on the frame, the axis of the bracket is perpendicular to the axis of the frame, the bracket is opposite to the pressure sensor, a pressure sensor connector is installed on the pressure sensor, an axial loading screw rod is threadedly connected to the bracket, one end of the axial loading screw rod abuts against the sensor connector through a top ball, and the other end of the axial loading screw rod is connected to a hand wheel, and turning the hand wheel drives the axial loading screw rod to move in the axial direction, thereby pushing the air floating guide rail to move in the axial direction.

7. The non-contact air film axial loading device for spindle stiffness testing according to claim 1, characterized in that: An eighth through hole is arranged on one side wall of the O-shaped frame, and a ninth through hole is arranged on the other side wall, a first ball bearing is arranged in the eighth through hole, a second ball bearing is arranged in the ninth through hole, a first follower shaft is arranged in the first ball bearing, a second follower shaft is arranged in the second ball bearing, the first follower shaft is connected to one side wall of the fixed block, the second follower shaft is connected to the other side wall of the fixed block, the first ball bearing drives the fixed block to swing around the first follower shaft through the support of the first follower shaft, the second ball bearing drives the fixed block to swing around the second follower shaft through the support of the second follower shaft, so that the air-floating guide rail swings in the vertical direction.

8. The non-contact air film axial loading device for spindle stiffness testing according to claim 7, characterized in that: Two first pin fixing holes are provided on one side wall of the O-shaped frame, and two second pin fixing holes are provided on one side wall of the fixing block. The two first pin fixing holes and the two second pin fixing holes correspond to and match each other, and pins are detachably penetrated through the corresponding first pin fixing holes and the second pin fixing holes, and the pins are used to fix the fixing block.

9. A non-contact air film axial loading method for spindle stiffness testing, characterized in that: The non-contact air film axial loading device for spindle stiffness testing according to any one of claims 1 to 8, the method comprising: S1, installing the electric spindle on the electric spindle support frame; S2. Adjust the position of the air-floating guide rail so that the axial loading block faces the core shaft of the electric spindle; S3, ventilating the first air inlet head and the second air inlet head, so that the axial loading block generates an air film to generate an axial loading force on the electric spindle, thereby pushing the electric spindle; S4, obtaining the axial loading force through the pressure sensor, and obtaining the horizontal displacement and vertical displacement of the electric spindle through the first displacement sensor and the second sensor; S5. Measuring the stiffness of the electric spindle according to the axial loading force, horizontal displacement and vertical displacement.

10. The non-contact air film axial loading method for spindle stiffness testing according to claim 7, characterized in that: The step of adjusting the position of the air-floating guide rail in S2 so that the axial loading block faces the core shaft of the electric spindle comprises: Make the positioning member pass through the positioning groove and be installed in the groove of the base plate, make the positioning plate be installed on the base plate, make the axis of the air-floating guide rail and the axis of the electric spindle be in the same vertical plane, turn the first knob and the second knob to make the axis of the air-floating guide rail in the O-frame and the axis of the electric spindle be at the same height, turn the hand wheel to make the axial loading block close to the core shaft of the electric spindle, drive the fixed block in the O-frame to swing by rotating the first bearing and the second bearing, and drive the fixed block to swing by rotating the first ball bearing and the second ball bearing, and when the angle of the air-floating guide rail is aligned with the core shaft of the electric spindle, pass the pin through the first pin fixing hole and the second pin fixing hole to fix the fixed block; The step of measuring the stiffness of the electric spindle according to the axial loading force, the horizontal displacement and the vertical displacement in S5 includes: The calculation formula of the horizontal stiffness of the electric spindle is formula (1) （1） is the horizontal stiffness of the electric spindle, F is the axial loading force, is the horizontal displacement of the electric spindle; The calculation formula of the vertical stiffness of the electric spindle is formula (2) （2） is the vertical stiffness of the electric spindle, F is the axial loading force, is the vertical displacement of the electric spindle.

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