Hollow lead screw structure and numerical control machine tool

Abstract

The utility model discloses a hollow lead screw structure and a numerical control machine tool, and relates to the technical field of numerical control machine tool transmission, the hollow lead screw structure comprises a hollow lead screw, a spacer bush assembly and an oil seal assembly, and the hollow lead screw is provided with a first end and a second end in the length direction; the spacer bush assembly comprises a first spacer bush and a second spacer bush, the first spacer bush is arranged at the first end of the hollow lead screw in a sleeving mode and is in sealed connection with the first end of the hollow lead screw, and the second spacer bush is arranged at the second end of the hollow lead screw in a sleeving mode and is in sealed connection with the second end of the hollow lead screw; the oil seal assembly comprises at least two rotary oil seals, the peripheral wall of the first spacer bush is sleeved with at least one rotary oil seal in a sealed mode, and the peripheral wall of the second spacer bush is sleeved with the other rotary oil seal in a sealed mode. According to the scheme, the first spacer bush and the second spacer bush are arranged and are respectively matched and sealed with the hollow lead screw, so that friction with the periphery of the hollow lead screw is reduced, direct contact friction between the rotary oil seal and the hollow lead screw is avoided, and the service life of the hollow lead screw is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of CNC machine tool transmission, in particular to a hollow screw structure and a CNC machine tool. Background Art

[0002] In the field of CNC machine tool transmission technology, linear axes usually use servo motors to directly or indirectly connect precision ball screws to convert rotary motion into linear motion and perform motion control. In mid- and high-end CNC machine tools, in order to significantly improve their position accuracy, fast moving speed and dynamic response characteristics, more and more manufacturers use hollow internal cooling screws and use special fixing structures to fix the hollow screws.

[0003] The existing fixing structure or cooling device of the hollow screw adopts a rotary oil seal for radial sealing. The rotary oil seal is in direct contact with the surfaces of the two ends of the screw. After a certain period of operation, the friction between the lip of the rotary oil seal and the contact surface of the hollow screw causes wear, resulting in seal failure and reducing the service life of the hollow screw. Utility Model Content

[0004] The main purpose of the utility model is to provide a hollow screw structure, aiming to improve the sealing effect of the hollow screw and extend the service life of the hollow screw.

[0005] In order to achieve the above-mentioned purpose, the hollow screw structure proposed in the utility model includes:

[0006] A hollow lead screw having a first end and a second end along a length direction;

[0007] A spacer assembly, the spacer assembly comprising a first spacer and a second spacer, the first spacer being sleeved on a first end of the hollow lead screw and being sealed to the first end of the hollow lead screw, the second spacer being sleeved on a second end of the hollow lead screw and being sealed to the second end of the hollow lead screw;

[0008] The oil seal assembly comprises at least two rotating oil seals, the outer peripheral wall sealing sleeve of the first spacer is provided with at least one rotating oil seal, and the outer peripheral wall sealing sleeve of the second spacer is provided with another rotating oil seal.

[0009] In one embodiment, the hollow screw structure further includes a sealing ring; the inner circumferential walls of the first spacer and the second spacer are provided with sealing grooves, the sealing ring is arranged in the sealing grooves, and the sealing ring is in sealing contact with the hollow screw.

[0010] In one embodiment, the number of the sealing grooves on the first spacer and the second spacer is at least two, and one sealing ring is disposed in one sealing groove.

[0011] In one embodiment, the spacer assembly further includes a third spacer and a fourth spacer;

[0012] The first end of the hollow screw structure also includes an inlet flange, an intermediate flange, a tail flange gland, and a first bearing group sleeved on the first end of the hollow screw, the side of the third sleeve facing away from the first sleeve abuts against the first bearing group, the outer peripheral wall of the first sleeve abuts against the inner peripheral wall of the intermediate flange, the outer peripheral wall of the third sleeve abuts against the inner peripheral wall of the tail flange gland, and the inlet flange, the intermediate flange, the tail flange gland, the first sleeve, and the third sleeve enclose a tail seat sealing cavity;

[0013] The second end of the hollow screw structure also includes an outlet flange, a motor seat, a motor seat flange pressure cover, and a second bearing group sleeved on the second end of the hollow screw, the second bearing group is clamped between the motor seat and the motor seat flange pressure cover, the second spacer and the fourth spacer are axially arranged on both sides of the second bearing group, the outer peripheral wall of the second spacer is in contact with the water outlet flange and the inner peripheral wall of the motor seat, the outer peripheral wall of the fourth spacer is in contact with the inner peripheral wall of the motor seat flange pressure cover, the water outlet flange, the motor seat, the motor seat flange pressure cover, the second spacer and the fourth spacer enclose a motor seat sealing chamber.

[0014] In one embodiment, the oil seal assembly includes a first rotating oil seal, a second rotating oil seal, a third rotating oil seal, a fourth rotating oil seal, a fifth rotating oil seal and a sixth rotating oil seal.

[0015] The first rotating oil seal is provided on the outer peripheral wall of the first spacer and is axially sandwiched between the water inlet flange and the intermediate flange;

[0016] The second rotary oil seal is provided on the outer peripheral wall of the third spacer, and the outer peripheral wall of the second rotary oil seal abuts against the tail flange gland;

[0017] The third rotary oil seal, the fourth rotary oil seal and the fifth rotary oil seal are sequentially sleeved on the hollow screw in a direction close to the second bearing group, the outer peripheral walls of the third rotary oil seal and the fourth rotary oil seal are both in contact with the inner peripheral wall of the water outlet flange, and the outer peripheral wall of the fifth rotary oil seal is in contact with the inner peripheral wall of the motor base;

[0018] The sixth rotating oil seal is sleeved on the outer peripheral wall of the fourth spacer sleeve, and the outer peripheral wall of the sixth rotating oil seal abuts against the inner peripheral wall of the motor seat flange gland.

[0019] In one embodiment, the hollow screw structure further includes a first locking nut, a second locking nut, a third locking nut and a fourth locking nut.

[0020] A step surface is formed on the first end of the hollow screw, the first spacer abuts against the step surface, and the first locking nut is axially arranged on a side of the first spacer facing away from the step surface;

[0021] The second locking nut is axially arranged on a side of the third spacer sleeve facing away from the first bearing group;

[0022] The third locking nut is axially arranged on a side of the second spacer sleeve facing away from the second bearing group;

[0023] The fourth locking nut is axially arranged on a side of the fourth spacer sleeve facing away from the second bearing group.

[0024] In one embodiment, a first leakage hole is opened at the bottom of the middle flange, and the hollow screw, the first spacer, the third spacer, the second rotary oil seal, the middle flange and the tail flange gland form a first chamber. The first leakage hole is located at the bottom of the first chamber to discharge the coolant leaked into the first chamber.

[0025] In one embodiment, a water outlet hole is radially opened at the second end of the hollow screw, the water outlet hole is communicated with the water outlet joint on the water outlet flange, the second spacer is circumferentially arranged to pass through the water outlet hole, and the third rotary oil seal and the fourth rotary oil seal are axially arranged on both sides of the water outlet hole.

[0026] An oil seal spacer is provided between the third rotary oil seal and the fourth rotary oil seal, and the outer peripheral wall of the oil seal spacer abuts against the inner peripheral wall of the water outlet flange.

[0027] An oil seal pressure plate is provided on the side of the fourth rotary oil seal facing away from the oil seal spacer, and the oil seal pressure plate is connected to the axial side wall of the water outlet flange by screws to axially lock the fourth rotary oil seal.

[0028] In one embodiment, a second leakage hole is provided at the bottom of the water outlet flange, and the water outlet flange, the second spacer, the fifth rotating oil seal, the oil seal pressure plate and the motor seat form a second chamber. The second leakage hole is located at the bottom of the second chamber to discharge the coolant leaked into the second chamber.

[0029] The utility model also provides a CNC machine tool, the CNC machine tool comprising the above-mentioned hollow screw structure, the hollow screw structure comprising:

[0030] A hollow lead screw having a first end and a second end along a length direction;

[0031] A spacer assembly, the spacer assembly comprising a first spacer and a second spacer, the first spacer being sleeved on a first end of the hollow lead screw and being sealed to the first end of the hollow lead screw, the second spacer being sleeved on a second end of the hollow lead screw and being sealed to the second end of the hollow lead screw;

[0032] The oil seal assembly comprises at least two rotating oil seals, the outer peripheral wall sealing sleeve of the first spacer is provided with at least one rotating oil seal, and the outer peripheral wall sealing sleeve of the second spacer is provided with another rotating oil seal.

[0033] The technical solution of the utility model is to sleeve the first spacer and the second spacer on both ends of the hollow screw, and the first spacer and the second spacer are sealed with the outer peripheral wall of the hollow screw. The first spacer and the second spacer and the hollow screw remain in a relatively static state during rotation, thereby reducing the friction with the outer periphery of the hollow screw. The rotary oil seal is installed on the outer periphery of the first spacer and the second spacer to achieve axial sealing of the spacer assembly, thereby avoiding long-term wear caused by direct contact between the rotary oil seal and the hollow screw, which may lead to leakage caused by failure of the seal of the outer peripheral wall of the hollow screw, thereby extending the service life of the hollow screw. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0035] Figure 1 A structural schematic diagram of an embodiment of a hollow screw structure provided by the utility model;

[0036] Figure 2 for Figure 1 A bottom view of the hollow screw structure;

[0037] Figure 3 for Figure 1 Sectional view at AA in the middle;

[0038] Figure 4 for Figure 2 Sectional view at the middle BB;

[0039] Figure 5 for Figure 4 A local enlarged schematic diagram of point a in the middle;

[0040] Figure 6 for Figure 4 A partial enlarged schematic diagram of point b in the middle;

[0041] Figure 7 for Figure 3 A local enlarged schematic diagram of point c in the middle.

[0042] Description of Figure Numbers:

[0043] 1000, hollow screw structure; 1, hollow screw; 11, water outlet; 21, first spacer; 22, second spacer; 23, third spacer; 24, fourth spacer; 31, first rotary oil seal; 32, second rotary oil seal; 33, third rotary oil seal; 34, fourth rotary oil seal; 35, fifth rotary oil seal; 36, sixth rotary oil seal; 4, sealing ring; 51, water inlet flange; 52, middle flange; 521, first leakage hole; 53, tail flange gland; 54, first bearing group; 61, water outlet flange; 611, second leakage hole; 612, water outlet joint; 62, motor seat; 63, motor seat flange gland; 64, second bearing group; 65, oil seal spacer; 66, oil seal pressure plate; 71, first locking nut; 72, second locking nut; 73, third locking nut; 74, fourth locking nut.

[0044] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0046] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0047] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the utility model, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the utility model.

[0048] In the field of CNC machine tool transmission technology, linear axes usually use servo motors to directly or indirectly connect precision ball screws to convert rotary motion into linear motion and perform motion control. In mid- and high-end CNC machine tools, in order to significantly improve their position accuracy, fast moving speed and dynamic response characteristics, more and more manufacturers use hollow internal cooling screws and use special fixing structures to fix the hollow screws.

[0049] The existing fixing structure or cooling device of the hollow screw adopts a rotary oil seal for radial sealing. The rotary oil seal is in direct contact with the surfaces of the two ends of the screw. After a certain period of operation, the friction between the lip of the rotary oil seal and the contact surface of the hollow screw causes wear, resulting in seal failure and reducing the service life of the hollow screw.

[0050] In order to solve the above problems, the utility model proposes a hollow screw structure 1000, including a hollow screw 1, a spacer assembly and an oil seal assembly, the hollow screw 1 having a first end and a second end along the length direction; the spacer assembly includes a first spacer 21 and a second spacer 22, the first spacer 21 is sleeved on the first end of the hollow screw 1 and is sealed with the first end of the hollow screw 1, the second spacer 22 is sleeved on the second end of the hollow screw 1 and is sealed with the second end of the hollow screw 1; the oil seal assembly includes at least two rotating oil seals, the outer peripheral wall sealing sleeve of the first spacer 21 is provided with at least one rotating oil seal, and the outer peripheral wall sealing sleeve of the second spacer 22 is provided with another rotating oil seal.

[0051] The technical solution of the utility model is to sleeve the first spacer 21 and the second spacer 22 on both ends of the hollow screw 1, and the first spacer 21 and the second spacer 22 are matched with the outer peripheral wall of the hollow screw 1 to achieve sealing. The first spacer 21 and the second spacer 22 and the hollow screw 1 remain in a relatively static state during rotation, thereby reducing the friction with the outer periphery of the hollow screw 1, and the rotary oil seal is installed on the outer periphery of the first spacer 21 and the second spacer 22 to achieve axial sealing of the spacer assembly, thereby avoiding the rotary oil seal from directly contacting the hollow screw 1 for a long time and causing wear, which leads to leakage caused by failure of the seal of the outer peripheral wall of the hollow screw 1, thereby extending the service life of the hollow screw 1.

[0052] In an optional embodiment, in order to improve the sealing effect between the hollow screw 1 and the spacer assembly, the hollow screw structure 1000 further includes a sealing ring 4; the inner circumferential wall of the first spacer 21 and the second spacer 22 is provided with a sealing groove, the sealing ring 4 is arranged in the sealing groove, and the sealing ring 4 is in sealing contact with the hollow screw 1. Please refer to Figures 1 to 7 , by respectively opening sealing grooves on the inner sides of the first spacer 21 and the second spacer 22 to accommodate the sealing ring 4, the inner and outer sides of the sealing ring 4 respectively abut against the hollow screw 1 and the spacer, thereby improving the axial sealing effect of the hollow screw 1. Optionally, the sealing groove can be opened on the outer peripheral wall of the hollow screw 1 in addition to the spacer, and the sealing effect can also be achieved. It can be selected according to actual needs and is not specifically limited here.

[0053] To further ensure the sealing effect of the sealing ring 4, the number of sealing grooves on the first spacer 21 and the second spacer 22 includes at least two each, and one sealing ring 4 is arranged in one sealing groove. Optionally, the sealing effect can be ensured by arranging multiple sealing rings 4 on the inner side of the first spacer 21 and the second spacer 22, respectively, and each sealing ring 4 is arranged at intervals along the axial direction of the spacer. In this embodiment, the number of sealing grooves on the first spacer 21 is two, and the number of sealing grooves on the third spacer 23 is three.

[0054] In an optional embodiment, in order to further ensure the axial sealing effect of the hollow screw 1, the spacer assembly also includes a third spacer 23 and a fourth spacer 24; the first end of the hollow screw structure 1000 also includes an inlet flange 51, an intermediate flange 52, and a tail flange pressure cover 53, which are sequentially abutted in the direction close to the second spacer 22, and a first bearing group 54 sleeved on the first end of the hollow screw 1, the side of the third spacer 23 facing away from the first spacer 21 abuts against the first bearing group 54, the outer peripheral wall of the first spacer 21 abuts against the inner peripheral wall of the intermediate flange 52, the outer peripheral wall of the third spacer 23 abuts against the inner peripheral wall of the tail flange pressure cover 53, the inlet flange 51, the intermediate flange 52, the tail flange pressure cover 53, the first spacer 21 and the third spacer 23 enclose and form a tail Sealed cavity of the seat; the second end of the hollow screw structure 1000 also includes an outlet flange 61, a motor seat 62, a motor seat flange pressure cover 63, and a second bearing group 64 sleeved on the second end of the hollow screw 1, the second bearing group 64 is clamped between the motor seat 62 and the motor seat flange pressure cover 63, the second sleeve 22 and the fourth sleeve 24 are axially arranged on both sides of the second bearing group 64, the outer peripheral wall of the second sleeve 22 abuts against the water outlet flange 61 and the inner peripheral wall of the motor seat 62, the outer peripheral wall of the fourth sleeve 24 abuts against the inner peripheral wall of the motor seat flange pressure cover 63, the outlet flange 61, the motor seat 62, the motor seat flange pressure cover 63, the second sleeve 22 and the fourth sleeve 24 enclose a sealed chamber of the motor seat 62. Please refer to Figure 5 At the first end of the hollow screw structure 1000, the coolant enters the middle hole of the hollow screw 1 from the water inlet joint on the left side of the water inlet flange 51 to realize cooling of the hollow screw 1 from the inside. Since the inner cavity of the water inlet flange 51 and the hollow screw 1 enclose a cavity, after the coolant enters the water inlet flange 51, a part of the coolant will be retained in the cavity. In order to prevent this part of the coolant from entering the first bearing group 54 along the axial direction of the hollow screw 1, the sealing effect of the hollow screw 1 is further guaranteed by setting a third spacer sleeve 23, and the rotating oil seal is set on the outer peripheral wall of the third spacer sleeve 23 to prevent the rotating oil seal from directly contacting the hollow screw 1. In this embodiment, the water inlet joint of the coolant is set in the axial direction of the water inlet flange 51, and is connected to the hollow screw 1 through the axial direction to input the coolant. In other embodiments, the water inlet joint can also be set in the radial direction of the hollow screw 1. At the second end of the hollow screw structure 1000, please refer to Figure 6 and Figure 7In order to seal the right side end of the second bearing group 64 and prevent the wear caused by the continuous friction between the rotating oil seal and the surface of the hollow screw 1, a fourth spacer 24 is provided at the right end of the second bearing group 64, and a rotating oil seal is provided on the outer periphery of the fourth spacer 24 for sealing. The first end and the second end of the hollow screw 1 are sealed respectively by the tailstock sealing chamber and the motor seat 62 sealing chamber at both ends of the hollow screw structure 1000, so as to prevent the coolant from leaking in the axial direction and affecting the normal operation of the first bearing group 54 and the second bearing group 64, thereby ensuring the stability of the hollow screw structure 1000.

[0055] In this embodiment, the oil seal assembly includes a first rotary oil seal 31, a second rotary oil seal 32, a third rotary oil seal 33, a fourth rotary oil seal 34, a fifth rotary oil seal 35 and a sixth rotary oil seal 36. The first rotary oil seal 31 is sleeved on the outer peripheral wall of the first spacer 21 and is axially clamped between the water inlet flange 51 and the middle flange 52; the second rotary oil seal 32 is sleeved on the outer peripheral wall of the third spacer 23, and the outer peripheral wall of the second rotary oil seal 32 abuts against the tail flange gland 53; The rotary oil seal 33, the fourth rotary oil seal 34 and the fifth rotary oil seal 35 are sequentially sleeved on the hollow screw 1 in the direction close to the second bearing group 64. The outer peripheral walls of the third rotary oil seal 33 and the fourth rotary oil seal 34 are both in contact with the inner peripheral wall of the outlet flange 61, and the outer peripheral wall of the fifth rotary oil seal 35 is in contact with the inner peripheral wall of the motor seat 62; the sixth rotary oil seal 36 is sleeved on the outer peripheral wall of the fourth spacer 24, and the outer peripheral wall of the sixth rotary oil seal 36 is in contact with the inner peripheral wall of the motor seat flange gland 63. Please refer to Figures 1 to 7 , by respectively setting a rotary oil seal on the outer peripheral wall of the first spacer 21, the second spacer 22, the third spacer 23 and the fourth spacer 24, the outer periphery of the hollow screw 1 in contact with each flange and sealed by the rotary oil seal can be separated by the spacer during the journey of the coolant from the water inlet joint to the water outlet joint 612, and the surface of the hollow screw 1 will not be damaged without affecting the sealing of each rotary oil seal, thereby extending the service life of the hollow screw 1. Even if each spacer and rotary oil seal are worn during use, only the spacer and rotary oil seal need to be replaced, without replacing the hollow screw 1, thereby reducing the maintenance cost of the hollow screw 1. In order to improve the strength of each spacer, the outer surface of the spacer is subjected to matching heat treatment to improve the surface strength, and the surface is polished to minimize the friction between the spacer and the rotary oil seal.

[0056] In an optional embodiment, in order to achieve the fixation of the first spacer 21, the second spacer 22, the third spacer 23 and the fourth spacer 24, the hollow screw structure 1000 also includes a first locking nut 71, a second locking nut 72, a third locking nut 73 and a fourth locking nut 74. The first end of the hollow screw 1 is formed with a step surface, the first spacer 21 abuts against the step surface, the first locking nut 71 is axially arranged on the side of the first spacer 21 that is away from the step surface; the second locking nut 72 is axially arranged on the side of the third spacer 23 that is away from the first bearing group 54; the third locking nut 73 is axially arranged on the side of the second spacer 22 that is away from the second bearing group 64; the fourth locking nut 74 is axially arranged on the side of the fourth spacer 24 that is away from the second bearing group 64. Please refer to Figures 5 to 7 The first locking nut 71 fixes the first spacer 21 by abutting the first spacer 21 against the step surface and screwing it to the hollow screw 1. The second locking nut 72 fixes the third spacer 23 by abutting the third spacer 23 against one side of the first bearing group 54 and screwing it to the hollow screw 1. The third locking nut 73 and the fourth locking nut 74 respectively abut the second spacer 22 and the fourth spacer 24 against both sides of the second bearing group 64 and screwing them to the hollow screw 1 to fix them. In this way, the four spacers are fixed on the hollow screw 1, avoiding the spacers from slipping along the axial direction of the hollow screw 1, ensuring the stability of the hollow screw structure 1000. In addition, the locking nuts at both ends of the hollow screw 1 can be used to pre-stretch the hollow screw 1 to improve the rigidity of the hollow screw 1.

[0057] In an optional embodiment, in order to discharge the coolant leaking from the first end of the hollow screw structure 1000 out of the flange, a first leakage hole 521 is opened at the bottom of the middle flange 52, and the hollow screw 1, the first spacer 21, the third spacer 23, the second rotary oil seal 32, the middle flange 52 and the tail flange gland 53 enclose a first chamber, and the first leakage hole 521 is located at the bottom of the first chamber to discharge the coolant leaking into the first chamber. Please refer to Figure 5 Even if the seal of the first end of the hollow screw structure 1000 fails, causing the coolant in the water inlet flange 51 to leak axially from the hollow screw 1 or the first spacer 21 into the inner cavity of the intermediate flange 52, the coolant is discharged in time through the first leakage hole 521 at the bottom of the intermediate flange 52 to prevent the coolant from continuing to move in the cavity and affecting the normal operation of the hollow screw 1, thereby ensuring the stability of the first end of the hollow screw structure 1000.

[0058] In an optional embodiment, in order to achieve normal discharge of coolant from the water outlet of the hollow screw structure 1000, a water outlet hole 11 is radially opened at the second end of the hollow screw 1, and the water outlet hole 11 is connected to the water outlet joint 612 on the water outlet flange 61. The second spacer 22 is circumferentially connected to the water outlet hole 11, and the third rotary oil seal 33 and the fourth rotary oil seal 34 are axially arranged on both sides of the water outlet hole 11. An oil seal spacer 65 is provided between the third rotary oil seal and the fourth rotary oil seal 34, and the outer peripheral wall of the oil seal spacer 65 abuts against the inner peripheral wall of the water outlet flange 61. An oil seal pressure plate 66 is provided on the side of the fourth rotary oil seal 34 facing away from the oil seal spacer 65. The oil seal pressure plate 66 is connected to the axial side wall of the water outlet flange 61 by screws to axially lock the fourth rotary oil seal 34. Please refer to Figure 6 and Figure 7 , a water outlet hole 11 is provided in the circumferential direction of the hollow screw 1. In this embodiment, the number of the water outlet holes 11 is 4 and they are evenly distributed at 90° intervals along the circumferential direction on the outer side of the hollow screw 1 relative to the motor seat 62. In other embodiments, the number of the water outlet holes 11 can be other numbers, and the position of the water outlet holes 11 can be set on the inner side of the hollow screw 1 relative to the motor seat 62, which is not specifically limited here. Connecting holes are provided in the circumferential direction of the second spacer 22 corresponding to each water outlet hole 11, and each connecting hole is coaxially arranged with each water outlet hole 11, so that the coolant can be discharged to the outside of the second spacer 22 through the connecting hole. In order to separate the third rotary oil seal 33 and the fourth rotary oil seal 34, an oil seal spacer 65 is provided between the third rotary oil seal and the fourth rotary oil seal. The outer periphery of the oil seal spacer 65 abuts against the inner wall of the outlet flange 61, and the two sides along the axial direction respectively abut against the third rotary oil seal and the fourth rotary oil seal, and the oil seal pressure plate 66 is fixed to the outlet flange 61 by screws to achieve the axial fixing and positioning of the third rotary oil seal, the oil seal spacer 65 and the fourth rotary oil seal. The outlet flange 61 is provided with an outlet joint 612 to communicate with the outlet hole 11 on the hollow screw 1, so as to discharge the coolant in the hollow screw 1 and ensure the cooling effect of the hollow screw 1.

[0059] Furthermore, in order to prevent the coolant from leaking from the axial direction of the fourth rotary oil seal to the second bearing group 64, a second leakage hole 611 is provided at the bottom of the outlet flange 61. The outlet flange 11, the second spacer 22, the fifth rotary oil seal 35, the oil seal pressure plate 66 and the motor seat 62 enclose a second chamber. The second leakage hole 611 is located at the bottom of the second chamber to discharge the coolant leaking into the second chamber. Please refer to Figure 6 and Figure 7 Even if the lip of the fourth rotary oil seal and the outer wall of the second spacer 22 produce a poor seal, causing the coolant to leak into the second chamber along the axial direction of the second spacer 22, the coolant can be discharged in time through the second leakage hole 611 at the bottom of the outlet flange 61 to ensure the stability of the second end of the hollow screw structure 1000.

[0060] The utility model also proposes a CNC machine tool, which includes a hollow screw structure 1000. The specific structure of the hollow screw structure 1000 refers to the above-mentioned embodiment. Since the CNC machine tool adopts all the technical solutions of all the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0061] The above are only exemplary embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A hollow screw structure, characterized in that: include: A hollow lead screw having a first end and a second end along a length direction; A spacer assembly, the spacer assembly comprising a first spacer and a second spacer, the first spacer being sleeved on a first end of the hollow lead screw and being sealed to the first end of the hollow lead screw, the second spacer being sleeved on a second end of the hollow lead screw and being sealed to the second end of the hollow lead screw; The oil seal assembly comprises at least two rotating oil seals, the outer peripheral wall sealing sleeve of the first spacer is provided with at least one rotating oil seal, and the outer peripheral wall sealing sleeve of the second spacer is provided with another rotating oil seal.

2. The hollow screw structure according to claim 1, characterized in that: The hollow screw structure also includes a sealing ring; the inner circumferential walls of the first spacer and the second spacer are provided with sealing grooves, the sealing ring is arranged in the sealing grooves, and the sealing ring is in sealing contact with the hollow screw.

3. The hollow screw structure according to claim 2, characterized in that: The number of the sealing grooves on the first spacer and the second spacer is at least two, and one sealing ring is arranged in one sealing groove.

4. The hollow screw structure according to any one of claims 1 to 3, characterized in that: The spacer assembly also includes a third spacer and a fourth spacer; The first end of the hollow screw structure also includes an inlet flange, an intermediate flange, a tail flange gland, and a first bearing group sleeved on the first end of the hollow screw, the side of the third sleeve facing away from the first sleeve abuts against the first bearing group, the outer peripheral wall of the first sleeve abuts against the inner peripheral wall of the intermediate flange, the outer peripheral wall of the third sleeve abuts against the inner peripheral wall of the tail flange gland, and the inlet flange, the intermediate flange, the tail flange gland, the first sleeve, and the third sleeve enclose a tail seat sealing cavity; The second end of the hollow screw structure also includes an outlet flange, a motor seat, a motor seat flange pressure cover, and a second bearing group sleeved on the second end of the hollow screw, the second bearing group is clamped between the motor seat and the motor seat flange pressure cover, the second spacer and the fourth spacer are axially arranged on both sides of the second bearing group, the outer peripheral wall of the second spacer is in contact with the water outlet flange and the inner peripheral wall of the motor seat, the outer peripheral wall of the fourth spacer is in contact with the inner peripheral wall of the motor seat flange pressure cover, the water outlet flange, the motor seat, the motor seat flange pressure cover, the second spacer and the fourth spacer enclose a motor seat sealing chamber.

5. The hollow screw structure according to claim 4, characterized in that: The oil seal assembly includes a first rotating oil seal, a second rotating oil seal, a third rotating oil seal, a fourth rotating oil seal, a fifth rotating oil seal and a sixth rotating oil seal. The first rotating oil seal is provided on the outer peripheral wall of the first spacer and is axially sandwiched between the water inlet flange and the intermediate flange; The second rotary oil seal is provided on the outer peripheral wall of the third spacer, and the outer peripheral wall of the second rotary oil seal abuts against the tail flange gland; The third rotary oil seal, the fourth rotary oil seal and the fifth rotary oil seal are sequentially sleeved on the hollow screw in a direction close to the second bearing group, the outer peripheral walls of the third rotary oil seal and the fourth rotary oil seal are both in contact with the inner peripheral wall of the water outlet flange, and the outer peripheral wall of the fifth rotary oil seal is in contact with the inner peripheral wall of the motor base; The sixth rotating oil seal is sleeved on the outer peripheral wall of the fourth spacer sleeve, and the outer peripheral wall of the sixth rotating oil seal abuts against the inner peripheral wall of the motor seat flange gland.

6. The hollow screw structure according to claim 5, characterized in that: The hollow screw structure also includes a first locking nut, a second locking nut, a third locking nut and a fourth locking nut. A step surface is formed on the first end of the hollow screw, the first spacer abuts against the step surface, and the first locking nut is axially arranged on a side of the first spacer facing away from the step surface; The second locking nut is axially arranged on a side of the third spacer sleeve facing away from the first bearing group; The third locking nut is axially arranged on a side of the second spacer sleeve facing away from the second bearing group; The fourth locking nut is axially arranged on a side of the fourth spacer sleeve facing away from the second bearing group.

7. The hollow screw structure according to claim 6, characterized in that: A first leakage hole is provided at the bottom of the middle flange, and the hollow screw, the first spacer, the third spacer, the second rotary oil seal, the middle flange and the tail flange gland form a first chamber. The first leakage hole is located at the bottom of the first chamber and is used to discharge the coolant leaked into the first chamber.

8. The hollow screw structure according to claim 7, characterized in that: A water outlet hole is radially opened at the second end of the hollow screw, the water outlet hole is communicated with the water outlet joint on the water outlet flange, the second spacer is circumferentially arranged to pass through the water outlet hole, the third rotary oil seal and the fourth rotary oil seal are axially arranged on both sides of the water outlet hole. An oil seal spacer is provided between the third rotary oil seal and the fourth rotary oil seal, and the outer peripheral wall of the oil seal spacer abuts against the inner peripheral wall of the water outlet flange. An oil seal pressure plate is provided on the side of the fourth rotary oil seal facing away from the oil seal spacer, and the oil seal pressure plate is connected to the axial side wall of the water outlet flange by screws to axially lock the fourth rotary oil seal.

9. The hollow screw structure according to claim 8, characterized in that: A second leakage hole is provided at the bottom of the water outlet flange, and the water outlet flange, the second spacer, the fifth rotating oil seal, the oil seal pressure plate and the motor seat form a second chamber. The second leakage hole is located at the bottom of the second chamber to discharge the coolant leaked into the second chamber.

10. A numerically controlled machine tool, characterized in that: Comprising the hollow screw structure as claimed in any one of claims 1 to 9.

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