A ball screw

Abstract

The present invention provides a ball screw, belonging to the technical field of ball screws. It solves the problems of poor driving force and low service life of the existing ball screws. The ball screw includes a screw rod and a screw sleeve. The outer circumference of the screw rod has externally threaded teeth distributed in a spiral manner, and a pitch groove is formed between adjacent externally threaded teeth. The inner side of the screw sleeve protrudes with internally threaded teeth distributed in a spiral shape and extending into the pitch groove. Both side surfaces of the externally threaded teeth are perpendicular to the outer circumferential surface of the screw rod, and both side surfaces of the internally threaded teeth are parallel to both side surfaces of the externally threaded teeth. A number of balls are provided on both sides of the internally threaded teeth in the pitch groove. In this design, the directions of the forces received by the two rows of balls when the screw sleeve moves forward or backward are always consistent with the moving direction of the screw sleeve, so that there will be no waste of extra force or idle work. Compared with the existing ball screws, under the same motor and the same output torque, the screw sleeve on the ball screw of this design can provide a more powerful driving force.

Description

Technical Field

[0001] The present invention belongs to the technical field of ball screws and relates to a ball screw. Background Art

[0002] A ball screw is a transmission device that converts rotary motion into linear motion. The main structure of a conventional ball screw, as shown in the accompanying instructions Figure 11 includes a screw rod, a nut sleeve, and balls. The nut sleeve is sleeved on the screw rod, and the balls are arranged between the nut sleeve and the screw rod. On the inner side surface of the nut sleeve and the outer circumferential surface of the screw rod, there are respectively semi-grooves I and semi-grooves II distributed in a spiral shape. The upper end of the ball can be stuck in the semi-groove I, and the lower end of the ball can be stuck in the semi-groove II. In this way, when the screw rod rotates circumferentially, it can drive the balls to roll along the semi-grooves I and II for guiding, that is, it can control the nut sleeve to reciprocate along the axis direction of the screw rod.

[0003] For example, for the screw rod and the screw nut introduced in a ball screw ball bearing described in the application number: 201820806370.8, there are steel balls arranged between the two. The connection relationship among these three is basically similar to the transmission principle of the above-mentioned ball screw. For example, for a high-precision wear-resistant ball screw described in the application number: 202122512264.3, balls are also embedded between the screw rod body and the screw nut, and its working principle is basically the same as the above. Figure 7 We can know that when the screw rod rotates forward and the nut sleeve moves forward, the force on the ball is in the direction marked a1 in the figure. When the screw rod rotates backward and the nut sleeve moves backward, the force on the ball is in the direction marked b1 in the figure. We can clearly conclude that no matter whether the nut sleeve moves forward or backward, the force on the ball is always oblique and not in the same direction as the forward and backward directions of the nut sleeve. We split the inclined forces in the a1 and b1 directions into a forward force parallel to the axis of the screw rod and a thrust perpendicular to the axis of the screw rod. We find that the actual forward force is the one that drives the screw rod to move forward and backward, while the acting direction of the thrust is perpendicular to the forward direction of the nut sleeve, so it does not play any role. Instead, it will increase the friction between the balls and the screw rod and the nut sleeve, resulting in excessive wear of the balls. Summary of the Invention

[0004] The purpose of the present invention is to address the above problems existing in the prior art and propose a ball screw. It solves the technical problems of poor driving force and low service life of the existing ball screw.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A ball screw, comprising a screw rod and a nut sleeve, wherein the outer periphery of the screw rod has externally threaded teeth distributed in a spiral manner, and a pitch groove is formed between adjacent externally threaded teeth. It is characterized in that the inner side of the nut sleeve protrudes with internally threaded teeth distributed in a spiral manner and extending into the pitch groove. The two side surfaces of the externally threaded teeth are perpendicular to the outer peripheral surface of the screw rod, and the two side surfaces of the internally threaded teeth are parallel to the two side surfaces of the externally threaded teeth. A plurality of balls are provided on both sides of the internally threaded teeth in the pitch groove.

[0007] The screw rod has externally threaded teeth distributed in a spiral manner, and a pitch groove is provided between adjacent externally threaded teeth. On the inner side of the nut sleeve, there are internally threaded teeth in a spiral shape that can cooperate with the pitch groove. The internally threaded teeth extend into the pitch groove and divide the pitch groove into two left and right channels. In these two channels, a row of balls is arranged respectively. When the screw rod of this design rotates forward and backward, it can respectively act on different rows of balls. That is, when rotating forward, due to the cooperation of the externally threaded teeth and the internally threaded teeth, the radial space of the above-mentioned left channel will become smaller, and the corresponding right channel will become larger. Therefore, the balls in the left channel are squeezed to make the balls receive force and conduct the force to the nut sleeve to drive it forward, while the balls in the right channel are not affected due to the enlarged channel. When rotating backward, the cooperation of the externally threaded teeth and the internally threaded teeth makes the radial space of the above-mentioned right channel become smaller, and the balls in the left channel are squeezed to transmit force to drive the nut sleeve to move backward. The right channel becomes larger and the balls in it are not affected. This ball screw controls forward and backward movements with different balls respectively. When moving forward, the left balls work and the right balls rest. When moving backward, the left balls rest and the right balls work. In this way, the wear of the same ball can be greatly reduced, thereby significantly increasing the service life of this ball screw.

[0008] The two side surfaces of the externally threaded teeth of this ball screw are perpendicular to the outer peripheral surface of the screw rod, and the two side surfaces of the internally threaded teeth are parallel to the two side surfaces of the externally threaded teeth. The two side walls of the above-mentioned two channels for accommodating balls are actually the side walls of the externally threaded teeth and the internally threaded teeth. Such a design means that the two side surfaces on both sides of the above-mentioned two channels along the length direction of the screw rod are parallel to each other and are both perpendicular to the outer peripheral surface of the screw rod. The balls are embedded between these two parallel surfaces. When the screw rod rotates to drive the nut sleeve to move forward and backward, the direction of the force received by the balls is always perpendicular to the two parallel surfaces and is consistent with the moving direction of the nut sleeve. In this way, there will be no waste of extra force or empty work. Compared with the existing ball screws under the same motor and the same output torque, the nut sleeve on the ball screw of this design can provide a more powerful driving force.

[0009] In the above-mentioned ball screw, concave portions are provided on both side surfaces of the externally threaded teeth. The concave portions have arc-shaped side surfaces, and partial portions of the sides of the balls are caught in the concave portions.

[0010] The design of the concave part can well hold the balls on both sides of the internal thread, restricting the balls from moving radially in the nut sleeve, preventing radial runout and the generation of noises, etc., making the entire ball screw operate more stably. At the same time, the concave part increases the contact area between the balls and the internal thread, making the driving force act more evenly and concentratedly, and further improving the strength of the driving force.

[0011] In the above-mentioned ball screw, the internal thread has a second top surface parallel to the central axis of the nut sleeve. The second top surface is in clearance fit with the bottom of the pitch groove. The external thread has a first top surface parallel to the axis of the screw rod. The first top surface is in clearance fit with the inner surface of the nut sleeve.

[0012] In this design, the inner diameter of the nut sleeve is very close to the outer diameter of the screw rod, and the fit degree between them is very high. This will enable the two side surfaces of the internal thread and the two side surfaces of the external thread to always remain parallel, making the force direction of the balls between them stably maintained in the movement direction of the nut sleeve. The thrust of the screw rod is only used to push the nut sleeve forward, which can further improve the driving force of the nut sleeve.

[0013] In the above-mentioned ball screw, bead inlet holes and bead outlet holes are respectively provided on the outer circumference at both ends of the nut sleeve opposite to the internal thread. A reversing device is arranged between the bead inlet holes and the bead outlet holes.

[0014] This ball screw has two rows of balls. One row is for bearing force during forward movement and the other row is for bearing force during backward movement. In order to enable the nut sleeve to move over a long distance, a reversing device needs to be installed on it to make the two rows of balls circulate respectively. When rotating forward, the reversing device can make the two rows of balls be discharged from the bead outlet holes one by one and then re-enter the bead inlet holes one by one to achieve long-distance movement. When rotating backward, the functions of the bead inlet holes and the bead outlet holes are swapped. The reversing device can make the balls be discharged from the bead inlet holes and enter from the bead outlet holes to form a cycle. This design has a clever structure and is very suitable for this ball screw.

[0015] In the above-mentioned ball screw, the reversing device includes a bead discharging seat and a bead entering seat. The bead discharging seat is embedded in the bead outlet hole. The bead entering seat is embedded in the bead inlet hole. The bead discharging seat has two bead discharging channels arranged side by side. The inlets of the two bead discharging channels are respectively located in the pitch grooves on both sides of the internal thread and both inlets are close to the bottom of the pitch groove. The bead entering seat has two bead entering channels arranged side by side. The outlets of the two bead entering channels are located in the pitch grooves on both sides of the internal thread and the inlets of the two bead entering channels are close to the bottom of the pitch groove. The outlets of the two bead discharging channels are respectively connected to the inlets of one bead entering channel through connecting pipes.

[0016] The reverse device of this design is composed of a ball inlet seat and a ball outlet seat. The ball inlet seat has two ball inlet channels, and the ball outlet seat has two ball outlet channels. When the screw rotates forward, two rows of ball bearings in the pitch groove can enter one by one from the inlet of the ball inlet channel, move along the ball inlet channel, enter the connecting pipe, be transmitted into the ball outlet seat, and then re-enter the pitch groove from the outlet of the ball outlet channel. When the screw rotates in reverse, the above cycle is just the opposite. The ball bearings can enter the ball outlet seat from the outlet of the ball outlet channel, then be introduced into the connecting pipe, then from the connecting pipe into the ball inlet seat, and then re-enter the pitch groove from the inlet of the ball inlet channel. Such a design can make the ball bearings on this ball screw circulate, and such an independent cycle can reduce the wear of the ball bearings and increase the service life.

[0017] In the above-mentioned ball screw, the reverse device includes a ball outlet seat and a ball inlet seat. The ball inlet seat and the ball outlet seat are respectively embedded in the ball inlet hole and the ball outlet hole. The ball outlet seat is provided with two parallel ball outlet channels, and the ball inlet seat is provided with two parallel ball inlet channels. Two ball passing channels that can respectively connect the outlet of one ball outlet channel and the inlet of one ball inlet channel are opened on the outer peripheral surface of the screw sleeve. The ball outlet seat partially passes through the ball outlet hole and abuts against the external thread, and the inlets of the two ball outlet channels are respectively located on both sides of the external thread. The ball inlet seat partially passes through the ball inlet hole and abuts against the external thread, and the outlets of the two ball inlet channels are respectively located on both sides of the external thread.

[0018] This is another technical solution of this case. In this technical solution, other structures are basically the same as the above solution. The difference is that the ball outlet channel and the ball inlet channel in this solution are connected through the ball passing channels opened on the screw sleeve instead of through the connecting pipe. Such a design can achieve the same technical effect as connecting through the connecting pipe.

[0019] In the above-mentioned ball screw, the two ball passing channels are parallel to each other and are both arranged around the outer periphery of the screw sleeve.

[0020] The ball passing channels arranged around the outer periphery of the screw sleeve can extend its length, making the arrangement of the ball bearings longer and making the ball bearing circulation softer and more stable.

[0021] In the above-mentioned ball screw, the reverse device includes two rigid conduits. Each conduit has an inner hole through which the ball bearings can pass. The two ends of the two conduits are respectively inserted into the ball inlet hole and the ball outlet hole, and the two ends of one of the conduits are near the bottom of the pitch groove between side one and side two, and the two ends of the other conduit are near the bottom of the pitch groove between side three and side four.

[0022] This is another technical solution of this case. In this technical solution, the reversing device uses two tubes to reverse the balls. Compared with the first technical solution, this solution is simpler. The tubes are directly inserted into the ball holes and the ball discharge holes. The tubes are made of hard materials and their ends can be directly extended to the bottom of the pitch groove. The balls can directly enter the tubes and move after rolling over. This design can achieve the same effect as the above technical solution and improve the service life.

[0023] In the above-mentioned ball screw, both ends of the two guide tubes have oblique cuts.

[0024] In the above scheme, the ends of the two conduits have bevel cuts, which can be arranged upward so that the tip of the conduit is close to the bottom of the pitch groove, so that the ball can enter the conduit more easily, reduce resistance and increase driving force.

[0025] In the above-mentioned ball screw, a first clamping groove is provided at the bottom of the ball seat along its length direction, and the ball seat is clamped on the external thread through the first clamping groove, and when the screw rotates, the ball seat can be guided and moved along the external thread through the first clamping groove. A second clamping groove is provided at the bottom of the ball entering seat along its length direction, and the ball entering seat is also clamped on the external thread through the second clamping groove, and when the screw rotates, the ball entering seat can also be guided and moved along the external thread through the first clamping groove.

[0026] The ball entry seat and ball removal seat of the present invention are respectively clamped on the external thread by means of the first clamping groove and the second clamping groove and can move along the guide of the external thread. Such a structure similar to a slide rail can make the fit between the ball entry seat and the ball removal seat and the external thread tighter and smoother, making the circulation of the ball smoother.

[0027] In the above-mentioned ball screw, the ball discharge seat is provided with a guide part 1 located at the entrance of the ball discharge channel, which can smoothly guide the balls on both sides of the external thread into the corresponding ball discharge channel, and the ball entering seat is provided with a guide part 2 located at the exit of the ball entering channel, which can smoothly guide the balls in the ball entering seat into the two sides of the external thread.

[0028] Guide part one and guide part two can be closer to the outer circumference of the screw, so that the roller can easily roll into the ball discharge channel along guide part one when passing through one guide part, and then enter the connecting pipe through the ball discharge channel and then enter the ball entry channel, and then be re-introduced into the pitch groove by guide part two. The design of guide part one can make the ball be guided out more easily, and the design of guide part two makes the ball enter the pitch groove more smoothly and quietly.

[0029] In the above-mentioned ball screw, the ball inlet hole and the ball outlet hole are arranged opposite to each other and the two connecting pipes are both surrounded on the outer side of the outer circumference of the screw sleeve.

[0030] The sleeve is arranged around the outer periphery of the screw sleeve, enabling the balls inside to move more smoothly and having better stability.

[0031] Compared with the prior art, the advantages of this product are as follows:

[0032] 1. When the screw rotates forward and backward, the force can act on different rows of balls respectively. That is, for forward and backward movement, two rows of balls are used for transmission. When moving forward, the left-side balls work and the right-side balls rest; when moving backward, the left-side balls rest and the right-side balls work. In this way, compared with the existing design where the same row of balls is squeezed during both forward and backward movement, resulting in double wear, the service life of this ball screw is significantly increased.

[0033] 2. In this design, the direction of the force received by the two rows of balls during the forward or backward movement of the screw sleeve is always consistent with the moving direction of the screw sleeve. Thus, there will be no waste of extra force or empty work. Compared with the existing ball screw, under the same motor and the same output torque, the screw sleeve on this ball screw can provide a more powerful driving force.

[0034] 3. The recessed parts on the external threads can well hold the balls on both sides of the internal threads, restricting the balls from moving in the radial direction of the screw sleeve and preventing radial runout and the generation of noise, etc., making the entire ball screw operate more stably. At the same time, the recessed parts increase the contact area between the balls and the internal threads, making the driving force act more evenly and concentrated, further improving the intensity of the driving force. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a half-sectional view of the present invention;

[0036] Figure 2 is the present invention in Figure 1 local enlarged view at A;

[0037] Figure 3 is the force direction marking diagram of the balls during the operation of the present invention;

[0038] Figure 4 is the installation schematic diagram of the reverse device of the present invention;

[0039] Figure 5 is the schematic diagram of the installation position of the reverse device of the present invention;

[0040] Figure 6 is the schematic diagram of the cooperation between the reverse device and the screw of the present invention;

[0041] Figure 7 is the present invention in Figure 6 local enlarged view at B;

[0042] Figure 8 is the structural schematic diagram of the reverse device of the present invention;

[0043] Figure 9 It is the part drawing of the bead row seat of the present invention;

[0044] Figure 10 It is the part drawing of the bead inlet seat of the present invention;

[0045] Figure 11 It is the force direction diagram of the balls on the existing ball screw;

[0046] Figure 12 It is the partial structure sectional view of Embodiment 3 of the present invention.

[0047] In the figure, 1 is the screw; 11 is the external thread; 111 is the first top surface; 112 is the recessed part; 12 is the pitch groove; 2 is the screw sleeve; 21 is the internal thread; 211 is the second top surface; 22 is the ball inlet hole; 23 is the bead row hole; 3 is the ball; 4 is the reverse device; 41 is the bead row seat; 411 is the bead row channel; 412 is the first guiding part; 413 is the first guiding surface; 42 is the bead inlet seat; 421 is the bead inlet channel; 422 is the second guiding part; 423 is the second guiding surface; 43 is the connecting pipe. Specific Embodiments

[0048] The following are specific embodiments of the present invention and in combination with the accompanying drawings, the technical solutions of the present invention will be further described, but the present invention is not limited to these embodiments.

[0049] Embodiment 1

[0050] Such as Figures 1 - 10A ball screw as shown includes a screw rod 1 and a screw sleeve 2. The outer periphery of the screw rod 1 has externally threaded teeth 11 distributed in a spiral manner. Pitch grooves 12 are formed between adjacent externally threaded teeth 11. The inner side of the screw sleeve 2 protrudes with internally threaded teeth 21 distributed in a spiral shape and extending into the pitch grooves 12. The two side walls of the pitch grooves 12 are perpendicular to the outer peripheral surface of the screw rod 1, and the two side surfaces of the internally threaded teeth 21 are parallel to the two side walls of the pitch grooves 12. A row of ball groups 3 is arranged on both sides of the internally threaded teeth 21 in the pitch grooves 12, and the ball groups 3 are formed by arranging balls 3 one by one. The screw rod 1 has externally threaded teeth 11 distributed in a spiral manner, and pitch grooves 12 are provided between adjacent externally threaded teeth 11. The inner side of the screw sleeve 2 has internally threaded teeth 21 in a spiral shape and capable of cooperating with the pitch grooves 12. The internally threaded teeth 21 extend into the pitch grooves 12 to divide the pitch grooves 12 into two left and right channels. A row of balls 3 is arranged in each of these two channels. In the present design, when the screw rod 1 rotates forward and backward, forces can be respectively applied to different rows of balls 3. That is, when rotating forward, due to the cooperation of the externally threaded teeth 11 and the internally threaded teeth 21, the radial space of the left channel mentioned above will become smaller, and the corresponding right channel will become larger. Therefore, the balls 3 in the left channel are squeezed to make the balls 3 receive force and conduct the force to the screw sleeve 2 to drive it forward, while the balls 3 in the right channel are not affected due to the enlarged channel. When rotating backward, the cooperation of the externally threaded teeth 11 and the internally threaded teeth 21 makes the radial space of the right channel mentioned above become smaller, and the balls 3 in the left channel are squeezed to transmit force to drive the screw sleeve 2 to move backward, and the right channel becomes larger and the balls 3 in it are not affected. This ball screw controls forward and backward movements respectively with different balls 3. When moving forward, the left balls 3 work and the right balls 3 rest. When moving backward, the left balls 3 rest and the right balls 3 work. In this way, the wear of the same ball 3 can be greatly reduced, thereby significantly increasing the service life of this ball screw. The two side surfaces of the externally threaded teeth 11 of this ball screw are perpendicular to the outer peripheral surface of the screw rod 1, and the two side surfaces of the internally threaded teeth 21 are parallel to the two side walls of the externally threaded teeth 11. Such a design means that the two side surfaces on both sides of the two channels along the length direction of the screw rod 1 are parallel to each other and perpendicular to the outer peripheral surface of the screw rod 1, as Figure 3 As shown in the force condition of the balls 3, when moving forward, the force on the balls 3 is in the direction pointed by a2 in the figure, that is, consistent with the forward direction of the screw sleeve 2. Conversely, when moving backward, the force on the balls 3 is in the direction pointed by b2 in the figure, that is, consistent with the backward direction of the screw sleeve 2. The direction of the force received by the balls 3 is also always perpendicular to the two parallel planes and consistent with the moving direction of the screw sleeve 2, so that no extra force is wasted or useless work is done. Compared with the existing ball screws under the same motor and the same output torque, the screw sleeve 2 on this designed ball screw can provide a more powerful driving force.

[0051] The inner thread 21 has a second top surface 211 parallel to the center line of the screw sleeve 2. The second top surface 211 is in clearance fit with the bottom of the pitch groove 12. The outer thread 11 has a first top surface 111 parallel to the axis of the screw 1. The first top surface 111 is in clearance fit with the inner surface of the screw sleeve 2. The inner diameter of the screw sleeve 2 in this design is very close to the outer diameter of the screw 1, and the fit degree between the two is very high. This will enable the two side surfaces of the inner thread 21 and the two side surfaces of the outer thread 11 to always remain parallel, so that the force direction of the ball 3 between the two can be stably maintained in the moving direction of the screw sleeve 2. The thrust of the screw 1 is only used to push the screw sleeve 2 forward, which can further improve the driving force of the screw sleeve 2.

[0052] On the outer peripheries at both ends of the screw sleeve 2, a ball inlet hole 22 and a ball outlet hole 23 are respectively formed opposite to the internal thread 21. A reverse device 4 is arranged between the ball inlet hole 22 and the ball outlet hole 23. This ball screw has two rows of balls 3, one row for bearing force during forward movement and the other row for bearing force during backward movement. In order to enable the screw sleeve 2 to move over a long distance, it is necessary to install a reverse device 4 on it to make the two rows of balls 3 circulate independently. When rotating forward, the reverse device 4 can make the two rows of balls 3 be discharged from the ball outlet hole 23 one by one and then re-enter the ball inlet hole 22 one by one to achieve long-distance movement. When rotating backward, the functions of the ball inlet hole 22 and the ball outlet hole 23 are swapped. The reverse device 4 can make the balls 3 be discharged from the ball inlet hole 22 and enter from the ball outlet hole 23 to form a cycle. This design has a clever structure and is very suitable for this ball screw. The reverse device 4 includes a ball discharge seat 41 and a ball inlet seat 42. The ball discharge seat 41 is embedded in the ball outlet hole 23, and the ball inlet seat 42 is embedded in the ball inlet hole 22. The ball discharge seat 41 has two juxtaposed ball discharge channels 411. The inlets of the two ball discharge channels 411 are respectively located in the pitch grooves 12 on both sides of the internal thread 21, and the inlets of the two ball discharge channels 411 are both arranged close to the bottom of the pitch groove 12. The ball inlet seat 42 has two juxtaposed ball inlet channels 421. The outlets of the two ball inlet channels 421 are located in the pitch grooves 12 on both sides of the internal thread 21, and the inlets of the two ball inlet channels 421 are close to the bottom of the pitch groove 12. The outlets of the two ball discharge channels 411 are respectively communicated with the inlets of one ball inlet channel 421 through a connecting pipe 43. When the screw 1 rotates forward, the two rows of balls 3 in the pitch groove 12 can enter from the inlets of the ball inlet channels 421 one by one, move along the ball inlet channels 421, enter the connecting pipe 43, be transmitted into the ball discharge seat 41, and then re-enter the pitch groove 12 from the outlets of the ball discharge channels 411. When the screw 1 rotates backward, the above cycle is just the opposite. The balls 3 can enter the ball discharge seat 41 from the outlets of the ball discharge channels 411, then be introduced into the connecting pipe 43, be introduced from the connecting pipe 43 into the ball inlet seat 42, and then re-enter the pitch groove 12 from the inlets of the ball inlet channels 421. This design can make the balls 3 on this ball screw circulate, and such an independent cycle can reduce the wear of the balls 3 and increase the service life. On the ball discharge seat 41, a first guiding part 412 is arranged at the inlet of the ball discharge channel 411. The first guiding part 412 has an inclined first guiding surface. The highest point of the first guiding surface is flush with the bottom wall of the ball discharge channel 411, and the lowest point of the first guiding surface abuts against the bottom of the pitch groove 12. On the ball inlet seat 42, a protruding second guiding part 422 is arranged at the outlet of the ball inlet channel 421. The second guiding part 422 has an inclined second guiding surface. The highest point of the second guiding surface is flush with the bottom wall of the ball inlet channel 421, and the lowest point of the second guiding surface abuts against the bottom of the pitch groove 12.On the bead inlet seat 42 and the bead row seat 41 of this design, there are respectively protruding a first guiding part 412 and a second guiding part 422 for cooperating with the bottom of the pitch groove 12. The first guiding part 412 and the second guiding part 422 can abut against the bottom of the pitch groove 12, and there are a first guiding surface and a second guiding surface thereon, which can allow the ball 3 to roll into the channel therein along the first guiding surface or the second guiding surface, enabling the ball 3 to circulate more smoothly, effectively reducing wear and increasing the service life. On the outer peripheral surface of the screw sleeve 2, between the bead inlet hole 22 and the bead row hole 23, there are provided two side-by-side and helically arranged mounting grooves, and each of the two connecting pipes 43 is embedded in one mounting groove. Along the length direction of the bottom of the bead row seat 41, there is provided a first clamping groove 413. The bead row seat 41 is clamped on the external thread 11 through the first clamping groove 413, and when the screw rod 1 rotates, the bead row seat 41 can be guided to move along the external thread 11 through the first clamping groove 413. Along the length direction of the bottom of the bead inlet seat 42, there is provided a second clamping groove 421. The bead inlet seat 42 is also clamped on the external thread 11 through the second clamping groove 421, and when the screw rod 1 rotates, the bead inlet seat 42 can also be guided to move along the external thread 11 through the first clamping groove 421. The bead inlet seat 42 and the bead row seat 41 of this design are respectively clamped on the external thread 11 through the first clamping groove 413 and the second clamping groove 423 and can be guided to move along the external thread 11. Such a structure similar to a slide rail can make the cooperation between the bead inlet seat 42 and the bead row seat 41 and the external thread 11 closer and smoother, making the ball 3 circulate more smoothly when circulating.

[0053] Working process of this ball screw: When the screw rod 1 rotates forward and the screw sleeve 2 remains stationary circumferentially, the left channel formed between the external thread 11 and the internal thread 21 will become smaller and the right channel will become larger. That is, the ball 3 in the left channel will be squeezed by the side surface of the external thread 11 and roll along the side surface of the external thread 11 for guiding. In this way, the internal thread 21 will be driven to be stressed. If the internal thread 21 does not rotate circumferentially, it will move forward. The ball 3 in the right channel will not be squeezed by the internal thread 21 and the external thread 11 because the radial area of the right channel becomes larger, and it only needs to roll along the right channel with small friction and small wear. When the balls 3 in the left channel and the right channel roll to the bead row seat 41, they can be respectively discharged from the two bead row channels 411 and re-enter the pitch groove 12 through the bead inlet channel 421 on the bead inlet seat 42. In this way, the ball 3 reciprocally circulates and rolls and the screw sleeve 2 moves forward; When the screw rod 1 rotates reversely and the screw sleeve 2 remains stationary circumferentially, the left channel formed between the external thread 11 and the internal thread 21 will become larger and the right channel will become smaller. When the ball 3 in the right channel is squeezed and guided to roll, the friction increases. The ball 3 in the left channel will follow the rotation with smaller friction and smaller wear. The balls 3 in the left channel and the right channel can enter the connecting pipe 43 from the two bead inlet channels 421 of the bead inlet seat 42 and then re-enter the pitch groove 12 through the bead row channels 411 on the bead row seat 41 to form a cycle and make the screw sleeve 2 retreat.

[0054] Embodiment 2

[0055] In this embodiment, the reverse device 4 includes two rigid conduits, each of which has an inner hole through which the balls 3 can pass. The two ends of the two conduits are respectively inserted into the ball inlet holes 22 and the ball outlet holes 23, and the two ends of one of the conduits are near the bottom of the pitch groove 12 between the first side and the second side, and the two ends of the other conduit are near the bottom of the pitch groove 12 between the third side and the fourth side. The two ends of the two conduits each have an inclined cut. In the above solution, the ends of the two conduits have inclined cuts, and the inclined cuts can be arranged upward so that the tip ends of the conduits are close to the bottom of the pitch groove 12, making it easier for the balls 3 to enter the conduits, reducing the resistance generated, and increasing the driving force. There are clamping blocks for limiting the two conduits in both the ball inlet holes 22 and the ball outlet holes 23. The clamping blocks can fix the ends of the two conduits to keep their positions unchanged when reversing the balls 3, increasing the stability. Compared with the first technical solution, this solution is relatively simple. By directly inserting the conduits into the ball inlet holes 22 and the ball outlet holes 23, and the conduits are made of rigid materials and can directly extend their ends near the bottom of the pitch groove 12. When the balls 3 roll over, they can directly enter the conduits for movement. Such a design can achieve the same effect as the above technical solution and improve the service life.

[0056] Embodiment III

[0057] As Figure 12 shown, in this embodiment, recessed portions 112 are provided on both sides of the external thread 11 of the screw rod 1 along its helical direction. The recessed portions 112 are actually grooves, but the arc surfaces on the groove walls fit the outer circumference of the balls 3. The sides of the balls 3 are partially caught in the recessed portions 112. The design of the recessed portions 112 can well catch the balls 3 on both sides of the internal thread 21, limit the balls 3 in the radial direction of the nut 2 so that they cannot move, prevent radial runout from generating noise and other situations, making the entire ball screw run more stably. At the same time, the recessed portions 112 increase the contact area between the balls 3 and the internal thread 21, making the driving force act more evenly and concentrated, and further improving the strength of the driving force.

[0058] Embodiment IV

[0059] In this embodiment, two parallel ball passing channels are provided around the outer peripheral surface of the nut 2. Such two channels can play the same role as the connecting pipe 43, that is, connecting the ball inlet channel 421 and the ball outlet channel 411, and allowing two rows of balls 3 to pass through.

[0060] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art of the present invention can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A ball screw, comprising a screw rod (1) and a screw sleeve (2), wherein the outer periphery of the screw rod (1) has externally threaded teeth (11) distributed in a spiral manner, and a pitch groove (12) is formed between adjacent externally threaded teeth (11), characterized in that, On the inner side of the screw sleeve (2), there protrude inner screw teeth (21) which are spirally distributed and extend into the pitch groove (12). Both side surfaces of the outer screw teeth (11) are perpendicular to the outer peripheral surface of the screw rod (1), and both side surfaces of the inner screw teeth (21) are parallel to both side surfaces of the outer screw teeth (11). A number of balls (3) are provided on both sides of the inner screw teeth (21) within the pitch groove (12). On the outer peripheries at both ends of the screw sleeve (2), a ball inlet hole (22) and a ball outlet hole (23) are respectively formed. A reverse device (4) for allowing the balls (3) to circulate and roll is arranged between the ball inlet hole (22) and the ball outlet hole (23). The reverse device (4) includes a ball outlet seat (41) and a ball inlet seat (42). Two parallel ball outlet channels (411) are provided on the ball outlet seat (41), and two parallel ball inlet channels (421) are provided on the ball inlet seat (42). The outlets of the two ball outlet channels (411) are respectively communicated with the inlets of one ball inlet channel (421). The inlets of the two ball outlet channels (411) are respectively located on both sides of the outer screw teeth (11), and the outlets of the two ball inlet channels (421) are respectively located on both sides of the outer screw teeth (11). A first card slot (413) is formed at the bottom of the ball outlet seat (41) along its length direction. The ball outlet seat (41) is clamped on the outer screw teeth (11) through the first card slot (413), and when the screw rod (1) rotates, the ball outlet seat (41) can be guided to move along the outer screw teeth (11) through the first card slot (413). A second card slot (423) is formed at the bottom of the ball inlet seat (42) along its length direction. The ball inlet seat (42) is also clamped on the outer screw teeth (11) through the second card slot (423), and when the screw rod (1) rotates, the ball inlet seat (42) can also be guided to move along the outer screw teeth (11) through the second card slot (423). The inlets of the two ball outlet channels (411) are connected to the first card slot (413), and the outlets of the two ball inlet channels (421) are connected to the second card slot (423).

2. A ball screw according to claim 1, characterized in that, Depressions (112) are provided on both side surfaces of the outer screw teeth. The depressions (112) have arc-shaped side surfaces, and part of the sides of the balls (3) are respectively clamped into the depressions (112).

3. A ball screw according to claim 2, characterized in that, The inner screw teeth (21) have a second top surface (211) parallel to the center line of the screw sleeve (2). The second top surface (211) is in clearance fit with the bottom of the pitch groove (12). The outer screw teeth (11) have a first top surface (111) parallel to the axis of the screw rod (1). The first top surface (111) is in clearance fit with the inner surface of the screw sleeve (2).

4. A ball screw according to claim 3, characterized in that Both the ball inlet hole (22) and the ball outlet hole (23) are located between two adjacent inner screw teeth (21).

5. A ball screw according to claim 1 or 2 or 3 or 4, characterized in that The outlets of the two ball outlet channels (411) are respectively communicated with the inlets of one ball inlet channel (421) through a connecting pipe (43). The ball outlet seat (41) is located within the ball outlet hole (23), and the ball outlet seat (41) partially passes through the ball outlet hole (23) and abuts against the outer screw teeth (11). The ball inlet seat (42) is located within the ball inlet hole (22), and the ball inlet seat (42) partially passes through the ball inlet hole (22) and abuts against the outer screw teeth (11).

6. A ball screw according to claim 1 or 2 or 3 or 4, characterized in that, The bead inlet seat (42) and the bead outlet seat (41) are respectively embedded in the bead inlet hole (22) and the bead outlet hole (23). Two bead passing channels are formed on the outer peripheral surface of the screw sleeve (2), which can respectively connect the outlet of a bead outlet channel (411) with the inlet of a bead inlet channel (421). Part of the bead outlet seat (41) passes through the bead outlet hole (23) and abuts against the external thread (11), and part of the bead inlet seat (42) passes through the bead inlet hole (22) and abuts against the external thread (11).

7. A ball screw according to claim 6, characterized in that, The two bead passing channels are parallel to each other and are both arranged around the outer periphery of the screw sleeve (2).

8. A ball screw according to claim 5, characterized in that, At the inlet of the bead outlet channel (411) on the bead outlet seat (41), a first guiding part (412) is provided, which can smoothly guide the balls (3) on both sides of the external thread (11) into the corresponding bead outlet channel (411). At the outlet of the bead inlet channel (421) on the bead inlet seat (42), a second guiding part (422) is provided, which can smoothly guide the balls (3) in the bead inlet seat (42) into both sides of the external thread (11).

9. A ball screw according to claim 5, characterized in that The bead inlet hole (22) and the bead outlet hole (23) are oppositely arranged, and the two connecting pipes (43) are both arranged around the outer periphery of the screw sleeve (2).

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