Rolling nut and rolling screw rod pair thereof

Abstract

A rolling nut and a rolling screw rod pair thereof are characterized in that the rolling screw rod pair is provided with a central screw rod and 2-30 peripheral screw rods which are meshed with the central screw rod and have equal pitch, and the shaft end of each peripheral screw rod is provided with a rolling bearing for bearing axial thrust, a bearing for bearing radial force and a bearing seat. The bearing seat ensures that the meshing center distance and the axis of the central screw rod and the peripheral screw rods are parallel, and all the peripheral screw rods, the bearings at the shaft ends and the bearing seat form a rolling nut; the rolling nut can be a complete cylinder or a part of the cylinder; the central screw rod can actively rotate, or the peripheral screw rods can actively rotate while the peripheral screw rod bearing seats do not rotate, or the rolling nut can integrally rotate, that is, the bearing seats at the two ends of the peripheral screw rods are connected together and synchronously rotate, and the peripheral screw rods rotate and revolve; and a rolling bearing for bearing axial thrust is arranged at the end part of each rotating central screw rod or rolling nut.

Description

Technical Field

[0001] The utility model belongs to a mechanical part of a spiral transmission, in particular to a rolling screw pair, a rolling nut and a rolling screw pair thereof. Background Art

[0002] The various existing rolling screws include ball screws and roller screws. The ball screw has a smaller load-bearing capacity and is mainly used for feed mechanisms. The roller screw has a large load but has not been widely promoted in China and is expensive. The existing roller screw is composed of a screw, a roller, and a nut. The outer diameter of the nut is provided with a flange, and the nut and the flange bear the axial thrust. When the screw stiffness requirements are high or the installation space is limited, it is difficult to choose a suitable model. Summary of the invention

[0003] The problem to be solved by the utility model is to provide a rolling nut and a rolling screw pair thereof, wherein the rolling nut may not have a flange, the rolling nut may be cylindrical, or may be only a part of a cylinder, the diameter of the screw rod may be increased, the rigidity of the screw rod pair may be improved, and the installation size may be reduced.

[0004] In order to achieve the above-mentioned purpose, a rolling nut and a rolling screw pair thereof are characterized in that: the rolling screw pair comprises a central screw and 2 to 30 peripheral screws with equal pitch meshing therewith, each peripheral screw shaft end is provided with a rolling bearing that bears axial thrust, a bearing that bears radial force, and a bearing seat, the bearing seat ensures that the meshing center distance and axis of the central screw and the peripheral screw are parallel, and all the peripheral screws and the bearings and bearing seats at the shaft ends constitute a rolling nut; the rolling nut can be a complete cylinder or a part of a cylinder; the central screw can actively rotate, or the peripheral screw can actively rotate while the peripheral screw bearing seats do not rotate, or the rolling nut can rotate as a whole, that is, the bearing seats at both ends of the peripheral screw are connected together and rotate synchronously, the peripheral screw rotates and revolves, and the end of each rotating central screw or rolling nut is provided with a rolling bearing that bears axial thrust.

[0005] The full complement tapered roller thrust bearings and various thrust roller bearings used in the rolling mill's pressing mechanism have a greater ability to withstand axial forces and can be used as a priority. The tapered roller bearings at the ends of the peripheral screw shafts can also be used to withstand axial and radial forces at the same time. Depending on the size of the radial force and the spatial dimensions, the bearing that withstands the radial force can be a rolling bearing or other bearing.

[0006] The rolling nut and rolling screw pair described above are characterized in that the thread rotation directions of the central screw and the peripheral screw are opposite, the force-bearing tooth surface has a small bevel angle and can be self-locking or nearly self-locking in the radial direction, and the tooth shape is designed to ensure that the contact line is near the center line connecting the central screw and the peripheral screw and has sufficient contact strength, meet the bending strength of the tooth root, reduce the outer diameter of the rolling nut and the radial load of the rolling bearing.

[0007] Since the peripheral screw is equipped with rolling bearings that bear axial thrust, the diameter of the peripheral screw is larger, but the difference in the helix angle between the peripheral screw and the central screw is reduced, and the width of the root subjected to bending moment is also longer. Under the condition of sufficient contact stress on the tooth surface, the sliding friction loss of the tooth surface is small when the contact line is short; the stress tooth surface has a smaller bevel angle, which can increase the radius of the two contact surfaces at the contact line and reduce the contact stress; the bevel angle of the stress tooth surface of the serrated thread is 3 degrees, which can self-lock in the radial direction, and the bevel angle of the non-stress tooth surface is 30 degrees, which can increase the thickness of the root, and is a usable tooth surface bevel angle.

[0008] Most existing roller screws use triangular tooth profiles. The radial friction force of the roller cannot be self-locking. The roller is subjected to large radial force, but there is a fixed nut outside the roller to withstand radial force and axial force. The roller is in a balanced state under the radial force. The difference in the helix angle between the roller and the fixed nut is large, requiring a larger radial tooth surface bevel angle.

[0009] The rolling nut and rolling screw pair described above are characterized in that: the rolling nut is composed of 2 to 15 coaxial short rolling nuts connected in series to reduce the load on the rolling bearing of each short rolling nut, and the axial thrust of the rolling screw pair is directly transmitted to each other by the bearing seats of each short rolling nut, and can also be transmitted to the components for installing the short rolling nuts by the bearing seats of each short rolling nut, and each short rolling nut only bears part of the axial thrust of the rolling screw pair; 2 to 5 rolling nuts are coaxially connected in series, and the bearing seats of some or all of the rolling nuts are provided with springs to limit the axial thrust they are subjected to, so that the rolling nut only bears part of the preset axial thrust of the rolling screw pair, and the axial thrust can also be transmitted to the components for installing the rolling nut by each rolling nut and the rolling nut and its spring respectively.

[0010] Over the meshing length of the screw rod and the nut, the force on each tooth is uneven, and the number of tooth circles used for strength calculations is limited. The bearing seats of some rolling nuts are equipped with springs to limit the axial thrust they receive, which can increase the number of tooth circles used for calculations and can also be used for equipment with impact force.

[0011] The beneficial effects of the utility model are as follows: when the rigidity of the screw rod is required to be high or the installation space is limited, the rolling nut and the rolling screw rod pair of the present invention can meet the requirements, various connection modes can be designed by themselves, and combined with the promotion and application of full-filled tapered roller thrust bearings and various thrust roller bearings for the pressing mechanism of the rolling mill, the application of the rolling screw rod pair in various forging equipment can be expanded. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 , Figure 2 This is a schematic diagram of Example 1 of the utility model, Figure 2 for Figure 1 A partial enlarged view of

[0013] Figure 3 This is a schematic diagram of Embodiment 2 of the present utility model;

[0014] Figure 4 This is a schematic diagram of Embodiment 3 of the present utility model;

[0015] In the figure, 1 is the upper bearing seat of the peripheral screw, 2 is the radial rolling bearing of the peripheral screw, 3 is the peripheral screw, 4 is the thrust rolling bearing of the peripheral screw, 5 is the thrust rolling bearing of the rolling nut, 6 is the center screw, 7 is the lower bearing seat of the peripheral screw, 8 is the end gear of the peripheral screw, 9 is the main driving gear, 10 is the short rolling nut, and 11 is the butterfly spring. DETAILED DESCRIPTION

[0016] Embodiment 1:

[0017] Figure 1 It is an eleven-roller plate straightening machine. The eleven working rollers are respectively installed on the upper movable beam and the lower fixed beam. The four corners of the upper movable beam are provided with pressing devices. The pressing device is driven by two motors to drive two pairs of gear reducers and rolling screws respectively. The pressing device realizes the pressing down and swinging of the upper movable beam as a whole.

[0018] Figure 2 for Figure 1 The enlarged partial view shows that six peripheral screws (3) are meshed with the central screw (6), the peripheral screws (3) and the central screw (6) have opposite thread directions and the same pitch, each peripheral screw (3) has two sets of peripheral screw radial rolling bearings (2) and one set of peripheral screw thrust rolling bearings (4), one set of peripheral screw radial rolling bearings (2) is mounted on the peripheral screw upper bearing seat (1), and the other set of peripheral screw radial rolling bearings (2) and one set of peripheral screw thrust rolling bearings (4) are mounted on the peripheral screw lower bearing seat (7); the six peripheral screws (3), all peripheral screw radial rolling bearings (2), all peripheral screws The rod thrust rolling bearing (4), the peripheral screw upper bearing seat (1), and the peripheral screw lower bearing seat (7) form a rolling nut, and the rolling nut and the central screw form a rolling screw pair. The central screw is fixed, and the lower part of the peripheral screw lower bearing seat (7) is provided with a rolling nut thrust rolling bearing (5). The peripheral screw (3) both rotates and revolves. The peripheral screw upper bearing seat (1) and the peripheral screw lower bearing seat (7) are fixed together. The motor and the gear reducer of the pressing device drive the rolling nut to rotate as a whole, so as to realize the lifting and swinging of the upper movable beam. The two bearing seats ensure that the meshing center distance and the axis parallelism of the central screw (6) and the peripheral screw (3) are maintained.

[0019] The rolling bearing installed on the lower bearing seat (7) of the peripheral screw rod can be a combination of a full-filled tapered roller thrust bearing and a radial needle roller bearing for a rolling mill press-down mechanism.

[0020] Figure 2The enlarged view of part A shows that the tooth profile of the rolling screw pair is trapezoidal, the tooth pitch is 22mm, the basic tooth profile height is 5mm, the outer diameter of the center screw is 200mm, the outer diameter of the peripheral screw is 120mm, the tooth surface bevel angle is 3 degrees, and the rolling screw pair can be self-locking in the radial force.

[0021] The total efficiency of the pressing device can reach more than 75-80%, and the pressing amount can be adjusted online, and no creeping will occur during the load pressing process.

[0022] The diameter of the central screw and the peripheral screw is larger than that of the existing roller screw and has good rigidity, which meets the higher rigidity requirements of the straightening machine for the whole machine. Since the pressing device is directly connected and has no frame, the rigidity of the whole machine is mainly determined by the rigidity of the pressing screw.

[0023] Embodiment 2:

[0024] Figure 3 It is a three-layer roller seven-roller plate straightening machine. The upper roller has a larger diameter and has no supporting rollers and supporting beams. The lower roller is slightly thinner. The two middle rollers have supporting rollers. The lower roller and supporting rollers are installed on the lower fixed beam. The center distance between the bearings at both ends of the upper roller is longer than the center distance between the bearings at both ends of the lower roller. The upper roller is a single roller directly connected and pressed down. The pressing force does not pass through the frame. The pressing device is composed of a motor, a reducer, and a rolling screw pair. The pressing device is installed on the lower fixed beam. The pressing amount of the rollers on both sides can be adjusted online. The upper roller bearing seat is directly connected to the pressing device through a pin, a thread and a pull rod.

[0025] Figure 3 In the middle (7), a peripheral screw lower bearing seat is provided, a set of peripheral screw radial rolling bearings and a set of peripheral screw thrust rolling bearings are installed on the peripheral screw lower bearing seat (7); (1) is a peripheral screw upper bearing seat, a set of peripheral screw radial rolling bearings are installed on the peripheral screw upper bearing seat (1); in the sectional enlarged view AA, four peripheral screws (3) are meshed with the central screw (6), the four peripheral screws (3) are unevenly distributed on the circumference, and the rolling nut is a part of the cylinder; in the sectional enlarged view BB, the main driving gear (9) on the reducer drives the four peripheral screw end gears (8), the peripheral screw actively rotates and the central screw passively rotates while the peripheral screw bearing seat does not rotate, and the central screw end is provided with a rolling bearing that bears axial thrust.

[0026] Due to the reduction of the primary gear and the reduction of the peripheral screw rod (3) and the central screw rod (6), the transmission ratio of the reducer of the pressing device is reduced, and the reducer model is one level smaller, which makes up for the limitation of the small size space of the single-roll pressing device, so that the pressing reducer can be just installed.

[0027] The diameter of the rolling screw pair of the pressing device is large and the rigidity is good. The non-circumferential uniform distribution of the peripheral screws (3) also meets the limitation of the small size and space of the single roller pressing. The existing roller screw can only be a complete cylinder.

[0028] Embodiment 3:

[0029] Figure 4 The rolling nut 4a is composed of two coaxial short rolling nuts (10) connected in series to reduce the load of the rolling bearing of each short rolling nut (10) that bears the axial thrust. The bearing seats of each short rolling nut (10) directly transmit the axial thrust of the rolling screw pair to each other, which is used in the case where the rated load of the rolling bearing that bears the axial thrust is insufficient.

[0030] The axial thrust can also be transmitted to the components on which the short rolling nuts are installed by the bearing seats of each section of the short rolling nut, and each section of the short rolling nut only bears part of the axial thrust of the rolling screw.

[0031] Figure 4 In the middle 4b, a butterfly spring (11) is arranged between the bearing seats of the two rolling nuts to limit the axial thrust received by one of the rolling nuts, so that the rolling nut only bears a part of the preset axial thrust of the rolling screw. The length of the rolling nut to which the axial thrust is limited is determined according to the size of the axial thrust.

[0032] Over the meshing length of the screw rod and the nut, the force on each tooth is uneven, and the number of tooth circles used for strength calculations is limited. Some rolling nuts are equipped with springs on their bearing seats to limit the axial thrust, which can increase the flexibility of the rolling nut and increase the number of tooth circles used for calculation. This can be used when a single rolling nut is underloaded, and can also be used for equipment with impact force.

[0033] The axial thrust can also be transmitted by each rolling nut and the rolling nut and its spring to the component on which the rolling nut is installed.

[0034] When the rolling screw pair cannot self-lock and needs to maintain pressure or position, the rotating drive mechanism is equipped with a braking device.

[0035] The use of large pitch, high-strength steel and hardened tooth surface can improve the bearing capacity of the rolling screw pair.

Claims

1. A rolling nut and a rolling screw pair thereof, characterized in that: The rolling screw has a central screw and 2 to 30 peripheral screws with equal pitch meshing therewith. The shaft end of each peripheral screw is provided with a rolling bearing that bears axial thrust, a bearing that bears radial force, and a bearing seat. The bearing seat ensures that the meshing center distance and axis of the central screw and the peripheral screw are parallel. All the peripheral screws and the bearings and bearing seats at the shaft ends form a rolling nut. The rolling nut can be a complete cylinder or a part of a cylinder; the central screw can rotate actively, or the peripheral screw can rotate actively while the peripheral screw bearing seats do not rotate, or the rolling nut can rotate as a whole, that is, the bearing seats at both ends of the peripheral screw are connected together and rotate synchronously, and the peripheral screw rotates and revolves. The ends of the rotating central screw or rolling nut are provided with rolling bearings that bear axial thrust.

2. A rolling nut and rolling screw pair according to claim 1, characterized in that: The threads of the center screw and the peripheral screw have opposite rotation directions, and the force-bearing tooth surface has a small bevel angle and can be self-locking or nearly self-locking in the radial direction. The tooth design satisfies that the contact line is near the center line connecting the center screw and the peripheral screw and has sufficient contact strength, meets the bending strength of the tooth root, reduces the outer diameter of the rolling nut and the radial load of the rolling bearing.

3. A rolling nut and rolling screw pair according to claim 1 or 2, characterized in that: The rolling nut is composed of 2 to 15 coaxial short rolling nuts connected in series to reduce the load on the rolling bearing of each short rolling nut. The bearing seats of each short rolling nut directly transmit the axial thrust of the rolling screw pair to each other, and can also be transmitted to the components where the short rolling nuts are installed by the bearing seats of each short rolling nut. Each short rolling nut only bears part of the axial thrust of the rolling screw pair. 2 to 5 rolling nuts are coaxially connected in series, and the bearing seats of some or all of the rolling nuts are provided with springs to limit the axial thrust they are subjected to, so that the rolling nut only bears part of the preset axial thrust of the rolling screw pair. The axial thrust can also be transmitted to the components where the rolling nut is installed by each rolling nut and the rolling nut and its spring respectively.

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