Screw drive structure suitable for vertical axis and its pre-stretching process

Abstract

The invention relates to a screw transmission structure suitable for a vertical shaft, and its pre-stretching process, and belongs to the technical field of machine tool screw structures. Its structure is: an upper bearing seat and a lower bearing seat are coaxially arranged above and below the mounting base; the upper bearing seat and the lower bearing seat are jointly connected to the screw, the bottom thread of the screw is connected to the lower locking nut, the lower end face of the lower bearing group is limited to the upper surface of the lower sealing sleeve, and the lower surface of the lower sealing sleeve is supported on the lower locking nut; the upper end of the lower bearing group is coaxially matched with the screw through a sealing adjustment device, and is connected and positioned with the lower bearing seat at the same time. This structure not only ensures the sealing performance of the lower bearing, but also improves the rigidity of the upper bearing seat, and optimizes the vertical shaft transmission structure as a whole.

Description

Technical Field

[0001] The invention relates to a screw transmission structure suitable for a vertical shaft and a pre-stretching process thereof, belonging to the technical field of machine tool screw structures. Background Art

[0002] The screw drive system is one of the important structures of machine tools, which mainly includes a drive motor, a screw nut pair, bearings and other accessories. The ultimate goal is to convert the rotational motion of the motor into the linear motion of the nut, and then drive the connected parts to move. The accuracy and stability of the movement process directly affect the performance of the machine tool.

[0003] The working environment faced by the screw drive system for the vertical axis is more stringent than that of the horizontal axis. The bearing seat above it needs to bear the preload of the screw itself and the gravity of the dragging part. The force is relatively large, and extremely high requirements are placed on the contact stiffness and installation process of the bearing seat mounting surface. In addition, due to the influence of gravity, the lubricating oil overflowing from the nut will flow into the bearing seat below along the screw with impurities, contaminating the internal bearing grease and thereby reducing the service life of the bearing.

[0004] The conventional solution is to scrape the mounting surface of the bearing seat to increase the rigidity of the contact surface as much as possible. This method is labor-intensive, inefficient, and ineffective. As for the problem of easy contamination of bearing grease, the current mainstream approach is to install sealing rings at both ends of the bearing seat to protect the bearings and grease. However, due to the large force on the vertical axis, the contact stress between the moving parts is large, resulting in high heat generation. The sealing ring is a contact seal. When the screw rotates, the sealing ring will slide relative to the screw shaft diameter, generating heat through friction, further aggravating the impact of thermal expansion on the transmission system. Summary of the invention

[0005] The technical problem to be solved by the invention is to provide a screw transmission structure suitable for a vertical shaft, which structure not only ensures the sealing performance of the lower end bearing, but also improves the rigidity of the upper end bearing seat, thereby optimizing the vertical shaft transmission structure as a whole.

[0006] In order to solve the above problems, the specific technical scheme created by the present invention is as follows: a screw transmission structure suitable for a vertical shaft, an upper bearing seat and a lower bearing seat are coaxially arranged above and below the mounting base, the upper bearing seat is fixed to the mounting base or connected with the integral structure, the lower bearing seat is a split structure, one half is fixedly connected to the mounting base, and the other half is connected by flange bolts; the upper end of the screw cooperates with the upper bearing seat through the upper bearing group, the bottom of the upper bearing group is seated on the bottom limit platform of the upper bearing seat, the top of the upper bearing group is limited by the bottom surface of the upper pressure cover connected to the upper bearing seat, an upper sealing sleeve is provided on the inner hole of the upper pressure cover, and an upper locking nut is fixed to the The lead screw is threadedly connected, and the bottom surface of the upper locking nut presses the top surface of the upper sealing sleeve; the top of the lead screw passes through the upper bearing seat and is connected to the motor through a coupling, and is buckled on the upper end of the mounting base through a cover plate on the outside of the coupling, and the mounting base and the top of the cover plate are jointly connected to a transition plate, and the transition plate is connected to the motor; the bottom of the lead screw is coaxially matched with the lower bearing seat through the lower bearing group, and the bottom of the lead screw is threadedly connected to the lower locking nut, the lower end face of the lower bearing group is limited to the upper surface of the lower sealing sleeve, and the lower surface of the lower sealing sleeve is supported on the lower locking nut; the upper end of the lower bearing group is coaxially matched with the lead screw through a sealing adjustment device, and is connected and positioned with the lower bearing seat at the same time.

[0007] The sealing adjustment device structure includes: the top surface of the lower end bearing seat is connected to the lower pressure cover through a grinding pad, the center hole of the lower pressure cover is coaxially matched with an oil slinger ring, the bottom of the oil slinger ring is supported on the upper surface of the inner ring of the lower end bearing group, and the top surface of the oil slinger ring is in contact with the limit platform on the screw.

[0008] The matching grinding pad is a middle split structure.

[0009] The pre-tensioning and stretching process of the screw transmission structure comprises the following steps:

[0010] 1) Alignment and installation of upper and lower bearing seats:

[0011] 1.1) Insert the 300mm upper test rod into the upper bearing seat above the mounting base, and insert the 300mm lower test rod into the lower bearing seat;

[0012] 1.2) Measure the parallelism between the upper and lower test rods and the reference guide rail in the X and Z directions, and the parallelism is required to be ≤0.015 / 300mm; measure the coaxiality between the upper and lower test rods, and the coaxiality is required to be ≤φ0.02mm; if it does not meet the technical requirements, grind the circumferential surface;

[0013] 1.3) After meeting the requirements of parallelism and coaxiality, position the upper bearing seat, and position half of the lower bearing seat in the mounting hole through a tapered pin;

[0014] 1.4) After positioning, align the upper and lower bearing seats. The parallelism of the upper inspection rod and the reference guide rail is guaranteed by the machining accuracy of the bearing hole of the mounting base. Only re-inspection is required during assembly. The parallelism of the lower inspection rod and the reference guide rail and the coaxiality with the upper inspection rod need to be manually aligned by scraping the mounting surface of the lower bearing seat. The upper and lower inspection rods and the lower inspection rod are warped in the Z direction on the premise that the coaxiality requirement is ≤φ0.02mm.

[0015] 2) Calculate the screw stretch

[0016] 2.1) Install the screw, oil slinger, lower gland, lower bearing seat, lower bearing assembly and lower sealing sleeve in sequence. Do not install the grinding pad and locking nut at this time.

[0017] 2.2) Take four evenly spaced points around the outer edge of the lower gland, measure the gap distance between the bottom surface of the lower gland and the top surface of the lower end bearing seat at the four points, and calculate the average value as the gap distance a;

[0018] 2.3) Calculate the stretch: The stretch of the screw can be estimated by the following formula:

[0019] δ=1 / 100·ΔT·l

[0020] Where ΔT is the temperature rise of the screw during operation, l is the length of the screw, and δ is in mm;

[0021] 2.4) Calculate the required thickness b of the grinding pad, b=a-δ;

[0022] 3) Divide the grinding pad with the required thickness b into two halves and insert them between the lower pressure cover and the lower bearing seat. Lock the lower pressure cover and tighten the locking nut to ensure that there is no gap between the limit table of the screw and the oil ring.

[0023] The screw drive structure and pre-stretching process applicable to the vertical shaft of the present application are to solve the problems of bearing seat rigidity and bearing sealing in the vertical shaft screw drive structure. The present invention designs the bearing seat and the mounting base as an integral form to improve the rigidity of the bearing seat; a labyrinth seal is formed in the form of an oil-slinging pan to achieve the sealing of the bearing; and the overall performance of the screw drive system is guaranteed through a perfect manufacturing and assembly process, which provides a new idea for the design and application of the vertical shaft screw drive structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the overall assembly drawing of the screw transmission structure.

[0025] Figure 2 for Figure 1 A partial enlarged view of point Ⅰ in the middle.

[0026] Figure 3 for Figure 1 A partial enlarged view of point II in the middle.

[0027] Figure 4 This is the application diagram of the upper and lower test rods.

[0028] Figure 5 This is a schematic diagram of measuring the distance for matching sanding pads.

[0029] Figure 6 This is a schematic diagram of the split structure of the grinding pad.

[0030] Figure 7 This is an enlarged view of the lower bearing seat connection after the screw is pre-stretched. DETAILED DESCRIPTION

[0031] like Figures 1 to 3 As shown, a screw transmission structure suitable for a vertical axis, an upper bearing seat 19 and a lower bearing seat 14 are coaxially arranged above and below the mounting base 18, the upper bearing seat 19 is fixed to the mounting base 18 or connected as an integral structure, the lower bearing seat 14 is a split structure, one half is fixedly connected to the mounting base 18, and the other half is connected by flange bolts; the upper end of the screw 5 cooperates with the upper bearing seat 19 through the upper bearing group 10, the bottom of the upper bearing group 10 is seated on the bottom limit platform of the upper bearing seat 19, the top of the upper bearing group 10 is limited by the bottom surface of the upper pressure cover 9 connected to the upper bearing seat 19, an upper sealing sleeve 8 is provided in the inner hole of the upper pressure cover 9, the upper locking nut 7 is threadedly connected to the screw 5, and the upper locking nut 7 The bottom surface presses the top surface of the upper sealing sleeve 8; the top of the screw 5 passes through the upper bearing seat 19 and is connected to the motor 1 through the coupling 3. The cover plate 4 is buckled on the upper end of the mounting base 18 outside the coupling 3, and the mounting base 18 and the top of the cover plate 4 are jointly connected to the transition plate 2, and the transition plate is connected to the motor 1; the bottom of the screw 5 is coaxially matched with the lower bearing seat 14 through the lower bearing group 15, and the bottom of the screw 5 is threadedly connected to the lower locking nut 17, and the lower end surface of the lower bearing group 15 is limited on the upper surface of the lower sealing sleeve 16, and the lower surface of the lower sealing sleeve 16 is supported on the lower locking nut 17; the upper end of the lower bearing group 15 is coaxially matched with the screw 5 through the sealing adjustment device, and is connected and positioned with the lower bearing seat 14 at the same time.

[0032] The sealing adjustment device structure includes: the top surface of the lower end bearing seat 14 is connected to the lower pressure cover 12 through a grinding pad 13, the center hole of the lower pressure cover 12 is coaxially matched with an oil slinger 11, the bottom of the oil slinger 11 is supported on the upper surface of the inner ring of the lower end bearing group 15, and the top surface of the oil slinger 11 is in contact with the limit platform on the screw 5.

[0033] like Figure 6 As shown, the grinding pad 13 is a split structure in the middle, which is easy to install.

[0034] The pre-tensioning and stretching process of the screw transmission structure is characterized by comprising the following steps:

[0035] 1) Alignment and installation of upper bearing seat 19 and lower bearing seat 14:

[0036] 1.1) If Figure 4 As shown, the 300 mm upper test rod 20 is inserted into the upper end bearing seat 19 above the mounting base 18, and the 300 mm lower test rod 21 is inserted into the lower end bearing seat 14;

[0037] 1.2) Measure the parallelism between the upper check rod 20 and the lower check rod 21 and the reference guide rail in the X and Z directions, and the parallelism is required to be ≤0.015 / 300mm; measure the coaxiality between the upper check rod 20 and the lower check rod 21, and the coaxiality is required to be ≤φ0.02mm; if it does not meet the technical requirements, grind the circumferential surface;

[0038] 1.3) After meeting the requirements of parallelism and coaxiality, the upper bearing seat 19 is positioned, and half of the lower bearing seat 14 is positioned in the mounting hole through a tapered pin;

[0039] 1.4) After positioning, align the upper bearing seat 19 and the lower bearing seat 14. The parallelism of the upper inspection rod 20 and the reference guide rail is guaranteed by the machining accuracy of the bearing hole of the mounting base. Only re-inspection is required during assembly. The parallelism of the lower inspection rod 21 and the reference guide rail and the coaxiality with the upper inspection rod 20 need to be manually aligned by scraping the mounting surface of the lower bearing seat; the upper and lower inspection rods 21 and the lower inspection rod 21 meet the coaxiality requirement of ≤φ0.02mm, and the ends are warped in the Z direction. The amount of warping can offset the preload deformation;

[0040] 2) Calculate the screw stretch

[0041] 2.1) Install the screw 5, oil slinger 11, lower gland 12, lower bearing seat 14, lower bearing assembly 15 and lower sealing sleeve 16 in sequence. At this time, do not install the grinding pad 13 and locking nut 17;

[0042] 2.2) Take four evenly spaced points on the outer periphery of the lower gland 12, measure the gap distance between the bottom surface of the lower gland 12 and the top surface of the lower end bearing seat 14 at the four points, and calculate the average value as the gap distance a, such as Figure 5 As shown;

[0043] 2.3) Calculate the stretch: The stretch of the screw can be estimated by the following formula:

[0044] δ=1 / 100·ΔT·l

[0045] Where ΔT is the temperature rise of the screw during operation in °C, l is the length of the screw in m, and δ is in mm;

[0046] 2.4) Calculate the required thickness b of the grinding pad, b=a-δ;

[0047] 3) Divide the grinding pad with the required thickness b into two halves, such as Figure 6 As shown, insert it between the lower gland 12 and the lower end bearing seat 14, lock the lower gland 12, tighten the locking nut 17, and ensure that there is no gap between the limit platform of the screw 5 and the oil slinger 11, as shown in FIG. Figure 7 shown.

Claims

1. A pre-tensioning and stretching process for a screw transmission structure of a vertical axis, characterized in that: The screw transmission structure suitable for a vertical axis is as follows: an upper bearing seat (19) and a lower bearing seat (14) are coaxially arranged above and below a mounting base (18); the upper bearing seat (19) is connected to the mounting base (18) as an integral structure; the lower bearing seat (14) is a split structure, one half of which is fixedly connected to the mounting base (18) and the other half is connected via flange bolts; the upper end of the screw (5) cooperates with the upper bearing seat (19) via an upper bearing group (10); the bottom of the upper bearing group (10) is seated on a limit table at the bottom of the upper bearing seat (19); the top of the upper bearing group (10) is limited by the bottom surface of an upper pressure cover (9) connected to the upper bearing seat (19); an upper sealing sleeve (8) is provided in the inner hole of the upper pressure cover (9); an upper locking nut (7) is threadedly connected to the screw (5); and the bottom surface of the upper locking nut (7) presses the upper sealing sleeve. The top of the lead screw (5) passes through the upper end bearing seat (19) and is connected to the motor (1) through the coupling (3). The cover plate (4) is buckled on the upper end of the mounting base (18) outside the coupling (3), and the mounting base (18) and the top of the cover plate (4) are connected to the transition plate (2), and the transition plate is connected to the motor (1); the bottom of the lead screw (5) is coaxially matched with the lower end bearing seat (14) through the lower end bearing group (15), the bottom of the lead screw (5) is threadedly connected to the lower locking nut (17), the lower end surface of the lower end bearing group (15) is limited on the upper surface of the lower sealing sleeve (16), and the lower surface of the lower sealing sleeve (16) is supported on the lower locking nut (17); the upper end of the lower end bearing group (15) is coaxially matched with the lead screw (5) through the sealing adjustment device, and is connected and positioned with the lower end bearing seat (14) at the same time; The pre-tightening and stretching process based on the above-mentioned screw transmission structure includes the following steps: 1) Alignment and installation of the upper bearing seat (19) and the lower bearing seat (14): 1.1) Insert the 300 mm upper test rod (20) into the upper bearing seat (19) above the mounting base (18), and insert the 300 mm lower test rod (21) into the lower bearing seat (14); 1.2) Measure the parallelism between the upper check rod (20) and the lower check rod (21) and the reference guide rail in the X and Z directions. The parallelism is required to be ≤0.015 / 300mm; measure the coaxiality between the upper check rod (20) and the lower check rod (21). The coaxiality is required to be ≤φ0.02mm; if it does not meet the technical requirements, grind the circumferential surface; 1.3) After meeting the parallelism and coaxiality requirements, position the upper bearing seat (19) and position half of the lower bearing seat (14) in the mounting hole through a tapered pin; 1.4) After positioning, align the upper bearing seat (19) and the lower bearing seat (14). The parallelism of the upper check rod (20) and the reference guide rail is guaranteed by the machining accuracy of the bearing hole of the mounting base. During the assembly process, only rechecking is required. The parallelism of the lower check rod (21) and the reference guide rail and the coaxiality with the upper check rod (20) need to be manually aligned by scraping the mounting surface of the lower bearing seat. The upper and lower check rods (21) and the lower check rod (21) are warped in the Z direction on the premise that the coaxiality requirement ≤φ0.02mm is met; 2) Calculate the screw stretch 2.1) Install the lead screw (5), oil slinger (11), lower gland (12), lower bearing seat (14), lower bearing assembly (15) and lower sealing sleeve (16) in sequence. Do not install the grinding pad (13) and lock nut (17) at this time. 2.2) Take four evenly spaced points on the outer periphery of the lower gland (12), measure the gap distances between the bottom surface of the lower gland (12) and the top surface of the lower end bearing seat (14) at the four points, and calculate the average value as the gap distance a; 2.3) Calculate the stretch: The stretch of the screw can be estimated by the following formula: δ=1 / 100·ΔT·l Where ΔT is the temperature rise of the screw during operation (°C), l is the length of the screw (m), and δ is in mm; 2.4) Calculate the required thickness b of the grinding pad, b=a-δ; 3) Divide the grinding pad of the required thickness b into two halves and insert them between the lower gland (12) and the lower end bearing seat (14). Lock the lower gland (12) and tighten the locking nut (17) to ensure that there is no gap between the stopper of the screw (5) and the oil slinger (11).

2. The pre-tightening and stretching process for a screw transmission structure of a vertical shaft according to claim 1, characterized in that: The structure of the sealing adjustment device includes: the top surface of the lower end bearing seat (14) is connected to the lower pressure cover (12) through a grinding pad (13); the center hole of the lower pressure cover (12) is coaxially matched with an oil slinger (11); the bottom of the oil slinger (11) is supported on the upper surface of the inner ring of the lower end bearing group (15); and the top surface of the oil slinger (11) is in contact with the limit platform on the screw (5).

3. The pre-tightening and stretching process for a screw transmission structure of a vertical shaft according to claim 2, characterized in that: The grinding pad (13) is a middle split structure.

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