Device for detecting axial clearance of nut and screw

Abstract

The utility model relates to a detection device, in particular to a device for detecting the axial clearance of a nut and a screw. The detection device comprises a rack, and a loading mechanism for pulling a screw upwards, a positioning mechanism for positioning a nut and a detection mechanism for detecting the displacement of the screw are sequentially arranged on the rack from top to bottom. According to the detection device, the nut is fixed, the displacement of the screw is detected after tension is applied to the screw, and then the gap between the nut and the screw is detected, so that the gap between the nut and the screw is ensured to be qualified; the quality problems of loose steering or clamping, abnormal steering sound or abnormal vibration, accelerated abrasion of parts, aggravated load of a power-assisted motor and the like in the operation process of the nut and the screw rod are not easy to occur; as the displacement of the screw rod is directly detected, the detection result can be ensured to be accurate and credible. The problem of inaccurate detection caused by indirect detection of an existing detection device is solved.

Description

Technical Field

[0001] This utility model relates to a detection device, specifically a device for detecting the axial clearance of a nut screw. Background Technology

[0002] The eRCB steering system is an electric power steering system that includes a housing, a power steering motor, a nut, a screw, and an input shaft. The power steering motor drives the screw to rotate, which in turn moves the nut. The moving nut then drives the input shaft to rotate, reducing the reaction force of the input shaft on the steering wheel and thus reducing the resistance to turning the steering wheel. The eRCB steering system has very high requirements for the axial clearance of the nut and screw. Inadequate axial clearance in the eRCB steering system (excessive or insufficient clearance between the nut and screw) can lead to quality problems such as loose or stuck steering, abnormal steering noise or vibration, accelerated wear of parts, and increased burden on the power steering motor.

[0003] Patent application CN207540520U discloses a screw gap detection device, which includes: a turntable; a screw feeding mechanism, a screw sleeve feeding mechanism, a gap detection mechanism, and a sorting mechanism arranged sequentially around the turntable and along the rotation direction of the turntable, which automatically completes the gap detection of the screw and screw sleeve, with high working efficiency and a high degree of automation.

[0004] The aforementioned detection device can detect the gap between the screw and the nut, but it indirectly detects the nut's displacement by detecting the displacement of the upper gripper, thereby detecting the gap between the nut and the screw. Since there may be displacement between the upper gripper and the nut, indirect detection can lead to inaccurate results. Therefore, it is necessary to improve the device to solve this problem. Summary of the Invention

[0005] The purpose of this invention is to provide a device for detecting the axial clearance of nuts and bolts, which can detect gaps and ensure that the detection results are reliable and accurate.

[0006] The technical solution of this utility model is:

[0007] A device for detecting the axial clearance of a nut screw comprises a frame, a loading mechanism, a positioning mechanism, and a detection mechanism. The frame is characterized by the following components arranged sequentially from top to bottom: a loading mechanism for pulling the screw upwards, a positioning mechanism for positioning the nut, and a detection mechanism for detecting the screw displacement. The positioning mechanism consists of a nut support, grippers, and a pneumatic clamping cylinder. The nut support has a through hole, and grippers are movably mounted on both sides of the through hole via connecting rods. A pneumatic clamping cylinder is mounted on the nut support outside the connecting rods, and the piston rod end of the pneumatic clamping cylinder is movably connected to the outer end of the grippers via a pin.

[0008] A limit cylinder is installed on the frame between the grippers, and a limit block is installed at the piston rod end of the limit cylinder through a guide frame.

[0009] The loading mechanism consists of a loading electric cylinder, an assembly plate, and a pneumatic collet. The piston rod end of the loading electric cylinder is equipped with an assembly plate, and the assembly plate is provided with a pneumatic collet for clamping the screw. The loading electric cylinder is fixedly connected to the nut support seat through a bracket.

[0010] The detection mechanism consists of a sensor lifting cylinder, a support plate, and a displacement sensor. The piston rod end of the sensor lifting cylinder is fixedly mounted with a support plate, and a displacement sensor is installed on the support plate. The sensor lifting cylinder is connected to the frame.

[0011] The beneficial effects of this utility model are as follows:

[0012] This nut and screw axial clearance detection device fixes the nut, applies tension to the screw, and detects the screw's displacement, thereby detecting the clearance between the nut and screw. This ensures the clearance between the nut and screw is within acceptable limits, preventing quality problems such as loose or jammed steering, abnormal steering noise or vibration, accelerated wear of parts, and increased burden on the power steering motor during operation. Because it directly detects the screw's displacement, the detection results are accurate and reliable. This solves the problem of inaccurate detection caused by indirect detection in existing devices. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of this utility model;

[0014] Figure 2 This is a schematic diagram of the positioning mechanism of this utility model;

[0015] Figure 3 This is a schematic diagram of the loading mechanism of this utility model;

[0016] Figure 4 This is a schematic diagram of the structure of the testing mechanism of this utility model;

[0017] Figure 5 This is a schematic diagram of the detection status of this utility model.

[0018] In the diagram: 1. Frame, 2. Positioning mechanism, 3. Loading mechanism, 4. Detection mechanism, 5. Workpiece (screw and nut), 201. Nut support, 202. Clamping jaw, 203. Pneumatic clamping cylinder, 204. Through hole, 205. Connecting rod, 206. Limiting cylinder, 207. Guide frame, 208. Limiting block, 301. Loading electric cylinder, 302. Assembly plate, 303. Pneumatic collet, 401. Sensor lifting cylinder, 402. Support plate, 403. Displacement sensor. Detailed Implementation

[0019] The device for detecting the axial clearance of a nut screw consists of a frame 1, a loading mechanism 3, a positioning mechanism 2, and a detection mechanism 4. The loading mechanism 3, positioning mechanism 2, and detection mechanism 4 are arranged sequentially from top to bottom on the frame 1. The positioning mechanism 2 secures the nut to itself, keeping the nut stationary during relative movement between the screw and nut, thus allowing the screw to move only within the clearance range between them. The loading mechanism 3 clamps the screw and applies tension or pressure, causing it to move within the clearance range, thus detecting the clearance between the screw and nut. The detection mechanism 4 directly detects the displacement of the screw, using the displacement under tension or pressure to determine the clearance between the screw and nut.

[0020] The positioning mechanism 2 consists of a nut support 201, grippers 202, and a pneumatic clamping cylinder 203. The nut support 201 has a through hole 204, and grippers 202 are movably mounted on both sides of the through hole 204 via connecting rods 205. The pneumatic clamping cylinder 203 is mounted on the nut support 201 outside the connecting rods 205. The piston rod end of the pneumatic clamping cylinder 203 is movably connected to the outer end of the grippers 202 via a pin. The function of the pneumatic clamping cylinder 203 is to push the outer end of the grippers 202 upwards, thereby causing the inner end of the grippers 202 to move downwards under the action of the connecting rods 205. This clamping mechanism 2 thus presses and fixes the nut onto the nut support 201, positioning and fixing the nut so that it will not move during the testing process.

[0021] A limit cylinder 206 is installed on the frame 1 between the grippers 202. The piston rod end of the limit cylinder 206 is fitted with a limit block 208 via a guide frame 207. The function of the limit cylinder 206 is to push the limit block 208 upward toward the nut, thereby further restricting the nut and preventing it from moving upward during the inspection process. On the other hand, the limit block 208 determines the inspection position of the screw, enabling the inspection mechanism to inspect the screw.

[0022] The loading mechanism 3 consists of a loading electric cylinder 301, an assembly plate 302, and a pneumatic collet 303. The piston rod end of the loading electric cylinder 301 (SDG32-002 type reversible electric cylinder) is equipped with an assembly plate 302. The assembly plate 302 is equipped with a pneumatic collet 303 (Taiwan Chao-Chuan JAS-40 type) for clamping screws. The loading electric cylinder 301 is fixedly connected to the nut support seat 201 through a bracket. The function of the loading electric cylinder 301 is to drive the assembly plate 302 to rise and fall, and in turn, drive the pneumatic collet 303 to rise and fall during the process of the assembly plate 302. This allows the pneumatic collet 303 to descend and fit onto the top end of the screw, thereby clamping the screw. As a result, the loading electric cylinder 301 can sequentially press down or pull up the screw through the assembly plate 302 and the pneumatic collet 303, causing the screw to move up and down within the gap between the screw and the nut. During the up and down movement of the screw, the displacement of the screw is detected, thereby detecting the gap between the screw and the nut.

[0023] The detection mechanism 4 consists of a sensor lifting cylinder 401, a support plate 402, and a displacement sensor 403. The piston rod end of the sensor lifting cylinder 401 is fixedly mounted with the support plate 402, and the displacement sensor 403 (Omron ZS-HLDC11 type) is mounted on the support plate 402. The sensor lifting cylinder 401 is connected to the frame 1. The function of the sensor lifting cylinder 401 is to drive the displacement sensor 403 to rise and fall, so that the top end of the displacement sensor 403 can abut against the bottom end face of the screw, allowing the displacement sensor 403 to detect the up and down movement of the screw.

[0024] When using the axial clearance detection device for the nut screw, the bottom end of the screw with the nut installed is inserted into the through hole 204 of the positioning mechanism 2, so that the bottom end face of the nut abuts against the nut positioning seat 201. After the screw is inserted into place, the pneumatic clamping cylinder 203 is activated. The clamping cylinder 203 presses down on the nut through the jaws 202, fixing the nut onto the nut positioning seat 201. After the nut is clamped and fixed, the limiting cylinder 206 is activated. The limiting cylinder 206 pushes the limiting block 208 towards the screw through the guide frame 207, locking the screw into the arc groove of the limiting block 208. After the limiting block 208 moves into place, the screw is rotated so that the shoulder end face of the screw abuts against the limiting block 208 to position the screw at the detection position. After the nut is rotated into position, the sensor lifting cylinder 401 of the detection mechanism is activated. The sensor lifting cylinder 401 drives the displacement sensor 403 upward through the support plate 402, placing the displacement sensor 403 against the bottom end face of the screw. After the displacement sensor 403 is in position, the limit cylinder 206 drives the limit block 208 to reset. During the reset of the limit block 208, the loading electric cylinder 301 of the loading mechanism 3 drives the pneumatic collet 303 downward through the assembly plate 302, fitting the pneumatic collet 303 onto the top end of the screw. After the pneumatic collet 303 is in position, it is activated to clamp and fix the screw. After the pneumatic collet 303 clamps and fixes the screw, the loading electric cylinder 301 continues to descend, applying a downward force to the screw through the assembly plate 302 and the pneumatic collet 303 in sequence, pushing the screw downward. During the downward movement of the screw, the downward displacement of the screw is detected by the displacement sensor 403. After the screw descends and the detection is completed, the loading electric cylinder 301 drives the screw to reset to a state where it is no longer under downward pressure. The limiting cylinder 206 drives the limiting block 208 to move towards the screw, positioning the limiting block 208 above the nut to further prevent the nut from moving upwards. After the limiting block 208 is in position, the loading electric cylinder 301 moves upwards, applying an upward force to the screw through the assembly plate 302 and the pneumatic collet 303, pulling the screw upwards. During the upward movement of the screw, the displacement sensor 403 detects the upward displacement of the screw, and the gap between the screw and the nut is calculated by the difference between the two displacements.

[0025] This nut and screw axial clearance detection device fixes the nut, applies tension to the screw, and detects the screw's displacement, thereby detecting the clearance between the nut and screw. This ensures the clearance between the nut and screw is within acceptable limits, preventing quality problems such as loose or jammed steering, abnormal steering noise or vibration, accelerated wear of parts, and increased burden on the power steering motor during operation. Because it directly detects the screw's displacement, the detection results are accurate and reliable. This solves the problem of inaccurate detection caused by indirect detection in existing devices.

Claims

1. A device for detecting the axial clearance of a nut screw, comprising a frame (1), a loading mechanism (3), a positioning mechanism (2), and a detection mechanism (4), characterized in that: The frame (1) is provided with a loading mechanism (3) for pulling the screw upward, a positioning mechanism (2) for positioning the nut, and a detection mechanism (4) for detecting the displacement of the screw, arranged from top to bottom. The positioning mechanism (2) consists of a nut support seat (201), a gripper (202), and a pneumatic clamping cylinder (203). The nut support seat (201) is provided with a through hole (204), and grippers (202) are movably installed on both sides of the through hole (204) via connecting rods (205). A pneumatic clamping cylinder (203) is provided on the nut support seat (201) outside the connecting rod (205). The piston rod end of the pneumatic clamping cylinder (203) is movably connected to the outer end of the gripper (202) via a pin.

2. A device for detecting axial clearance of a nut screw as claimed in claim 1, wherein: A limit cylinder (206) is installed on the frame (1) between the grippers (202), and a limit block (208) is installed on the piston rod end of the limit cylinder (206) through the guide frame (207).

3. A device for detecting axial clearance of a nut screw as claimed in claim 1, wherein: The loading mechanism (3) consists of a loading electric cylinder (301), an assembly plate (302) and a pneumatic collet (303). The piston rod end of the loading electric cylinder (301) is equipped with an assembly plate (302), and a pneumatic collet (303) for clamping screws is provided on the assembly plate (302). The loading electric cylinder (301) is fixedly connected to the nut support seat (201) through a bracket.

4. The apparatus for detecting the axial gap of a nut screw according to claim 1, wherein: The detection mechanism (4) consists of a sensor lifting cylinder (401), a support plate (402) and a displacement sensor (403). The piston rod end of the sensor lifting cylinder (401) is fixedly mounted with the support plate (402), and the displacement sensor (403) is provided on the support plate (402). The sensor lifting cylinder (401) is connected to the frame (1).

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