Clamp for thread friction coefficient detection

Abstract

The utility model discloses a clamp for thread friction coefficient detection. The clamp comprises an assembly seat, a clamping execution seat and a circumferential locking pin. The clamping execution seat is connected with the assembling seat through double threads, the head end of the clamping execution seat is provided with a clamping end head with an anti-rotation clamping groove and a through hole, and the tail end of the clamping execution seat is exposed out of the main machine base. The corresponding half holes in the assembling base and the clamping executing base can form limiting holes for the circumferential locking pin to be inserted so as to lock relative rotation. The clamp is further provided with an axial adjusting hole and a pressing rod matched with the axial adjusting hole. When a thread pair slips, the whole clamp can be quickly disassembled from the outside, lossless unloading is achieved, and time and labor are saved during operation.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the threaded friction coefficient test field, specifically relates to a fixture for threaded friction coefficient detection. BACKGROUND

[0002] In the conventional threaded friction coefficient testing machine, an internal fixture is usually used to fix the counterpart (i.e. the nut matched with the bolt to be tested, or the bolt matched with the nut to be tested) during the test. The fixture is usually an integral component or is fixedly installed in the cavity inside the main base of the testing machine, and the clamping groove for accommodating and limiting the rotation of the counterpart is located deep inside the equipment. During the test, the counterpart is placed in the internal fixture, and the rod of the threaded connection pair passes through the backing plate.

[0003] However, this internal structure has a prominent engineering defect: when the threaded pair slips during the test, the operator cannot directly contact and operate from the outside because the fixture and the counterpart inside it are completely enclosed inside the main base. At this time, it is extremely difficult to try to take out the "locked" threaded connection pair from the internal fixture after slipping.

[0004] To solve this problem, the existing technology can only resort to destructive means, such as using a sawing device to cut off the rod or head of the bolt, so as to take out the entire failed threaded pair from the testing machine. This method not only directly destroys the test sample, increasing the test cost, but also takes time and effort to operate, and generates debris that may contaminate the equipment. More importantly, it interrupts the test process, reducing the overall efficiency of the equipment and the throughput capacity of the laboratory.

[0005] Therefore, it is urgent to develop a new type of fixture structure that is easy to maintain, so that it can be quickly, non-destructively and conveniently disassembled when a test failure occurs, thereby fundamentally solving the above problems. UTILITY MODEL CONTENTS

[0006] In view of the deficiencies in the prior art, the utility model provides a special fixture for threaded friction coefficient detection, aiming to solve the technical problem that in the prior art, when the threaded pair (bolt and nut) slips during the test, the nut and the fixing mechanism are completely built-in inside the testing machine base, making it impossible to non-destructively and conveniently unload the slipping threaded connection pair, and ultimately only the destructive way (such as cutting off the bolt) can be used to take out.

[0007] The technical solution of the utility model is as follows:

[0008] A fixture for threaded friction coefficient detection, comprising an assembly seat, a clamping execution seat and a circumferential locking pin.

[0009] The assembly base is used for assembly connection with a main base of a testing machine.

[0010] Corresponding half holes are arranged on the assembly base and the clamping execution base, and when the two are connected, the two half holes jointly form a limiting hole; the circumferential locking pin is pluggably assembled in the limiting hole, and is used for limiting rotation of the clamping execution base relative to the assembly base.

[0011] Further, a double-line external thread is arranged on the outer periphery of the clamping execution base, and a double-line internal thread that matches the double-line external thread is arranged on the assembly base.

[0012] Further, an adjusting hole that is axially through to the anti-rotation clamping slot is arranged at the tail end of the clamping execution base.

[0013] Further, a pressing rod is arranged, and the pressing rod is threadedly connected with the adjusting hole; an abutting surface is formed on the end face of the end of the pressing rod that extends into the anti-rotation clamping slot, and an avoiding hole is arranged on the abutting surface.

[0014] Compared with the prior art, the utility model has the following beneficial effects:

[0015] 1. By designing the tail end of the clamping execution base to be exposed from the outside of the main base, and matching the pluggable circumferential locking pin, when a slip failure occurs, the operator does not need to perform any destructive operation. Only the locking pin needs to be pulled out, and a general tool is used to rotate the tail end from the outside, so that the entire clamp together with the internally jammed counter-hand piece (nut or bolt) can be rotated out from the testing machine as a whole, thereby facilitating the removal of the failure piece, and significantly improving the maintainability and testing efficiency of the testing machine.

[0016] 2. By matching the limiting hole formed by the half holes on the assembly base and the clamping execution base and the circumferential locking pin, accidental loosening of the clamping execution base can be effectively prevented during high-torque testing, the locking state of the clamp is ensured to be stable, and the accuracy and repeatability of the test data are ensured.

[0017] 3. By using double-line thread matching, the number of rotation circles required when the clamping execution base is rotated in and out is halved, not only the disassembly and assembly speed of the clamp is faster, but also the labor intensity of the operator is greatly reduced, and the operation convenience is improved.

[0018] 4、By setting the adjusting hole axially through to the anti-rotation clamping groove and the matched compression rod, the clamp can be not only used for the conventional bolt friction coefficient test (fixed nut), but also can be conveniently converted into the nut friction coefficient test mode. In the test of the nut, the bolt can be put into from the adjusting hole side and be tightly pressed by the compression rod as the opponent. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a perspective view of a thread friction coefficient testing machine.

[0020] Figure 2 It is a sectional view of a main machine base.

[0021] Figure 3 It is a perspective view of a clamp.

[0022] Figure 4 It is an exploded view of the clamp.

[0023] Figure 5 It is a plan structure view when the opponent is installed on the clamping execution base.

[0024] Component name and corresponding label list:

[0025] 100, workbench; 110, test driving unit; 111, joint; 120, backing plate; 130, fastener to be tested; 140, opponent;

[0026] 200, main machine base; 210, installation cavity; 220, axial positioning ring table; 221, center hole; 222, circumferential limiting column;

[0027] 300, clamp; 310, assembly seat; 311, circumferential positioning hole; 312, double-line internal thread; 313, half hole; 320, clamping execution base; 321, double-line external thread; 322, clamping end; 323, anti-rotation clamping groove; 324, through hole; 325, adjusting hole; 330, circumferential locking pin; 340, compression rod; 341, avoiding hole. DETAILED DESCRIPTION

[0028] The utility model will be further described in detail below in combination with the drawings and specific embodiments.

[0029] In the following embodiments, the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout, and the following embodiments described by referring to the drawings are exemplary and are only used to explain the utility model, and cannot be understood as the limitation of the utility model.

[0030] In the description of the utility model, it needs to be understood that the terms: center, longitudinal, transverse, length, width, thickness, upper, lower, front, rear, left, right, vertical, horizontal, top, bottom, inner, outer, clockwise, counterclockwise and other indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, therefore cannot be understood as limiting the utility model. In addition, the terms: first, second and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the shown technical features. In the description of the utility model, unless otherwise explicitly specified and limited, the terms: mounting, connection, connection and the like should be understood in a broad sense, and the person skilled in the art can understand the specific meaning of the above terms in the utility model according to the specific circumstances.

[0031] Reference Figures 1 to 5 A kind of thread friction coefficient testing machine, to solve the technical problem that existing equipment is difficult to remove from inside after the thread connection pair (such as bolt and nut) slip during testing process, leading to unloading difficulty. The thread friction coefficient testing machine main workbench 100, the test drive unit 110 is assembled on the workbench 100, main machine base 200, backing plate 120 and the core clamp 300.

[0032] The torque sensor and angle encoder are integrated inside the test drive unit 110, which is used to provide rotation torque and angular displacement measurement, and the output end is connected with replaceable joint 111, which can be selected according to the head size and shape of the fastener 130 (bolt or nut) to be tested to reliably clamp and drive its rotation.

[0033] Reference Figure 2 The main machine base 200 is connected to the workbench 100 by slide rail, and an installation cavity 210 is arranged in the main machine base 200. An annular axial positioning ring table 220 is machined on the inner wall of the side of the installation cavity 210 close to the test drive unit 110. The hole diameter of the center hole 221 of the axial positioning ring table 220 is smaller than the inner diameter of the installation cavity 210, so as to form a stepped surface. A plurality of circumferential limiting columns 222 extending in the axial direction are uniformly distributed on the axial positioning ring table 220. The force sensor is also integrated in the main machine base 200 for accurately measuring the axial pre-tightening force generated during tightening. The backing plate 120 is fixedly installed on the side end face of the main machine base 200 facing the test drive unit 110 by bolts, and a center hole 221 is arranged thereon for the threaded rod to pass through.

[0034] During testing, the torque sensor in the test drive unit 110 measures the rotation torque, and the force sensor in the main machine base 200 measures the axial force. The control system can calculate the friction coefficient of the thread pair according to the torque-angle-axial force data collected.

[0035] Reference Figures 3 to 5 The clamp 300 is designed as an independent module that can be integrally detached from the main base 200, mainly including an assembly seat 310, a clamping execution seat 320 and a circumferential locking pin 330.

[0036] The assembly seat 310 is generally cylindrical, and its outer periphery is in clearance fit with the mounting cavity 210 of the main base 200. A plurality of circumferential positioning holes 311 corresponding in number and position to the circumferential limiting columns 222 are formed in the assembly seat 310. When the clamp 300 is assembled into the main base 200, the end face of the assembly seat 310 abuts against the stepped face of the axial positioning ring table 220, and the circumferential limiting columns 222 are inserted into the circumferential positioning holes 311, thereby completing the axial and circumferential positioning and fixing of the clamp 300 in the main base 200, preventing rotation or movement of the clamp 300 during testing. The inner hole of the assembly seat 310 is provided with internal threads.

[0037] The clamping execution seat 320 is threadedly connected with the assembly seat 310. As a preferred solution, the outer periphery of the clamping execution seat 320 is provided with double-line external threads 321, and the internal threads of the assembly seat 310 are corresponding double-line internal threads 312. The double-line threads make the axial movement distance (lead) of the clamping execution seat 320 per rotation one circle twice that of ordinary single-line threads. This design halves the number of rotation circles required for screwing in and out when the clamp 300 is installed and detached, making the detachment faster and more labor-saving.

[0038] At the connection part of the clamping execution seat 320 and the assembly seat 310, corresponding half-holes 313 with a generally semicircular cross-section are formed in the two. When the clamping execution seat 320 is completely screwed into the assembly seat 310 to a predetermined position, the two half-holes 313 are just aligned to form a complete circular limiting hole. At this time, the circumferential locking pin 330 is inserted into the limiting hole, which effectively limits the rotation of the clamping execution seat 320 relative to the assembly seat 310, ensuring that the threaded connection does not loosen during testing of high torque, and maintaining the locking state of the clamp 300. When detachment is needed, the circumferential locking pin 330 is first pulled out.

[0039] The clamping execution seat 320 is provided with a clamping end head 322 at the head end facing the test drive unit 110. The end face of the clamping end head 322 facing the pad 120 is higher than the end face of the assembly seat 310 after the clamp 300 is assembled. This protruding design shortens the suspended distance between the fixed counterpiece 140 (such as a nut) and the pad 120, so that the test machine can not only test standard length bolts, but also reliably test bolts with shorter shanks, expanding the application range of the equipment.

[0040] The clamping end head 322 is provided with a rotation-preventing clamping slot 323 which is completely through along the radial direction of the clamping end head 322. When the counter-piece 140 (for example, a hexagonal nut) is placed in the clamping slot 323, the side surface of the clamping slot 323 can effectively limit the rotation of the counter-piece 140 in the clamping slot 323, thereby achieving fixation. The center of the end surface of the clamping end head 322 is provided with a through hole 324 which is in communication with the rotation-preventing clamping slot 323, and the through hole 324 is used for allowing the rod body (the screw rod of the bolt) of the threaded connection pair to be tested to freely pass through.

[0041] The tail end of the clamping execution seat 320 is processed into a shape which is convenient for clamping by a standard tool, for example, an outer hexagonal head, an inner hexagonal hole or a square head. When the clamp 300 is integrally installed on the main machine base 200, the tail end is exposed from the rear end surface of the main machine base 200 which is away from the base plate 120, so as to facilitate external operation and rapid disassembly.

[0042] In order to further expand the functions, the tail end of the clamping execution seat 320 of the embodiment is further provided with an axial adjusting hole 325 which is through to the rotation-preventing clamping slot 323. The adjusting hole 325 has two main uses: firstly, when the friction coefficient test of the nut is needed to be performed, the bolt can be placed from the adjusting hole 325; and secondly, when the friction coefficient test of the bolt or the nut is performed, a pressing rod 340 can be screwed into the adjusting hole 325. The end surface of the pressing rod 340 which extends into the rotation-preventing clamping slot 323 constitutes an abutting surface which is used for abutting against the end surface of the counter-piece 140 from the back, so as to prevent the counter-piece 140 from rotating or axially moving when the bolt and the nut are assembled. The abutting surface is further provided with an avoiding hole 341 which is used for avoiding the end portion of the rod body of the bolt when the friction coefficient test of the bolt is performed, so as to ensure that the pressing is in place.

[0043] The working principle and operation process of the test machine are as follows (taking the test of the bolt as an example):

[0044] 1. Installation and test preparation: the clamping execution seat 320 is screwed into the assembly seat 310, the circumferential locking pin 330 is inserted, and the clamping execution seat 320 is locked. Then the assembly seat 310 is placed into the installation cavity 210 of the main machine base 200, so that the circumferential limiting column 222 is inserted into the positioning hole. Then the counter-piece 140 (the nut) is placed into the rotation-preventing clamping slot 323 of the clamping execution seat 320, and the rod body of the fastener 130 (for example, the bolt) to be tested is sequentially passed through the base plate 120, the through hole 324 and the rotation-preventing clamping slot 323, and is screwed with the counter-piece 140 (the nut). Then the connector 111 of the test driving unit 110 is clamped to the head of the fastener 130 (the bolt) to be tested.

[0045] 2. Normal test: the equipment is started, the test driving unit 110 drives the fastener 130 to be tested to rotate, the system records the torque and the rotation angle, and the friction coefficient is calculated. After the test is completed, the above steps are reversed to unload the test piece.

[0046] 3. Fault handling (slip off load): when the bolt slips, the nut and the bolt rotate together, and cannot be normally unscrewed, the traditional method needs to damage the bolt.

[0047] When the present application is used, the operator first pulls out the circumferential locking pin 330. Then using a wrench or other standard tools, the tail end of the clamping execution seat 320 is exposed from the rear end of the main machine base 200 for operation, and the entire clamping execution seat 320 is rotated out of the assembly seat 310 together with the tool 140 (nut). Since the tool 140 (nut) has been removed from the main machine base 200, the slipping fastener 130 (bolt) to be tested can be very conveniently removed for subsequent processing, and the entire process does not need to damage any component, is fast and labor-saving, greatly improves the availability and maintenance efficiency of the equipment.

[0048] The protection scope of the present application includes but is not limited to the above embodiments, and the protection scope of the present application is subject to the claims, and any replacement, deformation, improvement of the present technology easily thought by the skilled in the art falls within the protection scope of the present application.

Claims

1. A fixture for detecting the coefficient of friction of threads, characterized in that, It includes a mounting base (310), a clamping actuator (320), and a circumferential locking pin (330); The mounting base (310) is used for assembly and connection with the main base (200) of the testing machine; The clamping actuator (320) is threadedly connected to the assembly base (310). The head end of the clamping actuator (320) is provided with a clamping end (322). The clamping end (322) is provided with a radially penetrating anti-rotation groove (323) for placing and restricting the rotation of the handpiece (140). The end face of the clamping end (322) is provided with a through hole (324) communicating with the anti-rotation groove (323). The mounting base (310) and the clamping actuator (320) are respectively provided with half holes (313). When the two are connected, the two half holes (313) together form a limiting hole. The circumferential locking pin (330) is pluggably mounted in the limiting hole to limit the rotation of the clamping actuator (320) relative to the mounting base (310). The tail end of the clamping actuator (320) is configured to facilitate tool clamping, and when the clamp (300) is assembled on the main unit base (200), the tail end protrudes from the end face of the main unit base (200).

2. The clamp according to claim 1, characterized in that, The outer periphery of the clamping actuator (320) is provided with a double-threaded external thread (321), and the mounting base (310) is provided with a double-threaded internal thread (312) that mates with the double-threaded external thread (321).

3. The clamp according to claim 1, characterized in that, The tail end of the clamping actuator (320) is provided with an adjustment hole (325) that extends axially through to the anti-rotation slot (323).

4. The clamp according to claim 3, characterized in that, It also includes a clamping rod (340), which is threadedly connected to the adjusting hole (325); the end face of the clamping rod (340) extending into one end of the anti-rotation groove (323) forms an abutment surface, and the abutment surface is provided with a clearance hole (341).

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