Calibration device for impact wrenches

Abstract

The application provides a calibration device of an impact wrench, which comprises a bottom plate, a torque sensor, a support column, a top plate and a bolt simulator; the torque sensor is installed on the bottom plate; a bearing hole in the middle of the top plate is embedded with a ball bearing; the bolt simulator comprises a nut seat, a gasket chamber, a lower gasket, a butterfly spring, an upper gasket, a force sensor seat, a first pressure sensor and a bolt; the torque sensor is installed below the bolt simulator, directly measuring the torque of the locking bolt of the impact wrench; the impact wrench is directly connected with the bolt, and the transmission of the energy of the impact wrench is not affected; the ball bearing is installed in the middle of the top plate; before the bolt is locked, the bolt head is in contact with the end face of the inner ring of the ball bearing; the rolling friction of the ball bearing has little loss on the torque, thereby improving the accuracy of the determination of the locking torque. The calibration device can directly measure the torque T and the locking force F of the locking of the impact wrench on the bolt, and accurately obtain the torque coefficient K of the impact wrench.

Description

TECHNICAL FIELD

[0001] The present application relates to the impact wrench measurement technical field, and particularly relates to a calibration device of an impact wrench. BACKGROUND

[0002] The wrench is a tool for tightening nuts and bolts, and ensures that the torque between the nut and the bolt reaches the set torque.

[0003] There are two types of wrenches, one is a continuous output type wrench, and the other is an impact wrench. The output shaft of the continuous output type wrench continuously rotates with the nut until it is locked. The other is the impact wrench. The impact wrench is driven by a prime mover through a reducer to drive the driving part of the impact mechanism, and then drives the driven part through the meshing of the toothed insert. The rotation of the striking part of the driving part will produce intermittent rotation strikes from the output shaft of the driven part when the torque of the wrench exceeds the static torque. The rotation strike is repeated to finally rotate the nut.

[0004] For the continuous output type wrench, its performance only needs to be measured by measuring the output torque. A rotary torque sensor is connected to the output shaft to directly measure the output torque.

[0005] For the impact wrench, its performance is generally defined by the torque coefficient K, K=T / (F*D), wherein T is the torque, F is the locking force, and D is the bolt diameter.

[0006] At present, the calibration of the impact wrench is completed by means of a bolt simulator with a locking force test function. First, the torque coefficient of the bolt simulator is calibrated. The output torque and the locking force are linearly fitted to obtain the torque coefficient of the bolt simulator by performing multiple screwing tests on the bolt simulator by means of a torque output device with a torque measurement function. Then, the impact wrench to be tested is used to perform a screwing test on the bolt simulator. Finally, the locking force measured by the bolt simulator is multiplied by the torque coefficient of the bolt simulator to obtain the torque T of the impact wrench, T=K*F*D.

[0007] There are two main deficiencies in the current measurement of the torque of the impact wrench. First, the calibration of the torque coefficient of the bolt simulator is performed by means of a torque output device with a torque measurement function, which is different from the torque output characteristics of the impact wrench. Second, the torque coefficient K of the bolt simulator is obtained by curve fitting of a large amount of measured data, but the torque coefficient K may change with the repeated use of the bolt simulator, thereby affecting the accuracy of the detection result of the impact wrench. Therefore, there is an urgent need for a device that can directly measure the torque coefficient K of the impact wrench to facilitate the detection and calibration of the torque coefficient K. SUMMARY

[0008] In order to overcome the above-mentioned deficiencies of the prior art, the purpose of the present application is to provide a calibration device for impact wrench.

[0009] In order to achieve the above-mentioned purpose, the technical solution adopted by the present application to solve its technical problems is: a calibration device for impact wrench, comprising:

[0010] a bottom plate;

[0011] a torque sensor mounted on the bottom plate, the bottom plate being provided with a limiting structure limiting the rotation of the torque sensor shell part;

[0012] a support vertically fixedly mounted on the bottom plate;

[0013] a top plate fixedly mounted on the top end of the support, the middle of the top plate being provided with a bearing hole, the bearing hole being embedded with a ball bearing, the inner diameter of the ball bearing being greater than the outer diameter of the threaded part of the bolt, and the head of the bolt having an outer diameter smaller than the inner diameter of the outer ring body of the ball bearing;

[0014] a bolt simulator mounted between the ball bearing and the torque sensor, the bolt simulator comprising a nut seat, a gasket chamber, a lower gasket, a butterfly spring, an upper gasket, a force sensor seat, a first pressure sensor and a bolt, the lower end of the nut seat being connected with the upper shaft body of the torque sensor, and the center of the nut seat being provided with a threaded hole; the gasket chamber is located at the periphery of the nut seat, the bottom of the gasket chamber is provided with a stop structure limiting the upward movement of the nut seat relative to it, the lower gasket, the butterfly spring, the upper gasket and the force sensor seat are sequentially arranged in the gasket chamber from bottom to top, the lower gasket, the butterfly spring and the upper gasket are located at the periphery of the nut seat and have a gap between the outer circumferential wall of the nut seat, the force sensor seat has the freedom of moving up and down relative to the gasket chamber; the first pressure sensor is installed at the middle position of the force sensor seat, the first pressure sensor has a through hole in the center for the bolt to pass through, and the first pressure sensor is located below the ball bearing; the bolt passes through the ball bearing, the first pressure sensor, the force sensor seat and the threaded hole of the nut seat in sequence from top to bottom.

[0015] By adopting the technical solution of the present application, the torque sensor is installed below the bolt simulator, which can directly measure the torque of the bolt locked by the impact wrench, the output shaft of the impact wrench is directly connected with the bolt, and the transmission of the energy of the impact wrench will not be affected; the ball bearing is installed in the middle of the top plate, before the bolt is locked, after the bolt head contacts the end face of the inner ring body of the ball bearing, the inner ring body of the ball bearing will rotate, the rolling friction of the bearing has very small loss on the torque, thereby improving the accuracy of the determination of the locking torque. Through the calibration device, the torque T and the locking force F of the bolt locked by the impact wrench can be directly measured, and the torque coefficient K of the impact wrench can be directly obtained by substituting the formula.

[0016] Further, the wrench clamping unit comprises a support, a lifting frame, a lifting drive mechanism, a baffle, a second pressure sensor and a clamping plate, the support is fixedly connected to the bottom plate, the lifting frame is movably installed on the support, the lifting drive mechanism drives the lifting frame to move up and down relative to the support, the baffle is fixedly connected to the lower end of the lifting frame, the clamping plate is movably installed on the lifting frame below the baffle, the second pressure sensor is installed between the baffle and the clamping plate, and the clamping plate is provided with a detachable locking piece for clamping the impact wrench to be tested.

[0017] With the preferred scheme, the second pressure sensor provided on the wrench clamping unit can detect the pressure of the impact wrench on the bolt in real time, facilitate the impact wrench to maintain consistent pressure on the bolt during testing, and help eliminate the influence of different wrench pressures on the test results.

[0018] Further, a spring is sleeved on the lifting frame below the clamping plate.

[0019] With the preferred scheme, the spring buffers the clamping plate, ensuring the stability of the impact wrench.

[0020] Further, during testing, the lifting drive mechanism drives the lifting frame to move before the impact wrench is started, so that the detection force value of the second pressure sensor is within the set range; after the impact wrench is started, the lifting drive mechanism drives the lifting frame to move downward synchronously with the bolt, so that the detection force value of the second pressure sensor is also within the set range.

[0021] With the preferred scheme, the impact wrench maintains a constant pressure range on the bolt during the detection process.

[0022] Further, the lifting frame comprises a first guide rod, a second guide rod and an upper connecting plate, the first guide rod and the second guide rod are vertically and parallelly arranged, the upper connecting plate is connected to the top ends of the first guide rod and the second guide rod, the baffle is connected to the lower part of the first guide rod and the second guide rod, and the first guide rod and the second guide rod are movably installed on the top plate of the support through guide sleeves.

[0023] Further, the lifting drive mechanism comprises a lead screw and a motor, the screw rod of the lead screw is rotatably and vertically installed on the upper connecting plate through a bearing, the nut of the lead screw is installed on the support, and the motor drives the screw rod to rotate to realize the lifting movement of the lifting frame.

[0024] With the preferred scheme, the lifting and pressure stability are improved.

[0025] Further, the force sensor seat is provided with a check shaft extending radially outward on each side, and the check shaft is provided with a bearing outside the check shaft, the top of the gasket chamber is provided with a U-shaped groove, the bearing is located in the U-shaped groove and can move up and down in the U-shaped groove, and the side wall of the U-shaped groove is in contact with the outer periphery of the bearing and limits the left and right positions of the bearing.

[0026] The preferred scheme ensures that the force sensor seat has a vertical freedom degree when locked, and improves the accuracy of the first pressure sensor in measuring the locking force.

[0027] Further, the center of the force sensor seat is provided with an inner recessed embedding groove, the first pressure sensor is embedded in the embedding groove, the top end of the first pressure sensor is provided with a pressure ring, and the outer diameter of the pressure ring is smaller than the inner diameter of the outer ring of the ball bearing.

[0028] The preferred scheme maximally reduces the torque loss and ensures that the torque of the impact wrench fully acts on the locking of the bolt. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0030] Figure 1 is a structural schematic diagram of an embodiment of the present application.

[0031] Figure 2 is a sectional view of an embodiment of the present application.

[0032] Figure 3 is a structural schematic diagram of another embodiment of the present application.

[0033] Figure 4 is a structural schematic diagram of a wrench clamping unit.

[0034] Names of corresponding components represented by numbers and letters in the drawings:

[0035] 10-base plate; 11-limiting structure; 20-torque sensor; 30-strut; 31-top plate; 32-roller bearing; 40-bolt simulator; 41-nut seat; 42-gasket chamber; 421-U-shaped groove; 43-lower gasket; 44-clip spring; 45-upper gasket; 46-force sensor seat; 461-check shaft; 462-bearing; 47-first pressure sensor; 471-pressure ring body; 48-bolt; 50-wrench clamping unit; 51-bracket; 52-lifting frame; 521-first guide rod; 522-second guide rod; 523-upper connecting plate; 524-guide sleeve; 53-lifting drive mechanism; 531-motor; 532-screw rod; 533-nut; 54-baffle; 55-second pressure sensor; 56-clamping plate; 57-locking piece; 58-spring; 60-impact wrench. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0037] As shown in Figure 1 , 2 , an embodiment of the present application is: a calibration device of an impact wrench, comprising:

[0038] a base plate 10;

[0039] a torque sensor 20 installed on the base plate 10, the base plate 10 being provided with a limiting structure 11 limiting the rotation of a shell part of the torque sensor 20;

[0040] a strut 30 vertically fixedly installed on the base plate 10;

[0041] a top plate 31 fixed to the top end of the strut 30, the top plate 31 being provided with a bearing hole in the middle, the bearing hole being embedded with a roller bearing 32, the inner diameter of the roller bearing 32 being greater than the outer diameter of the threaded part of a bolt 48, and the head outer diameter of the bolt 48 being smaller than the inner diameter of the outer ring body of the roller bearing 32;

[0042] A bolt simulator 40 is installed between the ball bearing 32 and the torque sensor 20, the bolt simulator 40 comprises a nut seat 41, a gasket chamber 42, a lower gasket 43, a butterfly spring 44, an upper gasket 45, a force sensor seat 46, a first pressure sensor 47 and a bolt 48, the lower end of the nut seat 41 is connected with the upper input end of the torque sensor 20, and a threaded hole is arranged in the center of the nut seat 41; the gasket chamber 42 is located at the periphery of the nut seat 41, and a stop structure for limiting the upward movement of the nut seat 41 is arranged at the bottom of the gasket chamber 42; the lower gasket 43, the butterfly spring 44, the upper gasket 45 and the force sensor seat 46 are sequentially arranged in the gasket chamber 42 from bottom to top, the lower gasket 43, the butterfly spring 44 and the upper gasket 45 are located at the periphery of the nut seat 41 and have a gap with the outer circumferential wall of the nut seat, and the force sensor seat 46 has a freedom degree of moving up and down relative to the gasket chamber 42; the first pressure sensor 47 is installed at the middle position of the force sensor seat 46, the first pressure sensor 47 has a through hole in the center for the bolt to pass through, and the first pressure sensor 47 is located below the ball bearing 32; the bolt 48 passes through the ball bearing 32, the first pressure sensor 47 and the force sensor seat 46 from top to bottom and is connected with the threaded hole of the nut seat 41.

[0043] The beneficial effects of the above technical scheme are that the torque sensor is installed below the bolt simulator, the torque of the impact wrench for locking the bolt can be directly measured, the output shaft of the impact wrench is directly connected with the bolt, and the energy transmission of the impact wrench is not affected; the ball bearing is installed in the middle of the top plate, before the bolt is locked, the inner ring body of the ball bearing rotates after the bolt head contacts the end face of the inner ring body of the ball bearing, the rolling friction of the bearing has little loss on the torque, and the accuracy of the locking torque measurement is improved. The torque T and the locking force F of the impact wrench for locking the bolt can be directly measured through the calibration device, and the torque coefficient K of the impact wrench can be directly obtained by substituting the formula K=T / (F*D).

[0044] As Figure 3 , 4As shown in the drawings, in some other embodiments of the present application, a wrench clamping unit 50 is further included, which comprises a support 51, a lifting frame 52, a lifting drive mechanism 53, a baffle 54, a second pressure sensor 55 and a clamping plate 56, the support 51 is fixedly connected to the bottom plate 10, the lifting frame 52 is movably installed on the support 51, the lifting drive mechanism 53 drives the lifting frame 52 to move up and down relative to the support 51, the baffle 54 is fixedly connected to the lower end of the lifting frame 52, the clamping plate 56 is movably installed on the lifting frame 52 below the baffle 54, the second pressure sensor 55 is installed between the baffle 54 and the clamping plate 56, and the clamping plate 56 is provided with a detachable locking piece 57 for clamping the impact wrench to be tested. The beneficial effect of the above technical solution is that the second pressure sensor arranged on the wrench clamping unit can detect the pressure of the impact wrench on the bolt in real time, which facilitates the consistent pressure condition of the impact wrench on the bolt during testing and helps to eliminate the influence of different wrench pressing forces on the test results.

[0045] As shown in the drawings, Figure 4 In some other embodiments of the present application, a spring 58 is sleeved on the lifting frame 52 below the clamping plate 56, and the bottom end of the lifting frame 52 is provided with a stop ring body for limiting the lower end of the spring. The beneficial effect of the above technical solution is that the spring provides a buffer for the clamping plate, ensuring the stability of the impact wrench repositioning.

[0046] During detection, the lifting drive mechanism 53 drives the lifting frame 52 to move before the impact wrench is started, so that the detection force value of the second pressure sensor 55 is within the set range; after the impact wrench is started, the lifting drive mechanism 53 drives the lifting frame 52 to move downward synchronously with the bolt, so that the detection force value of the second pressure sensor 55 is also within the set range. The beneficial effect of the above technical solution is that the impact wrench keeps the bolt within a constant pressure range during the detection process.

[0047] As shown in the drawings, Figure 4 In some other embodiments of the present application, the lifting frame 52 comprises a first guide rod 521, a second guide rod 522 and an upper connecting plate 523, the first guide rod 521 and the second guide rod 522 are vertically and parallelly arranged, the upper connecting plate 523 is connected to the top ends of the first guide rod 521 and the second guide rod 522, the baffle 54 is connected to the lower parts of the first guide rod 521 and the second guide rod 522, and the first guide rod 521 and the second guide rod 522 are movably installed on the top plate of the support 51 through guide sleeves 524. The lifting drive mechanism 53 comprises a lead screw and a motor 531, the screw rod 532 of the lead screw is vertically rotatably installed on the upper connecting plate 523 through a bearing, the nut 533 of the lead screw is installed on the support 51, and the motor 531 drives the screw rod 532 to rotate to realize the lifting movement of the lifting frame 52. The beneficial effect of the above technical solution is to improve the lifting and pressing stability.

[0048] As Figure 1 shown in the drawings, in some embodiments of the present application, the force sensor seat 46 is provided with a check shaft 461 extending radially outward on each side thereof, the check shaft 461 is provided with a bearing 462 on the outer periphery thereof, the top of the chamber wall of the gasket chamber 42 is provided with a U-shaped groove 421, the bearing 462 is located in the U-shaped groove 421 and can move up and down in the U-shaped groove, the side wall of the U-shaped groove 421 is in contact with the outer periphery of the bearing 462 and limits the left and right positions of the bearing 462. The beneficial effect of the above technical solution is that the force sensor seat can keep a certain degree of freedom in the vertical direction during locking, and the accuracy of the locking force measured by the first pressure sensor is improved.

[0049] As Figure 2 shown in the drawings, in some embodiments of the present application, the force sensor seat 46 is provided with a check shaft 461 extending radially outward on each side thereof, the check shaft 461 is provided with a bearing 462 on the outer periphery thereof, the top of the chamber wall of the gasket chamber 42 is provided with a U-shaped groove 421, the bearing 462 is located in the U-shaped groove 421 and can move up and down in the U-shaped groove, the side wall of the U-shaped groove 421 is in contact with the outer periphery of the bearing 462 and limits the left and right positions of the bearing 462. The beneficial effect of the above technical solution is that the force sensor seat can keep a certain degree of freedom in the vertical direction during locking, and the accuracy of the locking force measured by the first pressure sensor is improved.

[0050] The above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application, and any equivalent changes or modifications made according to the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. A calibration device for an impact wrench, characterized by, The torque sensor is installed on the bottom plate, and the bottom plate is provided with a limiting structure for limiting the rotation of a shell part of the torque sensor and a check structure for limiting the rotation of a lower shaft body of the torque sensor. The top plate is fixed to the top end of the support column, and a bearing hole is arranged in the middle of the top plate, wherein a ball bearing is embedded in the bearing hole, the inner diameter of the ball bearing is larger than the outer diameter of the threaded part of the bolt, and the head of the bolt has an outer diameter smaller than the inner diameter of the outer ring body of the ball bearing. The torque coefficient K of the impact wrench is calculated by the formula K=T / (F*D), wherein T is the torque measured by the torque sensor, D is the diameter of the bolt, and F is the locking force measured by the first pressure sensor. The wrench clamping unit comprises a support, a lifting frame, a lifting driving mechanism, a baffle, a second pressure sensor and a clamping plate. A spring is arranged on the lifting frame below the clamping plate. During detection, before the impact wrench is started, the lifting driving mechanism drives the lifting frame to move so that the detection force value of the second pressure sensor is within a set range; after the impact wrench is started, the lifting driving mechanism drives the lifting frame to move downward synchronously with the bolt, so that the detection force value of the second pressure sensor is also within the set range. ​ 2. The calibration device for impact wrenches of claim 1, wherein, ​ 3. The calibration device for impact wrenches of claim 2, wherein, ​ 4. The calibration device for impact wrenches of claim 3, wherein, ​ 5. The calibration device for impact wrenches of claim 2, wherein, The lifting frame comprises a first guide rod, a second guide rod and an upper connecting plate, the first guide rod and the second guide rod are vertically and parallel arranged, the upper connecting plate is connected to the top ends of the first guide rod and the second guide rod, the baffle is connected to the lower parts of the first guide rod and the second guide rod, the first guide rod and the second guide rod are respectively and vertically installed on the top plate of the support through guide sleeves.

6. The calibration device for impact wrenches of claim 5, wherein, The lifting driving mechanism comprises a lead screw and a motor, the screw rod of the lead screw is rotatably and vertically installed on the upper connecting plate through a bearing, the nut of the lead screw is installed on the support, and the motor drives the screw rod to rotate to realize the lifting movement of the lifting frame.

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