GB2488696A

GB2488696A - On-line detecting device with force feedback of internal thread cutting machine tool of oil pipe connecting hoop

Info

Publication number: GB2488696A
Application number: GB1209377.9A
Authority: GB
Inventors: Qiang Zhou; Fengyan Xiao
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2009-12-18
Filing date: 2010-09-26
Publication date: 2012-09-05
Also published as: CN101745844B; WO2011072473A1; CN101745844A; GB201209377D0

Abstract

An on-line detecting device with force feedback of internal thread cutting machine tool of oil pipe connecting hoop, the device detects the tooth profile parameter of internal thread while processing the internal thread of oil pipe connecting hoop through cutting machine tool. The device is consisted of an axial moving mechanism subassembly (101), a radial moving mechanism subassembly (102), a force detection probe head subassembly (103); the radial moving mechanism subassembly (102) is fixed on extremity of the axial moving mechanism subassembly (101), and the center shaft of the radial moving mechanism subassembly (102) is orthogonally perpendicular to the central axial line of axial moving mechanism subassembly (101); the force detection probe head (103) is coaxially installed on extremity of axial moving mechanism subassembly (101). The invention has force feedback function, it can be determined precisely whether the detection needle (251) existed on the extremity of the detecting device touches the tooth face of the internal thread tooth profile measured and how much is the touch force, and the labor can be reduced greatly, and all oil hoops processed can be detected one-by-one on-line, the internal thread detecting precision can be improved and the detection speed can be improved and the quality of the product can be improved.

Description

DEVICE WITH FORCE FEEDBACK FOR ON-LINE INSPECTION OF THE

INTERNAL THREAD OF TUBE COUPLINGS ON A TREADING MACHINE

FIELD OF TIlE INVENTION

This invention presents a novel testing device with force feedback, used for inspecting and monitoring the internal thread of tube couplings when they are threaded on a treading machine. This invention is categorized into the field of high precision automatic testing technology.

BACKGROUND OF INVENTION

Tube coupling, an important mechanical part of machines used in oil fields, plays a critical role in the normal operation of machines used underground. It connects tubes to form an air-tight route. The tapered internal thread on the tube coupling is typical conoid thread.

Currently, two testing methods are used to inspect the thread of tube coupling. One is sample-testing on the spot. Inspectors periodically take samples from the coupling products according to certain rules, then visually inspect the surface of the thread and measure the samples with thread plug gauges. Thread pitch and taper gauges are also used to measure the pitch and taper of the thread. The other method is called laboratory inspection. Inspectors pick one sample of the tube couplings, and use a pen-and-paper record to collect data of the internal thread profile which will be manually processed and archived.

However, both of the above-mentioned methods have many disadvantages. First, they require intensive laboL Second, the measurement may be inconsistent across different inspectors. Third, not all the tube coupling products are inspected. Moreover, the traditional gauges can only find out the disqualified threads, but they cannot be used to identify the exact cause of failure. By the time the threading machine is adjusted based on the measurement of the samples, many disqualified products may have been already manufactured, which is a waste of resources. Therefore, it is necessary to invent an inspection device that can automatically inspect and monitor all of the internal thread of tube couplings during the threading process, so that all final products can meet the quality standards.

SUMMARY OF THE INVENTION

The objective of this invention is to provide a testing device for threading machine, capable of measuring the thread parameters on-line during the threading process of tube couplings. It features the feedback of contact force which enables precise measurement of the contact force between the probe and the internal thread surface. Since the device is fully automatic, it can dramatically improve the efficiency of the thread inspection of tube couplings. As a result, it can improve the quality control of all final products.

This on-line inspecting device consists of two motion components and one force feedback component. So, the device has two orthogonal degrees of freedom (DOFs). One DOE is along the axis (X direction) of the device, driven by a precise motion component to achieve the position of the probe (Xi); and the other is in the radial direction (Y direction) driven by a precise motion component capable of accurate positioning and outputting the moving distance. A force sensor is installed at the end of the radial motion component to measure contact force between the probe and the inspected thread surface. As soon as the measurement result of the force sensor is larger than the contact force threshold, indicating that contact between the probe and thread surface has occur, the motion in Y direction will stop and return the position of the probe on the thread surface in the Y direction (Yi).

The thread parameters of the inspected tube coupling are calculated from the probe position (Xi, Yi) ( i=i,2 n)during the entire testing. Since (Xi, Yi)is collected on a plane passing the center axis of the thread, they can be combined to obtain the two dimensional profile of the thread on the center plane. Then the data is processed to calculate the thread parameters including pitch, taper, thread depth, and thread angle.

The testing device is installed on the chuck of a thread machine at a specific location through an installation plate. When the tube coupling passes this location during its machining, its internal thread is monitored and inspected automatically A device with force feedback for on-line inspecting the internal thread of tube couplings on a treading machine should have the following components.

An axial motion component providing fast and precise motion for the radial component and the force feedback component in the axial direction, and installing the device on onto the chuck of a thread machine A radial motion component mounted at the end of the axial motion component providing fast and precise motion for the force feedback component in the radial direction.

A force feedback component with force sensor and probe installed at the end of radial motion component, monitoring the contact and contact force between the probe and the internal thread of the inspected tube coupling.

Wherein the axial motion component comprises: An installation plate, for positioning and installing the testing device onto the chuck of the thread machine.

An outer socket with two guiding sleeve holes parallel to the center line, mounted on the installation plate.

Four guiding sleeves, two in each guiding sleeve hole of the outer socket, locked in radial direction with a big locking ring.

Two guiding pins, inserting in the guiding sleeves.

A lead screw with a smooth shaft end, a small shoulder, and the right shaft end.

Two bearings, with a separator sleeve in between. The bearings and the sleeve are concentrically mated to the lead screw, positioned by the small shoulder, and then they are installed on the installation plate.

A large pulley, fixed on the end of the lead screw away from the shoulder by a set screw in the radial direction. A short sleeve ring is installed between the pulley and the bearing.

A step motor, fixed on the installation plate and driving the motion mechanism, receives control signals, rotates by the input angle, and drives the lead screw.

A small pulley fixed on the step motor shaft. A tooth belt linking the two pulleys transfers the torque from the step motor to the lead screw.

A ball screw nut, with a concentric fender attached, is screwed on the lead screw. The two guiding pins are inserted and fixed into the guiding pin hole I and II.

A protecting cover for the lead screw is installed on the fender concentrically to the ball screw nut.

A U-shape fixture, outside of the protecting cover, is perpendicularly mounted to the fender.

Wherein the radial motion component comprises: A linear step motion, fixed inside the motor hole in the U-shape fixture, provides an accurate linear motion.

A protecting sleeve for the linear motor is fixed on the end of the motor to protect the linear motor from accident collision.

A protecting cover for the linear motor is fixed on the front of the motor to protect the linear motor from accident collision.

Wherein the force feedback component includes: A sensor socket.

A linear bearing, concentrically installed into the bearing hole in the middle of the sensor socket and locked into position by a locking ring, is used for guiding the probe to move along the axis of the sensor socket.

A force sensor, installed inside the hole at the end of the sensor socket and in contact with the bottom face of the probe, detects and measures the contact between the probe and the thread surface of the internal thread of tube coupling. It converts the contact pressure into voltage values and feeds them back.

A probe, with a cylindrical body, and a bottom face, and a shoulder. The cylindrical body is concentric to the linear bearing, and the bottom face of the probe is in contact with the force sensor. This probe detects the contact between the probe and the thread surface of the internal thread of tube coupling, and transfer the contact force.

A locking cap, with its internal thread mated with the end external thread of the sensor socket at its end such that the bottom face of the counterbore hole is coincident with the front face of the shoulder of the probe, limits the position of the probe in its axis direction and prevent it from dropping off. It also provides a pre-tensor force to the force sensor.

A coupling nut, that is attached to the shaft of the linear step motor and locks the force sensor in the axial direction of the sensor socket.

Wherein the above mentioned bearings are all ball bearings.

Wherein the hole I and II for the guiding pins are symmetric about the center line of the fender.

Wherein the U-shape fixture has an upper cylinder and a lower cylinder whose axes are parallel.

Wherein the typical motion resolution of the step motor is 0.0254mm. Its flange has two through holes for installation.

Wherein the linear bearing is a ball linear bearing.

Wherein the sensor socket has an external thread on the front end, and the senor installation hole on the tail end. It also has internal thread on the tail end.

Wherein the tip of the probe is cone shaped.

Wherein the coupling nut has external thread and a threaded hole.

This invention presents an inspection device for threading machine which has many advantages. It is capable of measuring the thread parameters during the threading process of tube couples. It features the feedback of contact force which enables precise measurement of the contact force between the probe and the internal thread surface. Since the device is fully automatic, it can dramatically improve the efficiency of the thread inspection of tube couplings. As a result, it can improve the quality control of all final products.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention can be obtained when the following detailed description of the preferred embodiment is considered in conjunction with the following drawings, in which: Fig. 1 is the 3D view of the mechanical design of the invented device.

Fig. 2A is the front section view of the invented device.

Fig. 2B is the top section view of the invented device without the radial motion component 102 and the force feedback component 103.

Fig. 2C is the 3D exploded view of the radial component of axial motion component of the invented device.

Fig. 2D is the exploded view of the force feedback component 103 without the protecting cover 241.

Fig. 2E is the front section view of the force feedback component 103.

Fig. 3A is the 3D view of the installation plate 201.

Fig. 3B is the front section view of the installation plate 201.

Fig. 4 is the front section view of the outer socket 203.

Fig. 5 is the front view of the lead screw 214.

Fig. 6 is the 3D view of the fender 205.

Fig. 7 is the U-shape fixture 208 Fig. 8 is the 3D view of the probe 251.

Fig. 9 is the front section view of the middle socket 253.

Fig. 10 is the front section view of the threaded lock cap 252.

Fig. 11 is the from section view of the coupling nut 257.

FIGURE LEGENDS

101 Axial motion component 102 Radial motion component 103 Force feedback component 201 Installation plate 202 Screw 203 Outer socket 204 Ball guiding sleeve 205 Fender 206 Guiding pin 207 Nut for the U-Shape fixture 208 U-Shape fixture 209 Protecting cover for the lead screw 210 Hexagon socket countersunk head cap screw 211 Set screw for the guiding pins 212 Big locking ring.

213 Ball screw nut 214 Lead screw 215 Separator sleeve 216 Bearing lock nut 217 Ball bearing 218 Short sleeve 219 Big pulley 220 Long lock screw 221 Tooth belt 230 Round-head screw 231 Step motor 232 Small pulley 233 Short lock screw 240 Hexagon nut 241 Protecting cover 242 Linear Step motor 243 Flat screw 244 Motor protecting cover 251 Probe 252 Lock cap 253 Socket 254 Linear bearing 255 Bearing lock ring 256 Force sensor 257 Coupling nut 301A Reference outer cylindrical face 302A Reference end face 303A Reference inner cylindrical face 304A Through hole for motor installation 3OlB Big counterbore hole 302B Bottom face of the big counterbore hole 401 Reference cylindrical face 402 Upper guiding sleeve hole 403 Upper groove 404 Lower groove 405 Lower guiding sleeve hole 501 Smooth shaft end 502 Small shoulder 503 Right shaft end 601 Guiding pin installation hole I 602 Guiding pin installation hole II 603 Upper positioning hole 604 Lower positioning hole 605 Front end face 701 Upper shoulder positioning cylinder 702 Lower shoulder positioning cylinder 703 Motor hole 801 Cylindrical body 802 Shoulder of the probe 803 Bottom face of the probe 901 End external thread 902 End face of the middle socket 903 Middle bearing hole 904 Positioning groove 905 Force sensor installation hole 906 Internal threaded hole 1001 Internal thread 1002 End face of the locking cap 1003 Bottom face of the counterbore hole 1101 External thread of the coupling nut 1102 Internal thread of the coupling nut

DETAILED DESCRIPTION OF EMBODIMENT

The detailed embodiment of the invented device is listed below with referring to the attached Figures.

As shown in Figures 1, the invented device consists of an axial motion component 101, a radial motion component 102, and a force feedback component 103.

As shown in Figures 2A and 3A, the invented device is mounted onto the lathe through installation plate and the three jaw chuck. The 220mm reference outer cylindrical face 301 A of the installation plate 201 is concentric with the chuck and the reference end face 302A is coincident with the chuck, so that the device is fixed to the treading machine.

Align the reference cylindrical face 401 of the outer socket 203 with the reference inner cylindrical face 303 A of the installation plate 201. Then fix them with three screws 202.

Insert two ball guiding sleeves 204 into the upper guiding sleeve hole 402 of the outer socket 203. Put a big locking ring 212 into the upper groove 403 to lock two ball guiding sleeves 204 along the axis. Following the same steps, insert two ball guiding sleeves 204 into the lower guiding sleeve hole 405 of the outer socket 203. Put a big locking ring 212 into the upper groove 404 to lock them. Insert a guiding pin 206 into the guiding sleeves 204 of each of the holes 402 and 405. Thus, the axes of the two guiding pins are parallel so that they can guide motion in the axial direction, Put a ball bearing 217, a separator sleeve 215, and a second ball bearing around the smooth shaft end 501 of the lead screw 214. Position them to the small shoulder 502. Then insert the lead screw into the big counterbore hole 301B of the installation plate 201, position them against the bottom face of the big counterbore hole 302B. Us a bearing lock nut 216 to lock the ball bearing 217. Put a short sleeve 218 around the smooth shaft end 501 of lead screw 214, positioning it against the ball bearing 217. Install a big pulley 219 onto the smooth shaft end 501 of the lead screw 214, positioning it against the short sleeve 218. Lock the pulley 219 to the lead screw 214 with a long lock screw 220.

As shown in Figures 2A, 2B, and 3A, install the step motor 231 into the through hole for motor installation 304A of the installation plate 201, and lock it in the axial direction with four round-head screws 230. Put a small pulley 232 on the shaft of the step motor 231, and lock it to the motor shaft with a short lock screw 233. Connect the big pulley 219 and small pulley 232 with a tooth belt 221.

Referring to Figures 2A, 5, and 6, use two hexagon socket countersunk head cap screws 210 to fix the fender 205 and the ball screw nut 213. Then turn the nut onto the lead screw 214 to a position where the front end face 605 of the fender 205 is to the left of the right shaft end 503 of the lead screw 214. Tweak the axial position and radial angle of the fender 205s to align the two guiding pins 206 with the guiding pin installation hole I 601 and hole II 602 of the fender 205. Also make the end face of the two guiding pins are coincident with front end face 605 of the fender 205. Then use two set screws for the guiding pins 211 to fix the guiding pins 206 and fender 205 together.

Install the lead screw protecting cover 209 concentrically onto ball screw nut 213, and glue it to fender 205.

Referring to Figures 2A, 6, and 7, insert the upper shoulder positioning cylinder 701 and lower shoulder position cylinder 702 of the U-shape fixture 208 into the upper positioning hole 603 and lower positioning hole 604 of the fender 205 respectively. Then use two nuts 207 to fix the U-shape fixture 208 to the fender 207.

When the step motor 231 rotates by a specified angle, it drives the small pulley 232 and transfers the motion to the big pulley 219 and the lead screw 214 by the tooth belt 221. Due to the linear constraints by the two guiding pins 206, the ball screw nut 213 cannot rotate. It can only move in the axial direction driven by the lead screw. So the axial motion component 102 moves with it in the axial direction for certain displacement As shown in Figures 2C and 7, glue the motor protecting cover 244 to the end of the linear step motor 242. Then install the linear step motor 242 to the motor hole 703 of the U-shape fixture 208.

Put the protecting cover 214 around the front end of the linear step motor 242. Then use two flat screws 243 and two hexagon nut 240 to fix together the linear step motor 242, the U-shape fixture 208, and the protecting cover 241.

As shown in Figures 2E and 9, insert the linear bearing 254 into the middle bearing hole 903 of the socket 253. Put the bearing lock ring 255 into the positioning groove 904 of the socket 253 so that the linear bearing 254 is locked in the axial direction of the socket 253.

As shown in Figures 2E, 8, and 9, insert the cylindrical body 801 of the probe into the linear bearing 254, 50 that the bottom face of the probe 803 of the probe 251 faces to the end face 902 of the socket 253.

As shown in Figures 9, 10, and 11, mate the internal thread 1001 of the lock cap 252 to the end external thread 901 of the socket 253, so that the end face of the locking cap 1002 of the lock cap 252 is coincident with the end face 902. The bottom face of the counterbore hole 1003 of the lock cap 252 is coincident to the Shoulder of the probe 802.

As shown in Figures 2E, 9, and 11, insert the force sensor 256 into the force sensor installation hole 905 of the socket 253. Screw the coupling crewing 257 into the socket 253 so that the force sensor 256 comes in contact with the bottom face of the probe 803 of the probe 251 and locks its position in the axial direction of the socket 253. Finally, screw the coupling nut 257 onto the shaft of the linear step motor and lock in place with the internal thread 1102.

The linear step motor 242 in the radial motion component 102 provides the force feedback component 103 fast and precise radial motion, and enables the force feedback component 103 to approach the internal thread surface of the tube coupling slowly and precisely. When the probe 251 in the force feedback component 103 does not contact the internal thread surface of the tube coupling, the force sensor has an initial pre-tension FO.

When the probe 251 comes into contact with the thread surface, the force sensor 256 will feedback contact force Fl. The contact force between the probe 251 and the thread surface is F = Fl -FO. Thus, the radial motion component 102 can stop its motion if the contact force is larger than the set threshold. The radial displacement is also recorded.

So far, a complete device with force feedback for on-line inspecting the internal thread of tube couplings on a treading machine is presented.

Although this invention is described, it is not limited to the description. Any engineers in this field can modify the design in the scope of this invention. Therefore, this invention is protected by the claims.

The above described preferred embodiments are intended to illustrate the principles of the present invention, but not to limit the scope of the invention. Other embodiments and variations to these preferred embodiments will be apparent to those skilled in the art and may be made without departing from the scope of the invention as defined in the claims.

Claims

CLAIMSWhat is claimed is: 1. A device with force feedback for on-line inspecting the internal thread of tube couplings on a treading machine, comprising: An axial motion component.A radial motion component mounted to the end of the axial motion component so that their center lines are orthogonal.A force sensor installed coaxially at the end of the radial motion component. So, they have the same axis.The axial motion component comprises: An installation plate, for positioning and installing the inspection device onto the chuck of the thread machine.An outer socket with two guiding sleeve holes parallel to the center line, mounted on the installation plate, Four guiding sleeves, two in each guiding sleeve hole of the outer socket, locked in place with a big locking ring.Two guiding pins, inserting in the guiding sleeves.A lead screw with a smooth shaft end, a small shoulder, and the right shaft end.Two bearings, with a separator sleeve in between. The bearing and the sleeve are concentrically mated to the lead screw, positioned by the small shoulder, and installed on the installation plate.A large pulley, fixed on the end of the lead screw away from the shoulder by a set screw in the radial direction. A short sleeve ring is installed between it and the bearing.A step motor, fixed on the installation board and driving the motion mechanism receives control signals, rotates by the input angle, and drives the lead screw.A small pulley fixed on the step motor shaft. A tooth belt linking the two pulleys transfers the torque from the step motor to the lead screw.A ball screw nut, with a concentric fender attached, is screwed on the lead screw. The two guiding pins are inserted and fixed into the guiding pin hole I and II.A protecting cover for the lead screw is installed on the fender concentrically to the ball screw nut.A U-shape fixture, outside of the protecting cover, is perpendicularly mounted to the fender.The axial motion component comprises: A linear step motion, fixed inside the motor hole in the U-shape fixture, provides an accurate linear motion.A protecting sleeve for the linear motor is fixed on the end of the motor to protect the linear motor from accident collision A protecting cover for the linear motor is fixed on the front end of the motor to protect the linear motor from accident collision.The force sensor component comprises: A sensor socket.A linear bearing, concentrically installed into the bearing hole in the middle of the socket and locked into position by a locking ring, is used for guiding the probe to move along the tube axis.A force sensor, installed inside the hole at the end of the sensor socket and in contact with the bottom face of the probe, detects and measures the contact between the probe and the thread surface of the internal thread of tube coupling. It converts the contact pressure into voltage values and feeds them back.A probe, with a cylindrical body, and a bottom face, and a shoulder. The cylindrical body is concentric to the linear bearing, and the bottom face of the probe is in contact with the force sensor. This probe detects the contact between the probe and the thread surface of the internal thread of tube coupling, and transfer the contact force.A locking cap, with its internal thread mated with the external thread of the sensor socket at its end such that the bottom face of the counterbore hole is coincident with the front face of the should of the probe, limits the position of the probe in its axis direction and prevent it from dropping off It also provides a pre-tensor force to the force sensor.A coupling nut, attached to the shaft of the linear step motor and locks the force sensor in the axial direction of the sensor socket.
2. The device with force feedback of claim 1, wherein the bearing is the ball bearing.
3. The device with force feedback of claim 1, wherein the guiding pin hole I and the guiding pin hole II are symmetrical around the axis of the fendeL
4. The device with force feedback of claim 1, wherein the U-shape fixture has an upper shoulder positioning cylinder and a lower shoulder positioning cylinder. The axis of the upper shoulder positioning cylinder is parallel to the axis of the lower shoulder positioning cylinder.
5. The device with force feedback of claim 1, wherein the linear step resolution of the linear step motor is 0.0254mm. Also, there are two installation holes on the flange of the linear step motor.
6. The device with force feedback of claim 1, wherein the linear bearing is linear ball bearing.
7. The device with force feedback of claim 1, wherein the sensor socket has a section of the end external thread and a force sensor installation hole. Also, the sensor socket has an internal threaded hole.
8. The device with force feedback of claim 1, wherein the head of the probe is conoid.
9. The device with force feedback of claim 1, wherein the coupling nut has a section of external thread and a section of internal thread.