JPH0326340B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention provides a tapered thread gauge (hereinafter also referred to as a thread gauge) for a tapered thread (hereinafter also referred to as a thread) carved into an object to be inspected, such as a drill pipe for oil drilling, a coupling ring, etc. The present invention relates to a fitting inspection method and apparatus for tapered screws that determine the degree of fitting accuracy or compatibility of tapered screws by screwing them together.

Conventionally, this type of fit inspection method was generally
A manual tightening inspection method based on API (American Petroleum Institute) standards is applied. In this method, a screw gauge equipped with a handle arm of a predetermined length is rotated in the forward direction and screwed into a screw carved into the specimen. In this case, since it is a tapered screw, tighten it carefully immediately after starting screwing so that it does not bite and does not damage the screw surface.
If bite occurs, you will be able to tell intuitively.
Rotate the screw gauge in the opposite direction to return it to its original position, then screw it in again. In this way, it is visually confirmed that the distance (standoff) between the screw gauge screwed in with the tightening torque specified by the API (0.75 to 1.50 kg-m) and the subject is within a predetermined range, and the value is measured and recorded. The fitting accuracy of the screws is then inspected by rotating the screw gauge in the opposite direction and removing it from the test object.

In this method of inspecting the fit of screws using manual screwing, it is necessary to carefully screw the thread gauge into the screw engraved on the test object so as not to bite the screw or damage the thread surface. Therefore, there is a problem in that it requires a skilled person who is physically and mentally sound and also has low testing ability.

In view of the above, it is an object of the present invention to automate screw fitting inspection, quantitatively detect and display tightening torque values and standoff values as index values of screw fitting accuracy or degree of compatibility. It is an object of the present invention to provide a fitting inspection method and device for a tapered screw that is easy to handle, can increase inspection ability, and can prevent biting immediately after the start of screwing.

The gist of the present invention is that in the first invention, after the advancing taper screw gauge and the taper screw carved on the test object come into contact with each other in an aligned state, the screwing between the taper screw gauge and the taper screw starts. a first step of detecting a position; a second step of measuring a tightening torque value and a standoff value when the tapered thread gauge and the tapered screw are screwed together while rotating forward; and the tapered thread gauge. and a third step of retracting the taper screw gauge while rotating it in the opposite direction to separate it from the taper screw when it reaches a predetermined standoff value, and operating and measuring in the order of the first, second, and third steps. This is a fitting inspection method for tapered screws.

Further, in the second aspect of the present invention, a gripping mechanism for an object to be inspected is provided at a lower part of the machine frame, and a rotary lifting mechanism for a taper screw gauge is arranged in an aligned manner at the upper part of the machine frame, a screwing start position detection means for detecting a screwing start position between the thread gauge and the tapered screw of the test object; a tightening torque meter that detects the torque when the taper screw gauge and the tapered screw of the test object are screwed together; This is a threading inspection device for a taper screw, characterized in that it is further equipped with a standoff measuring mechanism for measuring a standoff value of the taper screw of the object.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the structure and inspection method will be explained based on FIGS. 1 to 5 showing an embodiment of a fitting inspection device for a tapered screw according to the present invention.

In FIG. 1, F1 is a machine frame, and 1 is an object to be inspected, for example, a coupling ring having a tapered female thread 1A carved on its inner surface. Reference numeral 2 denotes a pedestal for fixing the subject 1 in a predetermined position, and is fixed to the machine frame F1. As shown in FIG. 2, split chucks 42A and 42B can be brought into contact with the stepped portion 1B of the subject 1.
Reference numeral 43 denotes a ring-shaped spring that surrounds the split chucks 42A and 42B from the outer periphery and always urges them to converge at the center. 44 is a first cylinder, and the upper end of the first piston 45 that slides inside this first cylinder 44 has a split chuck 42A,
It is formed to surround the lower end of 42B. 46 is a second cylinder, and this second cylinder 4
The upper end of the second piston 47, which slides within the piston 6, is screwed onto a downwardly directed truncated cone 41 for sliding the split chucks 42A, 42B in the radial direction from the center. 50 is a pressure device in which a first cylinder 44 and a second cylinder 46 are bored on the same axis. In this configuration, when pressure medium is introduced from the pipe line 48 into the first cylinder 44 and the second cylinder 46, the first piston 45 descends and the second piston 47
will rise. Therefore, the divided chucks 42A and 42B due to the biasing force of the ring-shaped spring 43 slide toward the center and do not come into contact with the stepped portion 1B of the subject 1. Further, when the pressure medium is introduced from the pipe line 49 into the first cylinder 44 and the second cylinder 46, the first piston 45 rises and the second piston falls. Therefore, the divided chucks 42A and 42B slide in the radial direction against the biasing force of the ring-shaped spring.
It comes into contact with the stepped part 1B of the subject 1 and always keeps the subject 1
is held on the pedestal 2 with its axis shared with the axis of the pressure device 50.

Next, numeral 3 shown in FIG. 1 is a thread gauge having a tapered male thread having the same shape as the female thread 1A carved on the outer peripheral surface, and the female thread 1A and the thread gauge 3 are disposed on the same axis. A key 31 is fixed to the screw gauge 3 as shown in FIG. 3, and is slidable in the axial direction of the spindle 4. 32 is a nut for preventing the screw gauge 3 from coming off. A beam 30 attached to the inner cylinder 5 by a rod 38 is disposed above the screw gauge 3, and a coil spring 33 fitted onto the spindle 4 is installed between the beam 30 and the screw gauge 3. The screw gauge 3 is always urged to be in contact with the nut 32 by interposing the screw gauge 3. A two-contact microswitch MS is attached to this beam 30, and its stylus N faces the screw gauge 3 with a small space between them. Reference numeral 35 denotes a standoff detection rod, the lower end of which passes through the beam 30, and a contact piece 35A is attached approximately on an extension of the upper end surface of the screw gauge 3. Reference numeral 36 is a rod that is vertically disposed on the beam 30 and has an indicator 37 attached to the upper part for indicating the amount of standoff, and 39 is a conductor that connects the indicator 37 and the micro switch MS.

Next, reference numeral 5 shown in FIG. 1 is an inner cylinder that is slidable in the vertical direction along splines 6A carved on the inner surface of an outer cylinder 6 fixed to the machine frame F1. 7 is a permanent magnet piece provided around the outer surface of the spindle 4, and 8 is a permanent magnet piece provided around the inner surface of the inner cylinder 5. These permanent magnet pieces 7 and 8 repel each other, and a small gap C is formed between them as shown in FIG. 4.

Next, reference numeral 11 shown in FIG. 1 is a flange integral with the spindle 4, and an electromagnet piece 12 is provided around the lower surface of the flange. Further, an electromagnet piece 13 is provided around the inner surface of the inner cylinder 5 at a position opposite to the electromagnet piece 12 to form a slight gap D. These permanent magnet pieces 7,
8 and electromagnetic pieces 12 and 13, the spindle 4 is automatically maintained in an aligned state. 14 is a reversible torque motor fixed inside the upper part of the inner cylinder 5, and the bolt 1
5 to the flange 11. 16 is a conductor connecting the micro switch MS and the torque motor 14; 17 is a tightening torque meter (torque motor 14) equipped with the torque motor 14 and an alarm bell B;
(detected by current fluctuation)
18 is tightening torque meter AM and micro switch
This is the conductor that connects the MS. 19 is a hanging fitting for suspending the upper end of the inner cylinder 5, 20 is an eye bolt screwed into the center of the hanging fitting, and 21 is attached to one end of the eye bolt 2.
A wire rope 22 is connected to a drive source (for example, a reversible motor with a clutch), not shown, and the other end is connected to a weight 23. Note that when the screw gauge 3 and the female screw 1A are not screwed together, the weight of the weight 23 is adjusted so that it can be lowered by its own weight.

Before putting into practical use the tapered screw fitting inspection apparatus having the above-described configuration, the following operational adjustments and inspections are carried out in order to provide operating conditions for each part using a defect-free test object 1.

(1) With the subject 1 placed on the pedestal 2, the strokes of the first piston 45 and the second piston 47 are adjusted such that the split chucks 42A, 42B contact and grip the stepped portion 1B of the subject 1. To adjust.

(2) The above permanent magnet pieces 7, 8 and electromagnet piece 12,
To adjust the gap C so that the spindle 4 is automatically maintained in an aligned state by balancing the repulsive force caused by the spindle 4.

(3) When the screw gauge 3 comes into contact with the female thread 1A of the test object 1, the stylus N immediately comes into contact with the upper end surface of the screw gauge 3, turning on the first contact of the micro switch MS, and turning on the second contact. Adjust so that the torque motor 14 rotates in the opposite direction by switching it to the OFF state.

(4) When the thread rising part of the thread gauge 3 comes into contact with the female thread 1A and the contact load starts to increase gradually, and passes through the threading start position of the female thread 1A, the elastic force of the coil spring 33 causes the thread gauge 3 to When the contact with the stylus N is released momentarily and a change in position is detected, the first contact of the micro switch MS is turned OFF and the second contact is turned ON, and the torque motor 14 is turned on. Adjust to rotate.

(5) Contact piece 35A of standoff detection rod 35
comes into contact with the upper end surface of the test object 1, and when the upper end surface of this detection rod 35 contacts the indicator 37, the first contact of the micro switch MS is turned on, and the second
Switch the contact to the OFF state and turn the torque motor 14 on.
is adjusted so that it rotates in the opposite direction for a predetermined period of time using a timer (not shown).

(6) Adjust the circumferential speed of the pulley 22 using a drive source (not shown) so that it almost matches the pitch of the female thread 1A of the subject 1, and balance the circumferential speed of the pulley 22 with the rotational speed of the thread gauge 3. .

(7) Adjust the reverse rotation speed of the pulley 22 so that the screw gauge 3 returns to its original position within the timer operation time described in Section 5.

(8) The tightening torque of the screw gauge 3 is applied by the torque motor 14, and the current fluctuation range of this torque motor 14 is adjusted within the above-specified allowable tightening torque range (0.75 to 1.50 kg-m). be.

Next, an embodiment of a method for inspecting the fit of the subject (coupling) 1 in the flow process after the thread cutting process will be described in the order of the first, second, and third processes.
First, after applying a small amount of thread oil to the female thread 1A, the subject 1 is placed on a predetermined position on the pedestal 2. Next, pressure oil as a pressure medium is supplied from the pipe 49 to the first cylinder 4.
4. When introduced into the second cylinder 46, the first piston 45 rises, and the second piston 47 and the downward truncated cone 41 screwed thereto descend. As a result, the split chucks 42A and 42B slide in the radial direction, come into contact with the stepped portion 1B of the subject 1, and hold it.

Next, when the pulley 22 is rotated at a predetermined circumferential speed in the direction of arrow A, the spindle 4 is aligned in the inner cylinder 5.
The thread gauge 3 attached to the inner cylinder 3 gradually descends and comes into contact with the female thread 1A and stops, but the inner cylinder 5 further descends. As a result, the stylus N of the micro switch MS comes into contact with the upper end surface of the screw gauge 3, and the first contact point is
In the ON state, the second contact is switched to the OFF state. Therefore, the torque motor 14 rotates in the opposite direction (the screw gauge 3 rotates to the left), and the moment the screw gauge 3 passes the screwing start position of the female thread 1A, the screw gauge 3 descends and comes into contact with the stylus N. To be released. Note that the screw gauge 3 comes into contact with the female thread 1A of the test object 1, the torque motor 14 rotates in reverse, and the coil spring 3
The process of lowering the screw gauge 3 and releasing the contact of the stylus N by the biasing force 3 corresponds to the screwing start position detecting means of this embodiment. This allows the micro switch MS
The first contact is switched to the OFF state, and the second contact is switched to the ON state, and the torque motor 14 rotates forward (screw gauge 3 rotates clockwise) while descending together with the inner cylinder 5, and the thread gauge 3 connects with the female thread 1A. A tightening torque meter AM measures the current fluctuation of the torque motor 14 when screwed together.
Measure with. In the unlikely event that this current fluctuation range fluctuates more than that during the above-mentioned operation adjustment, the alarm bell B rings to notify that the fitting accuracy between the screw gauge 3 and the female screw 1A is poor. In this case, immediately rotate the torque motor 14 in the reverse direction and
to retreat (raise). As the screw gauge 3 rotates clockwise in this manner, the contact piece 35A comes into contact with the upper end surface 1C of the test object 1 as shown in FIG. Standoff value (distance between the upper end surface 3A of the screw gauge 3 and the upper end surface 1C of the test object 1)
For example, S is ±1 thread/in for a round thread screw (8 threads/in).
When it reaches in, the indicator 37 comes into contact with the standoff detection rod 35, and the first contact of the micro switch MS turns ON and the second contact turns OFF, so the torque motor 14 rotates in the opposite direction again (screw gauge 3 is rotated to the left), and the pulley 22 also rotates in the direction of the arrow, so the thread gauge 3 rises together with the inner cylinder 5. In this case, since the signal output from the indicator 37 is transmitted to a timer (not shown), the drive source for the torque motor 14 and the pulley 22 is activated for a predetermined period of time (the screw gauge 3 moves from the position shown in FIG. 5 to the position shown in FIG. 1). (predetermined time until recovery).

After that, pressure oil is supplied from the pipe line 48 to the first cylinder 4.
4. The test object 1 is introduced into the second cylinder 46 to release the contact between the divided chucks 42A and 42B and the stepped portion 1B of the test object 1, and the test object 1 is transferred to the next process by manual operation.

In the tapered screw fitting inspection device described above, in order to maintain the spindle 4 on which the thread gauge 3 is attached to the lower end in an aligned state, the repulsive permanent magnet pieces 7 and 8 and the electromagnet pieces 12 and 13 are attached to the spindle 4.
, the inner surface of the inner cylinder 5, the lower surface of the flange 11, etc., but an attractive magnet piece can also be used instead. It is also effective to maintain the alignment by introducing gas or liquid at a predetermined pressure between the spindle 51 and the outer cylinder 52, as shown in FIG.

Next, the current fluctuation of the torque motor 14 during the screwing of the screw gauge 3A and the screw 1A is measured as a fluctuation of the tightening torque, and the standoff value is also measured with the indicator 37, which is displayed on a digital display. It is also easy to do. Furthermore, instead of the pulley, wire rope, and weight shown in FIG. 1 as the means for raising and lowering the screw gauge, a pneumatic or hydraulic cylinder 67 as shown in FIG. 6 can be used.

Furthermore, in the above embodiment, the thread gauge in contact with the female thread 1A is rotated in the opposite direction (to the left) to detect the screwing start position of the screw 1A. By using this in combination, the screwing start position of the female thread can be detected in the same way even when the screw gauge 3 is slightly moved in the vertical direction and rotated reversely (leftward) or forwardly (rightward).

Note that although the above embodiment uses a vertical inspection method, even if this is changed to a horizontal inspection method, the control operation and measurement control can be performed in the same manner.

Furthermore, in the present invention, it is also possible to easily fix a drill pipe to the machine frame instead of the test object, attach a test object (coupling) to the spindle instead of the thread gauge, and screw this into the drill pipe. Therefore, it can also be applied to the tightening force introduction means.

As described above, the present invention allows the screw gauge to be (1) lowered (advance) toward the screw, (2) lowered in reverse rotation (advance), and (3)
The screws are controlled in the order of forward rotation down (forward), (4) reverse rotation up (backward), and (5) stop, and are also controlled by measuring the tightening torque value and standoff value when the screw is screwed into the screw gauge. This method is more accurate than the conventional intuitive judgment by an inspector, and it is possible to increase reliability in terms of quality control in ensuring proper screw fitting accuracy. In addition, by being equipped with a screwing start position detection means, it is possible to detect the rising part of the thread between the thread gauge and the test object screw, which is the screwing start position, and rotate the taper screw gauge in the opposite direction until the screwing start position is reached. let me,
Since the tapered screw is rotated in the normal direction after the screwing start position, it is possible to prevent the occurrence of biting between the two at the start of screwing. Furthermore, the results are significant in that the screw surface can be inspected without damaging it and the inspection capability can be dramatically increased.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a partially sectional side view of the screw fitting inspection device, Fig. 2 is an enlarged view of the specimen gripping part shown in Fig. 1, and Fig. 3 is the same as Fig. 1. 4 is a sectional view taken along the arrow line A-A' shown in FIG. 1, and FIG. 5 shows the screwed state of the thread gauge and the test object. The explanatory diagram, FIG. 6, is a partially sectional side view showing another embodiment of the screw fitting inspection device. 1...Test, 1A...Screw, 3...Screw gauge, 4
...Spindle, 5...Inner cylinder, 7, 8, 12, 13...
Magnet piece (alignment means), 14...torque motor, 35
...Standoff detection rod, 37...Indicator, AM
...Tightening torque meter, S...Standoff.

Claims (1)

[Scope of Claims] 1. After the advancing taper thread gauge and the tapered screw carved on the test object come into contact with each other in an aligned state, a first step detecting a screwing start position between the tapered thread gauge and the tapered screw. a second step of measuring a tightening torque value and a standoff value when the tapered thread gauge and the tapered screw move forward while rotating in the forward direction; a third step in which the taper screw gauge is removed from the taper screw by retracting the taper screw gauge while rotating in the opposite direction;
A fitting inspection method for a tapered screw, characterized by operating and measuring in the order of the second and third steps. 2. A gripping mechanism for the specimen disposed at the bottom of the machine frame, and a rotational lifting mechanism for a taper screw gauge arranged in alignment at the top of the machine frame, the taper screw gauge and the taper of the subject being aligned. a screwing start position detection means for detecting a screwing start position with a screw; a tightening torque meter that detects the torque when the tapered thread gauge and the tapered screw of the test object are screwed together; A threading inspection device for a tapered screw, characterized in that it is equipped with a standoff measuring mechanism for measuring a standoff value, and the following. 3. The fitting inspection device for a tapered screw according to claim 2, wherein a magnet piece is provided around the spindle and inner cylinder of the rotary lifting mechanism. 4. The fitting inspection device for a tapered screw according to claim 2, wherein gas or liquid at a predetermined pressure is introduced between the spindle and the inner cylinder of the rotary elevating mechanism.