JPS58114830A - Automatic thread screwing device - Google Patents

Abstract

PURPOSE:To enable to establish accurate torque control by a method wherein two or more torque sensors are used and detection systems independent to each other are adopted and then abnormality is judged by the dissidence of the detection outputs from both sensors. CONSTITUTION:Two or more torque sensors 14 and 15 to detect the spindle torque of a driver bit are provided on the transmission spindle of the automatic thread screwing device. When no abnormality occurs during thread screwing work, an output is sent through the coincident output line a of an equality circuit 34 in order to complete the work. If abnormality occurs in either of the respective detection systems 22 and 25, when the detection output of one of the detection systems 22 and 25 reaches the screwing torque value set by a setter 28 while the detection output of the other of the detection systems 25 and 22 does not reach said fastening torque value within a certain period of time after the attainment of said torque value by the output of the former detection system, an output is sent from a dissident output line (b) of the equality circuit 34 in order to stop the operation of a drive spindle and at the same time to return the bit to its original position.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic screw tightening machine that detects shaft torque and controls screw tightening torque based on this detection signal.

In this type of screw tightening machine, a five-torque sensor or a detection system including the sensor occupies a core position in performing highly accurate torque control.

Therefore, it is an absolute condition that the detection system always performs a normal detection operation, especially that the torque sensor operates normally. However, in the detection system, abnormalities may occur, including initial failures at the time of installation, failures in the torque sensor, and deviations in calibration due to changes in the vanofer amplifier section or torque sensor over time or temperature changes.

Current screw tightening machines only have a single detection system, and do not have a function to monitor whether the detection system is operating normally. Therefore, it is not always possible to perform highly accurate torque control.

In the present invention, when a plurality of detection systems with the same configuration are used, if all the detection systems are operating normally, the detection power of all the detection systems is equal and the values match; Focusing on the fact that when a system malfunctions, the value will differ and the timing at which the detection force reaches the desired value will vary greatly, by using multiple detection systems, we can eliminate the need for a separate mechanism for monitoring malfunctions. Both have been devised to detect malfunctions in the detection system.

That is, in the automatic screw tightening machine according to the present invention, two or more torque sensors are provided and each torque sensor is independently operated. The system is configured to have a detection system that detects shaft torque, compare the detected forces of each detection system, and determine that the detection system including the torque sensor is abnormal when all detected forces do not match. This is the summary. Here, the detection system refers to a circuit system that includes not only the torque sensor but also a circuit that performs zero correction and gain correction of the detection signal to perform caliper adjustment, and a balance amplifier section.

Although two or more detection systems are required, it is usually desirable to use two detection systems. If three or more are provided, two of them can be used and the rest can be used as replacements in case the one in use breaks down. Although it is possible to compare the detected forces of each detection system by constantly comparing them from the start to the end of screw tightening, it is preferable to compare them at each turning point of the screw tightening operation. For example, in the case where the screw tightening work is divided into a temporary tightening stage and a final tightening stage, the turning point refers to the time when the preliminary tightening is completed and the time when the final tightening is completed. However, if any of the detection systems has malfunctioned, it is unclear at what point the preliminary tightening or final tightening is completed, so these milestones are determined by the amount of each detection force. It is preferable that one of them is set as a period from when a predetermined temporary tightening torque value or a final tightening torque ffl is reached first until a certain period of time has elapsed.

If the detected force of the other detection system does not reach the predetermined torque value within this certain period of time, it can be determined that an abnormal operation has occurred. In addition, if the detection system determines that there is an abnormality, one method is to issue an alarm and notify the worker, but automated work is better at stopping the screw tightening work after the detection system determines that there is an abnormality. It is desirable in practice.

Hereinafter, one embodiment of the present invention will be described based on the drawings. 1st
The figure shows a stationary single-shaft type automatic screw tightening machine as an example of an automatic screw tightening machine. +
A rod rod (4) is inserted into 31 so as to be vertically slidable. An attachment member (6) for attaching the screw tightening machine body 15) is inserted into the rod (4) so as to be slidable up and down, and a tension spring (7) connects both. Also, this rod (4)
is provided with a retaining ring (not shown), and the bar rod (4;
The upper end of the mounting member (6) is maintained at a constant distance from the mounting member (6). Further, a support plate (9) supporting the capture (8) is freely inserted into the rod rod (4), and is received by a nut αα screwed into the lower end of the rod rod. 5) is assembled from a pulse motor αD, a driver bit α2, and a transmission shaft 03 that transmits rotational power from the pulse motor aD to the driver bit α,
A plurality of, for example two, torque sensors α4Q are provided on the transmission shaft 0 to detect the shaft torque of the driver bit.

In addition, this screw tightening machine main body (5) has a support plate f21
It is configured to be able to move up and down by an up/down cylinder 0υ provided at. The vertical movement of the lifting cylinder αG is also transmitted to the catcher (81) via the rod (4), so the catcher (81) also moves up and down together with the screw tightening machine main body 151, but the amount of descent is determined by the upper end of the rod (4j). It is regulated by the upper arm (3). Also, the catcher (8)
Is the driving means [17+] tied to the end of the rod marked 0'? (18a) The driver bit α2 can be locked by the operation of the driving means G7+.
An upward movement is possible separately and independently. Although not shown, a switch for confirming return to the original position, such as a riminotosinch, which is turned on when the screw tightening machine body (5) has risen and returned to the original position, is provided. The pulse motor, lifting cylinder ae, and g movement means (171) are controlled by the circuit shown in FIG. 2 to perform automatic screw tightening operation.

In Figure 2, ■ is the screw tightening start part, and ■ is the torque sensor Q41, the buff fan knob, and the calf.

The first detection system is configured by a register shoulder circuit, (
(to) is a second detection system composed of a torque sensor α, a buffer amplifier (support), and a caliplay scene circuit. (Support) is a setting device in which a predetermined temporary tightening torque value is set, and (in) is a setting device in which a predetermined main tightening torque value is set. The pulse motor αυ is rotated at high speed until the shaft torque of the driver pit reaches the predetermined temporary tightening torque value, and rotates at low speed until it reaches the temporary tightening torque value and then reaches the final tightening torque value. be done. Said first detection system □□□
The detected force is compared with the temporary tightening torque value set in the setting device @ by a comparator (to), and compared with the main tightening torque value set in the setting device by a comparator 3B. On the other hand, the detected force of the second detection system is compared with the temporary tightening torque value set on the setting device (to) by a comparator, and compared with the actual tightening torque value set on the setting device. are compared by the comparator (to). Then, the comparative outputs of the comparators and Suzu are input to the one-number circuit 1, and when both comparison outputs match, the -several output line of the -several circuit (to)
Output is generated from a), and if they do not match, the mismatch output line tb+
emits output from. Similarly, the comparison outputs of the comparators on and ) emits output. The fact that an output is emitted from the mismatch output line (b) of one of the -number circuits □□□ means that the detection power of ■ does not match the two detection spears, which means that one of the detection systems @( c) means that an abnormal operation has occurred.

In addition, even when each detection system NIMS does not have any abnormal operation,
These detection powers do not necessarily show similar changes at the same time, and in many cases, there is a slight difference in the detection power of each detection system.
There is a time difference. Therefore, the points at which the detected forces match the set value set in the setting device θ (support) also differ. Therefore, the -several circuit otca first receives the detected force that has reached the predetermined temporary tightening torque value or the main tightening torque value, and then, after that, the predetermined temporary tightening torque value or the main tightening torque. A holding circuit is built in to hold the sensor for a certain period of time corresponding to the time it takes for the detection force to reach the value to be input through the comparator.

Next, the can is the power supply section, (9) is the high-speed drive pulse supply section, (to) is the low-speed drive vane supply section, ■ is the pulse motor drive control section, and ■ is the main body of the screw tightening machine (5). The solenoid valve for lifting and lowering that drives the lifting cylinder, (turn) is the solenoid valve that drives the drive means α to raise the catcher (8) independently, and (turn) is the -several switch mentioned above.

Further, OR1 and OR2 are OR circuits.

In this configuration, when the screw tightening start part clll is activated, the power supply part is activated and starts supplying power to the pulse motor drive control part, and at the same time, the high speed pulse supply part (support) is activated. Pulse motor drive control section (
The pulse motor O1l is rotated at a high speed at a frequency higher than the self-starting frequency. At the same time, the electromagnetic field chrysanthemum is energized and the lifting cylinder stop is lowered. This allows screw tightening to be performed at high speed rotation.

Furthermore, screw tightening start part c! By the operation of wa, the memory contents of the judgment display section 0, - number of circuits (to) moxibustion are reset.

As the screw tightening work progresses in this way, when the detected force of each detection system -■ matches the temporary tightening torque value set in the setting device α, the output from the -dissipated output line fa) of the -several circuits (to) Then, the high-speed drive pulse supply section is stopped and the temporary tightening work is completed. At the same time as this work is completed, the electromagnetic valve is energized by the output to drive the driving means u9. Drive means α
Since the catcher (8) is raised independently by the drive of 9, even if the head of the screw is held or caught in the catcher (81) when the temporary tightening is completed, the catcher (8) will not rise. After that, this situation will be resolved and each detection system will be able to detect only the shaft torque that is purely related to the tightening torque.

The output emitted from the dispersion output line (al) of the several circuits (to) is also applied to the low-speed drive pulse supply (to). This supply (to) waits for the drive means 0η to complete its operation. The screw tightening machine body (5) rotates the pulse motor αυ at a low speed below the self-starting frequency through the pulse motor drive control unit (Misaki, ′).
Start the final tightening work by rotating at low speed in step 1). and,
When the detected force of each detection system 24 matches the final tightening torque value set in the setting device Stop the operation of the supply section (G), de-energize the solenoid valve (T), and move the lifting cylinder α upward.
A pass is displayed through the judgment display section. The pulse motor αυ stops rotating due to the stoppage of the low-speed drive pulse supply unit (to), and the pulse motor αυ stops rotating due to the stoppage.
υ becomes de-energized and the state of restraint at stall torque is released. The lifting cylinder Oe is designed to be raised after this restrained state is released. This is to prevent the screw head of the driver bit t from being damaged. Lifting Siri.

As the driver Oυ rises, the screw tightening machine body (51) returns to its original position, and the switch (c) for confirming return to its original position operates. As a result, the solenoid valve (411) becomes de-energized and the screw is supplied to the catcher (81). , then screw start part 2
Waits in that state until +1 or activates. The screw tightening operation is thus completed.

By the way, the above screw tightening work is performed when there is no abnormality in the operation of each detection thread or plane, but if there is an abnormality in the operation of either one of the detection systems or the machine.
On the other hand, even if the detected force in the 0 detection system or 1 reaches the temporary tightening torque value set in the setting device color, the detected force in the other detection system or @ reaches the temporary tightening torque value set in the setting device color. The tightening torque value is not reached. Therefore, the mismatch output line f for several circuits
An output is generated from b), and the high-speed drive pulse supply section (to) stops operating, the solenoid valve (a) is energized, the power supply section of the plane stops operating, and the solenoid valve (a) is de-energized, causing the elevating cylinder to scream. A series of movements called upward movements are performed to return the screw tightening machine main body (5) to its original position without starting the final tightening work.

At the same time, an abnormal operation is displayed through the judgment display section by the output of the mismatch output line (b). Screw tightening machine body (
5) returns to the original position without performing final tightening, thereby avoiding screw tightening work due to inaccurate torque control, and the display on the judgment display section (turn) allows the operator to detect malfunctions and quickly correct them. Repair work can be undertaken.

On the other hand, each detection system @5 performs four normal operations up to the temporary tightening torque value, but if any of the detection systems operates abnormally above the temporary tightening torque value, temporary tightening work is not performed. However, during the final tightening work, even if one detection system reaches the final tightening torque value set for the detection force or setting device heat, the other detection system will not be able to detect it within a certain period of time. The detected force of system ■ or ■ does not reach the final tightening torque value. For this reason, the output is emitted from the mismatched output line (bl) of - several circuits, the operation of the low-speed drive pulse supply unit ■ and the power supply unit is stopped, and the lifting cylinder +l is de-energized with the solenoid valve de-energized.
The screw tightening machine body 5 is returned to its original position by performing a series of upward movements (1), and an abnormal operation is displayed through the judgment display section. In this case as well, screw tightening work due to inaccurate torque control can be avoided by returning the screw tightening machine body (5) to its original position, and the operator can detect abnormal operation by the display on the judgment display section O and promptly take action. Repair work may be required.In addition, causes of malfunction in the detection system include changes in the buffer amplifier section or torque sensor 041 us: over time, misalignment of the caliper silane due to temperature changes, and initial failure during installation. In the case of the former, please adjust the zero correction amount and gain correction amount of the Cali Precision Faulty Circuit (C).
The problem can be repaired by recalculating the detection system including the 51yk, or in the case of the latter, by replacing the torque sensor.

In the above embodiment, only two torque sensors (141051) are used, but it is of course possible to use three or more, and if the detection forces of the respective detection systems do not match,
Of course, it is also possible to simply issue a warning of abnormal operation.

As explained above, according to the present invention, two or more torque sensors are provided to form a detection system that independently detects shaft torque, and the four detected forces of each detection system are compared. Since it is determined that there is an abnormality in the detection system including the torque sensor when the forces do not match, the following effects are achieved.

■ Screw tightening work caused by inaccurate torque control can be eliminated. This allows for highly accurate and reliable torque management, which greatly contributes to improving the quality of fastened products.

■ No separate mechanism or means is required to determine malfunction of the detection system. That is, in the case of a single detection system, a special judgment mechanism is required to determine abnormal operation of the detection system, but according to the present invention, such a mechanism is not necessary, and the operation of the detection system can be easily determined. Abnormalities can be determined.

Although this embodiment has been explained using a single-shaft type screw-driving machine, the same effect can be obtained even if it is used in a multi-shaft type screw-driving machine. Further, although a pulse motor is described in this embodiment, the same effect can be obtained even if a motor other than the pulse motor is used.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is an overall view of an automatic screw tightening machine, and FIG. 2 is an electric circuit diagram that controls the automatic screw tightening operation of the screw tightening machine. ■-Example: Raibabi Noto, Q~Q51---) Luxensor, ■---Detection system. Patent applicant: Nitto Seiko Co., Ltd. Figure 1

Claims (1)

[Claims] Detecting the shaft torque of the Dophypa bit with a torque sensor,
In an automatic screw tightening machine that controls the tightening torque of a screw based on this detection signal, a detection system is provided in which two or more of the above-mentioned torque sensors are provided to independently detect the shaft torque, and each detection An automatic screw tightening machine characterized in that the detected forces of the systems are compared, and when all the detected forces do not match, it is determined that the detection system including the torque sensor is abnormal.