JPS5822312B2 - Tightening device for tightening fasteners - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a Fastener tightening device;
More specifically, the present invention relates to a fastener tightening device for tightening a fastener to a predetermined condition.

With the increased emphasis on product reliability and safety, joint assemblies within products are becoming more important to improve assembly integrity and therefore product reliability and safety. Ta.

For optimal joint integrity, the fasteners used to stiffen the joint assembly must be in such a condition that the axial design loads are exerted on the fasteners and acting on the joint assembly. Because it has long been known that the fastener should be tightened to Particular emphasis has been placed on tightening devices because they have long been known to be relatively inaccurate.

As a result, a variety of complex tightening devices are used to more precisely control the tightening of fasteners in joint assemblies to a predetermined state relative to the design load, thus achieving relatively high precision in the final state of the joint. It is supposed to be done.

When tightening a given joint assembly, the magnitude or other condition of the determining input characteristic, the tightening cycle input characteristic, is used to determine that the fastener has been tightened to a predetermined condition. It has been found desirable to provide an indication of the condition of the fixture and joint.

Such indications are used to notify assembly line operators, quality control supervisors, or others that fasteners and joints have been tightened to a predetermined condition.

However, some of the complex tightening devices described above do not rely solely on the magnitude or other condition of a particular tightening cycle input characteristic, but rather their use is based on readily identifiable and Trusting certain relationships that do not provide meaningful representation.

Thus, time-consuming tests must be performed to check the condition of the fasteners at the end of the tightening cycle, and such tests may not be suitable for certain assembly line tightening operations.

Some conventional tightening devices, such as the torque control devices used in some of the joint assemblies mentioned above, can, of course, facilitate the condition of the fasteners in a given condition, even if these devices are not highly precise. It should also be pointed out that it can be identifiably displayed.

However, if the tightening device itself becomes malfunctioning, the indication that the fastener is tightened in place may be meaningless.

Therefore, a tightening device for tightening a fastener in a predetermined condition includes a quality control checking device for checking whether the condition of the fastener is in a predetermined condition and also checking the operation of the tightening device. It is an object of the present invention to provide a fastening device that is simple.

A tightening device for tightening a fastener in a predetermined state, which checks whether the condition of the fastener is in a predetermined state, and also checks the operation of the fastener, so that the fastener is tightened in a predetermined state. It is a further object of the present invention to provide such a tightening device that includes a quality control check device that provides an indication both that the tool is working properly and that the tool is functioning properly.

These and other objects of the present invention are achieved by providing a tightening device that includes a wrench for tightening a fastener and a control device for stopping the wrench when the fastener is tightened to a predetermined condition. Ru.

Also included is a quality control check device that checks the condition of the fasteners and checks the operation of the spanner and controls to determine if they are working properly.

More particularly, the quality control check device is configured to determine whether the first and second tightening characteristics at a predetermined condition are within ranges where those characteristics are expected to be at the predetermined condition. The device and various output signals within the device are
It includes a device for determining whether the tool is within a predetermined range that it would normally be expected to be in if it is functioning properly.

Depending on the result of the determination, an appropriate display signal may be issued.

For a better understanding of the invention, reference is made to the following description of a preferred embodiment of a tightening device according to the invention, taken together with the accompanying drawings.

Referring now to FIG. 2, a preferred embodiment of the tightening device according to the present invention is shown, including a spanner 50 for tightening the tightener, and a wrench for stopping the spanner when the tightener is tightened to a predetermined condition. and a quality control system, generally indicated at 53, for providing an indication that the joint has been tightened to a predetermined condition and that the tool has not malfunctioned during the tightening cycle. Contains checking equipment.

As shown in FIG. 2, spanner 50 includes an air motor 52 whose operation is controlled by a suitable solenoid valve 5.
4, which drives the output shaft 56 through a reduction gearbox 58 so that the output shaft does not rotate as fast as the motor.

The output shaft 56 has an adapter 57 for attachment to the driver pit 59 and is mounted on a suitable rotating bearing assembly 60 that facilitates its rotation and also absorbs any bending stresses in the output shaft.

Bearing-assembly 60 may be mounted to a fixed frame 62, although the use of a frame is not necessary to practice the invention.

In this regard, although motor 52 is described as an air motor, it may be of any type, e.g.
Note that it can be hydraulic or any combination of air, electric, or hydraulic power.

It should also be noted that the devices described so far may be quite conventional and will not be described in more detail.

Between the gearbox 58 and the bearing assembly 60 is a conversion device in the form of a torque cell 64 which provides a signal representative of the instantaneous torque delivered to the fastener.

Torque cell 64 includes a first mount 66 for mounting the cell to gearbox 58 and a second mount 68 for mounting it to bearing assembly 60 .

The portion of the wrench that mounts and extends axially between platforms 66 and 68 are a plurality of strut members 70, which are somewhat deformable.

That is, they are relatively lateral members that twist somewhat around the axis of the wrench.

When the wrench 50 tightens a fastener, the reaction torque applied thereto causes the strut member 70 to twist about the axis of the wrench, the amount of twist being proportional to the reaction torque and, of course, applied to the fastener. Equal to and opposite to the torque.

Each strut member 70 is equipped with a strainer'-shift 2,
This is connected to a Wheatstone bridge circuit (not shown) and provides an electrical signal representative of the instantaneous torque applied to the fastener.

Instead of strain gauges, contact or proximity displacement gauges can also be used to provide electrical signals.

Additionally, the preferred embodiment of the present invention includes a proximity globe 74 that is mounted through the housing of motor 52 adjacent to and radially spaced from rotating vanes 76, as shown in more detail in FIG. .

Proximity probe T4 may be in the form of an induction coil that emits an electrical signal when metal passes through its magnetic field.

Thus, as the vane 76 rotates when the fastener is tightened, a signal is emitted by the proximal globe 74 representing a fixed increment in the fastener's rotation.

The amount of increase depends on the number of vanes 76 in motor 52 and the gear ratio in gearbox 58.

Of course, it should also be understood that the proximity glove 74 could cooperate with one of the gears in the gearbox 58 in a similar manner.

Here, the control device 51 is based on a patent application filed on May 7, 1973 and currently abandoned by John T. Boys.
U.S. Patent Application No. 357.92 for ng Sys-1em
Method and Apparatus for John T. Boys, a continuation-in-part of No. 0
I) etermining Rotation-nal
It should be noted that U.S. Pat.

Torque cell 6 represents the instantaneous torque delivered to the fastener
The output signal from 4 is fed through a torque amplifier 78 which amplifies the torque signal to a magnitude compatible with the rest of the controller.

From the amplifier 78, the torque signal is provided through a shift register device, which in this embodiment of the invention includes a sample-and-bold circuit 80,
It includes a series of charge couple devices of the 82, 84 and 86 type.

The shift register device is clocked by a signal representing fixed angular increments of the displacement of the fastener.

Accordingly, the signal from the proximity globe 74, which is in the form of a spiked balloon, is fed through a square wave generator 88 that shapes this signal and provides the shaped signal through a code length divider 90 to an analog switch driver 92. The analog switch driver 92 sequentially clocks the sample and hold circuit.

The code length divider 90 is connected to the square wave generator 8
Any suitable division circuit that electronically divides the pulses from 8 by 1, 2, 4, 8, 16 or 32, so that each pulse, or each second pulse, or each fourth pulse, etc., is shifted. Used to clock registers.

Although not necessarily required, analog switch driver 9
2 ensures that each sample-and-hold circuit has discharged its stored signal before receiving a new signal.

Accordingly, analog switch driver 92 sequentially clocks the sample and hold circuits, first circuit 86, then circuit 84, then circuit 82, and finally circuit 80.

Therefore, sample and hold circuit 86 has discharged its stored signal before receiving a new signal from sample and hold circuit 84.

The output from the sample-and-hold circuit 86 represents the fixed increment of torque of the revolution prior to that particular moment;
It is fed through a gradient amplifier or comparator circuit 94 in the form of a differential amplifier, which also receives an input signal representative of the instantaneous torque applied to the fastener from the torque amplifier 78.

Comparator circuit 94 subtracts its input signal and provides an output signal representative of the instantaneous slope of the torque rotation curve that may be plotted for the particular fastener being tightened.

The gradient signal from comparator circuit 94 is fed through a suitable gradient signal amplifier 96 which amplifies it to a magnitude compatible with the rest of the controller.

From the gradient signal amplifier 96, the instantaneous gradient signal is provided to a device for determining the maximum gradient and a device for comparing the maximum and instantaneous gradient signals.

First, looking at the device for determining the maximum gradient, the distribution signal amplifier 96 and the sample-and-hold circuit 102
A maximum gradient comparator 100 is included which receives an input signal from a gradient signal amplifier 96 (which also receives a signal from gradient signal amplifier 96).

As will be hereinafter defined, the sample and hold circuit 102 stores the signal representing the maximum gradient generated at any point in the tightening cycle prior to the instantaneous output from the gradient signal amplifier.

Comparator 100 determines which is greater: the instantaneous gradient signal from gradient signal amplifier 96 or the previously stored signal from sample-and-hole circuit 102.

If the instantaneous gradient signal is larger, comparator 100 provides an output signal to AND gate 104, which gate 104 outputs a clock signal to sample-and-hold circuit 84 when switch driver outputs a clock signal to sample-and-hold circuit 84. It also receives signals from 92.

If both signals are received by AND gate 104, it sends the enable signal to sample and hold circuit 102.
, which causes the sample and hold circuit to receive a new signal from gradient signal amplifier 96 representing a larger gradient.

If the instantaneous gradient is smaller, comparator 100 does not provide an output, AND gate 104 does not provide an output, and as a result, sample and hold circuit 102 cannot receive a new gradient signal.

By using the clock signal from analog switch driver 92 to sample and hold circuit 84, a delay is introduced so that a comparison is made before the clock signal is provided through AND gate 104 and before a new gradient signal can be issued. Ru.

Now looking at the apparatus for comparing maximum and instantaneous gradient signals, when the signal representing the maximum gradient is provided from sample-and-hold circuit 102 to comparator 100, it is divided and provided to divider circuit 106. and this circuit is driven by a preset relationship that is used to determine the yield point shown at X on the torque rotation curve shown in FIG. 1 for the particular fastener being tightened. It works like dividing the signal.

If the current relationship is 50% (which is preferred and explained in the John T. Boys application cited above), divider circuit 106 divides the largest stored gradient signal in half. and provides that signal to a control comparator 98 so that it can be compared with the instantaneous gradient signal from the gradient signal amplifier 96 that is also provided to the control comparator.

If the input signals to the control comparator 98 are equal, or if the gradient signal is less than the divided maximum gradient signal, the control comparator provides an output signal that is applied to another AND gate 108.

Here, the output signal from comparator 98 converts the signal to valve 5.
Note that the signal can be fed directly through the valve drive amplifier 110 which amplifies the signal to a magnitude suitable for closing the solenoid in 4 and stopping the motor 52.

However, when the comparator 98 detects that the pre-tightening region of the torque rotation curve, that is, the region from the intersection of the axes to point A, the fastener is rotating relatively freely and begins to exert a clamping load. To prevent unintentional output signals from entering areas of the joint that are not engaged, an AND gate 108 is used to generate output signals from the snag torque comparator 112 on the curve shown in FIG. receives additional input signals.

The instantaneous torque signal is provided from the torque amplifier 78 to a snag torque comparator 112, which also receives an input signal from a preset snag torque signal generator 114, which of course represents a torque approximately corresponding to the snag torque. Any suitable potentiometer providing a predetermined input signal may be used.

The settings in the snag torque signal generator 114 do not need to accurately represent the snag point, but may be approximate;
For example, a signal representing approximately 20% of the torque value expected at the yield point is sufficient.

When the instantaneous torque signal from amplifier 78 exceeds that produced by snag torque signal generator 114, comparator 112 provides an output signal to AND gate 108 and A
ND gate 108 provides a signal from control comparator 98 to valve drive amplifier 110 .

The output of valve drive amplifier 110 is provided to control valve 54 to close it and stop motor 52.

Thus, any signal inadvertently issued by control comparator 98 in the pretension region of the torque rotation curve will not close control valve 54.

Finally, a reset switch 116 is provided and is used to clear the circuit and prepare the tool for a new tightening operation with another fastener.

The previous description of spanners and controls provides a relatively accurate tightening device that operates to stop the spanner at a predetermined condition precisely related to the load on the fastener, i.e., at the yield point of the fastener. I understand that.

It will also be apparent that the use of a stop signal from comparator 98 or a gradient signal from comparator 96 does not necessarily provide an easily discernible and meaningful indication of the condition of the fastener.

That is, these signals are generated if the fastener is outside the specifications defining its properties or is otherwise defective.

Therefore, the quality control checking device according to the invention checks the condition of the joint when the wrench is stopped and ensures that the fastener is in balance with the connected parts and that the joints and parts are free of defects and thus that the fastener It operates to indicate that it has been properly tightened.

Before describing a preferred embodiment of the quality control checking device according to the invention, reference is made to FIG. 1, in which the principle of its operation is graphically illustrated.

As mentioned above, the curves shown in FIG. The signal is processed to determine the yield point of the fastener on the curve and act to stop the spanner 50.

The yield point, which is of course a predetermined condition, is more precisely related to the axial load on the fastener.

Torque is theoretically related to the axial load on similar fasteners tightened by similar joints, but in practical use of fasteners, this relationship is related to the and/or vary widely due to different frictional properties produced by other components.

For example, the torque required to produce the same load on several theoretically identical fasteners can vary by as much as ±30%.

Thus, for any desired axial load to be exerted on the fastener, a range of torque values can be determined, and the torque to be delivered to the fastener at a desired axial load is within that range. It can be normal inside.

According to the invention, a torque range is determined, defined by an upper limit Tu on the curve and a lower limit Tl on the curve, such that when the spanner is stopped, the torque being supplied to the fastener is such that it It is checked whether it is within the range.

Similarly, the rotation of the fastener is checked when the spanner is turned off to determine if it is also within a predetermined range that the desired axial load is normally expected to be carried.

This range is also defined by the upper and lower limits shown in FIG. 1, Ru and R1, respectively.

Here, the rotation of the fastener during the tightening cycle is also related to the axial load, but in practical use, as will be understood by those skilled in the art, when to begin measuring the effective rotation of the fastener? Note that the relationship changes due to errors in determining .

The range defined by Ru and R1 should be made to adjust for commonly occurring errors.

Further referring to FIG. 1, the limits Tz-, Tu, R1°R
The projection of u defines a rectangle or "window" within which the point X on the curve is normally thought to lie.

If the spanner 50 is stopped within the "window" by the control device 51, the fastener is assumed to be correctly tightened in place and provides an easily discernible and meaningful indication.

If desired, it is possible for only one of the tightening characteristics to be checked, but the high accuracy provided by the control device 51 makes it possible to use a quality control check device that exceeds the accuracy of previous devices. In order to provide, it is desirable to check two such properties.

Finally, although other tightening characteristics can be used, such as time and torque, rotation and torque are specifically indicated since the controller 51 already provides a signal representative of the rotational increment of the fastener. Please be careful.

Referring now to FIG. 2 of the drawings, it can be seen that a signal representative of the torque applied to the fastener is provided from torque amplifier 78 to low torque comparator 118 and high torque comparator 120.

The low torque comparator also receives an input signal from the preset signal generator 122, which signal is representative of the predetermined range of low torque limits Tl described above.

It can also be seen that high torque comparator 120 receives a signal from preset signal generator 124 representing a predetermined range of high torque limits Tu.

If the instantaneous torque delivered to the fastener is less than the low torque limit, comparator 118 provides a high output signal which is used to turn on indicator light 126.

Similarly, if the instantaneous torque delivered to the fastener is greater than the high torque limit, comparator 120 provides a high output signal which is used to turn on another indicator light 128.

When either light is on, it indicates that the torque being supplied to the fastener is outside of the normal range.

the torque delivered to the fastener is greater than the low torque limit;
If less than the high torque limit, comparators 118 and 12
0 gives low output signals, these signals are passed through NOR gate 1
30.

If both input signals are low, NOR gate 130 provides a high output signal that turns on another indicator light 132, indicating that the instantaneous torque delivered to the fastener is within the range defined by the limits set in signal generators 122 and 124. It shows that there is.

If either signal to NOR gate 130 is high, it outputs a low output signal and does not turn on indicator lamp 132.

The rotation signal is processed by much the same circuitry used to process the torque signal, except that the proximal globe T4 provides an output pulse representing an increment in the angle of rotation of the fastener.

Therefore, the signal from square wave generator 88 is a digital signal.
can be supplied to analog converter 134;
This converter operates to add increments and represent the total angular displacement of the fastener.

Rotations of the fastener in the pre-tightening region of the torque-rotation curve should not be counted (thus, the output signal from the snag torque comparator 112 indicates that the joint assembly is being pulled together and actually tightening the joint). Note that it is used as the energization signal to energize the digital-to-analog converter 134 when .

The output signal from digital-to-analog converter 134 is provided to a conventional amplifier 136 to size the signal to be compatible with the rest of the circuit.

Similar to the torque signal, the rotation signal from amplifier 136 is
A low angle comparator 138 and a high angle comparator 140 are provided.

Comparators 138 and 140 receive signals from preset signal generators 142 and 144, respectively.

The preset signal generator 142 outputs a signal representing the low rotation limit R in the predetermined range described above, and the signal generator 144
An output signal representing a high rotation limit Ru in a predetermined range is produced.

If the rotation signal is less than the signal from signal generator 142, a high signal is issued to turn on indicator lamp 146; similarly, if the rotation signal is greater than the signal from signal generator 144, comparator 140 A high output signal is generated which turns on the indicator lamp 148.

When either lamp is turned on, the rotation of the fastener is shown to be outside of the normally expected range.

If the rotation signal is within the range defined by signal generators 142 and 144, comparators 138 and 140 provide low output signals, which are provided to NOR gate 150.

If both input signals are low, NOR gate 150 provides a high output signal and turns on lamp 152, indicating that the fastener rotation is within the expected range.

If any input signal to NOR gate 150 is high, it will output a low output signal, which indicates rung 1.
Do not add 52.

Of course, the indicator lamp can be colored to facilitate determination of joint status.

Since the final tightened state of the fastener is the state to be checked, AN gives the signal to stop the spanner.
The signal from D-gate 1108 may be used as an enable signal to switch NOR gates 130 and 150 into operation.

The signal from ANDNO gate 1 is sent to comparators 118, 12
0° 138 and 140 could also be used as an energizing signal to switch them into operation, but are not shown as such.

In other words, the indicator lamps 126 and 146 are turned on to indicate that the lower limit has been reached, and the lamps 128 and 148 are turned on.
It may be desirable to inform the machine operator that the upper limit has been exceeded during tightening.

In the latter case, the operator can turn off the wrench 50 before the fastener breaks.

Of course, it should also be understood that the output signals from comparators 120 and 140 can be used to automatically shut off spanner 50 before the fastener breaks.

Finally, it should be appreciated that the torque and rotation signals may be recorded when the spanner 50 is turned off to keep a record for future use of the condition of the joint.

In order to check whether the spanner 50 and the control device 51 are malfunctioning, a signal from the torque amplifier 78 (it will be recalled that this signal represents the instantaneous torque supplied to the fastener) is received. invert
rting) amplifier 154 is provided.

Inverting amplifier 154 outputs a signal from torque amplifier 78 such that
It has the ability to detect if the signal has the opposite polarity to what would normally be expected.

Thus, if the wrench is malfunctioning for any reason and is rotating in the wrong direction, or if torque cell 64 is malfunctioning and issuing a reverse polarity signal, or if torque amplifier T8 is out of balance. and are providing reversed polarity signals, inverting amplifier 154 detects these conditions via conventional OR gate 155 and sends an output signal representative of the same to overflow amplifier 156, which is a differential amplifier or comparator. and its purpose is fully explained below.

OR gate 155 is typically a John Wiley
&5ons Inc., published in 1968, I)avi
dF, Hoeschele, J r, Author Analo
g-1o -Dig-ital / l) digital
-1o-analog Conversi-on T
It may have three diodes as shown in "Ec'hniques", pages 29 and 32.

Overflow amplifier 156 is also connected from torque amplifier 78 via OR gate 155 and from gradient signal amplifier 96.
The fastener is also connected to receive an input signal from the fastener, the latter signal being indicative of the instantaneous slope of the torque-rotation curve that may be applied to the fastener being tightened.

One input to overflow amplifier 156 is selectively provided from inverting amplifier 154, torque amplifier 78, or gradient amplifier 96;
0 and a signal from preset signal generator 158 that is representative of, or somewhat greater than, the maximum signal that can be produced by inverting amplifier 154, torque amplifier 78, or gradient amplifier 96 if controller 51 is operating properly. .

If the above input device is working properly, comparator 1
56 provide a high power signal to indicator lamp 160 to provide a visual indication that, if the input devices described above are operating properly, their input signals to comparator 156 will exceed the signal from signal generator 158. Without this, the comparator 156
Outputs only a low output signal that does not light up the indicator lamp.

From the foregoing discussion, operation of the tool is such that the various output signals within the device have predetermined upper limits determined by the preset signal generator 158 and lower limits determined by the detection of the reversed polarity signal from the torque amplifier 78. It will be appreciated that this is checked by determining whether it is within range.

It will also be understood that the torque component of the controller 51 is checked, the gradient calculation part is checked, and the rotational component is checked due to the fact that the gradient signal is determined by a signal representing the rotational increment. .

Note that it is desirable to have a single indication that both the joint and tool are determined to be OK.

Thus, the output signal from NOR gate 130 representing the correct torque that was being supplied to the fastener, and the output signal from NOR gate 150 representing the correct rotation angle of the fastener, are connected in parallel to signal inverters 166 and 168 and to the normal restraint. Signal inverter 1 through diodes 164, 164
70.

Once the fasteners are properly tightened, the NOR gate 130
Since the outputs of and 150 are high output signals, inverters 166 and 168 invert the signals and signal inverter 17
Send low power signal to 0.

The output signal from overflow comparator 156 is coupled in parallel with the signals from signal inverters 166 and 168;
Indicator lamp 172 through a conventional suppression diode 164
is applied to a signal inverter 170 having an output to .

If the spanner 50 and the control device 51 operate correctly,
Overflow comparator 156 has a low output signal.

If all signals supplied to impark 170 are low, lamp 172 will be illuminated by a high output signal from the inverter, indicating that the fastener has been tightened in place and that the tightening device is functioning properly. Display that it is present.

If any input signal to inverter 170 is high, it will give a low output signal, which will not illuminate lamp 172, indicating that the tool is malfunctioning or that the fasteners are not tightened in place. Display what was not present.

Lamp 126.128.132.146,148,15
By checking 2 and 160, the defective device can be determined.

From the foregoing description it should be understood that a tightening device has been provided with a complete quality control check system.

It is also understood that the occurrence of a stop signal from the stop comparator 98 is also checked by the apparatus described above, and that if the stop signal did not energize the NOR gates 130 and 150, no torque and rotation signals would be provided to the inverter 170. sea bream.

It should be appreciated that an alternative signal from AND gate 108 could be sent to inverter 170 through a suitable signal inverter so that generation of a stop command provides a low input signal to inverter 170.

However, with the arrangement of the preferred embodiment, no additional equipment is required to determine whether a stop signal has been issued.

Although preferred embodiments of the tightening device according to the present invention have been described above, it will be obvious to those skilled in the art that various modifications can be made within the scope of the present invention as set forth in the claims.

[Brief explanation of drawings]

FIG. 1 is a graph illustrating the relationship between two tightening characteristics used in accordance with a preferred embodiment of the present invention. FIG. 2 is a schematic diagram of a preferred embodiment of a tightening device according to the invention. 3 is a sectional view taken along line 3--3 in FIG. 2. 50... Spanner, 51... Control device,
52...Air motor, 53...Quality control check device, 54...Solenoid valve, 60...Bearing assembly, 64...
... Torque cell, 72 ... Strain gauge, 74 ... Proximity glove, 78 ...
Torque amplifier, 80, 82, 84, 86... Sample and hold circuit, 94... Gradient comparator, 98... Control comparator, 118...
・Low torque comparator, 120...High torque comparator, 138...Low angle comparator, 140...
・High angle comparator, 154...Inverting amplifier, 15
6...Overflow amplifier, 130.150.
...NOR gate, 166.168°170
...Inverter.

Claims (1)

[Scope of Claims] 1. A tightening device for tightening a fastener to a predetermined tightening state, the spanner device 50 for transmitting an input tightening characteristic to the fastener, operatively associated with the spanner device. a control device 51 for stopping the wrench device in the predetermined tightening state; a device 64, 74 for measuring the input tightening characteristic and supplying a first signal representative of the instantaneous value of the characteristic; , a second instantaneous value representing a target instantaneous value of the input tightening characteristic in the predetermined tightening state.
Devices 122, 124, 142° 144 for supplying signals of
, a device 158 for providing a third signal representative of a target operating characteristic of the tightening device when the spanner device and the control device are functioning properly; Checking device 118, 12
0.138° 140 and a quality control device 53 comprising a device 156 for continuously checking said operating characteristics of the tightening device with respect to said third signal. 2. A tightening device according to claim 1, comprising:
The third signal represents a target maximum value of one of the first signals, and the quality control device 53 determines whether one of the first signals is less than or greater than the third signal. A tightening device for tightening a fastener, including device 156. 3. A tightening device according to claim 1, comprising:
The quality control device 53 includes a device 154 for determining whether one of the first signals has a predetermined polarity;
156, a tightening device for tightening a fastener. 4. A tightening device according to claim 1, comprising:
The control device 51 includes a slope calculation device 94 for producing a signal representing the slope of a curve that can be plotted for two of the input tightening characteristics, the third signal representing the target maximum value of the slope signal and determining the quality The control device 53 includes a device 156 for determining whether the slope signal is less than or greater than the third signal. 5. A tightening device according to claim 1, comprising:
The quality control device 53 includes a device 118 for determining whether at least one of the first signals is within a predetermined region.
, 120 or 138, 140. 6. A tightening device according to claim 1, comprising:
A tightening device for tightening a fastener, wherein said predetermined tightening state is a yield point of the fastener.