JPS5822669A - Screw stop clamping device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power tool, particularly a screw fastener.
The present invention relates to a portable power tool for tightening (stsner). A new screw tightening method or technique known as the log ratio method has recently been introduced.

This technology was published in US Patent Application No. 912 dated June 2, 1978.
, No. 151. Basically, this technique involves analyzing the entire angle signal to determine the shutoff parameters specific to the joint being tightened.

In the design of tool families implementing the logarithmic rate method, it is possible, if desired, to incorporate it into a portable tool, i.e. the operator can store the data processor or calculation circuitry, along with the necessary power supply, in the transport case or in the tool itself. There has been a desire for a simplified technology that can be carried around.

One issue when designing a tool using the logarithmic ratio method is whether the operator can change the orientation of the tool relative to the work point during screw tightening. If the operator rotates the tool, for example, 100 times during tightening, the shutoff parameter in degrees must be off by 10 degrees. Whether the joint is under-tightened or over-tightened depends largely on the direction in which the tool is rotated relative to the rotation of the tool. Shut-off parameters measured at corners are inappropriate for portable tools because a 10° error at the end of the tightening cycle creates a large amount of tension in the screw fastening.

According to a very superficial examination, the above-mentioned U.S. Patent Application No. 91
The technique disclosed in No. 2,151 is a very sophisticated technique, requiring large computational power and large-scale software. One condition for the simplified method is that the result must be minimal, ie, the tension dispersion within the standard deviation should not be substantially reduced. One of the surprising features of the present invention is that the tightening performance or force dispersion is quite advantageously similar to the sophisticated logarithm method of the above-mentioned U.S. patent application, and is substantially superior to the torque control method or the nut rotation method. This means that it is in good condition. For example, in tests performed on fairly stiff joints, the tension distribution within one sigma or is standard deviation of the present technique was approximately 5 degrees of the desired tension value. In the identical screw connections tested, the tool exhibited a variance of 11[3Q% within the readiness difference in torque at constant tension. Therefore, it can be said that the torque control method exhibits a tension dispersion of approximately 301 seconds per standard deviation at constant torque. Also, empirically speaking, the tension distribution in the nut rotation method has a standard deviation of about 8 inches.

According to one feature, the invention seeks to determine the value of a tightening parameter that is sufficient to tighten each of the screws in the pair to a final desired tension value; The value changes for each screw pair. The tightening of the screw is then completed in response to the determined variable value of the parameter.

This is accomplished by providing a power tool with a screw tightening input characteristic to the screw fastener, and sensing that input characteristic to generate a signal that indicates it. Means are provided for determining a final shutoff parameter in response to the generated signal and the ratio of a final desired tension value in the screw fastening to a tension factor in the screw fastening, and responsive to the final shutoff parameter. Means are also provided for terminating operation of the tool.

Accordingly, it is an object of the present invention to provide an improved and simplified technique that provides a logarithmic method of tightening screw fasteners.

Figure @1 shows the actual torque-angle curve 10 and its corresponding tension-angle curve 12t which occur during successive screwing of the screw pair to the point where the elastic limit t of the melt is barely exceeded. These can be measured and glotted in the laboratory with suitable equipment. Torque curve 10 typically includes a free-running region or period 14 during which only a small torque is required to propel the vehicle and there is no appreciable bolt tension. This is followed by a first clamping zone or period 16 in which the joint is engaged. During this period 16, the torque rate TR
The period or region 18 during which the However, the first simplification according to the invention is to assume that region 18 exhibits a single tension factor FR1-.With this simplification, observing the tension in the tightened melt, However, it was found that there was no appreciable dispersion involved.

In the free two running region 14 the torque rate is essentially zero. 1 - The amount of torque required to advance depends on the thread-to-thread friction of the screw-fastening pair and therefore on the integrity of the threads'? It is a function of lubricity etc. 1 - Prevailing screws that require the application of large torque to advance
The torque required to advance the screw in this region is known as the predominant torque τpy.

The torque rate τR begins to rise substantially during the initial crans amplifier region 16. In region 18, the torque rate TR approaches linearity (. The linear approximation of curve 100 does not intersect the angular axis of tension curve 12. There is an offset angle α.6 which is proportional to such velocity dependent losses.

α. 8 is the beginning of the average torque gradient TH and the average tension gradient PR
is the separation angle between the beginning of Torque of the tool to be used
α because of the velocity curve. 6 depends on the torque rate, so the offset torque T. 6 is the joining characteristic #) T is the offset angle α. 8, the torque rate TR, and 0θ. In the simplest application of the invention, T
is a relatively small value, so we ignore it. 6 I can do it.

The elastic limit point 20, beyond which the strain is not recovered when the load is removed, occurs at the upper end of the region 18, as is known in classical machines. d
Somewhere within region 22, the e-rut begins to deform plastically rather than elastically. It is difficult to determine the exact starting point of the yield region 22, so the normal practical definition of the yield point is 0.
．． This is the point at which 1-0.2% strain occurs, which is somewhat arbitrary. The proportional limit is substantially below the yield point of 20,
This occurs where the stress/strain ratio is no longer constant.

In the simplest example of the invention, the only joint parameter that needs to be determined before the screw-tightening operation in the manufacturing process is the joint tension ratio PR. This can be conveniently accomplished by selecting a fairly large sample of screw fasteners that will ultimately be tightened by the technique of the present invention and empirically determining the value of the tension factor FR in the laboratory. . Offset torque T to give somewhat greater accuracy. 8. Other factors such as the prevailing torque T and the amount of tool overrun that can be varied in torque or angle units can be determined.

The following equation is shown in the above-mentioned US patent application Ser. No. 912,151.

aTβα corresponds to the screw tightening torque rate ti, and aF/aα corresponds to the tension rate. Rewriting the equation, D TD = -X T R (21 R), where T is the torque value required to tighten the screw to the desired tension value FD, PR is the joint tension ratio, and TR is the torque ratio. These tensions $FR and the final desired tension value FD are predetermined in the sense that the values are obtained or selected long before each screw tightening is performed. The torque rate TR of the screw set is determined during tightening and is the only value for deriving the torque value Tn necessary to advance the entire screw set to its final desired tension value F1).

Another simplification of the invention is to use two-point measurements of torque rate rather than multiple points, and use least squares to smooth the data. Therefore, it will stop. Here, as shown in FIG. 2, T1 is a torque value sufficient to lie on a substantially linear portion of the torque-angle curve 10, and T2) or T
It is the torque value that occurs at an angle apart from 1 by α.

The use of equation (31) involves several problems.

In addition to obtaining or selecting values for the final desired tension value F and tension factor FR- as the first torque parameter Tl, the torque-angle curve i is sufficiently high.

The value must be chosen so that the final shutoff command is given after the screw has reached its yield point, i.e. after passing through the desired shutoff point. do not have.

The selected value of T1 can be determined empirically in the laboratory and the tension factor FR determined by tightening the necessary screws. T
1 can vary somewhat, but typically it is within 20-50 factors of the average final torque value TDa.

Another difficulty is ensuring that T1 and T2 are spaced by the proper angular spacing. T1 and T
2 is too close to (T2-T1')/αk, the torque single chain calculated by αk will be unduly influenced by noise in the torque sensing and will be unreliable and contain errors. T
If 2 and T1 are too far apart and TI is large on the part, the tool may advance the screw set beyond the desired tension value before the necessary calculations are completed. Generally, the spacing between To and 'r2 depends on the elastic properties of the bond, ie, the bond tension factor. If the bond is very tight, T1
and T2 must be relatively close together. If the bond is very soft, T1 and T2 must be relatively far apart. Typically the spacing between N T2 and T1 is in the range 5-60°. The exact value of the interval between T1 and 72 can be obtained in the laboratory during the determination of the tension factor FH.

The software required to implement equation (3) can be made as simple or as complex as desired. Of course, simplicity has its advantages, and is one of the advantages achieved by the features of the present invention. Analyzing equation (3), the tightening is measured in 6
It can be seen that there are parameters T11T2 and αk. Instead of storing all the necessary values using sophisticated techniques, the method of the present invention uses six parameters in the sense that two of the six parameters are selected well in advance of the tightening of the industrial screw. Two of the parameters are determined in advance.

Using sophisticated memory capabilities, these two parameters can be TI and α, or T1 and T2. With sufficient memory, the T2 value αk can be determined in advance.

When it is desired to select T1 and T2, equation (3) becomes as follows.

For any junction, FD, FR, T1, and T2 are constants, so equation (4) becomes T'p=OXα−” (51 and C, where C is FD/PR(T2−Tl). be.

If you want to select T1 and α, use Equation 31.

For any junction, since FD1XPR1α and T1 are constants, equation (6) becomes 'rDm A(T2-B'+ (7)
, where A is equal to Fry'PR(αk) and B is equal to T1.

It can be seen that a calculation analog circuit including equation (5) or equation (7), or both, is relatively simple.

According to the teachings of U.S. Patent Application No. 912.151, there are some torque limitations that apply screwing tools that do not affect the tension in the bolt, so equation (3) accurately determines the actual connection. is not shown. In particular, the predominant torque T p v exhibited by screwing does not apply tension. There is yet another complicating factor. When the control circuit issues a stop signal to the tool, there is a delay between the time the shutoff signal is generated and the time the tool actually stops. This is known as over 2-in and is the angle α. 1 or torque T. r can be measured, and there is a correlation between the two as shown in the following equation.

T ==TRα. .

Or f8) According to one feature of the invention, means are provided to adjust the torque sensor and adjust for overrun without affecting the bolt tension.

(To improve the determination made according to Equation 51, the dominant torque Tpv offset torque Tas and the overrun T.r measured in torque can be included according to Equation 51.

TD=(C×α−1) 10Tas+Tpv ”or
(91) It is of course possible to omit any or all of these compensating torque strings if desired.

Similarly, (Formula 71 can be improved as
1.Determination of o1τ1 and T2 [Figure 2 shows the first part of the torque-angle curve 10, which shows that the actual tightening of the screw can be plotted from the data generated during.

Tl and T! Since the value of I is predetermined, the actual measurement requirement is only on the angle α.

FIG. 6 shows a tightening device 24 according to the invention.

The device 24 has a wrench 26 including a motor 28, an output drive shaft 3o, and a drive bit 32. Drive shaft 30 is driven by motor 28 to provide torque and rotation to a screw stop that engages drive bit 32 . Wrench 26 may be of any suitable type, most commonly pneumatically driven by a pressurized air flow controlled by a suitable electrically energized motor and locking solenoid 34. Motor 32 may be driven in any suitable manner. The exact details of the wrench 26 are uncomfortable to understand the invention, and since October 1979
Filed by Joke D., Paul, dated May 25,
1,000W+turn fIl Tokugin Deho Connection 88.32
Fry 77 pieces and set aside.

Preferably, the wrench 12 is portable and includes a torque sensor or transducer 36 that generates a variable signal indicative of the instantaneous torque applied to the screw fastening. Torque transducer 36 may be of any suitable type, such as those disclosed in the Hall patent application. An angular transducer or encoder 38 is mounted on the wrench 26, preferably in association with the shaft of the motor 28, to generate a signal indicative of the incremental angular displacement or rotation of the screw fastener. As amply pointed out in U.S. Application Ser. It may be of any suitable type that operates in the same manner. If desired, motor load, tightening time etc.
Other input tightening characteristics may also be employed. Typically, the output signal from torque sensor 36 is analog, whereas the output signal from angular encoder 38 is digital and consists of a series of pulses, each pulse indicative of a predetermined angle of rotation sensed by encoder 38.

As shown in FIG. 6, the control circuit 40
6, a conductor 44 that extends to the output of the angle encoder 38, and a conductor 46 that extends to the solenoid 34.
is connected to the tool 26 to stop the tool 26 in response to decisions made within the circuit 40. Circuit 40 includes a cycle start switch 48 that may be located within tool 26 in association with operator handle 50, as detailed in the Hall patent application cited above. desirable. Cycle start switch 48 also has a reset function so that the clamp is released at the end of the cycle to clear the memory elements of circuit 40.

As shown, the circuit 40 has two sub-circuits: a dominant torque Tpv supply circuit 52 and a main calculation circuit 54. Predominant torque circuit 52 includes a timer 56 connected to cycle start switch 48 by conductor 58. At the end of a fairly short predetermined interval, timer 56 outputs torque lead [4].
[6o
The signal is supplied via the V.V. The value stored in element 62 is output to lead 64 representing the prevailing torque Tpv. Second
As can be seen from the figure, the value of the predominant torque Tpv is the value of the torque conductor 4.
2, so the timer 560 interval must be relatively short. The maximum allowable length of the predominant torque interval depends on the length of the bolt for the flanged part and the idle speed of the tool 26, as will be apparent to those skilled in the art. Typically the predominant torque interval is approximately 0.
It takes about 5 seconds.

The predominant torque circuit 52 also includes a predominant torque limit comparator 66 having an input 68 that carries a signal indicative of the maximum allowable value or limit of the predominant torque T,v.

The output G of the comparator 66 is determined by the logic circuit 7 shown in detail in FIG.
Connected to 2. If the predominant torque value stored in element 62 is greater than the maximum punch predominant torque, comparator 6
6 sends a signal to logic circuit 72, which sends a signal through lensoid conductor 46 to turn tool 26 off.

In this situation, it is clear that there is something wrong with a screw fastener such as a cross-threaded nut.

The main calculation circuit 54 has a subtractor 74 which is connected to the torque conductor 4.
one input connected to 2 and sample-and-hold element 6
and another input connected to the output of 2.

Therefore, the subtracter 74 outputs the adjusted torque Ta-11
That is, an analog signal indicating the value obtained by subtracting the predominant torque T pv from the sensed torque is sent onto the output cuff 6 .

The subtractor ratio cuff 6 includes first and second torque comparators 7B,
ll0K connected. Comparator 78 includes an input 82 to which is applied a signal indicative of T1.

Comparator 78 therefore sends a signal on conductor 84 when adjusted torque value Ta exceeds T1. When comparator 78 conducts, the tightening cycle passes beyond position 86 in FIG. The comparator 80 includes an input 88 and an output 90t carrying a signal representative of T2, the comparator 80 detects when the adjusted torque value T1 is greater than T2, i.e., the tightening cycle is at the position shown in FIG. It is output when it reaches 92.

The question may arise as to whether the prevailing torque Tpv is always subtracted from the running torque T before sending the running torque signal to the torque comparator F8.80.

Since the predominant torque Tpv varies from joint to joint, subtracting the predominant torque from the running torque ensures that the values of T1 and T2 are within the desired range of the linear portion of the torque-angle curve. For example, assume that the screw being being tightened normally exhibits a relatively high predominant torque, but that the particular screw being currently being tightened has little or no predominant torque. In this case, KT2 will not appear on the running torque signal until perhaps much later in the cycle when tightening exceeds the desired shutoff point.

Similarly, if the particular screw being tightened has a slight amount of predominant torque, even though screw fasteners normally exhibit little or no predominant torque, the connection may still be present. While in the initial clamp-up region 16, KTl may appear on the running torque signal. In such a case, the calculated torque rate TR would be too low.

The output 84.90 of comparator 78.80 is connected to unique table OR circuit 94. As will be apparent to those skilled in the art, this OR circuit 94 provides a signal on output 96 when comparator output 84 is activated, and ceases to signal when output 90 is activated.

Therefore, the signal appearing on gate output 96 is from T1 to T
Represents torque intervals up to 2.

Output 96 is an AIJ with square barrel wire 44 as one input.
It is connected to the other input of the D circuit 98. Therefore, as long as there is a signal on gate output 96, gate 9B will deliver a series of angular pulses on its output 100. This is because it is clear that an angular pulse will occur on the angular groove line 44 whenever the tool 26 is rotating. Date 98 sends an output signal on conductor 100 and when the signal on conductor 96 stops and its output signal stops, P-) output 100 has a series of angles representing αk as shown in FIG. The signal that the pulse produces on the 0 date output 100 is digital and
To form a series of pulses, it is desirable to count the pulses to determine the magnitude of the angle α. Therefore, this output 100 is connected to the counter 102 and the counter 102
The output 104 of is connected to a digital-to-analog converter 106. This converter 106 delivers an analog signal on its output 108 representing αk.

The converter output 108 is the constant C of (Equation 51 or Equation (9))
is connected to a divider 110 having an input 112 carrying a signal representing . Of course, C is the ratio of the final desired tension value FD to the quotient of the tension factor FR divided by the torque difference T2-T. Divider power 114 carries a signal representing TD according to equation (5).

To improve the value of TD, this output 114 is sent to adder 11
Connected to 6. The adder 116 calculates the offset torque T
. Input 118 carrying a signal representing S and the prevailing torque T
An input 12 connected to a conductor 64 carrying a signal representing pv
0. The output 122 of adder 116 therefore carries a signal representing TDl according to the equation:

This formula represents the overrun torque element T. This is basically the same as equation (9) except that there is no term r. It is understood that adjustment for overrun can be accomplished by placing a subtractor in output 122 and subtracting the torque value corresponding to the average amount of overrun expressed in torque units to obtain the result of equation (9). Good morning.

Adjustment of the predominant torque Tpv can be done in one of two ways, as illustrated in FIG.

Comparator 124 has as one input conductor 76, which carries a signal representing T-T pv. Therefore, the following equation is obtained as a result of the comparison.

When transformed, we obtain, which is of course basically Equation (9). In this variation, the output 122 of adder 116 is
The conductor 76 carries a signal representative of T-Tpv. Then, when the value of T-Tpv becomes equal to TDi K, the comparator 1
24 provides a shutoff signal to tool solenoid 34 via conduction conductor 46, thereby terminating the tightening of the joint.

It will therefore be seen that this is done in response to a comparison of the end of tightening TDl and T-Tpv. Of course, this determination depends on the value T, vf: in addition to the signal on conductor 122, the running T
It should be understood that if you compare the value with the added value, it is the same as the book.

In this way, in the embodiment of FIG. 3, predetermined values are used for T1 and T2, the interval αk between them is measured, and the shaft-off parameter is finally determined in response to these six parameters. calculate. .

One surprising feature of the present invention is that the observed tension distribution is favorable even when compared to the more sophisticated digital method disclosed in the aforementioned US patent application Ser. No. 912.151. U.S. Patent Application No. 912.151
The tension dispersion garments listed in this issue are as follows.

Tension and Torque Variance/1 Standard Deviation These values are adjusted for a load washer error of 1.8 inches. The LRM values shown in this table are the results obtained by the sophisticated method of US patent application Ser. No. 912.151. The tension distribution of screw fasteners tightened according to the present invention is approximately 1-2 inches higher than that obtained with this more sophisticated technique, or within the range of approximately 3.2-4.6%.

The values of T1 and α in FIG. 2 are determined according to this embodiment of the invention and are therefore only values of the actual measurement requirements, FiT.

FIG. 4 shows another embodiment of a tightening device 128 according to the present invention. The device 128 includes a wrench 130 that includes a motor 132, an output drive shaft 134, and a drive bit 136. The drive shaft 134 is driven by the motor 132 and rotates by applying torque to the screw set engaged with the drive bit 136. The wrench 130 is typically pneumatically powered, with pressurized air flow controlled by a suitable electrically energized motor or solenoid F138. As in the embodiment of FIG. 3, the wrench 130 may be of the type disclosed in the above-referenced US patent application Ser. No. 88,627, filed October 1979.

Wrench 130 includes a torque sensor or transducer 140 that generates a variable signal representative of the instantaneous torque applied to the screw fastening. Preferably motor 132
An angular transducer or encoder 142 is mounted on the wrench 130 along with the shaft of the wrench, which generates a signal representing the incremental angular displacement or rotation of the screw fastening.

As shown in FIG.
: also includes a control circuit 144 connected to the tool 130 that controls the tool 13 in response to decisions made within the circuit 144.
Stop 0.

Circuit 144 includes a cycle initiation switch 152, which is preferably located within tool 130 along with an operator handle 154, which is disclosed in detail in the aforementioned US Ser. No. 88,327.

Cycle start switch 154 also has a reset function, the clamp being released at the end of the cycle to clear the memory elements of circuit 144.

As shown, the circuit 144 has two sub-circuits: a circuit 156 for adjusting the prevailing torque Tpv and a main calculation circuit 158. Predominant torque circuit 156 includes a timer 160' connected to cycle start switch 152 by conductor 218. At the end of a short predetermined interval, a timer 160 sends a signal along its output 162 to one input of a sample and hold element 164. Element 1
The other input of 64 is connected to torque conductor 146.

Of course, the signal on torque conductor 146 is the prevailing torque T. This value of the prevailing torque T pv is sent to the sample and pv hold element 164 and stored. element 164
is an output 16 carrying a signal representing T pv as described below.
It is equipped with 6.

The output is connected to one input of a 166-digit subtractor 167, and the other input of the subtractor 167 is connected to the torque conductor 146. The output 168 of the subtractor 167 carries a signal representing the running torque Tpv obtained by subtracting the predominant torque Tpv from the running torque T.

The main calculation circuit 158 has a comparison 51 connected to the output 168.
69't-, whose comparator 169 includes an input 170 for receiving a signal representing a predetermined value of Tl. T,
When the value of T1 exceeds T1, comparator 169 sends a signal on output 172. Its output 172 is connected to a counter 174 having an input connected to the square groove line 148.

The output 176 of counter 174 is connected to a digital-to-analog converter 178 which sends out an analog signal along its output 180 representing the angle traversed beyond T1. The output 180 of converter 178 is connected to comparator 1
82, and the other input 18.
4 has a signal representing a constant or predetermined angle expressed by 1 in a constant or predetermined angular increment α. Accordingly, comparator 182 sends a signal along output 186 when the measured angle exceeding TI't' exceeds the predetermined angular interval αk.

A sample and hold element 188 is connected to the output 186 of the comparator 184 and one input of the element 188 is connected to the output 16B of the subtractor 167.When a signal appears on both zero conductors 168 and 186, Element 188 conducts and provides on its output 190 a signal representative of the torque value Tzt-. The output 190 is connected to a subtractor 192 which carries a signal representing a predetermined value T1t-.
It has two inputs 194. Output 19 of subtractor 192
6 therefore carries a signal representing the 'rl-TlO value. This value is a value that cannot be ignored to complete the calculation of equation (7).

The output 196 of the subtractor 192 is connected to a multiplier 19B, and the other input 200 of the multiplier 198 carries a signal representing Δ in the equation (force), which Δ is, of course, the desired final tension FD The value of the ratio of the tension factor FR to the tension factor FR divided by the constant angular increment α.The output 202 of the multiplier 198 thus carries a signal representing the TD obtained by Eq.

The output 202 is connected to an adder 204, and the adder 2
04H has two inputs, one of which is connected to the conductor 166 of the sample and hold element 164,
On the other hand, the human power 206 is an offset torque T. It carries a signal representing 8. According to the output 208 of the adder 204, the following equation (14
) carries a signal representing the value of TD.

TDI=A(T2-B)”Tos
(14) This formula (14)F! , the overrun torque element T. Basically (10
) is equal to the expression. The overrun can be adjusted by placing a subtracter at output 208 and subtracting the torque value corresponding to the average overrun measured in torque units to obtain the result of equation (10).

In any case, output 20B is connected to comparator 210, and another input of comparator 210 is connected to output 168. If the value of T1 is equal to TD□, comparator 210 conducts and its output 212 provides a shutoff signal to tool solenoid 138 via output lead 15 (l) of logic circuit 214 to terminate tightening of the joint.

The predominant torque T pv may be adjusted in a manner as shown in FIG. In FIG. 4, comparator 210 has as one input conductor 168, which carries a signal representing T-Tpv. Therefore, the following equation is obtained as a result of the comparison.

Transforming this formula, we get becomes. This is, of course, basically equation (6).

As will be appreciated by those skilled in the art, logic circuit 214 is preferably similar to logic circuit 72 and essentially includes a set-reset flip-flop. logic U
Path 214 includes a signal inverter 216 in conductor 218 connected to cycle start switch 152.

Logic circuit 214 includes a HAND date pair 220.2'2;2, each date having an output 224.226t cross-connected to one input of the other date, as shown in FIG.
- have each. Input 228 of date 220 is connected to inverter 216 and input 2220 input 2
30 is the comparator output 212 of the embodiment of FIG.
It is connected to the comparator ratio cuff 0,126 of the illustrated embodiment. Output 224F of date 220! Drive transistor 23
2 to the solenoid lead 150. At the beginning of a cycle, closing the cycle start switch 152 sends a signal through the solenoid lead 150 to activate the tool 130. When the torque comparator 210 flips, the running torque T on the torque lead 11146 changes to the lead 20.
8, logic circuit 214 sends a signal through solenoid lead 150 to stop tool 130. When the operator loosens the handle 154, the cycle switch 152 opens and the logic circuit 124t is reset.

In the embodiment of FIG. 3, the adjusted running torque T1
The same series of events occurs when the signal on conductor 126 indicates that the torque shutoff parameter TD is worse than the calculated torque shutoff parameter TD. Essentially, the same series of events occurs when the predominant torque comparator 66 determines that the predominant torque Tpv experienced by any screw fastener exceeds the predominant torque limit.

It will be appreciated that in the example of FIG. 4, predetermined values of T1 and α1 are used, the value of T2 occurring at a predetermined interval α1 is measured, and the shutoff parameter is calculated in response to these three parameters. .

The embodiments shown in FIGS. 6 and 4 determine the final desired tension value F by determining the tightening of the shutoff parameter, which changes for each joint, while tightening the element below the yield point that can be correlated with the stress.
It can be seen that the tightening operation is completed near D.

The embodiment of FIG. 4 differs from the embodiment of FIG. 6 in addition to showing different technical conditions for determining the torque speed TR.

In particular, the embodiment of FIG. 4 does not include shutoff of the predominant torque Tpv when the predominant torque exceeds a predetermined maximum value. Of course, the embodiment of FIG. 4 can be provided with superior torque shutoff if desired.

For purposes of discussion, the torque component of the overrun T. rt - determined empirically in the laboratory as the average value of the screws tightened, can be easily used to subtract from TDl to provide an improved shutoff parameter.

Of course, it will be appreciated that the tightening of each screw can be predicted for even better determination of overruns in time. This technology is described in U.S. Patent Application No. 912.15.
It is expressly disclosed in No. 1.

The tightening of each screw is determined by the period T. It is clear to those skilled in the art that such a value of r is TDI
can be subtracted from.

Although the present invention has been described above with respect to embodiments having certain specificity, the disclosed embodiments are merely illustrative, and the detailed structure and structure are within the scope of the invention and the claims.
The combination and arrangement of parts and the operation mode can be changed in various ways. It is intended that the invention be covered by any patentable novelty features present in the disclosed invention by appropriate wording in the claims.

[Brief explanation of drawings]

Figure 1 is a graph showing typical torque-angle and tension-angle curves that occur during continuous tightening of a screw pair well beyond its full elastic limit; Figure 2 is a graph showing the torque-angle curves of Figure 1;
FIG. 3 is a schematic block diagram of the tightening device of the present invention; FIG. 8G4 is a schematic block diagram similar to FIG. 6 of another embodiment of the present invention; FIG. 5 is a schematic block diagram showing the configuration of a logic element in FIG. 4. FIG. Explanation of reference symbols 24.128...Tightening is done by device 26.130...Wrench 28.132...Motor 30.134-・Drive shaft 32.136...Drive bit 34.138...Solenoid 36.140...Transducer 38.142...Encoder representative Asamura Kogai 4 people

Claims (1)

[Scope of Claims] (1) A movable crab tool that provides an input characteristic to a screw fastening; means for sensing the iron force characteristic and generating a signal for suppressing it; means for determining a final shutoff parameter in response to a ratio of a desired tension value to a screw tension rate; and means for terminating operation of the tool in response to a final shutoff parameter. A device for tightening screws. +21% In the device according to claim 1,
49. The screw fastening device according to claim 49, wherein the input characteristic sensing means includes a means for sensing a torque applied to the screw fastening and a means for sensing a function of a rotation angle of the screw fastening. (3) In the apparatus according to claim 2, the shutoff parameter determining means responds to the generated signal to determine two torque values and three values of the interval between the two torque values. 4. The apparatus according to claim 3, further comprising means for calculating the final shutoff parameter from the parameter and the ratio. The determining means may include means for predetermining two of the three parameters prior to performing the tightening operation, and means for determining the third parameter during the tightening operation. 'n? The said screw tightening device is moldy. (5) Percentage Allowance In the device according to claim 4, the means for predetermining the two parameters includes means for inputting the two torque values, and the means for determining the third parameter in the table. said screw tightening method, characterized in that said screw fastening comprises means responsive to said two input torque values and actuated by a signal from said rotation angle function sensing means to measure the interval between said two torque values. Device. (6) In the device according to claim @5, the first torque value among the two torque values is lower than the w42nd torque value (and the sixth parameter determining means is the first torque value and the second torque value in response to the occurrence of the first torque value and the second torque value; The screw fastening device is characterized by: (7149) The device according to claim 6, characterized in that the rotation angle function sensing means includes means for sensing the rotation angle of the screw fastening. (8) In the apparatus according to claim 4, the means for determining the two parameters in advance comprises means for inputting a first torque value of the torque values and an interval between the two torque values. and means for determining a third parameter is responsive to the two input values and actuated by a signal from the torque sensing means to determine one of the torque values at a predetermined interval from the first torque value. said screw fastening device comprising: means for measuring a second torque value; (9) means for sensing a function of the torque applied to the screw fastening and generating a signal representative thereof; a movable tool containing means for sensing and generating a signal representative of the rotation of the fastener to apply torque and rotation to the screw fastener; a tightening control circuit that determines a tightening parameter that changes from joining to joining in response to the three parameters sensed by the sensing means while performing the tightening operation; means for predetermining two of the three parameters prior to the meeting; means for determining a sixth parameter during operation for tightening; and means for determining the operation of the tool in response to the final shutoff parameter. A device for tightening a joint, including screwing, characterized in that it comprises means for terminating the joint.
The tightening device is characterized in that the three parameters are two torque values and an interval between the two torque values. αυ In the apparatus according to claim 10, the means for predetermining the two parameters includes means for predetermining the two torque values, and the #! 3. The means for determining the third parameter includes means for determining an interval between the two torque values. (13% allowance) The apparatus according to claim 11, wherein the means for determining the 145 parameters includes means for determining an interval between the two torque values. (13I! #Claim I! In the apparatus according to claim 12, the means for predetermining the two parameters is
said sixth parameter determining means is responsive to said two inputs)/ref values and actuated by a signal from said rotation sensing means to determine the interval between said two torque values. Apparatus for tightening, characterized in that it comprises means for measuring. Q4 In the device according to claim lK13, the first torque value among the torque values is lower than the 211th torque value (and the third parameter determining means is lower than the 211th torque value). said tightening being equal to a torque value of t%, including means for measuring an interval between said first torque value and a second torque value in response to the occurrence of a sensed torque; α51% The apparatus according to claim 14, wherein the rotation function sensing means is a means for sensing the angle of rotation of a screw fastening. ae In the device according to claim 10,
The means for predetermining the two parameters includes means for inputting a first torque value of the torque values, and the parameter determining means 1i13 detects torque in response to the two input values. The tightening apparatus further comprises means for measuring a second one of the torque values at a predetermined distance from the first torque value when actuated by a signal from the first torque value.