JPH07186060A - Impact type screw tightening device - Google Patents

Abstract

PURPOSE:To provide an impact type screw tightening device capable of accurately calculating an actual fastening force. CONSTITUTION:A power source is controllably given to a drive means to calculate the increased amount of the fastening force in every impact for sequentially obtaining the fastening force and realizing a desired fastening force by using the peak value of torque.pulse obtained from the detecting results of an impact type screw tightening machine body 100 having drive means 102, 103 having pulse components in the drive output, a spindle 104 driven by the drive means to tighten a screw and a torque detecting means 101 for detecting a change in the torque of the spindle. In the calculation of the fastening force, a seating time is judged from the deformation of a waveform of torque.pulse accompanying the seating and a controlling means 120 is provided which sets the seating time as a starting time for the calculation of the fastening force to calculate the fastening force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention utilizes impact force to
A screw tightening device that performs screw tightening work, such as impact
The present invention relates to a wrench, an impact-type nut / runner, and the like, and more particularly to a technology for controlling the fastening force (tightening force) of a screw.

[0002]

2. Description of the Related Art As a conventional impact wrench for controlling tightening torque, there is, for example, a device described in Japanese Patent Application No. 3-12370. FIG. 35 is a cross-sectional view of the above device. In FIG. 35, the main shaft 15 is made of a material having a magnetostrictive effect. Then, a change in torque is detected by detecting a change in magnetic permeability on the surface of the main shaft 15 that accompanies a torque pulse generated during screw tightening as a change in inductance of the detection coils 26a and 26b of the torque detection unit 11. Then, when the detected torque reaches a value within a predetermined range, the shut-off valve 12 is closed by the control signal from the control device 110, and the air motor unit 13 is closed.
The compressed air is shut off, and the drive of the hydraulic pressure pulse generator 14 and the main shaft 15 is stopped. However, in the case of screw tightening with a torque wrench such as a taper beam wrench, the tightening torque and the tightening force generated at the tightening part are in a proportional relationship. -The torque value is not proportional to the fastening force. For example, the result of experiments shows that the fastening force often increases even when an impact with a peak torque value smaller than the immediately preceding impact occurs. found. Thus, the peak torque value of impact cannot be said to correspond to the fastening force on a one-to-one basis, so even if this peak torque value is accurately detected, the fastening force cannot be detected accurately. Therefore, even if the shut-off valve is cut off based on this, the fastening force is not accurately controlled. As described above, in the conventional device, the fastening force cannot be accurately detected, so that there is a problem in that it is difficult to accurately control the fastening force to a desired fastening force.

In order to solve the above problems, the applicant has
An application has already been filed for a device that calculates the amount of increase in fastening force using the peak torque value for each impact during screw tightening (Japanese Patent Application No. 4-254028: unpublished). FIG. 36 is a flowchart of calculation in the device. The mechanical portion is the same as that shown in FIG. This device
As shown in FIG. 36, the amount of increase in fastening force is calculated using the peak torque value for each impact during screw tightening, and the fastening force is calculated by sequentially adding this value, and that value is the preset fastening force. The target fastening force is obtained by shutting off the compressed air supplied to the impact wrench at the time when the pressure reaches the point.

A detailed description will be given below with reference to FIG.
First, after setting the value of the target fastening force cFc in step S301, the impact number counter is reset in step S302 <count i = 0>, and further in step S30.
The value of the fastening force up to that point is reset with 3. <F (0) =
0>. Next, in step S304, screw tightening is started. Further, steps S305 to S309 form a loop, and the fastening force is calculated for each impact. First, after incrementing the count i by 1 in step S305, the peak torque value T _P (i) of the impact is obtained and stored from the signal of the torque sensor in step S306. Next, in step S307, the torque-engagement force conversion coefficient _CTF (i) at F (i-1) is calculated based on the table of the engagement force data / memory unit. However, C
_TF (i) = C _TF [F (i-1)]. Next, step S30
8, the tightening force increase due to impact δF (i) =
C _TF (i) × T _P (i) is calculated, and the fastening force F (i) after this impact is used as the fastening force up to that point, that is, the fastening force F (i-1) after the previous impact. It is calculated by adding the increment δF (i). Therefore, F (i) = F (i−1) + C _TF (i) × T _P (i). Next, in step S309, the fastening force F after impact is applied.
It is determined whether or not (i) is equal to or greater than the target fastening force cFc, and if NO, the process returns to step S305 to repeat step S309. On the other hand, if YES in step S309,
The process proceeds to step S310, at which point a cut-off command is issued. This causes the compressed air valve to close. Next, in step S311, it is determined whether or not to end the process. If YES, the process ends as it is, and if NO, the process returns to step S302 to perform the next screw tightening. Although the above-mentioned conventional example and the description of the prior art by the applicant have been described by taking the impact wrench as an example, the same applies to the impact type nut runner and the like.

[0005]

As described above, as shown in FIG.
In the conventional device shown in (1), the fastening force cannot be accurately detected, so that there is a problem that it is difficult to accurately control the fastening force to a desired fastening force. Further, in the prior invention of the present applicant made to solve the above problem, the fastening force can be detected, but the fastening force is calculated immediately when the torque pulse is measured during screw tightening. Therefore, the fastening force is calculated even when torque is generated due to friction of the screw surface before the fastening force is actually generated, that is, before the bolt or the nut is seated. Therefore, the calculated value of the fastening force (calculated fastening force) becomes larger than the actual fastening force (actually measured fastening force), and there is a problem that an error occurs. Particularly, in the case of a detent nut that is often used in assembling chassis parts of automobiles, such a problem is likely to occur.

The present invention has been made in order to solve the problems of the prior art as described above and to further improve the prior art of the present applicant, and it is possible to accurately calculate the actual fastening force and to improve the accuracy. An object of the present invention is to provide an impact type screw tightening device capable of performing a good screw tightening work.

[0007]

In order to achieve the above object, the present invention is constructed as described in the claims. That is, in the invention described in claim 1, drive means having a pulse component in the drive output,
An impact type screw tightener main body having a main shaft which has a joint portion with a screw at one end thereof and is tightened by being driven by the drive device, and a torque detection device which detects a torque change of the main shaft; Using the peak value of the torque pulse obtained from the detection result of the torque detection means, the increase amount of the fastening force is calculated for each impact to sequentially obtain the fastening force, and the drive means is provided so as to realize the target fastening force. Control the power source applied to the vehicle, and determine the seating time from the deformation of the torque pulse waveform associated with seating when calculating the tightening force, and calculate the tightening force with the seating time as the starting time for calculating the tightening force. Control means for
The above-mentioned impact type screw tightener main body is, for example, the impact type screw tightener main body 1 in the embodiment of FIG. 1 described later.
00 (details shown in FIG. 2), similarly, the drive means corresponds to the motor 102 and the torque / pulse generator 103, and the spindle and the torque detection means respectively correspond to the spindle 104 and the torque detector. It corresponds to 101. Further, the control means corresponds to, for example, the control device 120 in the embodiment of FIG. 1 described later.

Further, in the invention described in claim 2,
The impact type screw tightening device according to claim 1,
As a waveform deformation of the torque pulse accompanying the seating, a change in the duration of the torque pulse is detected, and the time when the duration becomes a predetermined value, that is, the seating determination threshold duration, is the seating time. The calculation means for determining The arithmetic means corresponds to, for example, the control device 120 in the embodiment of FIG. 1 described later. Further, in the invention according to claim 3, in the impact type screw tightening device according to claim 1, as the waveform deformation of the torque pulse accompanying the seating, a torque pulse corresponding to the occurrence of impact by the driving means is generated. And a time point when the occurrence interval becomes a predetermined value, that is, a seating determination threshold value occurrence interval or more, and is determined to be a seating time point. The arithmetic means corresponds to, for example, the control device 130 in the embodiment shown in FIG.
Torque corresponding to the impact generated by the drive means
The pulse generation interval is, for example, the liner in FIG.
It corresponds to the rotation cycle of the case. According to a fourth aspect of the present invention, in the impact type screw tightening device according to the first aspect, as the waveform deformation of the torque pulse accompanying the seating, the duration of the torque pulse and the driving means are used. Equipped with a computing means for detecting a change in the generation interval of the torque pulse corresponding to the impact occurrence, and determining the time when at least one of the duration and the occurrence interval becomes a predetermined value or more as the seating time. ing. The computing means corresponds to, for example, the control device 140 in the embodiment shown in FIG. 8 described later.

In the invention described in claim 5,
The impact type screw tightening device according to claim 1,
As the waveform deformation of the torque pulse due to the seating, the interval between the torque pulse generated first and the torque pulse generated second among the plurality of torque pulses generated at each impact by the driving means. That is, there is provided computing means for detecting a change in the free running time, and determining a time when the free running time becomes a predetermined value, that is, a seating determination threshold free running time, as a seating time. The computing means corresponds to, for example, the control device 150 in the embodiment shown in FIG. Further, in the invention described in claim 6,
6. In the impact type screw tightening device according to claim 5, the seating determination threshold duration time and the seating determination are determined by using a measuring means for measuring an actual fastening force and a measurement result of the measuring means in a preliminary experiment. At least one of the threshold generation interval, the seating determination threshold free running time, and the dependency of the torque / fastening force conversion coefficient used when calculating the increase amount of the fastening force for each impact on the fastening force. And a calculation means for determining one by learning. The measuring means corresponds to, for example, the fastening force measuring bolt 172 to which the strain gauge 171 in the embodiment shown in FIG. 13 is attached, and the calculating means also corresponds to the control device 160.

Further, in the invention described in claim 7,
The impact type screw tightening device according to claim 1,
As the waveform deformation of the torque pulse due to the seating, a predetermined data is obtained at a constant sampling interval from the rising of the first torque pulse among the plurality of torque pulses generated at each impact by the driving means. The number of data (that is, the number of sampling data) that is less than or equal to a predetermined torque value (that is, the threshold torque for free running determination) when sampling the torque data, that is, the change in the number of free running data is detected. However, it is provided with a calculation means for determining whether the number of free running data is equal to or less than a predetermined seating determination threshold free running data number, and determining the time when it is less than or equal to the seating time. The arithmetic means is, for example, the control device 1 in the embodiment shown in FIG.
Equivalent to 80. Further, in the invention described in claim 8, in the impact type screw tightening device according to claim 1, as the waveform deformation of the torque pulse accompanying the seating,
From the rising of the first torque pulse generated among the plurality of torque pulses generated for each impact by the driving means, a predetermined number of data (that is, the number of sampling data) of torque data is obtained at a constant sampling interval. The number of data showing a value equal to or more than a predetermined torque value (that is, extraction determination threshold torque) at the time of sampling, that is, a change in the number of extracted data is detected, and the number of the extracted data is the predetermined seating determination threshold extraction data. A computing means is provided for determining the time when the number of seats is equal to or more than the seating time. The computing means corresponds to, for example, the control device 190 in the embodiment shown in FIG. In addition, claim 9
In the impact type screw tightening device according to the seventh aspect and the eighth aspect, the sampling time, which is the product of the number of sampling data times the sampling interval, is generated by one impact before sitting. It is set to be shorter than the time required from the rise of the torque pulse generated first among the plurality of torque pulses to the rise of the torque pulse generated second. The computing means corresponds to, for example, the control device 180 in the embodiment shown in FIG.

[0011]

In the invention of claim 1, when calculating the fastening force, the seating time is determined from the waveform change of the torque pulse accompanying the seating, and the fastening force is calculated with the seating time as the start time of the fastening force calculation. Is configured as follows. Therefore, the torque generated by friction of the screw surface before the actual fastening is started can be excluded from the calculation of the fastening force, so that the actual fastening force can be accurately calculated and the target fastening force can be calculated. You can tighten the screws with precision. Further, in the invention described in claim 2, the change in the duration of the torque pulse is detected as the waveform change of the torque pulse associated with the seating. According to the invention described in claim 4, the change in the corresponding torque pulse generation interval is detected.
Changes in both the duration and the occurrence interval are detected, and in the invention of claim 5, a change in free running time is detected. Therefore, the seating time can be accurately determined. In the embodiments described below, the above-mentioned "torque pulse corresponding to the occurrence of impact" is abbreviated as "impact torque".

Now, the change in the waveform of the torque pulse due to seating will be described. FIG. 23 shows an impact type screw tightening device which is a detent nut (for the detent nut,
For example, "Points for Designing Screw Tightening Mechanism", Japanese Standards Association, 1989, 4th edition, pages 299 to 301
(Described on page) is shown schematically when the torque pulse waveform changes when the screw is tightened by rotating (see page). Figure 2
As shown in Fig. 3, the characteristic of the waveform before seating is that a pair of torque pulses with a short duration is generated at each impact occurrence (one rotation of the liner case), and the peak value of the first torque pulse is And the peak value of the second torque pulse is 1/3 to 1/2. The first torque pulse is when the nut begins to move and is a large starting torque due to the effects of static friction and detents (eg caulking). After that, until the nut stops, the liner case and the main shaft rotate together (at this time, the nut is in a free running state with respect to the bolt), but due to dynamic friction, the main shaft rotation speed Gradually decreases. Immediately before stopping, the liner case rotates faster than the main shaft, and the second torque pulse is detected. The relative rotation angle between the main shaft and the liner case from the rising of the first torque pulse to the end of the second torque pulse is about 2 to 3 degrees. On the other hand, the characteristic of the waveform when seated is that it consists of the first and second torque pulses as before seating, but the interval between them, that is, the time during which the nut is in the free running state is extremely short. Moreover, the second torque pulse has a higher peak value and a longer duration than before sitting. In addition, the characteristic of the waveform after sitting is that a long-duration torque pulse causes impact (1 of liner case).
This is a point that occurs every rotation). That is, when the tightening force increases, the rotation angle of the nut due to the impact becomes smaller, the above-mentioned free running state disappears, and the first and second torque pulses in the waveform before seating are integrated. And the duration of the torque pulse becomes longer.

FIG. 24 shows the relationship between the change in the angular velocity ω of the liner case and the torque pulse during one rotation of the liner case. Before seating, the angular velocity ω decreases with the first torque pulse, then gradually increases due to the smaller load, decreases slightly with the second torque pulse, and then increases again. When the angular velocity ω during this one cycle is integrated at time t, it becomes 2π. On the other hand, at the time of sitting and after sitting, the angular velocity ω decreases with the torque pulse and then gradually increases to complete one cycle. At this time, the amount of decrease in angular velocity ω due to the torque pulse becomes larger in the order of sitting and after sitting than before sitting, and the rate of increase in angular velocity ω is considered to be almost constant. As a result, the angular velocity ω decreases, and the time required until the angular velocity ω becomes 2π when the angular velocity ω is integrated at time t, that is, the cycle becomes longer in the order of sitting and after sitting.
As a result, the seating interval increases the torque pulse generation interval corresponding to the occurrence of impact. As described above, after sitting, the duration of the torque pulse and the generation interval of the torque pulse corresponding to the occurrence of impact become long and the free running time becomes short. Therefore, by configuring as in claims 2 to 5, it is possible to accurately detect the seating time.

According to the invention of claim 6,
Equipped with a means for measuring the actual fastening force, by performing calculations based on the results of preliminary experiments, the seating determination threshold duration, seating determination threshold generation interval, and seating determination threshold free running time can be calculated. It can be automatically determined during the preliminary experiment, and the dependence of the torque-fastening force conversion coefficient on the fastening force, which is used when calculating the increase amount of the fastening force for each impact, that is, the _CTF- F characteristic ( For example, the characteristics (shown in FIG. 4) can be automatically determined in the same manner, so that the measurement is easy and accurate. Next, in the invention described in claim 7, the number of free-running data is detected as the waveform change of the torque pulse associated with seating. In the invention described in claim 8, the number of extracted data is detected. The change of is detected. Therefore, the seating time can be accurately determined.

FIG. 25 is a torque / data number characteristic chart for explaining the number of sampling data, the free running determination threshold torque, the number of free running data, the extraction determination threshold torque, and the number of extracted data. Is. As shown in FIG. 25, since the number of free running data corresponds to the number of data included in the free running time for each impact, the number of free running data in the pre-seating torque waveform with a long free running time is On the contrary, the number of free-running data is small in the torque waveform after seating where the free-running time is little. On the other hand, since the number of extracted data corresponds to the number of data included in the torque pulse for each impact, the extracted data is used in the pre-seated torque waveform consisting of the first and second torque pulses of short duration. The number is small, and conversely, the number of extracted data is large in the torque waveform after sitting, which consists of torque pulses having a long duration.

Further, in the configurations described in claims 2 to 5, the seating can be accurately determined,
Since the number of data required for seating determination is large and the determination logic is complicated, the determination processing time becomes long. Therefore, during the series of processing time including the fastening force calculation process that follows the seating determination process, the next impact will occur if the impact occurrence interval is short, and the torque waveform associated with it will be detected. You may not be able to. Therefore, in the invention described in claims 7 and 8, the data processing is simplified by configuring as described above and limiting the number of data to be processed to the number of sampling data, thereby shortening the seating determination processing time. ing. Further, in the invention described in claim 9, the sampling time, which is the product of the number of sampling data and the sampling interval described in claims 7 and 8, is set to a plurality of torque values generated by one impact before sitting. The first torque of the pulse
By setting the time required from the rise of the pulse to the rise of the second torque pulse to be about the same as or shorter than that, the second torque pulse in the pre-seating torque waveform shown in FIG. It is configured not to sample.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. In the first embodiment, the change in the duration of the torque pulse is detected as the waveform change of the torque pulse associated with seating, and the duration is a predetermined value, that is, the seating determination threshold duration, or more. In this example, it is determined that the time when the seating time becomes a seating time is determined. 1 to 3 are diagrams of a first embodiment of the present invention, FIG. 1 is a block diagram of the present invention, and FIG. 2 is a sectional view of an impact wrench body using compressed air as a power source.
FIG. 3 is a flowchart showing the arithmetic processing. First, in FIG. 1, an impact type screw tightener main body 100 is connected to a motor 102 and an output shaft of the motor 102, and a torque / pulse generator that converts a continuous rotational force of the motor 102 into a torque / pulse. 103, a torque detector 101 for detecting the torque acting on the output shaft of the torque / pulse generator 103, that is, the main shaft 104, and the main shaft 1
04 and a tightening socket (joint portion) 105. The motor 102 may be of any type as long as it can generate a driving force such as an electric motor or an air motor. Further, by selecting the shape of the tightening socket 105, it can be configured as a wrench or a nut / runner. A control device 120 is connected to the impact type screw tightener main body 100. The control device 120 includes a torque signal processing unit 12 that converts a signal from the torque detector 101 into a torque signal.
1, a peak value processing unit 122, a torque / pulse duration processing unit 128, a fastening force data / memory unit 123,
It is composed of a fastening force calculation unit 124 and a power control unit 125.

Next, FIG. 2 is a specific embodiment of the present invention and shows a sectional view in the case of being constructed as an impact wrench using compressed air as a power source. In FIG. 2, 10 is an impact wrench body (corresponding to 100 in FIG. 1)
The impact wrench body 10 is provided with an air supply unit 16, an air motor unit 13, a hydraulic pressure pulse generation unit 14, and a torque detection unit 11. An air passage 17 communicating with the air motor unit 13 is formed in the air supply unit 16, and a main valve 18 and a switching valve 19 are provided in this order in the air passage 17. Main valve 1
8 is opened by pulling the valve operating lever 20,
The switching valve 19 is opened by turning the rotation switching lever 21 to a predetermined rotation position. The air motor unit 13 includes a rotary drive shaft 22 arranged in an eccentric cylinder, and the rotary drive shaft 22 is rotated by the compressed air acting on the vanes 23. The hydraulic pulse generator 14 is connected to the rotary drive shaft 22 of the air motor unit 13 and is directly connected to the liner case 2.
The main shaft 15 is provided inside the main shaft 15, and the driving blade 25 is mounted on the main shaft 15. The liner case 24 is filled with oil liquid. The main shaft 15 rotates together with the rotary drive shaft 22 of the air motor section 13 by the resistance of the inner surface of the liner case 24 and the driving blade 25 when there is no load above a certain level, and the relief valve 28 when there is a load above a certain level. The hydraulic pressure acting on the inner surface of the driving blade 25 via the shaft fluctuates to shockly rotate. This spindle 15
The tip end of is shaped so as to be connected to a screw via a socket (box wrench), and the screw tightening can be performed by aligning the tip end with a desired screw. The torque detector 11 is arranged around the main shaft 15 and is composed of a pair of coils 26 a and 26 b fixed to the impact wrench body 10. The main shaft 15 is made of a material having a magnetostrictive effect in which a pair of left and right groove rows 27a and 27b having different spiral angles are provided, and the coils 26a and 26 are opposed to the groove rows 27a and 27b.
b is arranged. And these coils 26a,
The torque acting on the main shaft 15 can be detected by 26b. Regarding the structure of the compressed air cutoff mechanism, the compressed air sent to the air motor unit 13 is supplied.
A shut-off valve 12 for shutting off is provided in the middle of an air passage 17 that connects the switching valve 19 and the air motor unit 13.

Further, the control device 30 electrically connected to the impact wrench body 10 is a portion corresponding to 120 of FIG. 1, and torque signal processing for producing a torque signal by inputting a signal emitted from the torque detection portion 11 as an input. Part 121
And a peak value processing unit 122 that extracts a peak torque value for each impact from the torque signal, a torque pulse duration processing unit 128, and a function that indicates the relationship between the torque-fastening force conversion coefficient and the fastening force. Fastening force data
The memory unit 123, the fastening force calculation unit 124, and whether or not the calculated fastening force is within an appropriate range is determined, and
A power control unit 125 that sends an opening / closing control signal to the off valve 12. Note that the above 121 to 125 and 128 have the same configuration as in FIG.

FIG. 4 is an example of a function recorded in the fastening force data memory unit 123. As shown in FIG. 4, when an impact having a certain peak torque value is applied and the fastening force at that time is small, the amount of increase in the fastening force due to the given impact becomes large, while It can be seen that when a considerable level of fastening force is generated, even if the impact has the same peak torque value, the amount of increase in fastening force added by this is not large. The specific value differs depending on the combination of the bolt, the tightened body, and the impact wrench. Such coefficient data are prepared as a function for each combination of the impact wrench, the bolt and the object to be fastened, which are objects of use of the impact wrench. As will be described later, the fastening force calculator 124 calculates the fastening force based on the peak torque value and the function data described above.

Next, the operation of the first embodiment will be described based on the flow chart shown in FIG. When the valve operating lever 20 shown in FIG. 2 is pulled, the air motor unit 1 is supplied from the air supply unit 16 via the shut-off valve 12.
By the compressed air sent to 3, the rotary drive shaft 22 of the air motor unit 13 rotates, and the rotational force thereof is converted into a shocking rotational force in the hydraulic pressure pulse generation unit 14, transmitted to the main shaft 15, and screwed. Tightening work is performed. First, the value of the target fastening force cFc is determined in step S1 of FIG.
After setting Wp respectively, the impact number counter is reset in step S3 <count i = 0>, and the fastening force value up to that point is reset in step S4 <F
(0) = 0>. Next, in step S5, screw tightening is started. In steps S6 to S14, step S7 is the processing content of the torque / pulse duration processing unit 128, step S9 is the processing content of the peak value processing unit 122, and steps S12 and S14 are the processing content of the power control unit 125, Others are processing contents in the fastening force calculation unit 124.

Further, steps S6 to S8 form a loop, and the seating determination is performed for each impact up to the seating. First, after incrementing the count i by 1 in step S6, the duration W _P (i) of the torque pulse is obtained based on the signal (torque signal) from the torque signal processing unit 121 in step S7. Next, in step S8, it is determined whether or not the duration W _P (i) of the torque pulse is greater than or equal to the seating determination threshold duration sWp, and if NO, that is, seatless, the process returns to step S6 and continues to step S8 Repeat. On the other hand, if YES in step S8, that is, if it is determined that the vehicle is seated, the process proceeds to step S9. Further, steps S9 to S12 and step S13 form a loop, and the fastening force is calculated for each impact.
First, in step S9, an impact peak torque value T _P (i) is obtained from the torque signal and stored. At the time of sitting, the peak torque value T is calculated from the torque signal temporarily stored in step S8.
Find _P (i). Next, in step S10, F
(i-1) Torque in - fastening force conversion coefficient C _{T F} (i)
Is calculated based on the table of the fastening force data / memory unit 123. However, C _TF (i) = C _TF [F (i−
1)]. Next, in step S11, to calculate the increase δF fastening force by the impact _{(i) = C T F (} i) × T P (i), a further fastening force F after the impact (i), until it Fastening force, that is, the fastening force F after the previous impact
It is calculated by adding the above increment δF (i) to (i-1). Therefore, F (i) = F (i-1) + C _TF
(i) x T _P (i). Next, in step S12, it is determined whether or not the post-impact fastening force F (i) is greater than or equal to the target fastening force cFc. If NO, the count i is incremented by 1 in step S13, and the process returns to step S9. Step S
Repeat up to 12. On the other hand, if YES in step S12, the flow advances to step S14, at which point a cut-off command is issued. This causes the compressed air valve to close. Next, in step S15, it is determined whether or not to end the process. If YES, the process ends, and if NO, the process returns to step S3 to perform the next screw tightening. The "seating determination threshold duration sWp" is the change in the duration of the torque pulse and the tension of the bolt corresponding to the occurrence of impact at the time of fastening in the preliminary experiment conducted using the bolt whose tension can be measured. Can be obtained from Since the value of sWp varies depending on the combination of the screw tightener, the bolt, and the object to be fastened, sWp can be changed according to the combination. That is, the seating determination threshold duration can be variably set for each fastening site. Note that the above "torque pulse corresponding to impact occurrence" is referred to as "impact torque" below.
Will be abbreviated.

FIG. 5 is a comparison diagram of the calculation accuracy between the above-described embodiment and the comparative example (conventional example), in which the mark .largecircle. Represents the characteristic of the present embodiment, and the mark .circle-solid. The result of simulating by the processing of the conventional example) is shown. This example is the result when cFc = 32 kN and M12 bolts and nuts are used to fasten a fastened body having a seat surface distance of 40 mm at the time of sitting, and sWp = 1.5 in the working example.
ms. On the other hand, in the comparative example, the fastening force is calculated when the impact torque is T _P ≧ 36 Nm in the conventional technique. Regarding the dependence of the torque-engagement force conversion coefficient C _{TF on} the engagement force F (C _TF -F characteristic curve of FIG. 4), the same table is used for both. As is clear from the characteristics of FIG. 5, the accuracy of the fastening force calculation is significantly improved in this embodiment as compared with the conventional example. The types of detent nuts actually measured are:
"Points of screw tightening mechanism design" (published by the Japanese Standards Association), page 299, Figure 6.3.9 (a), "Nuts with crimped threads" and page 301, figure 6.
It is a "nut with nylon" described in 3.15 (a), and the same effect has been confirmed for both. As described above, in the present embodiment, when calculating the fastening force, the seating time is determined from the change in the waveform of the impact torque due to the seating, and the fastening force is calculated with the seating time as the fastening force calculation start time. Specifically, the change in the duration of the torque pulse is detected as the change in the waveform of the impact torque due to seating, and the above duration is a predetermined value,
That is, the seating determination threshold duration time is determined to be the seating time point when the seating determination threshold duration time is exceeded. Therefore, the impact torque generated due to the friction of the screw surface before the actual fastening is started can be excluded from the calculation of the fastening force, so that the actual fastening force can be accurately calculated.
It is possible to perform precise screw tightening up to the target tightening force.

Next, FIGS. 6 and 7 show a second embodiment of the present invention, FIG. 6 is a block diagram, and FIG. 7 is a flow chart showing arithmetic processing. In this embodiment, the above-mentioned impact
This is an example in which a change in the torque generation interval is detected, and a time point when the generation interval becomes a predetermined value, that is, a seating determination threshold value generation interval or more is determined to be a seating time point. First, the configuration will be described with reference to FIG. In FIG. 6, the impact type screw tightener main body 100 includes a motor 102, a torque / pulse generator 103, a main shaft 104, a torque detector 101, and a tightening socket 1 as in the first embodiment.
It consists of 05. This impact type screw tightener main body 100
A controller 130 is connected to the. Controller 130
In addition to the torque signal processing unit 121, the peak value processing unit 122, the fastening force data memory unit 123, and the power control unit 125 similar to those of the first embodiment, the impact torque generation interval processing unit 138 and the first A fastening force calculation unit 134 slightly different from that of the embodiment is provided. Next, the operation of the second embodiment will be described based on the flowchart shown in FIG.
First, in step S21, the value of the target fastening force cFc is set, and in step S22, the seating determination threshold generation interval sIp obtained in advance by experiment is set, and then, in step S23, the impact number counter is reset <count i = 0>, the value of the fastening force until then is reset in step S24 <F (0) = 0>. Next, step S25.
Now, tighten the screws. In steps S26 to S39, step S28 is the processing content of the impact / torque generation interval processing unit 138, and step S2 is
7 and step S38 are the processing contents in the peak value processing unit 122, steps S36 and S39 are the processing contents in the power control unit 125, and the others are the processing contents in the fastening force calculation unit 134. Further, steps S26 to S29 form a loop, and seating determination is performed for each impact until seating. First, after incrementing the count i by 1 in step S26, in step S27 the impact peak based on the torque signal is detected.
The torque value T _P (i) is calculated and stored, and further, step S2
In step 8, the impact torque generation interval I _P (i) is calculated.

Next, in step S29, the impact
It is determined whether or not the torque generation interval I _P (i) is greater than or equal to the seating determination threshold value generation interval sIp. If NO, that is, if the vehicle is not seated, the process returns to step S26 and repeats steps S29 to S29. On the other hand, if YES in step S29, that is, if it is determined that the vehicle is seated, the process proceeds to step S30, where the peak torque value T _P (i-1) of the previous impact is read, and then the fastening force F = 0 in step S31. The torque-engagement force conversion coefficient C _TF (i-1) in is calculated based on the table of the engagement force data memory unit 123. However, C _TF
(i-1) = C _TF [F (i-2)], F (i-2) = 0.
Next, in step S32, the fastening force after the previous impact, that is, the fastening force F (i-
Calculate 1). However, F (i-1) = C _TF (i-1)
× T _P (i-1). Thereafter, in step S33, the peak torque value T _P (i) of the immediately preceding impact is read. Next, steps S34 to S36 and step S37,
Step S38 forms a loop, and the fastening force is calculated for each impact. First, in step S34, the torque-engagement force conversion coefficient C _TF (i) is calculated based on the table of the engagement force data / memory unit 123. However, C _TF
(i) = C _TF [F (i-1)]. And step S35
Then, the increase in fastening force due to the impact immediately before is δF
(i) = C _TF (i) × T _P (i) is calculated, and the fastening force F (i) after this impact is calculated as the fastening force up to that time, that is, the fastening force F (i) after the previous impact. It is calculated by adding the above-described increment δF (i) to -1). Therefore, F (i) = F (i−1) + C _TF (i) × T
_P (i). Next, in step S36, it is determined whether or not the fastening force F (i) after impact is greater than or equal to the target fastening force cFc,
If NO, the count i is incremented by 1 in step S37, and then the peak torque value T _P (i) of the impact is obtained and stored based on the torque signal in step S38, and the process returns to step S34 to step S36. Repeat. On the other hand, if YES in step S36, step S39
Proceed to and a cut-off command will be issued at that time. This causes the compressed air valve to close. Next, in step S40, it is determined whether or not to end the process. If TES, the process ends as it is, and if NO, the process returns to step S23 to perform the next screw tightening. The "seating determination threshold generation interval sIp" can be obtained from the impact torque generation interval at the time of fastening and the change in bolt tension in a preliminary experiment performed using a bolt whose tension can be measured. . Further, since the value of sIp varies depending on the combination of the screw tightener, the bolt, and the object to be fastened, sIp can be changed according to the combination.
That is, the seating determination threshold generation interval can be variably set for each fastening site. When this example was applied to the same fastening part as in example 1, the same result as in FIG. 5 was obtained by setting sIp = 40 ms. As described above, in the present embodiment, when calculating the fastening force, the seating time is determined from the change in the waveform of the impact torque due to the seating, and the fastening force is calculated with the seating time as the fastening force calculation start time. Specifically, the change in the impact torque generation interval is detected as a change in the impact torque waveform associated with seating, and the occurrence interval is a predetermined value, that is, the seating determination threshold generation interval. The time point above is determined to be the sitting time point. Therefore, the impact torque generated by friction of the screw surface before the actual fastening is started can be excluded from the calculation of the fastening force, so that the actual fastening force can be accurately calculated and set as the target. Screw tightening can be performed up to the fastening force.

Next, FIGS. 8 to 10 show a third embodiment of the present invention, FIG. 8 is a block diagram, and FIGS. 9 and 10 are flow charts showing arithmetic processing. In this embodiment, as a waveform change of impact torque associated with seating, a change in the duration of the torque pulse included in the impact torque and a change in the generation interval of the impact torque are detected, and the duration and the generation interval are detected. This is an example in which at least one of the above is a predetermined value, that is, the seating determination threshold duration or the seating determination threshold generation interval, or more, is determined to be the seating time. First, the configuration will be described with reference to FIG. In FIG. 8, the impact type screw tightener main body 100 includes a motor 102, a torque / pulse generator 103, a main shaft 104, a torque detector 101, and a tightening socket 1 as in the first embodiment.
It consists of 05. This impact type screw tightener main body 100
A control device 140 is connected to the. Control device 140
Is the same as the torque signal processing unit 121, the peak value processing unit 122, and the torque / pulse duration processing unit 1 of the first embodiment.
28, the fastening force data / memory unit 123, and the power control unit 125, an impact torque generation interval processing unit 138 similar to that of the second embodiment, and a fastening force calculation unit 144 that is slightly different from that of the first embodiment. Is equipped with.

Next, the operation of the third embodiment will be described based on the flow chart shown in FIG. In this embodiment, the duration or the occurrence interval is an example configured to determine a sitting time when a seating determination threshold duration or a seating determination threshold occurrence interval or more is determined,
First, in step S51, the value of the target fastening force cFc is
Also, after setting the values of the sitting determination threshold duration sWp and the sitting determination threshold generation interval sIp which have been obtained by experiments in advance in steps S52 and S53, respectively, the impact number counter is reset in step S54.
Count i = 0>, and the value of the fastening force up to that point is reset in step S55 <F (0) = 0>. Next, in step S56, screw tightening is started. In step S57 to step S72, step S59 is the processing content in the torque / pulse duration processing unit 128, and step S59 is
Reference numeral 60 is the processing content in the impact / torque generation interval processing unit 138, step S58 and step S71 are the processing content in the peak value processing portion 122, and step S69.
And step S72 is the processing content in the power control unit 125, and the other is the processing content in the fastening force calculation unit 144. Further, steps S57 to S61 and step S62 form a loop, and seating determination is performed for each impact until seating. First, step S
After incrementing the count i by 1 at 57, step S5
In step 8, the impact peak torque value T _P (i) is obtained and stored, and in step S59, the torque pulse duration W _P (i) is obtained, and in step S60, the impact torque generation interval I. _{Find P} (i) respectively. Next, in step S61, it is determined whether or not the duration W _P (i) of the torque pulse is greater than or equal to the seating determination threshold duration sWp. If NO, the process proceeds to step S62.
Further, it is determined whether or not the impact torque generation interval I _P (i) is greater than or equal to the seating determination threshold generation interval sIp. If NO, it is determined that the vehicle is not seated yet, and the process returns to step S57 to repeat step S61. On the other hand, YES in step S62.
If it is determined that the seat is sitting, step S63
To the peak torque value T _P (i
After reading −1), the torque-engagement force conversion coefficient C _TF (i−1) at the engagement force F = 0 is calculated based on the table of the engagement force data memory unit 123 in step S64. However, C _TF (i-1) = C _TF [F (i-2)], F
(i-2) = 0. Next, in step S65, the fastening force after the previous impact, that is, the fastening force F (i-1) before the previous impact is calculated. However, F (i-1)
= _CTF (i-1) * _TP (i-1). After this, step S
Proceed to 66. If YES in step S61,
When it is determined that the vehicle is seated, the process proceeds to step S66, and the peak torque value T _P (i) of the immediately preceding impact is read. Next, steps S67 to S69, step S70, and step S71 form a loop, and the fastening force is calculated for each impact. First, in step S67, the torque-engagement force conversion coefficient _CTF (i) is _calculated as the engagement force data / memory unit 1.
Calculation is performed based on the table of 23. However, C
_TF (i) = C _TF [F (i-1)]. Then, step S6
In 8, the amount of increase in the fastening force due to the impact immediately before is δF.
(i) = C _TF (i) × T _P (i) is calculated, and the fastening force F (i) after this impact is calculated as the fastening force up to that time, that is, the fastening force F (i) after the previous impact. It is calculated by adding the above-described increment δF (i) to -1). Therefore, F (i) = F (i−1) + C _TF (i) × T
_P (i). Next, in step S69, it is determined whether or not the post-impact fastening force F (i) is greater than or equal to the target fastening force cFc,
If NO, the count i is incremented by 1 in step S70, then the impact peak torque value T _P (i) is obtained and stored based on the torque signal in step S71, and the process returns to step S67 to step S69. Repeat. On the other hand, if YES in step S69, step S72
Proceed to and a cut-off command will be issued at that time. This causes the compressed air valve to close.

Next, in step S73, it is determined whether or not to end the process. If YES, the process ends, and if NO, the process returns to step S54 to perform the next screw tightening. In this embodiment as well, similarly to the first and second embodiments, the seating determination threshold duration and the seating determination threshold generation interval can be variably set for each fastening portion. When this example was applied to the same fastening portion as that of Example 1, the same results as in FIG. 5 were obtained by setting sWp = 1.5 ms and sIp = 40 ms.

Further, the embodiment of FIG. 10 is configured so that the time when the duration and the occurrence interval are equal to or more than the seating determination threshold duration and the seating determination threshold generation interval are determined to be the seating time. This is an example of step S
If NO in 61, return to step S57, and YE
The difference from FIG. 9 is that the process proceeds to step S62 in the case of S. In some cases, this seating determination logic can determine the seating time more accurately.

As described above, in the present embodiment, when the fastening force is calculated, the seating time is determined from the waveform change of the impact torque due to the seating, and the seating time is used as the fastening force calculation start time. Is configured to calculate
Specifically, as a change in the impact torque waveform associated with seating, a change in the duration of the torque pulse included in the impact torque and a change in the impact torque generation interval is detected, and the duration and the generation interval are detected. The seating time is determined when at least one of the above values becomes the predetermined value, that is, the seating determination threshold duration time or the seating determination threshold generation interval, or more. Therefore, the impact torque generated by friction of the screw surface before the actual fastening is started can be excluded from the calculation of the fastening force, so that the actual fastening force can be accurately calculated and set as the target. Screw tightening can be performed up to the fastening force.

Next, FIGS. 11 and 12 show a fourth embodiment of the present invention, FIG. 11 is a block diagram, and FIG. 12 is a flow chart showing arithmetic processing. In this embodiment, as a change in the impact torque waveform associated with seating, the interval between the first torque pulse and the second torque pulse at each impact, that is, the change in free running time is detected, and the above free running is detected. In this example, the time when the time becomes a predetermined value, that is, the seating determination threshold free running time, is determined to be the seating time.

First, the structure will be described with reference to FIG.
In FIG. 11, the impact type screw tightener main body 100
Is composed of a motor 102, a torque / pulse generator 103, a main shaft 104, a torque detector 101 and a tightening socket 105, as in the first embodiment. A control device 150 is connected to the impact type screw tightener main body 100. The control device 150 includes the torque signal processing unit 121, the peak value processing unit 122, the fastening force data / memory unit 123, and the power control unit 125, which are the same as those in the first embodiment.
The free running time number processing unit 158 and the fastening force calculation unit 154, which is slightly different from that of the first embodiment, are provided.

Next, the operation of the fourth embodiment will be described based on the flow chart shown in FIG. First, step S
At 81, the value of the target fastening force cFc is set again, and in step S
After setting the values of the seating determination threshold free running time st _FR obtained by experiments in advance in step 82, step S
In step 83, the impact number counter is reset <count i = 0>, and in step S84, the value of the fastening force up to then is reset <F (0) = 0>. Next, in step S85, screw tightening is started. Step S86 to Step S
In 94, step S87 is a processing content in the free running time number processing section 158, step S89 is a processing content in the peak value processing section 122, and step S92.
And step S94 is the processing content in the power control unit 125, and the other is the processing content in the fastening force calculation unit 154. Further, steps S86 to S88 form a loop, and the seating determination is performed for each impact up to the seating. First, in step S86, the count i is 1
Then, the free running time t _FR is obtained based on the torque signal in step S87. Next, in step S88, it is determined whether or not the free running time t _FR is equal to or less than the seating determination threshold free running time st _FR . On the other hand, step S88
If YES, that is, if it is determined to be seated, the process proceeds to a loop including steps S89 to S92 and step S93, and the fastening force is calculated for each impact. First, in step S89, the impact peak torque value T _P (i) is obtained and stored based on the torque signal. At the time of sitting, the torque signal temporarily stored in step S87 is peaked.
The torque value T _P (i) may be calculated. Next, step S9
In 0, F (i-1) Torque in - a fastening force conversion coefficient C _{T F} (i), is calculated based on the tightening force data memory unit 123 table. However, C _TF (i) = C _TF [F
(i-1)]. Next, in step S91, the increment δF fastening force by the impact _{(i) = C T F (} i) × T P (i)
And the fastening force F (i) after this impact
Is calculated by adding the increasing amount δF (i) to the fastening force up to that point, that is, the fastening force F (i-1) after the impact one time before. Therefore, F (i) = F (i-
1) + C _TF (i) × T _P (i). Next, in step S92, the fastening force F (i) after impact is the target fastening force cFc.
If NO in step S93, the count i is incremented by 1 in step S93, the process returns to step S89, and steps up to step S92 are repeated. On the other hand, step S92
If YES, the process proceeds to step S94, at which point a cut-off command is issued. This causes the compressed air valve to close.

Next, in step S95, it is determined whether or not to end the process. If YES, the process ends, and if NO, the process returns to step S83 to tighten the next screw. In addition, the above-mentioned "seating determination threshold free running time s"
“T _FR ” can be obtained from a free running time at the time of fastening and a change in bolt tension in a preliminary experiment performed using a bolt whose tension can be measured. Also, above st _FR
The value, screw driver, bolt, since a different value by a combination of the fastener, depending on the combination st _FR
Can be changed. That is, the seating determination threshold value free running data number can be variably set for each fastening portion. When this example was applied to the same fastening portion as that of Example 1, the same result as in FIG. 5 was obtained by setting st _FR = 0.3 ms.

As described above, in the present embodiment, when the fastening force is calculated, the seating time is determined from the change in the waveform of the impact torque due to the seating, and the seating time is used as the fastening force calculation start time. Is configured to calculate
Specifically, as a change in the impact torque waveform associated with seating, the interval between the first torque pulse and the second torque pulse at each impact, that is, the change in free running time is detected, and the above free running time is detected. Is a predetermined value, that is, the seating determination threshold free running time, and the time when the value is less than or equal to is determined as the seating time. Therefore, the impact torque generated by friction of the screw surface before the actual fastening is started can be excluded from the calculation of the fastening force, so that the actual fastening force can be accurately calculated and set as the target. Screw tightening can be performed up to the fastening force.

Next, FIGS. 13 to 16 show a fifth embodiment of the present invention, FIG. 13 is a block diagram, and FIGS. 14 to 16 are flowcharts showing arithmetic processing. This example
Of the seating determination threshold duration, the seating determination threshold generation interval, the seating determination threshold free running time, and the torque-fastening force conversion coefficient used when calculating the increase amount of the fastening force for each impact. In this example, the dependency on the fastening force is determined by learning. First, the configuration will be described with reference to FIG. In FIG. 13, the impact type screw tightener main body 100 includes a motor 102 and a torque / pulse generator 10 as in the first embodiment.
3, a main shaft 104, a torque detector 101, and a tightening socket 105. A control device 160 is connected to the impact type screw tightener main body 100. The control device 160 has the same torque signal processing unit 121, peak value processing unit 122, torque / pulse duration processing unit 128, and impact / torque generation interval processing unit 1 as in the first to fourth embodiments.
38 and the free running time number processing unit 158, the fastening force data / memory unit 163, the fastening force calculation unit 164, and the power control unit 165, which are slightly different from those of the first to fourth embodiments, and the fastening force signal processing unit 166. And a fastening force data calculation unit 167. The fastening force signal processing unit 166 described above.
Converts the signal of the strain gauge 171 attached to the fastening force measuring bolt 172 into a fastening force value. In addition, the fastening force data calculation unit 167 and the peak value processing unit 122 and the torque
Pulse duration processing unit 128, impact / torque generation interval processing unit 138, free running time processing unit 1
58 and the fastening force signal processing unit 166, based on the signals given, the fastening force data is calculated, and the data is stored in the fastening force data memory unit 163. The fastening portion 170 includes a nut 173 and fastened bodies 174a and 174b in addition to the fastening force measuring bolt 172.

Next, the flow chart shown in FIGS.
The operation of the fifth embodiment will be described with reference to FIG. Note that the figure
14 to 16, parts with the same reference numerals are connected.
It is shown that. First, step S101 in FIG.
Set the cut-off torque value cTpc in
It The value of this cTpc exceeds the above target fastening force cFc.
Set the level so that the tightening force can be obtained. Next
Then, in step S102, a counter for the number of fastening shots is set.
Reset <count m = 0>. Next, step S1
At 03, a preliminary experiment is started. Step S104-
In step S146, step S109 is the peak value.
The processing content in the processing unit 122, step S110
Processing contents in the Luke pulse duration processing unit 128,
Step S111 is an impact / torque generation interval processing unit.
The processing contents in 138, step S112 is a freelancer
Processing contents and steps in the training time processing unit 158
S113 is the processing content in the fastening force signal processing unit 166,
Step S114 and step S115 are power control units.
125 is the processing content, and the other is fastening force data
This is the processing content in the calculation unit 167. Also step
S104 to step S116 form a loop,
Tighten the screws in the preliminary experiment. First, step S1
After incrementing the count m by 1 at 04, step S1
To store the number of fastening shots in the preliminary experiment in 05
Counter m_ASubstitute the value of m for_A= M>, then
Reset the impact counter in step S106.
<Count i = 0>. Also, from step S107 to step.
Up S114 forms a loop, and each impact
Measure and calculate fastening data. First, the step
After incrementing the count i by 1 in S107,
The number of impacts in this shot is stored in S108
Counter i for_ASubstitute the value of i into (m) <i
_A(m) = i>. Next, step S109 to step S1
12, based on the torque signal,
Peak torque value T_P(m, i), duration of torque pulse
Time W _P(m, i), impact torque generation interval I
_P(m, i) and free running time t_FR(m,
After i) is calculated and stored, in step S113, the
Strain gauge 141 attached to the binding force measuring bolt 142
Measured fastening force F from the signal_MFind and store (m, i).
Next, in step S114, T_P(m, i) is less than cTpc
Whether it is above or not, and if NO, returns to step S107.
Then, steps up to step S114 are repeated. On the other hand, step S
If the result in 114 is YES, the process proceeds to step S115.
A cut-off command is issued at. By this pressure
The compressed air valve is closed. Next, step S116.
Then, it is judged whether or not the preliminary experiment is finished, and if it is NO.
For example, return to step S104 and tighten the next screw.
If it is ES, the preliminary experiment is terminated and step S in FIG.
Proceed to 117 (→) to calculate the fastening force data.
Be done.

First, in step S117, the count m is reset again <m = 0>.

Further, steps S118 to S12
3 forms a loop, and the torque-fastening force conversion coefficient C _TF (m, i) is calculated from the fastening data in the preliminary experiment. First, in step S118, the count m is incremented by 1, and then in step S119, the count i is reset again <i = 0>. Further, steps S120 to S122 form a loop, and the torque-engagement force conversion coefficient C _TF (m,
Calculate i). First, in step S120, the count i is incremented by 1, and then in step S121, the torque-engagement force conversion coefficient C _TF (m, i) is calculated. _{However, C TF (m, i)} = {F M (m, i) -F M (m, i-
1)} / _TP (m, i). Next, in step S122,
Judge whether i is equal to i _A (m), and if NO,
That is, if there is unprocessed data in this shot, the process returns to step S120 and steps up to step S122 are repeated. On the other hand, if YES in step S122, that is, if the processing of the data of this shot is completed, step S12
Proceed to step 3 to determine whether m is equal to m _A. If NO in step S123, that is, if there is unprocessed shot data, the process returns to step S118 and step S118.
Repeat up to 123. Moreover, YES in step S123.
When, namely, when the processing of the fastening data in the preliminary experiment is completed, the process proceeds to step S124, and C _TF (m, i)
Plot F _M (m, i−1). In step S125, C _TF -F characteristic curve C _TF by the least square method
Determine (F).

Next, the process proceeds to step S126 of FIG. 16 (→), and the maximum value F of F _M (m, i) in the preliminary experiment is F.
Calculate and store _MH . However, F _MH = MAX [F
_M (m, i)]. Here MAX [F _M (m, i)] is F
_This means performing a calculation to obtain the maximum value of _M (m, i). Next, in step S127, the seating determination threshold fastening force F _MS is calculated and stored. However, F _MS = F
_MH / S. Here, S is a constant of about 5 to 10. Next, in step S128, after resetting the count m, <m = 0
>, The process proceeds to the loop from step S129 to step S137, the torque pulse duration W _PS (m), the impact torque generation interval I _PS (m), and the free running at the time of sitting in each fastening shot of the preliminary experiment Time t
Calculate _FRS (m). First, in step S129, the count m is incremented by 1, and then in step S130,
Reset the count i <i = 0>. In addition, steps S131 and S132 form a loop, and the number of impacts of seating in the mth fastening shot is determined. That is, the count i is incremented by 1 in step S131, and subsequently step S
At 132, it is determined whether F _M (m, i) is greater than or equal to F _MS , and if NO, it is determined that the person is unseated and step S1.
Then, the process returns to step 31, and steps up to step S132 are repeated.

On the other hand, if YES in step S132, that is, if seating is determined, the process proceeds to step S133, and the value of i is substituted into the counter is for storing the number of impacts until seating <is = i>. Next, in steps S134 to S136, the duration W of the torque pulse at the time of seating in the m-th fastening shot is W.
_{The PS} (m), the impact torque generation interval I _PS (m), and the free running time t _FRS (m) are calculated and stored. However, W _PS (m) = W _P (m, is), I
_PS (m) = I _P (m, is), t _FRS (m) = t _FR (m, i)
s). Next, in step S137, m is determined to or greater than m _A, if NO, the repeated until step S137 i.e. returns to step S129 if there is unprocessed shot data. On the other hand, step S13
When YES is obtained in 7, that is, when the processing of the fastening data in the preliminary experiment is completed, the process proceeds to step S138. In steps S138 and S139, respectively, W
Calculate and store the average value W _PSA and standard deviation σ _WPS of _PS (m). However, W _PSA = AVE [W _PS (m)], σ
_WPS = STD [W _PS (m)]. Here AVE [W
_PS (m)] and STD [W _PS (m)] are respectively W _PS
It means performing an operation for obtaining the average value and standard deviation of (m). Next, step S140 and step S
At 141, the average value I _PSA and the standard deviation σ _IPS of I _PS (m) are calculated and stored. However, I _PSA = AV
E [I _PS (m)], σ _IPS = STD [I _PS (m)]. Further, in step S142 and step S143, respectively, the average value t _FRSA of t _FRS (m) and the standard deviation σ _{tFRS are calculated.}
Calculate and store. However, t _FRSA = AVE [t
_FRS (m)], σ _tFRS = STD [t _FRS (m)]. Next, in steps S144 to S146, the sitting determination threshold duration sWp, the sitting determination threshold generation interval sIp, and the sitting determination threshold free running time st _FR are calculated and stored. However, for example, sWp =
W _PSA -4 × σ _WPS , sIp = I _PSA -4 × σ _IPS , st _FR
= T _FRSA + 4 × σ _tFRS . As described above, C _TF -F characteristic curve C _TF (F) and SWP, SIP, learning procedure of st _{F R} is completed. C _TF -F characteristic curve C determined here
_TF (F) and sWp, sIp, and st _FR are recorded in the fastening force data memory unit 123 and will be used in the actual fastening process shown in the first to fourth embodiments. For example, in the case where the actual fastening is performed after the learning by the above-mentioned preliminary experiment is completed, the flowchart of FIGS. 14 to 16 is followed by the aforementioned FIG.
It is sufficient to add the flowchart of. As described above, in the fifth embodiment, the means for measuring the actual fastening force is provided, and by performing the calculation based on the result of the preliminary experiment, the seating determination threshold duration time, the seating determination threshold value The generation interval and the seating determination threshold free running time can be automatically determined during the preliminary experiment, and the characteristic curve as well as _CTF- F can be automatically determined as well. Easy and accurate.

17 to 19 show a sixth embodiment of the present invention, FIG. 17 is a block diagram, FIG. 18 and FIG.
9 is a flow chart showing the arithmetic processing. In this example, as a change in the waveform of impact torque associated with seating,
From the rising of the first torque pulse of the plurality of torque pulses generated for each impact, a predetermined number of data (that is, the number of sampling data) at a certain sampling interval from the rising edge of the first torque pulse The change in the number of data (that is, the number of free-running data) that shows a value less than the torque value (that is, the threshold torque for free-running determination) is detected, and the above-mentioned number of free-running data is the predetermined number of data, that is, seating determination. Threshold free running data count,
In this example, it is determined whether or not it is the following, and the time when it is determined to be the following is determined to be the sitting time.

First, the structure will be described with reference to FIG.
In FIG. 17, the impact type screw tightener main body 100
Is the same as in the first embodiment.
Loose generator 103, spindle 104, torque detector 101
And a tightening socket 105. This impact formula
The controller 180 is connected to the screw tightener main body 100.
There is. The controller 180 uses the same torque as in the first embodiment.
Signal processing unit 121, peak value processing unit 122, fastening force data
In addition to the data memory unit 123 and the power control unit 125,
Free running / data count processing unit 188 and first implementation
A fastening force calculation unit 184, which is slightly different from the example, is provided.
Next, based on the flowcharts shown in FIG. 18 and FIG.
The operation of the sixth embodiment will be described. 18 and the figure
In 19, the parts with the same symbols are connected.
Is indicated. First, in step S201 of FIG.
Value of the target fastening force cFc, again in step S202,
In step S203 and step S204, the actual
Number of sampling data obtained in the test N_SG, Free runni
Judgment threshold torque sT_FR, And seating threshold
Value Free running data number sN_FRSet the value of
After setting, in step S205 the impact number counter
Is reset <count i = 0>, and in step S206
Reset the fastening force value up to that time <F (0) = 0
>. Next, in step S207, screw tightening is started.
It In steps S208 to S229,
Steps S213 to S218 are free running
-Processing content in the data number processing unit 188, step S
209 to step S212, step S220, and step S220.
Steps S225 to S228 are the peak value processing unit 1
22, the processing contents in step S223 and the step
Step S229 is a processing content in the power control unit 125.
The other is the processing content in the fastening force calculation unit 184.
It In addition, steps S208 to S219 are routines.
The seat is identified by impact until seating.
Set. First, in step S208, the count i is 1.
The sampling data in step S209.
After resetting the number counter <count j = 0>,
Step S210-S212
Predetermined sampling data number N for the impact
_SGJust sample the torque data T (i, j)
Remember. That is, in step S210, the count j is
After incrementing by 1, the torque signal is changed in step S211.
Torque data T (i, j) is sampled based on
To remember. Next, in step S212, the count j is
Number of sampling data N _SGTo determine whether
If NO, that is, if sampling is not completed, step S2
It returns to 10 and repeats to step S212. On the other hand,
If YES in step S212, that is, the sample pudding
If it is determined to end the sampling, sampling is performed in step S213.
・ Reset the data counter again <count j =
0>, free running until step S214
・ Number of data N_FRAfter resetting the value of <N_FR= 0>,
Step S215-Step S218:
Free running data number N at the impact_FR
Ask for. That is, in step S215, the count j is
After incrementing by 1, the torque date is set in step S216.
T (i, j) is the free running judgment threshold torque
sT_FRIt is determined whether or not the following, and if NO, step S2
Proceed to 18, and if YES, free in step S217
Number of running data N_FRAfter incrementing by 1,
Go to step S218. In step S218, the count j
Is the number of sampling data N_SGDetermine whether or not
If NO, that is, if the unprocessed torque data is
If it remains, the process returns to step S215 to return to step S2.
Repeat up to 18. On the other hand, YES in step S218.
In other words, that is, the number of free running data N_FRIs wanted
Then, the process proceeds to step S219 of FIG. 19 (→),
Free running data number N_FRIs the seating determination threshold
Rerunning data number sN_FRDetermine if the following,
If NO, that is, if the person is not seated, step S208 of FIG.
(→) and repeats steps up to step S219. one
If YES in step S219, that is, seated
If it is determined that steps S220 to S223
And steps S224 to S228.
Go to the next page and calculate the fastening force for each impact. Well
First, in step S220, in step S211 above.
Torque data T (i,
j) From impact peak torque value T_Pask for (i)
To remember. However, T_P(i) = MAX [T (i,
j)]. Next, in step S221, F (i-1)
Torque-fastening force conversion coefficient C_TF(i) is the fastening force
The calculation is performed based on the table of the data memory unit 123.
However, C_TF(i) = C_TF[F (i-1)]. Next,
In step S222, an increase δ in fastening force due to impact
F (i) = C_TF(i) x T_P(i) is calculated and this
The fastening force F (i) of the compact number is
In the fastening force F (i-1) after impact one time ago, the above
It is calculated by adding the increment δF (i) of. Shi
Therefore, F (i) = F (i-1) + C_TF(i) x T
_P(i). Next, in step S223, after the impact
Determine whether the fastening force F (i) is greater than or equal to the target fastening force cFc
If NO, steps S224 to S228
After performing the processing in step S220, the process returns to step S220
Repeat steps up to S223. In addition, from step S224 to step
The process of step S228 is the same as that of step S208 to step S208 described above.
This is the same as the processing in step S212.

On the other hand, if YES at step S223, control proceeds to step S229, at which point a cut-off command is issued. This causes the compressed air valve to close. Next, in step S230, it is determined whether or not to end the process. If YES, the process ends as it is, and if NO, the process returns to step S205 in FIG. 18 (→) to perform the next screw tightening. In addition, the "sampling data count N _SG " and "free running determination threshold torque s"
"T _FR " and "seating threshold free running
The number of data sN _FR "can be obtained from the waveform of the impact torque at the time of fastening and the change in the tension of the bolt in a preliminary experiment performed using a bolt capable of measuring the tension. The values of N _SG , sT _FR , and sN _FR are different depending on the combination of the screw tightener, the bolt, and the object to be fastened. Therefore, N _SG , sT _FR , and s depend on the combination.
N _FR can be changed, that is, it can be variably set for each fastening part. Also, N _SG , s
T _FR and sN _FR can also be determined by learning during preliminary experiments. For example, it may be configured as in the fifth embodiment. When this embodiment is applied to the same fastening part as the first embodiment, N _SG = 50, sT _FR = 20 Nm, sN
_By setting _FR = 10, the same result as in Fig. 5 was obtained.

As described above, in the present embodiment, when calculating the fastening force, the seating time is determined from the change in the waveform of the impact / torque associated with the seating, and the seating time is used as the fastening force calculation start time. Is configured to calculate
Specifically, as a change in the impact torque waveform associated with seating, from the rising of the first torque pulse of the multiple torque pulses generated for each impact, a predetermined number of data (i.e., When the torque data is sampled by the sampling data number), the change in the number of data (that is, the number of free-running data) showing a value equal to or less than a predetermined torque value (that is, the threshold torque for free-running determination) is detected, The time point when the above free running data number becomes a predetermined data number, that is, the seating determination threshold value free running data number, is determined to be the seating time point. In the configurations described in the first to fourth embodiments, seating can be accurately determined, but the number of data required for seating determination increases and the determination logic becomes complicated, so the determination processing time Becomes longer. Therefore, if the impact torque generation interval is short, the next impact will occur during the series of processing time including the fastening force calculation processing that follows the seating determination processing, and the resulting torque waveform May not be detected. On the other hand, in the present embodiment, with the configuration as described above, seating can be determined with the same accuracy as in the first to fourth embodiments, and the number of data to be processed is determined by the sampling data number. The data processing is simplified and the seating determination processing time is shortened by limiting it to

Further, the sampling time, which is the product of the number of sampling data times the sampling interval, is set to a plurality of torques included in one impact torque before sitting.
Second from the rising of the first torque pulse of the pulse
By setting the time required for the rising of the second torque pulse to be the same as or shorter than the time required,
The second torque pulse can be prevented from being sampled in the pre-seated torque waveform shown in FIG. That is, in the above application example, the time required from the rising of the first torque pulse to the rising of the second torque pulse of the plurality of torque pulses included in one impact torque before seating is approximately 2m
s, the number of sampling data is 50,
Sampling interval is 30μs and sampling time is 1.
It is set as short as 5 ms.

Next, FIGS. 20 to 21 show a seventh embodiment of the present invention, and FIG. 20 is a block diagram, FIG. 21 and FIG.
2 is a flowchart showing the calculation process. In this example, as a change in the waveform of impact torque associated with seating,
From the rising of the first torque pulse of the plurality of torque pulses generated for each impact, a predetermined number of data (that is, the number of sampling data) at a certain sampling interval from the rising edge of the first torque pulse A change in the number of data (that is, the number of extracted data) showing a value equal to or larger than the torque value (that is, the extraction determination threshold torque) is detected, and the above-mentioned number of extracted data is a predetermined number of data, that is, the seating determination threshold extraction data. This is an example in which it is determined that the seating time is the time when the number becomes equal to or more than the number.

First, the structure will be described with reference to FIG.
In FIG. 20, the impact type screw tightener main body 100
Is composed of a motor 102, a torque / pulse generator 103, a main shaft 104, a torque detector 101 and a tightening socket 105, as in the first embodiment. A control device 190 is connected to the impact type screw tightener main body 100. The control device 190 includes a torque signal processing unit 121, a peak value processing unit 122, a fastening force data / memory unit 123, and a power control unit 125, which are the same as those in the first embodiment.
The extraction data number processing unit 198 and a fastening force calculation unit 194, which is slightly different from that of the first embodiment, are provided.

Next, the operation of the seventh embodiment will be described with reference to the flow charts shown in FIGS. In addition, in FIG.21 and FIG.22, each shows that the part of the same code | symbol is connected. First, in step S241 of FIG. 21, the value of the target fastening force cFc is set, and the values of steps S242, S243, and S2 are set.
44, pre-sampling data number N _SG determined experimentally, extraction determination threshold torque sT _L, and sitting determination after the value of the threshold extracted data number sN _DS respectively set, impact number counter in step S245 Is reset <count i = 0>, and the value of the fastening force up to then is reset <F (0) = 0> in step S246. Next, in step S247, screw tightening is started. In step S248 to step S269, step S
253 to step S258 are the extraction data number processing unit 198.
Processing contents in step S249 to step S25
2, step S260 and step S265 to step S268 are processing contents in the peak value processing unit 122,
Steps S263 and S269 are processing contents in the power control unit 125, and others are processing contents in the fastening force calculation unit 194. In addition, step S24
From 8 to step S259, a loop is formed, and seating determination is performed for each impact until seating. First, in step S248, the count i is incremented by 1, and then step S2
After resetting the counter for the number of sampling data at 49 <count j = 0>, the process proceeds to the loop of steps S250 to S252, and the torque data T for the predetermined number of sampling data N _SG for the impact is obtained.
(i, j) is sampled and stored. That is, after incrementing the count j by 1 in step S250, the torque data T (i, j) is sampled and stored based on the torque signal in step S251. Next, in step S252, it is determined whether or not the count j is equal to the number of sampling data N _SG, and if NO, that is, sampling is not completed, the process returns to step S250 and step S250.
Repeat up to 252. On the other hand, YES in step S252.
If it is determined that the sampling has ended, the counter for the number of sampling data is reset again in step S253 <count j = 0>, and step S254.
After resetting the number of extracted data N _DS until then <
N _DS = 0>, the process proceeds to the loop from step S255 to step S258, and the number of extracted data N _{DS at the} impact.
Ask for. That is, after the count j is increased by 1 in step S255, it is determined whether the torque data T (i, j) is extracted determination threshold torque sT _L or more in step S256, step If NO S258 Go to, Y
If it is ES, the number of extracted data N _{DS is set} to 1 in step S257.
After only increasing the value, the process proceeds to step S258. In step S258, the count j is the sampling data number N _SG.
If NO, that is, if unprocessed torque data remains, step S255.
Then, the process returns to step S258 and is repeated. On the other hand, if YES in step S258, that is, the number of extracted data N
_{When the DS} is obtained, the process proceeds to step S259 in FIG. 22 (→
), It is determined whether or not the number of extracted data N _DS is equal to or more than the number of seating determination threshold value extracted data sN _DS , and if NO, that is, unseated, the process returns to step S248 of FIG. On the other hand, if YES in step S259, that is, if it is determined that the user is seated, steps S260 to S263 and steps S264 to S264 are executed.
The process proceeds to the loop including step S268, and the fastening force is calculated for each impact. First, in step S260, the impact peak torque value T _P (i) is obtained and stored from the torque data T (i, j) temporarily stored in step S251. However, T
_P (i) = MAX [T (i, j)]. Next, step S2
At 61, the torque-fastening force conversion coefficient C _TF (i) at F (i-1) is calculated based on the table of the fastening force data memory unit 123. However, C _TF (i) = C
_TF [F (i-1)]. Next, in step S262, the amount of increase in fastening force due to impact δF (i) = C _TF (i) ×
T _P (i) is calculated and the fastening force F after this impact is calculated.
(i) is calculated by adding the increasing amount δF (i) to the fastening force up to that point, that is, the fastening force F (i-1) after the impact one time before. Therefore, F (i) = F
(i−1) + C _TF (i) × T _P (i). Next, step S2
At 63, it is determined whether or not the fastening force F (i) after impact is equal to or greater than the target fastening force cFc. If NO, step S2
After performing the processing of 64 to step S268, step S
The process returns to 260 and the processes up to step S263 are repeated. In addition,
The processing of steps S264 to S268 is the same as the processing of steps S248 to S252 described above. On the other hand, if YES in step S263, the flow advances to step S269, at which point a cut-off command is issued. This causes the compressed air valve to close. Next, in step S270, it is determined whether or not to end,
If YES, the process ends as it is, and if NO, the process returns to step S245 in FIG. 21 (→) to perform the next screw tightening.

The above "sampling data number N"
_SG "," extraction determination threshold torque sT _L ", and" sitting determination threshold extract data number sN _DS "in preliminary experiments carried out using the possible bolt tension measurement, at the conclusion of impact torque It can be calculated from the waveform and the change in bolt tension. Further, the N _SG, sT _L, and sN
The value of _DS is, screw driver, bolt, since a different value by a combination of the fastened member can be changed to N _SG, sT _L, and sN _DS in response to the combination, i.e. the variable set for each fastening site It is possible to do. Further, N _SG, sT _L, and sN _DS can also be determined by learning the time of preliminary experiments. For example, it may be configured as in the fifth embodiment. When this embodiment is applied to the same fastening portion as in Embodiment 1, N _SG = 50, sT
_By setting _L = 15 Nm and sN _DS = 40, the same results as in FIG. 5 were obtained.

As described above, in the present embodiment, when the fastening force is calculated, the seating time is determined from the waveform change of the impact / torque associated with the seating, and the seating time is used as the fastening force calculation start time. Is configured to calculate
Specifically, as a waveform change of impact torque due to seating, a predetermined number of data (that is, a predetermined number of data at a constant sampling interval from the rise of the first torque pulse among a plurality of torque pulses generated for each impact) When the torque data is sampled by the sampling data number), a change in the data number (that is, the extraction data number) that shows a value equal to or larger than a predetermined torque value (that is, extraction determination threshold torque) is detected, and the above extraction is performed. When the number of data is a predetermined number of data, that is, the number of pieces of seating determination threshold extraction data, or more, it is determined that the seating time. Therefore, the seating can be determined with the same accuracy as in the first to fourth embodiments, and the data processing is limited to the sampling data number as in the sixth embodiment. The seating determination processing time is shortened. Also, the sampling time, which is the product of the number of sampling data times the sampling interval, is set as short as 1.5 ms as in the sixth embodiment.

Next, in the above-described embodiments, the screw tightening device for controlling the tightening force in the screw tightener so as to match the target value with reference to the torque pulse at the time of impact has been described. A measuring method and apparatus for controlling the rotation angle of the nut as a reference will be described. As a method of measuring the fastening force, that is, the tightening axial force, a strain gauge is attached to a bolt or a nut (hereinafter, abbreviated as a bolt), and the tension of the bolt is measured from the elongation of the bolt accompanying the tightening. There is a method of using a surface pressure gauge to measure the compressive force acting on the seat surface pressure gauge during tightening. However, in these methods, it is necessary to attach a strain gauge to a bolt and to arrange a seat pressure gauge on the part to be fastened. It is not realistic to use means. Therefore, in the manufacturing stage, the torque method (method based on the characteristics shown in FIG. 32), the rotation angle method (method based on the characteristics shown in FIG. 33), or the torque gradient method (shown in FIG. 34) specified in JIS 1083 is used. The tightening axial force is controlled by detecting the tightening torque and the bolt rotation angle by a tightening method such as a method based on characteristics.

In the torque method, however, the tightening torque and the tightening axial force have a proportional relationship including an error of about ± 30% because they are affected by the variations in the friction coefficient of the seat surface and the screw surface, and the tightening axial force is not always required. Does not mean that they are accurately measured or managed. Also, in the rotation angle method,
To determine the snag point, it is necessary to measure the tightening torque, and the torque gradient method also needs to measure the tightening torque and the rotation angle of the bolt. Therefore, a screw tightener such as a nut runner that manages the tightening axial force by the rotation angle method or the torque gradient method requires two types of detectors, a tightening torque detector and a rotation angle detector. further,
In an impact tightening device that tightens by a drive output having a pulse component, such as an impact type screw tightener having a tightening axial force estimating function described in Japanese Patent Application No. 4-254028 already filed by the present applicant, ,
The above-mentioned correspondence between the tightening torque and the tightening axial force is not always established. Therefore, when impact tightening is performed at the manufacturing stage, it is necessary to establish a method for measuring the tightening axial force and establishing an inspection method from the viewpoint of quality control.

This embodiment is made in order to solve the above problem, and detects the rotation angle of the bolt or nut for each impact, and the time when this rotation angle becomes a value within a predetermined range is the seating time. By determining the tightening axial force from the rotation angle after that, it is possible to accurately measure the tightening axial force at the time of impact tightening.

This embodiment will be described below with reference to the drawings. FIG. 26 is a block diagram showing the overall configuration. First, the structure will be described. The impact screw tightener main body 22
0 is a motor 202 powered by electricity or compressed air
And a torque pulse generator 203 for converting the torque of the motor into pulsed torque, and an output shaft 231. Further, the fastening portion 204 includes the fastened body 241 and the bolt 2.
42 and nut 243. The rotation angle detector 201 is arranged between the output shaft 231 of the impact type screw tightener main body 220 and the fastening portion 204.
The output of the rotation detector 201 is sent to the signal processing circuit 215 and is output as a tightening axial force.

Next, FIG. 27 is a sectional view showing the structure of the rotation angle detector 201. In FIG. 27, the socket 21
Reference numeral 1 denotes a member for transmitting the pulsed torque generated on the output shaft 231 of the torque / pulse generator 203 to the nut 243. The socket 211 is fixed with a code wheel 212 of a rotary encoder. In addition, the first housing 2 that rotatably supports the socket 211
14a and the first housing 214a are fixed,
A second housing 214b fixed to a support (not shown) and a rotary encoder detection head 213 fixed to the housing 214b are provided.

Next, the operation will be described. When fastening with an impact type screw tightener at a portion where a detent nut that is often used for fastening chassis parts of an automobile is used, the rotation angle of the nut for each impact changes as shown in FIG. In other words, even if the seat is not seated, “the impact occurs due to the frictional force generated between the detent part of the nut and the thread surface of the bolt, and when the maximum static friction torque is exceeded, the nut enters the free running state. , A large angle rotation, and at the end it slows down and stops due to dynamic friction. " When seated, the frictional force on the screw surface and seat surface increases due to the tension generated in the bolt, and the nut rotation angle sharply decreases at each impact. Is a value between the seating determination upper limit rotation angle sθ _MAX and the seating determination lower limit rotation angle sθ _MIN . FIG. 29 shows the result of an experiment on the relationship between the rotation angle θ _L of the nut due to the impact at the time of seating and the generated tightening axial force F _M using a bolt having a strain gauge attached to measure the tightening axial force. FIG. 29 shows that θ _L is a value in the range of sθ _MIN ≦ θ _L ≦ sθ _MAX , sθ _MIN and sθ _MAX can be experimentally determined, and that F _M can be approximated by the following (Equation 1) formula. There is.

[0058]

[Equation 1]

[0059] However, F _LMAX: maximum tightening axial force generated at the seating time point also, FIG. 30, the relationship between the axial force F _M tightening rotation angle theta _F of subsequent seating nut, strain measurements fastening shaft force the result of an experiment using a bolt fitted with gauge, _{F M} = kθ F (However, k: constant) shows that a good proportional relationship is established. Therefore, at the time of seating, the rotation angle of the nut after seating θ _FL
Can be obtained by the following equation (2).

[0060]

[Equation 2]

However, after that F _LMAX = k s θ _MIN , the rotation angle θ _F of the nut after seating can be obtained by sequentially adding the rotation angle of the nut for each impact. FIG. 28 also shows changes in the rotation angle θ _F of the nut after seating obtained based on such processing. From the rotation angle θ _F of the nut after seating thus obtained, it is possible to measure the tightening axial force with high accuracy based on the proportional relationship between the rotation angle θ _F and the tightening axial force F _M shown in FIG. Becomes

Next, FIG. 31 is a block diagram of another embodiment. This embodiment shows the rotation shown in FIG. 27 in bolt and nut fastening using the impact type screw fastening machine having the fastening axial force estimating function described in Japanese Patent Application No. 4-254028 already filed by the present applicant. The angle detector 201 is used for the tightening axial force inspection to measure the tightening axial force. In FIG. 31, an impact type screw tightener main body 250 with a tightening axial force estimating function includes a motor 251 using electric power or compressed air as a power source, and a torque pulse for converting the rotational force of the motor 251 into pulsed torque. Generator 252 and the torque pulse generator 25
And a torque detector 253 for detecting the torque generated in the second output shaft 254. Then, the signal of the torque detector 253 is sent to the torque control device 255, and the motor 251 is controlled according to the output thereof. Also, the fastening portion 2
Reference numeral 04 includes a fastened body 241, a bolt 242 and a nut 243. Then, the rotation angle detector 201 similar to that shown in FIG.
It is provided between the output shaft 254 of 50 and the fastening portion 204. The output signal of the rotation angle detector 201 is taken into the rotation angle signal processing unit 261 of the inspection data processing device 260. The inspection data processing device 260 further includes a comparison calculation unit 262 and a result display unit 263.

The rotation angle signal processing unit 261 outputs a signal obtained by converting the output signal of the rotation angle detector 201 into a tightening axial force, that is, an inspection value of the tightening axial force. Further, the torque control device 255 outputs a monitor signal of the calculated tightening axial force, that is, a calculated value of the tightening axial force, based on the torque signal from the torque detector 253. The comparison calculation unit 262 inputs the tightening axial force inspection value and the tightening axial force calculation value, calculates an error of the tightening axial force calculation value with respect to the inspection value, that is, calculates a calculation error, and determines pass / fail. Based on the result, the result display unit 263 displays the tightening axial force inspection value, the calculated value, the calculation error, the pass / fail judgment result, and the like. Further, the inspection data processing device 260 may be provided with an output terminal to a printer,
It is also possible to install a memory card and save the inspection data. According to the above configuration, in the impact type screw tightening machine with the tightening axial force estimating function, the target value and the actual value of the tightening axial force, their errors, etc.
And it becomes possible to inspect easily.

As described above, the rotation angle detector is attached to the socket portion for transmitting the pulsed torque generated on the output shaft of the impact type screw tightener to the bolt or nut of the fastening portion, and the bolt for each impact or The rotation angle of the nut is detected, and the time when this rotation angle reaches the "range between the seating determination upper limit rotation angle and the seating determination lower limit rotation angle that have been obtained in advance" is determined to be the seating time, and the impact during seating is also determined. Determine the "rotation angle of the bolt or nut after seating when seated" given as a function of the rotation angle of the bolt or nut by, and then add the rotation angle of the bolt or nut for each impact in sequence Since the method is to detect the rotation angle of subsequent bolts or nuts, only the signal from the rotation angle detector is used and the above "bolt or nut after seating" is used. The fastening shaft force with a good proportional relationship between the rotation angle "bets, effect that can also be accurately measured in the case of the impact tightening. Further, it is also possible to provide a tightening axial force inspection device that can be used at the time of tightening using an impact type screw tightening machine with a tightening axial force estimating function.

The measuring methods and devices based on the above rotation angle are summarized as the following first to fourth items. (Item 1) Bolts that use impact type screw tightening devices
When measuring the tightening axial force in the case of nut tightening, the rotation angle is detected on the output shaft of the impact type screw tightening device or the socket part for transmitting the pulsed torque generated on the output shaft to the bolt or nut of the tightening part. After mounting the device, determine the time when the rotation angle of the bolt or nut for each impact falls within the specified range as the seating time, and measure the tightening axial force by detecting the rotation angle of the bolt or nut after seating. Method and apparatus.

(Item 2) In the method and apparatus for measuring the tightening axial force described in item 1, the rotation angle of the bolt or nut for each impact is determined by the previously determined "seating determination upper limit rotation angle and seating determination lower limit". A method and an apparatus for measuring a tightening axial force, characterized in that a time when a value of "range between rotation angle" is determined to be a seating time.

(Claim 3) In the method and apparatus for measuring the tightening axial force described in the above items 1 and 2, the "rotation angle of the bolt or nut after the seating at the time of seating" is previously determined. Based on the function of the rotation angle of the bolt or nut depending on the impact at the time point, the rotation angle of the bolt or nut after impact is detected by sequentially adding the rotation angle of the bolt or nut for each impact. A method and apparatus for measuring a tightening axial force, which is characterized in that

(Item 4) When tightening bolts and nuts using an impact type screw tightening device having a function of estimating tightening axial force, the tightening axial force described in the above item 1, item 2 or item 3 And method for measuring tightening axial force, characterized by using the method and apparatus for measuring.

[0069]

As described above, in the invention described in claims 1 to 5, in the calculation of the fastening force, the seating time point is determined from the waveform change of the torque pulse accompanying the seating, and the seating position is determined. At the time, that is, when at least one of the duration and the generation interval of the torque pulse detected for each impact becomes equal to or greater than the corresponding predetermined value (seating determination threshold duration and seating determination threshold generation interval). Alternatively, since the time when the free running time becomes equal to or less than the predetermined value (seating judgment threshold free running time) is set as the start time of the fastening force calculation, Since the torque generated by friction of the surface etc. can be excluded from the calculation of the fastening force, the accuracy of the fastening force calculation can be greatly improved and the target It is possible to perform precise screwing up the fastening force, the effect is obtained that. Further, in the invention according to claim 6, in addition to the above effects, the seating determination threshold duration, the seating determination threshold generation interval, and the seating determination threshold free running time are automatically set in the preliminary experiment. Since the C _TF -F characteristic curve can also be automatically determined in the same manner, there is an effect that the measurement is easy and accurate.
Furthermore, in the invention described in claims 7 to 9,
From the rising edge of the first torque pulse of the multiple torque pulses generated for each impact, the torque data is sampled by a predetermined number of data at fixed sampling intervals, and the predetermined torque is sampled within the sampling data. Number of data showing a value less than the value (free running judgment threshold torque) (number of free running data)
Indicates a value equal to or less than a predetermined number of data (seating determination threshold free-running data number) or within the above sampling data, a value equal to or greater than a predetermined torque value (extraction determination threshold torque). In addition to the above effects, the seating determination can be performed by determining that the time when the number of data (the number of extracted data) that has reached a predetermined value (the number of data for extracting the seating determination threshold) is determined The effect that the processing time can be shortened is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIG. 2 is a cross-sectional view when configured as an impact wrench using compressed air as a power source.

FIG. 3 is a flowchart showing arithmetic processing in the first embodiment.

FIG. 4 is an example diagram of a function showing a relationship between a torque-fastening force conversion coefficient recorded in a fastening force data memory unit 123 and a fastening force.

FIG. 5 is a comparative characteristic diagram regarding arithmetic accuracy between an example and a comparative example (conventional example).

FIG. 6 is a block diagram of a second embodiment of the present invention.

FIG. 7 is a flowchart showing a calculation process in the second embodiment.

FIG. 8 is a block diagram of a third embodiment of the present invention.

FIG. 9 is a part of a flowchart showing a calculation process in the third embodiment.

FIG. 10 is another part of the flowchart showing the arithmetic processing in the third embodiment.

FIG. 11 is a block diagram of a fourth embodiment of the present invention.

FIG. 12 is a flowchart showing arithmetic processing according to the fourth embodiment.

FIG. 13 is a block diagram of a fifth embodiment of the present invention.

FIG. 14 is a part of a flowchart showing a calculation process in a fifth embodiment.

FIG. 15 is another part of the flowchart showing the arithmetic processing in the fifth embodiment.

FIG. 16 is another part of the flowchart showing the arithmetic processing in the fifth embodiment.

FIG. 17 is a block diagram of a sixth embodiment of the present invention.

FIG. 18 is a part of a flowchart showing arithmetic processing according to the sixth embodiment.

FIG. 19 is another part of the flowchart showing the arithmetic processing in the sixth embodiment.

FIG. 20 is a block diagram of a seventh embodiment of the present invention.

FIG. 21 is a part of a flowchart showing arithmetic processing according to the seventh embodiment.

FIG. 22 is another part of the flowchart showing the arithmetic processing in the seventh embodiment.

FIG. 23 is a schematic characteristic diagram showing changes in the waveform of impact torque when screwing is performed by rotating a detent nut with an impact type screw tightening device.

FIG. 24 is a characteristic diagram showing a change in the waveform of impact torque and the rotational angular velocity of the liner case.

FIG. 25 is a schematic characteristic diagram of the number of sampling data, the free running determination threshold torque, the number of free running data, the extraction determination threshold torque, and the number of extracted data.

FIG. 26 is a block diagram showing the overall configuration of an embodiment in which control is performed based on a rotation angle.

FIG. 27 is a sectional view showing the configuration of a rotation angle detector 201.

FIG. 28 is a characteristic diagram showing a rotation angle of a nut for each impact.

FIG. 29 shows the relationship between the nut rotation angle θ _L due to the impact at the time of seating and the generated tightening axial force F _M.
The characteristic view which shows the result of having experimented using the bolt which attached the strain gauge for the measurement of the tightening axial force.

FIG. 30 is a characteristic diagram showing a result of an experiment on a relationship between a rotation angle θ _F of a nut after seating and a tightening axial force F _M using a bolt equipped with a strain gauge for measuring the tightening axial force.

FIG. 31 shows a configuration of an example in which a tightening axial force is measured by using a rotation angle detector 201 for tightening axial force inspection in bolt / nut tightening using an impact type screw tightener having a tightening axial force estimating function. Block Diagram.

FIG. 32 is a characteristic diagram showing a relationship between a tightening torque and a tightening axial force used in the conventional torque method.

FIG. 33 is a characteristic diagram showing a relationship between a tightening rotation angle and a tightening axial force used in a conventional rotation angle method.

FIG. 34 is a characteristic diagram showing the relationship between the tightening rotation angle, the tightening torque, and the tightening axial force used in the conventional torque gradient method.

FIG. 35 is a cross-sectional view of an example of a conventional device.

FIG. 36 is a flowchart showing arithmetic processing in the prior art of the applicant.

[Explanation of symbols]

10 ... Impact wrench body 11 ... Torque detection part 12 ... Shut off valve 13 ... Air motor part 14 ... Hydraulic pulse generation part 15 ... Main shaft 16 ... Air supply part 17 ... Air passage 18 ... Main valve 19 ... Switching Valve 20 ... Valve operating lever 21 ... Rotation switching lever 22 ... Rotation drive shaft 23 ... Vane 24 ... Liner case 25 ... Driving blade 26a, 26b ... Detection coil 27a, 27b
... Groove row 28 ... Relief valve 30 ... Control device 100 ... Impact type screw tightener main body 101 ... Torque detection unit 102 ... Motor 103 ... Impact torque generator 104 ... Spindle 105 ... Tightening socket 110 ... Control device 120 ... Control device 121 ... Torque signal processing unit 122 ... Peak value processing unit 123 ... Fastening force data / memory unit 124 ... Fastening force calculation unit 125 ... Power control unit 128 ... Torque / pulse duration processing unit 130 ... Control device 134 ... Fastening force calculation unit 138 ... Impact / torque generation interval processing unit 140 ... Control device 144 ... Fastening force calculation unit 150 ... Control device 154 ... Fastening force calculation unit 158 ... Free running time processing unit 160 ... Control device 163 ... Fastening force data / memory unit 164 ... Fastening force calculation unit 165 ... Power control unit 166 ... Fastening force signal processing 167 ... Fastening force data calculation unit 170 ... Fastening portion 171 ... Strain gauge 172 ... Fastening force measurement bolt 173 ... Nuts 174a, 174b ... Fastened object 180 ... Control device 184 ... Fastening force calculation unit 188 ... Free running data number processing Part 190 ... Control device 194 ... Fastening force calculation part 198 ... Extracted data number processing part 201 ... Rotation angle detector 202 ... Motor 203 ... Torque / pulse generator 204 ... Fastening part 211 ... Socket 212 ... Rotary encoder code wheel 213 ... Detection head of rotary encoder 214a ... First housing 214b ... Second
Housing 215 ... Signal processing circuit 220 ... Impact type screw tightener main body 231 ... Output shaft 241 ... Fastened object 242 ... Bolt 243 ... Nut 250 ... Impact type screw tightener main body 251 with tightening axial force estimation function ... Motor 252 ... Torque / pulse generator 253 ... Torque detector 254 ... Output shaft 255 ... Torque control device 260 ... Inspection data processing device 261 ... Rotation angle signal processing unit 262 ... Comparison calculation unit 263 ... Result display unit

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Tatsumi Nabekura 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd.

Claims (9)

[Claims] Claim: What is claimed is: 1. A drive means having a pulse component in a drive output, a joint part for a screw at one end, and a main shaft for tightening the screw when driven by the drive means, and a torque change of the main shaft is detected. Using the impact type screw tightener main body having the torque detecting means and the peak value of the torque pulse obtained from the detection result of the torque detecting means, the increasing amount of the fastening force is calculated for each impact and the fastening force is sequentially calculated. And controlling the power source applied to the drive means so as to achieve the target fastening force, and determining the seating time from the waveform deformation of the torque pulse accompanying the seating when calculating the fastening force. An impact-type screw tightening device, comprising: a control unit that calculates a tightening force with the seating time as a tightening force calculation start time. 2. The impact type screw tightening device according to claim 1, wherein a change in the duration of the torque pulse is detected as the waveform deformation of the torque pulse accompanying the seating, and the duration is a predetermined value. That is, the impact type screw tightening device is provided with a calculating means for determining a time when the seating determination threshold duration is equal to or longer than the seating determination time. 3. The impact type screw tightening device according to claim 1, wherein a change in a torque pulse generation interval corresponding to an impact generated by the driving means is detected as a waveform deformation of the torque pulse accompanying the seating. An impact-type screw tightening device is provided with a calculation means for determining a time when the occurrence interval is a predetermined value, that is, a seating determination threshold value occurrence interval, as a seating time. 4. The impact type screw tightening device according to claim 1, wherein the waveform of the torque pulse associated with the seating is a torque that corresponds to the duration of the torque pulse and the occurrence of impact by the drive means. Impact characterized by comprising a calculating means for detecting a change in pulse generation interval and determining a time when at least one of the duration and the generation interval is equal to or more than a predetermined value as a seating time. Type screw tightening device. 5. The impact type screw tightening device according to claim 1, wherein, as the waveform deformation of the torque pulse accompanying the seating, first of a plurality of torque pulses generated at each impact by the driving means. The interval between the generated torque pulse and the second generated torque pulse, that is, the change in free running time is detected, and the above free running time becomes a predetermined value, that is, the seating determination threshold free running time, An impact-type screw tightening device, characterized in that the impact type screw tightening device is provided with a calculating means for determining a seating time as a seating time. 6. The impact type screw tightening device according to claim 1, wherein the seating determination is performed by using a measuring means for measuring an actual fastening force and a measurement result of the measuring means in a preliminary experiment. Threshold duration, seating determination threshold generation interval, seating determination threshold free running time,
And the dependence of the torque / fastening force conversion coefficient used when calculating the increase amount of fastening force for each impact,
An impact-type screw tightening device, comprising: a computing unit that determines at least one of the two by learning. 7. The impact type screw tightening device according to claim 1, wherein, as the waveform deformation of the torque pulse accompanying the seating, the first of a plurality of torque pulses generated for each impact by the driving means. From the rise of the torque pulse that occurs at the time, the change in the number of data showing a value equal to or less than the predetermined torque value when sampling the predetermined number of data at a fixed sampling interval, that is, the number of free-running data Detecting, it is determined whether the number of free running data is less than or equal to a predetermined seating determination threshold free running data number, and a calculation means for determining the time when it is less than or equal to the seating time is provided. Characteristic impact type screw tightening device. 8. The impact type screw tightening device according to claim 1, wherein, as the waveform deformation of the torque pulse accompanying the seating, first of a plurality of torque pulses generated at each impact by the driving means. From the rise of the generated torque pulse, the change in the number of data showing a value equal to or more than a predetermined torque value when sampling the predetermined number of data at a constant sampling interval, that is, the change in the number of extracted data, is detected. An impact-type screw tightening device comprising: a computing unit that determines a seating time when the number of extracted data becomes equal to or more than a predetermined seating determination threshold extraction data number. 9. The impact type screw tightening device according to claim 7 or 8, wherein a plurality of sampling times, which is a product of the number of sampling data and a sampling interval, are generated by one impact before sitting. An impact type screw tightening device characterized in that it is set to be shorter than the time required from the rise of the first torque pulse of the torque pulse to the rise of the second torque pulse of the torque pulse.