JPH07308866A - Fastening axial tension measuring device and impact type thread fastening device using the measuring device - Google Patents

Abstract

PURPOSE:To provide a measuring device capable of accurately measuring the fastening axial tension of the whole range from the generation of fastening axial tension to the completion of the fastening even in the case where the apparent rigidity of a body to be fastened is changed together with the progress of fastening. CONSTITUTION:A fastening axial tension measuring device is provided with a turning angle detecting section 201 to detect the turning angle of the output shaft of an impact type thread fastening device. The measuring device is also provided with a calculation device 120, and this calculation device 120 has the following function. That is, the time when the turning angle of a nut at each impact becomes equal to an angle in the 'range from the upper limit turning angle for judgment of seating to the lower limit turning angle for judgment of seating' is judged to be a seating time point, and 'the turning angle of the nut after the seating at the seating time point' is determined based on the 'function of the turning angle of the nut due to the impact at the time point of seating, and after that, the turning angle of the nut at each impact is added in order, and the turning angle of the nut after seating is detected, and fastening axial tension is calculated based on the data of the relation between the turning angle of the nut after seating and the fastening axial tension in the case where the apparent rigidity of a body to be fastened varies along with the progress of fastening.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bolt when a screw is tightened using an impact wrench, an impact type nut runner, or the like. The present invention relates to a technique for measuring a tightening axial force (hereinafter referred to as an axial force), and particularly to a technique for measuring an axial force from a rotation angle of a bolt or a nut (hereinafter abbreviated as a bolt).

[0002]

2. Description of the Related Art As a conventional device for measuring an axial force (described as a fastening force in the following description) generated on a bolt by detecting a rotation angle of the bolt when tightening an impact screw, Japanese Patent Application No. There is an apparatus described in 238616. FIG. 16A is a sectional view of the above device, and FIG. 16B is a plan view of the disc 42 of the rotation angle detection unit. In FIG.
The main shaft 15 of the impact wrench body 40 has the main shaft 15
A disk 42 that rotates together with is fixed. This disc 4
A slit 43 is provided in 2 and a rotation angle detector 41 is configured with a rotation sensor 44 (photo interrupter, magnetic sensor, etc.) provided so as to sandwich the disc 42. The main shaft 15 is made of a material having a magnetostrictive effect. Then, when tightening the screw, a change in magnetic permeability on the surface of the spindle 15 due to a torque pulse corresponding to the occurrence of impact (hereinafter abbreviated as impact torque) is detected as an inductance change of the detection coils 26a and 26b of the torque detection unit 11. By doing so, the change in torque is detected. Furthermore, the impact wrench body 40 described above
Is connected to the control device 110, and based on the signals from the rotation angle detection unit 41 and the torque detection unit 11 described above, the fastening force is calculated in the procedure of the flowchart shown in FIG.
When the target fastening force is reached, the shut-off valve 12 is closed by a control signal from the control device 110 to shut off the compressed air to the air motor unit 13, whereby the hydraulic pulse generation unit 14 and the main shaft. The drive of 15 is stopped.

The procedure for calculating and controlling the fastening force will be described below with reference to the flowchart shown in FIG. First,
After setting the value of the target fastening force cFc in step S201 and setting the calculation start determination threshold rotation angle sA in step S202, the impact number counter is reset in step S203 <count i = 0>, and further step S
At 204 and step S205, the values of the cumulative rotation angle and the fastening force up to that point are respectively reset <A (0) =
0, F (0) = 0>. Here, the cumulative rotation angle A (i) is i
The rotation angle of the bolt starting from the start of fastening after the th impact, and the calculation start determination threshold rotation angle sA is calculated from the rotation angle A (i) -A (i-1) of the bolt for each impact. That is, it is a threshold value for determining the time point when the calculation of the fastening force is started.

Next, in step S206, screw tightening is started. In addition, steps S207 to S209
Forms a loop, and seating determination, that is, calculation start determination is performed for each impact until seating. First, after incrementing the count i by 1 in step S207, the cumulative rotation angle A is calculated from the signal of the rotation angle detection unit 41 in step S208.
Find (i). Next, in step S209, it is determined whether or not the rotation angle A (i) -A (i-1) of the bolt for each impact is less than or equal to the calculation start determination threshold rotation angle sA, and N
If it is O, that is, if it is not seated, the process returns to step S207 and repeats steps up to step S209.

On the other hand, if YES in step S209, that is, if it is determined that the vehicle is seated, the process proceeds to a loop including steps S210 to S213 and step S214, and the fastening force is calculated for each impact. First,
In step S210, the peak value of the torque pulse (hereinafter referred to as the peak torque value) T _P (i) corresponding to the impact is obtained from the signal of the torque sensor and stored. Next, in step S211, 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 (an example is shown in FIG. 18). However, _CTF (i) = _CTF [F (i-1)]. Next, in step S212, the increase amount of the fastening force due to the impact δF (i) = C _TF (i) × T _P (i) is calculated, and the fastening force F (i) after this impact is calculated up to that time. Fastening force, that is, fastening force F (i-
It is calculated by adding the increment δF (i) to 1). Therefore, F (i) is F (i) = F (i-1)
+ C _TF (i) x T _P (i). Next, in step S213, 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, the count i is incremented by 1 in step S214, and then the process returns to step S210. And repeats steps up to step S213. On the other hand, step S
If YES in 213, the flow advances to step S215, and a cut-off command is issued at that point. This causes the compressed air valve to close. Next, step S216.
Then, 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 S203 to perform the next screw tightening. In the above description of the prior art, the impact wrench is taken as an example, but the same applies to the impact type nut runner and the like.

In this conventional example, the torque change of the main shaft of the impact type screw tightener main body is detected, the increase amount of the fastening force is calculated by using the peak torque value for each impact, and the fastening force is sequentially obtained. In the impact type screw tightening device that controls the power source so as to realize the tightening force, the rotation angle of the bolt is detected in order to determine the start time of the tightening force calculation. Therefore, the accuracy of detecting the rotation angle of the bolt does not have to be so high, but there is a problem that the torque detector is indispensable for accurately measuring the fastening force.

Further, the present applicant has already filed an application for a device for measuring the bolt tightening axial force by detecting the rotation angle of the bolt when tightening the impact screw (Patent Application No.
-333988 unpublished). 19 and 20 show
It is a block diagram of the said apparatus. FIG. 19 is a block diagram showing the overall configuration, and the rotation angle detector 201 is arranged between the impact screw type tightening machine main body 220 and the fastening portion 204. Further, the impact type screw tightener main body 22
0 is a motor 202 powered by electricity or compressed air
And an impact torque generator 203 for converting the torque of the motor into pulsed torque, and an output shaft 231. The fastening portion 204 includes the fastened body 241 and the bolt 2.
42 and nut 243. The rotation angle detector 2
The output of 01 is sent to the signal processing circuit 215 and is output as a tightening axial force. Further, FIG. 20 shows a rotation angle detector 20.
It is sectional drawing which shows the structure of 1. In FIG. 20, the socket 211 is a member that transmits the pulsed torque generated on the output shaft 231 of the impact torque generator 203 to the nut 243.
The encoder code wheel 212 is fixed. In addition, a first housing 214a that rotatably supports the socket 211, and the first housing 214a
Is provided, and a second housing 214b fixed to a support body (not shown) and a rotary encoder detection head 213 fixed to the second housing 214b are provided.

Next, the operation will be described. When tightening with an impact type screw tightener at a part where detent nuts that are often used to fasten chassis parts of automobiles are used, "Nut detent part and bolt screws An impact occurs due to the frictional force with the surface, and when the maximum static friction torque is exceeded, the nut goes into a free running state, rotates a large angle, and finally decelerates / stops due to dynamic friction. After being repeated, it takes a seat. When seated, the frictional force on the screw surface and seat surface increases due to the tightening axial force generated on the bolt, and the rotation angle of the nut sharply decreases at each impact. The rotation angle is a value between the seating determination upper limit rotation angle sθ _MAX and the seating determination lower limit rotation angle sθ _MIN . Then, assuming that the rotation angle of the nut due to the impact at the time of sitting is θ _L , the rotation angle θ _FL of the nut after the sitting at the time of sitting can be obtained by the following mathematical formula. θ _FL = s θ _MIN × (s θ _MAX −θ _L ) / (s θ _MAX −s θ _MIN ) Therefore, after that, by sequentially adding the rotation angle of the nut for each impact, the rotation angle of the nut after seating θ _F The rotation angle of the nut θ _F
Based on the proportional relationship between the tightening axial force F and the tightening axial force F, it is possible to measure the axial force with high accuracy.

[0009]

As described above, as shown in FIG.
In the conventional device shown in (1), there is a problem that a torque detector is indispensable in order to accurately measure the axial force. In the prior inventions of the present applicant shown in FIGS. 19 and 20, the axial force can be measured with high accuracy when the proportional coefficient between the rotation angle of the bolt and the axial force is constant after seating. As in the case of the bush bracket type fastening portion shown in FIG. 14 described later, the apparent rigidity of the fastened body changes with the progress of fastening (details will be described later),
Therefore, when the proportional constant in the proportional relationship between the rotation angle θ _{F of the} nut and the tightening axial force F changes, the axial force is accurately measured in the entire range from the start of the axial force to the end of the fastening. There was a problem that it was difficult.

The present invention has been made to solve the problems of the prior art and the prior art as described above,
Apparent rigidity changes with the progress of fastening,
A tightening axial force measuring device that can accurately measure the tightening axial force in the entire range from the start of the tightening axial force to the end of the tightening even if the proportional coefficient between the rotation angle of the bolt and the axial force changes. Another object of the present invention is to provide an impact type screw tightening device using the same.

[0011]

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, the rotation angle of the output shaft of the impact type screw tightening device or the socket portion for transmitting the pulsed torque generated in the output shaft to the bolt or the nut of the fastening portion is set. Based on the rotation angle detection means for detecting and the detection result of the rotation angle detection means, the rotation angle of the bolt or the nut for each impact is set in advance in the “range between the seating determination upper limit rotation angle and the seating determination lower limit rotation angle. Is determined as the seating time, and the "rotation angle of the bolt or nut after seating at the seating time" is obtained in advance based on the "function of the rotation angle of the bolt or nut depending on the impact at the seating time". After that, the rotation angle of the bolt or nut for each impact is sequentially added to detect the rotation angle of the bolt or nut after seating. Based on the "data on the relationship between the rotation angle of the bolt or nut after seating and the tightening axial force" when the apparent rigidity of the object to be tightened changes in advance as the tightening progresses. And a calculation means for calculating the tightening axial force. The rotation angle detecting means corresponds to, for example, the rotation angle detector 201 in the embodiment shown in FIG. 1 described later, and the calculating means corresponds to, for example, the calculating device 120.

The invention described in claim 2 is the same as claim 1.
In the tightening axial force measuring device described in (1), the calculating means is configured as follows. That is, from the rotation angle of the bolt or nut for each impact, the contact state between the seat surfaces of the plurality of members of the fastening portion, that is, the state where the seat surfaces are not in contact, the state where they are partially in contact, It is configured to determine which of the contact states and correct the above-mentioned "data on the relationship between the rotation angle after the seating of the bolt or nut and the tightening axial force" according to those states. It is a thing. The above-mentioned calculation means is, for example, the calculation device 13 in the embodiment shown in FIG.
Equivalent to 0.

According to a third aspect of the present invention, there is provided a drive means having a pulse component in the drive output, a main shaft having a joint portion with a screw at one end, and tightening the screw by being driven by the drive means. An impact type screw tightener main body having a rotation angle detecting means for detecting a rotation angle of the main shaft, and a tightening axial force is calculated based on a detection result of the rotation angle detecting means. An impact type screw tightening device is configured by the calculating means described above. According to a fourth aspect of the present invention, in the impact type screw tightening device according to the third aspect, the drive is performed so as to realize a target tightening axial force based on the tightening axial force obtained by the calculating means. The control means for controlling the power source supplied to the means is added. Note that claim 3
The respective means described in claim 4 correspond to, for example, the following means in the embodiment of FIG. 10 described later. That is, the impact type screw tightener main body is the impact type screw tightener main body 100 (details are shown in FIG. 11), and the driving means is the motor 1.
02 and the impact torque generator 103, the main shaft is the main shaft 104, and the rotation angle detecting means is the rotation angle detecting unit 101.
The control means corresponds to the control device 140, respectively.

[0014]

According to the first aspect of the present invention, the rotation angle after seating is detected, and the value and the apparent rigidity of the object to be fastened change as the fastening progresses. The tightening axial force is calculated on the basis of "the data on the relationship between the rotation angle and the tightening axial force". For the above-mentioned "data on the relationship between the rotation angle of the bolt or nut after seating and the tightening axial force", for example, the numerical values obtained in advance by experiments or the like are stored in a data table or the like, and the values are read and used. . Therefore, even when the apparent rigidity of the object to be fastened changes as the fastening progresses, the tightening axial force can be accurately measured over the entire range from when the tightening axial force starts to when the fastening ends. I can.

In the invention described in claim 2,
From the rotation angle of the bolt or nut for each impact, the contact state between the seat surfaces of the plurality of members of the fastening portion, that is, the state where the seat surfaces are not in contact with each other (corresponding to the region 1 described later),
It is determined whether it is in a state of partial contact (corresponding to area 2 described below) or in a state of complete contact (corresponding to area 3 described below), and in accordance with the result, the above-mentioned "bolt" is determined. Alternatively, the data regarding the relationship between the rotation angle after the nut is seated and the tightening axial force is corrected. Therefore, due to the dimensional variation of the member of the fastened part, the transition timing of the contact state of the above-mentioned bearing surfaces, especially the transition timing from the state where the bearing surfaces are not in contact to the state where they are in partial contact, The tightening axial force can be measured accurately even if the rotation angle of the bolt or nut set in the standard data table deviates from the seated position.

Here, a change in the apparent rigidity of the object to be fastened as the fastening progresses will be described with respect to the fastening axial force and the rotational angle of the bolt or nut for each impact as the fastening progresses. FIG. 14 is a side view of an example of a fastening portion of a bush bracket type.
FIG. 5 schematically shows the relationship between the tightening axial force F generated on the bolt, the rotation angle θ _I of the nut for each impact, and the rotation angle θ _F after the seating of the nut, using the fastening portion shown in FIG. 14 as an example. FIG. In FIG. 14, 24
2 is a bolt, 243 is a nut, 244 is a bush, 24
5 is a bracket. In this structure, the bush 244 and the bracket 255 are not in contact with each other in the initial state, but the bolt 242 and the nut 243 are tightened to gradually deform the bracket 245, and finally the bush 244 and the bracket 255. The bearing surface of and will come into contact. As shown in FIG. 15, in the fastening process, the region 1 to
It is divided into 3 areas. First, in region 1, bolt 2
42, the nut 243, and the bracket 245 are in contact with each other, but the bush 244 and the bracket 255 are not in contact with each other. Therefore, the tightening axial force F increases according to the bending deformation of the bracket. . Therefore, the proportional coefficient between the rotation angle θ _F of the nut after seating and the tightening axial force F, that is, the apparent rigidity of the object to be fastened is small,
Further, since the tightening axial force F is small, the frictional force generated on the screw surface or the bearing surface is small, so that the rotation angle θ _I of the nut for each impact is large. On the other hand, in region 3,
Since the bearing surfaces of the bolt 242, the nut 243, the bush 244, and the bracket 245 are in full contact with each other, the tightening axial force F generated on the bolt increases due to the compressive deformation of the fastened body. Therefore, the apparent rigidity of the object to be fastened is large, and since the tightening axial force F is large, the frictional force generated on the screw surface or the bearing surface is large, so that the rotation angle θ _I of the nut for each impact is small. Further, the region 2 is a transition process from the region 1 to the region 3, and in this region 2, the apparent rigidity of the fastened body rapidly increases. From the above, if the determination of the transition timing from the region 1 to the region 2 is incorrect, a large error will occur in the axial force measurement in the region 3, so it is essential to accurately determine the above transition timing. Becomes

Here, looking at the rotation angle θ _I of the nut for each impact accompanying the transition from the region 1 to the region 2,
When the bearing surface of the bracket 245 contacts the bush 244, the apparent bending rigidity of the bracket 245 sharply increases, so that the rotation angle θ _F after the nut is seated reaches the region transition rotation angle s θ _FR. The rotation angle θ _I of the nut for each impact suddenly decreases discontinuously. For this reason,
As shown in FIG. 15, the region determination threshold rotation angle sθ _IR can be determined, and by comparing and determining θ _I with sθ _IR, it is possible to accurately determine the region 1 or the region 2. . Therefore, by configuring as in claim 2, due to the dimensional variation of the members of the fastened portion, the transition timing of the contact state of the seating surfaces, particularly from the state where the seating surfaces are not in contact with each other Even if the timing of transition to the contact state deviates from the rotation angle after the seating of the bolt or nut set in the standard data table, the tightening axial force can be accurately measured.

Further, in the invention described in claim 3,
Detects the rotation angle of the main shaft of the impact type screw tightener,
Since the tightening axial force is obtained by the calculating means according to claim 1 or 2 based on the detection result, the tightening axial force generated in the bolt during impact screw tightening is determined for each impact. It can be measured with high accuracy. The tightening axial force thus measured can be easily and accurately tightened by displaying it on a display device and showing it to the operator. In addition, claim 4
In the invention described in claim 3, in the impact type screw tightening device according to claim 3, the power source supplied to the drive means is controlled so as to realize a target tightening axial force. Therefore, it is possible to accurately tighten the screw up to the target tightening force while accurately measuring the tightening axial force for each impact.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. In the first embodiment, "data on the relationship between the rotation angle after the seating of the bolt or nut and the tightening axial force" is obtained in advance when the apparent rigidity of the object to be fastened changes as the fastening progresses. It is an example in which the tightening axial force is calculated from the measured rotation angle and the above data.

1 and 2 are diagrams of a first embodiment of the present invention, FIG. 1 is a block diagram of the present embodiment, and FIG. 2 is a flow chart showing arithmetic processing. First, in FIG. 1, the rotation angle detector 201 has the same configuration as that of the prior art example shown in FIG. 20, and includes the abbreviated impact screw type tightening machine main body (impact torque generator 203, output shaft 231). It is arranged between the fastening portion (nut 243). Further, the arithmetic unit 120 electrically connected to the rotation angle detector 201 receives the signal emitted from the rotation angle detector 201 as an input and produces a rotation angle signal.
1 and "data on the relationship between the rotational angle θ _{F of the} bolt or nut after seating and the tightening axial force F" for the case where the apparent rigidity of the object to be fastened changes as the fastening progresses. The axial force data / memory unit 123,
The axial force calculation unit 124. FIG. 3 is an example of data (function) recorded in the axial force data memory unit 123. The specific value of this data differs depending on the combination of the bolt and the object to be fastened. Such data is prepared as a function for each combination of the bolt to be fastened and the object to be fastened, and is stored, for example, in the form of a data table. The axial force calculator 122 calculates the tightening axial force based on this data, as will be described later.

Next, the operation of the first embodiment will be described based on the flow chart shown in FIG. First, step S1
And in step S2, the seating determination upper limit rotation angle sθ _MAX
And the seating determination lower limit rotation angle sθ _MIN are set. Next, in step S3, the impact number counter is reset <count i = 0>. Next, in step S4, screw tightening is started. Step S5 to Step S1
3, step S6 is the processing content of the rotation angle processing unit 121, and the other is the processing content of the axial force calculation unit 122.

In addition, a loop is formed in steps S5 to S7, and seating determination is performed for each impact until seating. First, after incrementing the count i by 1 in step S5, the rotation angle θ _I (i) of the nut for each impact is calculated and stored in step S6. Next, step S
At 7, it is determined whether or not the rotation angle θ _I (i) of the bolt for each impact is less than or equal to the seating determination upper limit rotation angle s θ _MAX. If NO, that is, if the seat is not yet seated, the process returns to step S5 and step S5.
Repeat up to 7. On the other hand, if YES in step S7, that is, if it is determined that the vehicle is seated, the process proceeds to step S8,
The rotation angle θ _FL of the nut after seating at the time of seating is calculated by the following formula. θ _FL = sθ _MIN × [sθ _MAX −θ _I (i)] / (sθ _MAX −sθ
_MIN ) Then, the value of this rotation angle θ _FL is stored as the rotation angle θ _F (i) of the nut after seating <θ _F (i) = θ _FL >.

Next, the process proceeds to the loop of steps S9 to S13 to calculate the axial force. First, after incrementing the count i by 1 in step S9, the rotation angle θ _I (i) of the nut for each impact is calculated and stored in step S10. Next, in step S11, the rotation angle θ _F (i) of the nut after seating is calculated and stored. Where θ _F (i)
=? _F (i-1) +? _I (i). Next, in step S12, the tightening axial force F (i is based on the "data about the relationship between the rotation angle θ _F after the seating of the nut and the tightening axial force F" recorded in the axial force data / memory section 123. ) And memorize. Next, in step S13, it is determined whether or not to end the process. If YES, that is, if the ending condition is satisfied, the process is ended as it is, and if NO, the axial force measurement is continued, that is, step S9. Return to step S
Repeat up to 13.

FIG. 4 is a characteristic diagram showing the characteristics of the axial force measurement accuracy of the above embodiment and comparative example (preceding example). In FIG. 4, ◯ marks indicate the characteristics of this embodiment, and ● marks and ■ marks indicate the characteristics of the preceding example. The characteristics of the above prior art are
The mark indicates the characteristics when the seating determination lower limit rotation angle sθ _{M IN} and the seating determination upper limit rotation angle sθ _MAX are set to the same values as in this embodiment, and the ● mark indicates the set value of the seating determination lower limit rotation angle sθ _MIN . 1
5 shows the results when the rotation angle of the nut for each impact when moving from the region 1 to the region 2 in 5 is set, and the seating determination upper limit rotation angle sθ _MAX is set to a value slightly larger than that. In addition, the characteristic of FIG. 4 is M12 when cFc = 40 kN.
The distance between the seat surfaces when seated is 4 using the bolts and nuts
It is a result when a 0 mm to-be-fastened object was fastened, and in the Example and the comparative example of a mark, sθ _MIN = 120 deg, sθ
_{With MAX} = 180 deg, the data shown in FIG. 3 is used for the “data on the relationship between the rotation angle θ _F after seating of the nut and the tightening axial force F”. On the other hand, in the comparative example indicated by ●, sθ _MIN = 15 de in the method of the prior art.
g, s θ _MAX = 30 deg, and the inclination in region 3 of FIG. 3 is used as the proportional coefficient between the rotation angle θ _F after the nut is seated and the tightening axial force F. In the characteristics of FIG. 4, the axial force F _G (kN) measured with the strain gauge shown on the horizontal axis
Is used as a reference and the axial force F _R (kN) measured at the rotation angle shown on the vertical axis is compared. Therefore, if the values on the horizontal axis and the values on the vertical axis match, the measurement is accurate. Further, on the horizontal axis, a range of about 0 to 4 kN corresponds to the region 1, a range of about 4 to 10 kN corresponds to the region 2, and a range of 10 kN or more corresponds to the region 3. In FIG. 4, in the comparative example of the mark ■, the region 1 (only the mark ◯ is shown in the drawing because the data overlap) is in good agreement, but in the regions 2 and 3, the error is large, Also, in the comparative example marked with ●, the area 3 is in good agreement,
It cannot be measured in area 1 and area 2. On the contrary ○
In the mark (in this embodiment), all the ranges from region 1 to region 3 are in agreement.

As described above, in the present embodiment, in the case where the apparent rigidity of the object to be fastened changes with the progress of fastening, the previously determined "rotation angle and tightening after the seating of the bolt or nut and tightening". The tightening axial force is measured on the basis of "data on the relationship with the axial force".
Therefore, even when the apparent rigidity of the object to be fastened changes as the fastening progresses, the fastening axial force can be accurately measured in the entire range from the start of the fastening axial force to the end of the fastening.

Next, FIGS. 5 to 7 show a second embodiment of the present invention, FIG. 5 is a block diagram, and FIGS. 6 and 7 are flow charts showing arithmetic processing. In this embodiment, the seating surfaces of the plurality of members of the fastening portion are in contact with each other, that is, the seating surfaces are not in contact with each other (region 1), based on the rotation angle of the bolt or nut for each impact. State (area 2), complete contact (area 3)
Which of the above is determined, and corrects the above "data on the relationship between the rotation angle after the bolt or the nut is seated and the tightening axial force" according to those states (specifically,
For example, this is an example configured to have the characteristics shown in FIG. 8 below.

First, the structure will be described with reference to FIG. In FIG. 6, the rotation angle detector 201 has the same configuration as that of the prior art example shown in FIG. 20, and has the abbreviated impact screw type tightening machine main body (impact torque generator 203, output shaft 231) and fastening portion. It is arranged between (nut 243). Further, the arithmetic unit 130 electrically connected to the rotation angle detector 201 produces a rotation angle signal using the signal emitted from the rotation angle detector 201 as an input, and the same rotation angle signal processing as in the first embodiment. The part 121 and "data about the relationship between the rotation angle θ _{F of the} bolt or nut after seating and the tightening axial force F" are recorded, and the shaft having a function of correcting the above data as described later. The force data memory unit 133 and the axial force calculation unit 132, which is slightly different from that of the first embodiment, are included.

Next, the operation of the second embodiment will be described based on the flow charts shown in FIGS. 6 and 7. In addition, in FIG. 6 and FIG. 7, parts having the same reference numeral are connected. First, the values of the seating determination upper limit rotation angle sθ _MAX and the seating determination lower limit rotation angle sθ _MIN are determined in step S21 and step S22 of FIG.
In 3, the value of the area determination threshold rotation angle sθ _IR is set. Next, in step S24, the impact number counter is reset <count i = 0>. Next, in step S25, screw tightening is started. Step S26
~ In step S42, step S27, step S31 and step S39 are the processing contents in the rotation angle processing part 121, step S35 is the processing contents in the axial force data memory part 133, and others are the axial force calculating part 1.
The processing contents in 32. Also, from step S26
Step S28 forms a loop, and seating determination is performed for each impact until seating. First, step S26
After the count i is incremented by 1, the rotation angle θ _I (i) of the nut for each impact is calculated and stored in step S27. Next, in step S28, it is determined whether or not the rotation angle θ _I (i) of the bolt for each impact is less than or equal to the seating determination upper limit rotation angle s θ _MAX. If NO, that is, if the seat is not seated, the process returns to step S26 and step S28. Repeat up to.

On the other hand, if YES in step S28,
That is, if it is determined that the seat is seated, the process proceeds to step S29, and the rotation angle θ _FL of the nut after seating at the time of seating is calculated by the following mathematical expression. θ _FL = sθ _MIN × [sθ _MAX −θ _I (i)] / (sθ _MAX −sθ
_MIN ) Then, the value of this rotation angle θ _FL is stored as the rotation angle θ _F (i) of the nut after seating <θ _F (i) = θ _FL >. next,
Proceeding to a loop consisting of steps S30 to S32, step S33 and step S34, the tightening axial force in the region 1 is calculated, and the transition timing from the region 1 to the region 2 is determined. First, after incrementing the count i by 1 in step S30, the rotation angle θ _I (i) of the nut for each impact is calculated and stored in step S31. Next, in step S32, it is determined whether or not the rotation angle θ _I (i) of the nut for each impact is less than or equal to the region determination threshold rotation angle sθ _IR , and if NO, that is, the progress of fastening is in the region 1 If so, the process proceeds to step S33, and the rotation angle θ _F (i) of the nut after seating is calculated and stored. However, θ _F (i) = θ _F (i−1) + θ _I (i). Next, in step S34, the “rotational angle θ _F and the tightening axial force F after the nut is seated” recorded in the axial force data memory unit 133 is recorded.
After determining and storing the tightening axial force F (i) using the inclination in the region 1 of "Data about relationship with", the process returns to step S30 and repeats steps S32.

On the other hand, if YES in step S32,
The process proceeds to step S35 in FIG. 7 (→), and the axial force data
“Data on the relationship between the rotation angle θ _F of the nut after seating and the tightening axial force F” recorded in the memory 133.
To correct. Specifically, as shown in FIG. 8, the rotation angle θ _F (i) of the nut after the seating at this point is set as the area transfer rotation angle s θ _FR , and the characteristic lines of the area 2 and the area 3 are translated in parallel. Correct the data. In FIG. 8, A is the characteristic of the standard data table and B is s.
correction characteristic when theta _FR is smaller than the value in the standard data table, C is a correction characteristic when S.theta _FR is larger than the value in the standard data tables. Next, in step S36, the rotation angle θ _F (i) of the nut after seating is calculated and stored. However, θ _F (i) = θ _F (i-1) + θ
_I (i). Next, in step S37, after the tightening axial force F (i) is obtained and stored based on the data corrected in step S35, the process proceeds to the loop of steps S38 to S42 to determine the tightening axial force in the regions 2 and 3. Calculate. First, after incrementing the count i by 1 in step S38, the rotation angle θ _I (i) of the nut for each impact is calculated and stored in step S39. Next, in step S40, the rotation angle θ _F (i) of the nut after seating is calculated and stored. However, θ _F (i) = θ _F (i-1) +
θ _I (i). Next, in step S41, the tightening axial force F (i) is obtained and stored based on the data corrected in step S35. Next, in step S42, it is determined whether or not to end the process. If YES, that is, if the ending condition is satisfied, the process ends as it is, and if NO, the axial force measurement is continued, that is, step S38. Returning to step S42, the steps up to step S42 are repeated.

FIG. 9 is a comparison diagram of the axial force measurement accuracy between the above-mentioned embodiment and the comparative example, and the circle marks show the characteristics of this embodiment,
The mark ● indicates the characteristics of the comparative example (results obtained when the correction processing was not performed on the data of this example). This example is the result for the same fastening portion as the first embodiment, and in both the embodiment and the comparative example, sθ _MIN = 120 deg, sθ
_{With MAX} = 180 deg, the data shown in FIG. 3 is used for the “data on the relationship between the rotation angle θ _F after seating of the nut and the tightening axial force F”. As is clear from the characteristics of FIG. 9, in the state where the bushes and the seating surfaces of the brackets are not in contact with each other, that is, in the region 1, there is no difference between the example and the comparative example (due to the overlapping data, In the state where the bush and the bearing surface of the bracket are in partial contact (region 2) or in the state where they are in complete contact (region 3), in the embodiment, due to the effect of correction, Axial force measurement accuracy has improved significantly.

As described above, in the present embodiment, the contact state between the bearing surfaces of the plurality of members of the fastening portion is determined from the rotation angle of the bolt or nut for each impact, and "the bolt or nut is seated Data regarding the relationship between the rotation angle and the tightening axial force "is corrected. Therefore, due to the dimensional variation of the member of the fastened part, the transition timing of the contact state of the above-mentioned bearing surfaces, especially the transition timing from the state where the bearing surfaces are not in contact to the state where they are in partial contact, The tightening axial force can be accurately measured even if the rotation angle after the seating of the bolt or nut set in the standard data deviates.

Next, FIGS. 10 to 13 show a third embodiment of the present invention, and FIG. 10 is a block diagram of this embodiment, and FIG.
Is a cross-sectional view of an impact wrench body using compressed air as a power source, and FIGS. 12 and 13 are flowcharts showing arithmetic processing. This embodiment detects the rotation angle of the main shaft of the impact type screw tightener main body, and based on the detection result,
This is an example in which the tightening axial force is measured by the measuring method shown in the second embodiment, and the power source supplied to the drive means is controlled so as to realize the target tightening axial force. First, in FIG. 10, an impact-type screw tightener main body 100 is connected to a motor 102 and an output shaft of the motor 102, and an impact torque generator that converts continuous torque of the motor 102 into impact torque. 1
03 and a rotation angle detection unit 10 for detecting the rotation angle of the output shaft of the impact torque generator 103, that is, the main shaft 104.
1 and a tightening socket (joint portion) 105 attached to the main shaft 104. 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. A control device 140 is connected to the impact type screw tightener main body 100. The control device 140 converts the signal from the rotation angle detection unit 101 into a rotation angle signal, and a rotation angle signal processing unit 121 similar to that of the first embodiment and axial force data similar to that of the second embodiment. A power control unit 145 is provided in addition to the memory unit 133 and the fastening force calculation unit 132.

Next, FIG. 11 is a concrete example of this embodiment and shows a sectional view in the case of being constructed as an impact wrench using compressed air as a power source. In FIG.
Reference numeral 10 denotes an impact wrench body (corresponding to a portion 100 in FIG. 1). In the impact wrench body 10, an air supply unit 16, an air. A motor unit 13, a hydraulic pressure pulse generator 14, and a rotation angle detector 50 are provided. The air supply unit 16 has an air passage 1 communicating with the air motor unit 13.
7 is formed, and a main valve 18 and a switching valve 19 are provided in this order in the middle thereof. Maine·
The valve 18 is opened by pulling the valve operating lever 20, and 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.
Are rotated by the action of compressed air on the vanes 23. The hydraulic pulse generator 14 includes a liner directly connected to the rotary drive shaft 22 of the air motor unit 13.
The main shaft 15 is provided in the case 24, and the driving blade 25 is mounted on the main shaft 15. The liner case 24 is filled with the oil liquid. Spindle 1
5 is liner case 24 when there is no load above a certain level
By the resistance of the inner surface and the driving blade 25, it rotates together with the rotary drive shaft 22 of the air motor unit 13, and when there is a certain load or more, the hydraulic pressure acting on the inner surface of the driving blade 25 via the relief valve 28 fluctuates. It is designed to turn shockingly. The tip of the main shaft 15 is shaped so as to be connected to a screw via a socket (box / wrench), and the screw can be tightened by adjusting the tip to a desired screw. The rotation angle detection unit 50 includes a code wheel 212 of a rotary encoder that is fixed to the main shaft 15 and rotates together with the main shaft 15, and the code wheel 4 of the rotary encoder.
It is composed of a rotary encoder detection head 213 provided so as to sandwich 2 and detects the rotation angle of the main shaft 15. For the structure of the compressed air cutoff mechanism,
A shut-off valve 12 for supplying / shutting off the compressed air sent to the air motor unit 13 is provided in the middle of an air passage 17 connecting 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 140 in FIG. 10, and is a rotation for producing a rotation angle signal by inputting a signal emitted from the rotation angle detecting portion 50. Corner signal processing unit 121
And “data on the relationship between the rotation angle θ _{F of the} bolt or nut after seating and the tightening axial force F” are recorded, and the axial force data memory unit 133 having a function of correcting the above data is recorded. And an axial force calculation unit 132, and a power control unit 1 that determines whether or not the tightening axial force is within an appropriate range and sends an opening / closing control signal to the shut-off valve 12.
45. Note that the above 121, 132, 133
Since 145 and 145 have the same configuration as in FIG. 10, their illustration is omitted.

Next, the operation of the third embodiment will be described with reference to the flow charts shown in FIGS. In addition, in FIG. 12 and FIG. 13, and indicate that parts having the same reference numerals are connected. The compressed air sent from the air supply unit 16 to the air motor unit 13 via the shutoff valve 12 by pulling the valve operating lever 20 shown in FIG. 11 causes the rotary drive shaft of the air motor unit 13 to rotate. 22 rotates, and its rotational force is converted into a shocking rotational force in the hydraulic pressure pulse generator 14, and is transmitted to the main shaft 15 to perform screw tightening work. First, the value of the target fastening force cFc is set in step S51 of FIG. 12, and in step S52, step S53 and step S54, the seating determination upper limit rotation angle sθ _MAX , the seating determination lower limit rotation angle sθ _MIN and the region determination threshold value are set. Rotation angle s
After setting the respective values of θ _IR , the impact number counter is reset in step S55 <count i = 0.
>. Next, in step S56, screw tightening is started.
In step S57 to step S74, step S
58, steps S62 and S70 are processing contents in the rotation angle processing unit 121, step S66 is processing contents in the axial force data memory unit 133, and step S7.
3 and step S74 are processing contents in the power control unit 145, and others are processing contents in the axial force calculation unit 132.

Further, steps S57 to S59 form a loop, and the seating determination is performed for each impact up to the seating. First, in step S57, the count i is 1
After that, the rotation angle θ _I (i) of the nut for each impact is calculated and stored in step S58. Next, in step S59, the rotation angle θ of the bolt for each impact
_It is determined whether or not _I (i) is less than or equal to the seating determination upper limit rotation angle sθ _MAX. If NO, that is, if the vehicle is not seated yet, the process returns to step S57 and steps S59 to S59 are repeated. On the other hand, step S5
If YES in 9, that is, if it is determined that the seat is seated, the process proceeds to step S60, and the rotation angle θ _FL of the nut after seating at the time of seating is calculated by the following mathematical expression. θ _FL = sθ _MIN × [sθ _MAX −θ _I (i)] / (sθ _MAX −sθ
_MIN ) Then, the value of this rotation angle θ _FL is stored as the rotation angle θ _F (i) of the nut after seating <θ _F (i) = θ _FL >. next,
Proceeding to a loop consisting of steps S61 to S63, step S64 and step S65, the tightening axial force in the region 1 is calculated and the transition timing from the region 1 to the region 2 is determined. First, after incrementing the count i by 1 in step S61, the rotation angle θ _I (i) of the nut for each impact is calculated and stored in step S62. Next, in step S63, it is determined whether or not the rotation angle θ _I (i) of the nut for each impact is less than or equal to the region determination threshold rotation angle sθ _IR , and if NO, that is, the progress of fastening is in the region 1 If so, the process proceeds to step S64, and the rotation angle θ _F (i) of the nut after seating is calculated and stored. However, θ _F (i) = θ _F (i−1) + θ _I (i). Next, in step S65, “rotation angle θ _F and tightening axial force F after the nut is seated” recorded in the axial force data memory unit 133 is recorded.
After determining and storing the tightening axial force F (i) using the inclination in the region 1 of "Data about relationship with", the process returns to step S61 and steps S63 to S63 are repeated.

On the other hand, if YES in step S63,
Proceeding to step S66 of FIG. 7 (→), the axial force data
“Data on the relationship between the rotation angle θ _F of the nut after seating and the tightening axial force F” recorded in the memory 133.
To correct. Specifically, as shown in FIG. 8, the rotation angle θ _F (i) of the nut after the seating at this point is set as the area transfer rotation angle s θ _FR , and the characteristic lines of the area 2 and the area 3 are translated in parallel. Correct the data. Next, in step S67, the rotation angle of the nut after seating θ _F (i)
Calculate and store. However, θ _F (i) = θ _F (i-1)
+ Θ _I (i). Next, in step S68, step S66
Tightening axial force F (i) based on the data corrected in
Is calculated and stored, and then steps S69 to S73
Then, the tightening axial force in the regions 2 and 3 is calculated. First, after incrementing the count i by 1 in step S69, the rotation angle θ _I (i) of the nut for each impact is calculated and stored in step S70. next,
In step S71, the rotation angle θ of the nut after seating
Calculate and store _F (i). However, θ _F (i) = θ _F (i
−1) + θ _I (i). Next, in step S72, the tightening axial force F is determined based on the data corrected in step S66.
Find and store (i). Next, in step S73,
It is determined whether the tightening axial force F (i) is greater than or equal to the target axial force cFc. If NO, the process returns to step S69 and step S7.
Repeat up to 3. On the other hand, if YES in step S73, the flow advances to step S74 to issue a cut-off command. This causes the compressed air valve to close. Next, in a step S75, it is determined whether or not to end, and Y
If it is ES, the process ends, and if NO, step S
Return to 55 and perform the next screw tightening. As a result, the same result as in FIG. 9 is obtained.

As described above, in this embodiment, the rotation angle of the main shaft of the impact type screw tightener main body is detected, and based on the detection result, the tightening shaft is measured by the measuring method shown in the second embodiment. The force is measured and the power source supplied to the drive means is controlled so as to achieve the target tightening axial force. Therefore, the tightening axial force generated on the bolt during impact screw tightening can be accurately measured for each impact, so that the screw tightening can be performed up to the target tightening force. Further, due to the dimensional variation of the members of the fastened part, the transition timing of the contact state between the above-mentioned seat surfaces, especially the transition timing from the state where the seat surfaces are not in contact to the state where they are in partial contact, The tightening axial force can be accurately measured even if the rotation angle after the seating of the bolt or nut set in the standard data deviates.

[0040]

As described above, according to the first aspect of the invention, in the case where the apparent rigidity of the body to be fastened, which is obtained in advance, changes as the fastening progresses, The tightening axial force is calculated based on the data on the relationship between the rotation angle after seating and the tightening axial force. The effect that the tightening axial force can be accurately measured over the entire range from when the tightening axial force starts to be generated to when the tightening is completed is obtained. Further, in the invention according to claim 2, the contact state between the bearing surfaces of the plurality of members of the fastening portion is determined from the rotation angle of the bolt or nut for each impact, and the above-mentioned "bolt or nut The data regarding the relationship between the rotation angle after seating and the tightening axial force is corrected, so that due to the dimensional variation of the members of the fastened part, the transition timing of the contact state between the seat surfaces, particularly, Even if the timing of transition from the state where the bearing surfaces are not in contact with the state where they are partially in contact deviates from the rotation angle after the seating of the bolt or nut set in the standard data, the tightening shaft The effect is that the force can be measured accurately. In the invention according to claim 3, the rotation angle of the main shaft of the impact type screw tightener main body is detected, and the tightening axial force is calculated by the calculating means according to claim 1 or 2 based on the detection result. By configuring so that the tightening axial force generated on the bolt during tightening the impact screw can be accurately measured for each impact. According to a fourth aspect of the invention, in the impact type screw fastening device according to the third aspect, the power source supplied to the drive means is controlled so as to realize a target fastening axial force. As a result, it is possible to obtain the effect that the screw tightening can be precisely performed up to the target tightening force while accurately measuring the tightening axial force for each impact.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing a calculation process in the first embodiment.

FIG. 3 shows “rotation angle and tightening axial force of a bolt or nut after seating” when the apparent rigidity recorded in the axial force data memory unit 123 changes as the fastening progresses. FIG.

FIG. 4 is a comparative characteristic diagram regarding the axial force measurement accuracy between the first embodiment and the comparative example (preceding example).

FIG. 5 is a block diagram of a second embodiment of the present invention.

FIG. 6 is a part of a flowchart showing a calculation process in the second embodiment.

FIG. 7 is another part of the flowchart showing the arithmetic processing according to the second embodiment.

FIG. 8 is a characteristic diagram showing a correction characteristic of “data on a relationship between a rotation angle of a bolt or a nut after seating and a tightening axial force”.

FIG. 9 is a comparative characteristic diagram regarding the axial force measurement accuracy between the second embodiment and the comparative example.

FIG. 10 is a block diagram of a third embodiment of the present invention.

FIG. 11 is a cross-sectional view when configured as an impact wrench using compressed air as a power source.

FIG. 12 is a part of a flowchart showing a calculation process in the third embodiment.

FIG. 13 is another part of the flowchart showing the arithmetic processing in the third embodiment.

FIG. 14 is a side view showing a fastening portion of a bush bracket type.

FIG. 15 is a schematic characteristic diagram showing the relationship between the tightening axial force F, the rotation angle θ _I of the nut for each impact, and the rotation angle θ _F after the nut is seated.

FIG. 16 is a cross-sectional view of an example of a conventional device.

FIG. 17 is a flowchart showing a calculation process in a conventional example.

FIG. 18 is an example diagram of a function showing a relationship between a torque-fastening force conversion coefficient and a fastening force used in a conventional example.

FIG. 19 is a block diagram showing the overall configuration of axial force measurement in the preceding example.

FIG. 20 is a cross-sectional view showing the configuration of a rotation angle detector 201 of a prior example.

[Explanation of symbols]

10 ... Impact wrench main body 15 ... Spindle 11 ... Torque detecting section 16 ... Air supply section 12 ... Shut off valve 17 ... Air passage 13 ... Air motor section 18 ... Main
Valve 14 ... Hydraulic pulse generator 19 ... Switching valve 20 ... Valve operating lever 25 ... Driving blade 21 ... Rotation switching lever 26a, 26b
... Detection coil 22 ... Rotation drive shafts 27a, 27b
... Groove row 23 ... Vane 28 ... Relief valve 24 ... Liner case 30 ... Control device 40 ... Impact wrench body 44 ... Rotation sensor 41 ... Rotation angle detection unit 50 ... Rotation angle detection unit 42 ... Disc 100 ... Impact type Screw tightener main body 121 ... Rotation angle signal processing unit 101 ... Rotation angle detection unit 122 ... Axial force calculation unit 102 ... Motor 123 ... Axial force data / memory unit 103 ... Impact torque generator 130 ... Calculation device 104 ... Spindle 132 ... Axial force calculation unit 105 ... Tightening socket 133 ... Axial force data / memory unit 110 ... Control device 140 ... Control device 120 ... Calculation device 145 ... Power control unit 201 ... Rotation angle detector 220 ... Impact screw tightener main body 202 ... Motor 231 Output shaft 203 Impact torque generator 241 Fastened body 204 Fastening portion 242 Bolt 211 ... socket 243 ... Nut 212 ... rotary encoder code wheel 213 ... rotary encoder detection head 214a ... first housing 214b ... second housing 244 ... bush 215 ... signal processing circuit 245 ... Bracket

Claims (4)

[Claims] 1. A rotation angle detecting means for detecting a rotation angle of an output shaft of an impact type screw tightening device or a socket portion for transmitting a pulsed torque generated in the output shaft to a bolt or a nut of a fastening portion. Based on the detection result of the rotation angle detection means, the rotation angle of the bolt or nut for each impact is set in advance "range between the seating determination upper limit rotation angle and the seating determination lower limit rotation angle"
Is determined as the sitting time, and the "rotation angle of the bolt or nut after sitting at the sitting time" is obtained in advance based on the "function of the rotation angle of the bolt or nut due to the impact at the sitting time". After that, the rotation angles of the bolts or nuts for each impact are sequentially added to detect the rotation angles of the bolts or nuts after seating, and the pre-determined apparent rigidity of the object to be fastened A calculation means for calculating the tightening axial force based on "data on the relationship between the rotation angle of the bolt or nut after seating and the tightening axial force" in the case of changing with progress, Measuring device for tightening axial force. 2. The tightening axial force measuring device according to claim 1, wherein the computing means determines a contact state between seating surfaces of a plurality of members of the fastening portion, based on a rotation angle of a bolt or a nut for each impact. , The seating surfaces are not in contact with each other, are partially in contact with each other, or are in complete contact with each other. A device for measuring a tightening axial force, characterized in that it is configured to correct the "data regarding the relationship between the rotation angle and the tightening axial force thereafter". 3. A drive means having a pulse component in the 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 rotation angle of the main shaft is detected. An impact type screw tightener main body having a rotation angle detection means, and a calculation means according to claim 1 or 2 for calculating a tightening axial force based on a detection result of the rotation angle detection means. Impact type screw tightening device characterized by that. 4. The impact type screw tightening device according to claim 3, wherein the power supplied to the drive means so as to realize a target tightening axial force based on the tightening axial force obtained by the computing means. An impact type screw tightening device comprising a control means for controlling a power source.