JPH0354011B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a long metal member that is applied to bending the axial direction of a long metal member such as an automobile door sash or a guide rail into a predetermined shape. The present invention relates to a method for correcting axial bending.

BACKGROUND ART Conventionally, as a means for correcting the bent state of a workpiece, a method is known that corrects the installation position of a door frame after brazing in the manufacturing process of a door subassembly with an automobile frame (in practice). 1986-
No. 92413).

This correction means uses a drive source to move the correction part at the door frame installation position to the measurement origin position at the start of work, stops it by detecting it with the measurement origin position detection sensor, and then moves the correction part at the correction part. The installation position of the door frame is measured by the attached position measurement sensor, the amount of bending of the door frame to be corrected is calculated based on this measurement signal, and the drive source of the correction section is operated according to the amount of bending, and the correction is performed. After straightening the door frame by pressing the door frame by the bending amount, the correction unit is returned to its original position, and the installation position measurement sensor measures the installation position of the door frame again, and the measurement signal is sent to the controller to move the next door. The amount of bending of the frame is calculated, and the correction section is moved in accordance with the amount of bending, thereby repeatedly operating the correction section until the amount of bending becomes zero.

By applying the correction means, for example, a door sash S for an automobile having a cross-sectional shape as shown in FIG. 15 and an axially bent shape as shown in FIG.
When correcting, fix the axis line part _S1 , and check whether the axis line part _S2 or _S3 extending from it is located on the plus side or minus side with respect to the predetermined bending shape reference point O, and whether this position is the 17th As shown in the figure, the extent to which the tolerance is exceeded is measured as initial data before starting work, and after moving the orthodontic part based on the measured data, the measurement origin and the current axis are measured. This means that the next amount of bending must be measured between the position S ₂ or S ₃ and the correction section must be operated repeatedly until the amount of bending reaches the target value of zero.

Problems to be Solved by the Invention However, when applying the above-mentioned correction means to axial bending members such as automobile door frames, a large amount of data is required since correction is performed from both the plus and minus sides of the correction target value. Not only is it difficult to handle, but the amount of bending must also be determined by taking into account variations in the material, type of workpiece, correction location, initial setting position, etc., resulting in unclear data. .

Means for Solving the Problems In the method for correcting axial bending of a long metal member according to the present invention, a long straight metal material is bent at a bending angle within a small range exceeding the standard bending angle. Alternatively, a metal member whose axis has been bent in one of a large range of bending angles that do not reach the reference angle is fixed at a predetermined portion that is not corrected, and the shaft end side in the extension direction is set so as to be freely deflectable. The area between the initial set position corresponding to either one of the axis bending angles and the predetermined position of the bending reference angle is divided into multiple sections, and the extension direction of the metal member is determined when starting the first straightening operation based on the divisions. The straightening part that supports the metal member confirms its position from the machine origin, which is the initial set position of the metal member, and according to this confirmed position, the first comparison part compares it with the straightening target value, which is the desired bending reference angle, and determines the straightening target. Determine the amount of initial correction for the value and the amount of addition of the correction amount associated with this, and further check the position of the correction part from the machine origin, which is the initial setting position of the metal member, when starting the second and subsequent correction operations. In the plurality of series after the second comparison section, a comparison is made with respect to the correction target value, a comparison is made with a plurality of coarse target values, and the amount of addition of the correction amount to each coarse target value is determined, and the fixation of the metal member is determined based on the determined value. The shaft end side extending from a predetermined portion is moved and deformed several times from one side facing the bending reference angle side, thereby correcting and bending the axial line of the metal member.

In addition, metal whose axis has been bent from a long straight metal material to either a small bending angle that exceeds the standard angle or a large range of bending angles that do not reach the standard angle. The member is fixed at a predetermined portion that will not be corrected, and the shaft end side in the extension direction is set so as to be freely deflectable, and the initial set position and the predetermined position of the bending reference angle are determined according to the bending angle of either axis of this metal member. When starting the first straightening operation based on the division, it is necessary to check the position of the straightening part that supports the extension direction of the metal member from the machine origin, which is the initial set position of the metal member. , In accordance with this confirmation position, the first comparison section compares the correction target value, which is the desired bending reference angle, and determines the initial correction amount and the accompanying correction amount addition amount with respect to the correction target value, and also determines the initial correction amount. and the sum of the additional amount of correction amount and the correction amount accompanying it, at least the sum of the initial correction amount and the additional amount of correction amount accompanying it is stored in the storage unit as the total of the initial correction amount, and from the second time onwards. When starting the straightening operation, the straightening section confirms the position from the machine origin, which is the initial set position of the metal member, and compares it with the straightening target value in multiple series from the second comparison section onwards, and compares it with the rough target value provided. and determine the addition amount of the correction amount for each coarse aim value, and also determine the comparison setting condition set closest to the machine origin among the plural coarse aim values set in the comparison parts after the second comparison part. The addition amount of the correction amount is added to the total amount of correction until the condition is satisfied, and it is stored again in the memory unit as the total amount of correction. When this condition is satisfied, the next step is to move to the machine origin side. A comparison setting condition that is closest to the previous comparison setting condition on the correction target value side than the set condition is compared, and an additional amount of correction amount smaller than the addition amount of the initial correction amount is set until that condition is satisfied. The addition amount of correction amount is added to the total amount of correction, and the addition amount of correction amount is stored again in the storage unit as the total amount of correction, and the addition amount of correction amount set in the first, second, or subsequent comparison section is used as the initial correction amount. Alternatively, the total amount of correction is sequentially added and stored in the storage unit, and the second
Every time the addition of the correction amount after the comparison part satisfies the comparison condition, the shaft end side extending from the fixed axis line part of the metal member is bent at a small value that gradually approaches the correction target value to the standard angle. The metal member is moved and deformed several times from the other side to correct and bend the axis of the metal member.

Function: In this method for correcting axial bending of a long metal member, a long straight metal material is axially bent in advance to a bending angle that is smaller or larger than the bending standard angle, and the correction deformation is performed only from one side. This not only simplifies the calculation and means for calculating the amount of correction, but also allows the amount of correction to be determined by dividing the area between the initial set position and the predetermined position of the bending reference angle into multiple sections, and determining the amount for each section. Based on the value, the shaft end extending from the shaft end extending from a fixed predetermined portion of the metal member is moved and deformed several times toward the bending reference angle, and furthermore, the shaft end side extending from the shaft end portion extending from the fixed predetermined portion of the metal member is deformed several times toward the bending reference angle. Therefore, each time it passes through a predetermined dimension division, the incremental correction amount is reduced and the movement and deformation is performed within a minute range, so that highly accurate axial correction can be performed.

Embodiments The following description will be made with reference to FIGS. 1 to 14.

This axial bend correction method is applied to the axial bending of long linear metal members such as automobile door frames and guide rails into a predetermined shape. For example, as shown in Fig. 1, this door sash is made of a long straight metal material with an axis extending left and right around the axis _S1 at the middle side.
It is manufactured by bending S ₂ and S ₃ using a bending machine (not shown). At that time,
With respect to a predetermined bending reference angle line O, bending angles β ₁ , β ₂ in a small range that exceed the reference angle α or in a large range that does not reach the reference angle α are combined into each axis line portion S ₂ , S ₃ is bent along the axis. According to this axial bending process, the axial line portion S ₂ is shown bent in a small range of bending angles β ₁ , β ₂ . 2
All parts other than the allowable range shown in the white part shown in the figure are extremely bent in the negative direction as indicated by diagonal lines.

For the metal member S that has been previously processed, the third to
By applying the straightening device shown in FIG. 5, the bending of the axial portion S ₁ or S ₂ is straightened. The straightening device sets the metal members S in the same position by aligning them with a reference point 1 attached to the axis S ₁ and with a mark attached at a certain length from the tip of the metal member S before bending the metal member S. The clamp 2 is equipped with a clamp 2 that clamps the metal member S, and the clamp 2 is capable of clamping the uncorrected axial line portion _S1 of the metal member S along the longitudinal direction using a drive cylinder 2a such as an air pressure or hydraulic pressure cylinder. ing. A drive mechanism section operated by a drive motor 3 such as a servo, pulse, or stepping motor is disposed at a position projecting from the set position to the left and right of the axial line portions S ₂ and S ₃ of the metal member S. A ball screw shaft 4 connected by a coupling ring 4a is rotated to move a correction unit table 6 in a predetermined direction along a guide rail 5. The ball screw shaft 4 is a cradle 4
The guide rail 5 is mounted by fixing and supporting the left and right ends on brackets 5a and 5b, respectively, or directly fixing it to a board with bolts. An actuator dog 6a for the origin and overrun prevention is provided on the side of the movement path of the correction unit table 6, and a pulse generator 7 is provided on the opposite side. This pulse generator 7 detects the amount of movement of the wire 7a, whose end is connected to a metal fitting 6b attached to the orthodontic table 6, as the amount of movement of the wire 7a is transmitted via the sliding piece 7b. The wire 7a is rotatably stretched and supported by grooved guide pieces 7c and 7d. Also, on the side equipped with the actuator dog 6a, an origin detection actuator 8 and an overrun prevention actuator 9a,
9b is provided. The correction unit 10 mounted on the table 6 is a metal member S as shown in FIGS.
The lower part of the thrust bearing _11a is designed to be able to swing freely around the axis of the cam follower ₁₁ fixed to the table 6. Set the cam follower 11 with the set bolts 11b, 11
It is attached to the orthodontic unit table 6 by fixing it with c. The correction unit 10 is provided with position detection sensors 12a and 12b such as a light emitter and a light receiver at the upper and lower ends of the vertical portion to detect the position of the metal member S. Further, the position of the holder 13 that supports the ball screw shaft 4 can be detected by processing the signal from the pulse generator 7.

Using this straightening device, after setting the metal member S by clamping the axial line part S1 with the clamp ₂ in alignment with the reference point 1, the axial line parts _S2 and _S3 are moved several times by the straightening part 10. By deforming, the bending is corrected to a predetermined reference angle line. In order to correct this, as shown in Fig. 6, there are multiple positions between the initial set position and the predetermined position of the bending reference angle, as shown in Fig. area of
A ₁ , A ₂ , A ₃ ...A _o (hereinafter abbreviated as "AV value")
For each category, the initial correction amount (hereinafter referred to as
It is abbreviated as “BV value”. ), and also set the rough aim values C ₁ , C ₂ , C ₃ ... (hereinafter abbreviated as "CV values") starting from the one closest to the mechanical origin.
The correction amount is set by decreasing the added value of the correction amount little by little as the value is passed one step at a time. however,
The CV value is set in the (±) direction of the upper or lower target value detected by the position detection sensor 12a, 12b, and when it is within the (±) range, the CV value is not applied. As shown in Fig. 7, the predetermined value of the bending reference angle (hereinafter referred to as the "correction target value") is set as AV value → A ₁₂ , and as shown in Fig. 6, the CV value is When the axis line portions S ₂ and S ₃ are bent in the positive direction, that is, the tolerance value for over-correction = C ₃ - A ₁₂ , and when the axis portions are bent in the negative direction, the tolerance value for under-correction =
Set so that C ₂ − A ₁₂ . Further, an increase in the amount of correction is set for each of the set BV values (hereinafter abbreviated as "BVD value"). Also, set the amount of correction increase for each CV value (hereinafter,
It is abbreviated as "DV value". ). At this time, the BVD value is greater than the DV value, and the DV value is set to a larger value as the corresponding CV value approaches the origin, and a smaller value as the corresponding CV value approaches the correction target value. These AV, BV,
When the BVD, DV, and CV values are organized, they can be expressed as a line graph as shown in Figure 7, which is used as correction data. When using this correction data, the axis line portion S ₂ of the metal member S is determined based on the mechanical origin confirmation position by the origin detection actuator 8
When comparing the positional relationship between the position of S ₃ detected by sensors 12a and 12b and the correction target value,
Two series are set: a comparison section based on AV values and a comparison section based on CV values.

The operating system is shown in Figure 8. Prior to the first correction, before starting the comparison using the AV value, it is determined whether it is the first time or the second time or later, and it is determined whether the comparison is based on the AV value or the CV value. select. When the correction unit 10 starts moving from the origin and comes into contact with the metal member S, the position detection sensors 12a and 12b detect the axis portions S ₂ and S ₃ (hereinafter abbreviated as "FRC"), and the position is detected. Memorize it and move on to the comparison section. The comparison section determines whether it is the first comparison or the second or later comparison, compares and selects the AV value (or CV value), and prevents in advance the over-correction of the correction target value that occurs when the metal member is corrected. If this comparison operation does not satisfy A ₁ ≧ FRC, then A ₂ ≧
FRC, &A ₃ ≧FRC…Proceed sequentially. Furthermore, if it is satisfied, the AV value comparison section stores the fact that it has passed the first time and sets a flag. At this time, FRC
is in a positional relationship that satisfies the AV value A _K-1 <FRC≦A _K , so the corresponding initial correction amount BV value is selected. In addition, from the second time onward, the amount of correction will be added in order to advance the correction toward the CV value of C ₁ .
Select BVD value. In this way, the correction amount is determined including the initially set correction amount. That is,
A _K-1 <FRC≦A Correction amount for FRC satisfying the A _K category = (BV value) + (FRC) + (correction amount) is determined. The calculation result is stored as a summation and further preset. Furthermore, the movement of the correction section 10 is constantly checked via the pulse generator 7, and the drive motor 3 continues to operate up to the preset value. When the moving distance reaches the preset value by this operation, the drive motor 3 is stopped and after a short period of time, the return operation is started. At this time, a counter that stores the position of the correction section 10 is configured to count up in the correction direction and count down in the return direction. When the position detection sensors 12a and 12b detect that the correction part 10 has separated from the axial line portions _S2 and _S3 of the metal member S, the return operation is stopped and after a short period of time, the movement in the correction direction is started again. . Along with this, the counter that stores the position of the correction section 10 starts to count up.

Note that since the correction unit 10 can swing freely relative to the correction unit table 6, the metal member S is moved while maintaining a certain line or surface contact with the metal member S while the correction unit table 6 is moving forward or backward. Follow.
Therefore, the correction section 10 can apply a stable correction force to the metal member S during operation.

In the second and subsequent corrections, the position detection sensor 12
When a and 12b sense the axial line portions S ₂ and S ₃ of the metal member S, they memorize the position (FRC) and select a comparison portion. Since the flag is set the first time the selection is made, it can be determined based on that flag. 2
In the first time, the comparison with the CV value is started, and if the condition is satisfied with C ₁ ≧ FRC, it is selected in the first time.
The BVD value is added to the previous total (calculation result) and saved again as a total. Also, 2
In the subsequent correction operations, the increments of the correction amount for the BVD value selected at the first time are sequentially added until the conditions are no longer met toward the CV value _C1 . Therefore, instead of changing the correction amount to directly approach the correction target value (AV value A ₁₂ ), by proceeding with the correction operation toward the CV value C ₁ which is the rough correction target value, Even if there are variations in the material or properties, variations in the cross-sectional shape, variations from the processing process, etc., and the correction results for the correction amount include variations from uncertain factors, C can be achieved without exceeding the tolerance. ₁ <FRC≦C It becomes possible to obtain sufficient dimensional and positional relationships to satisfy the condition ₂ .
Incidentally, the increase or decrease in the amount of correction due to variations in the material or characteristics of the metal member is set as a coded correction amount using an external converter, thumb switch, etc., and this is used as the calculation element when calculating the initial amount of correction. By using it as ) can be avoided without major replacement.

If the previous correction operation satisfies the condition C ₁ < FRC ≦ C ₂ , subsequent comparisons are made with the CV value C ₂ , and if the condition is satisfied, the increase in the amount of correction is
By selecting an increment DV value smaller than the BVD value corresponding to the CV value, the correction amount becomes (DV value) + (total sum). Also, after that, FRC has C ₂ ≧
Since the DV value is added until the FRC condition is no longer met, the change in the amount of correction becomes as shown in FIG. 9. If the result does not meet the condition of C ₂ ≧FRC, then it will be compared with the CV value C _3.As shown in Figure 8, if the condition of C ₂ <FRC≦C ₃ is satisfied. is OK, and FRC>C ₃
In this case, the positive tolerance is exceeded, so it is rejected. Therefore, C ₂ of the CV value represents a tolerance in the negative direction, and C ₃ represents a tolerance in the positive direction. Furthermore, as shown in Fig. 10, if CV values are divided into several rough target values (c ₁ ≧, c ₂ ≧,
c ₃ ≧, c ₄ ≧), it is possible to change it little by little as it approaches the correction target value, so that the correction accuracy can be maintained sufficiently against variations in many conditions that the metal member S includes. In this case, the operation system diagram shown in FIG. 8 becomes the operation system diagram as shown in FIG. 11 since the comparison section based on the CV value is expanded.
Moreover, the AV, BV, BVD, DV, and CV values at that time are as shown in FIG. In addition, the operation system diagram shown in Fig. 13 can be applied as an example of using the CV value, which is a rough aim value, for the purpose of improving accuracy.
In this example, the width of the rough aim value and the addition amount are adjusted to gradually reduce the relationship between the coarse aim value classification and the addition amount, similar to the slope down method used in speed control, so that the correction aim value is approached. Furthermore, the AV value _A13 is used as the tolerance in the positive direction. At this time, the DV and CV values (other relationships remain unchanged) are set as shown in FIG. 14. In this way, the accuracy of the correction target value can be further ensured and the accuracy can be doubled, and at the same time, the X-Y axis relationship shown in Fig. 7, which can occur due to small variations in materials and characteristics within the same lot, can be improved. This will allow stable correction results to be obtained by fully absorbing changes in

In addition, although the above-mentioned embodiment explained only the linear correction operation, at the same time as the correction operation starts, the bar or clamp part that partially supports the metal member is moved upward or downward so as to apply surface pressure to the planar correction area. The surface shape can also be corrected by setting it closer to the side and controlling the surface pressure by making it guideable during the linear correction operation and controlling the movement in the vertical direction in accordance with the linear correction operation.

Effects of the Invention As described above, according to the method for correcting axial bending of a long metal member according to the present invention, even if the metal member has variations due to uncertain factors, the correction can be performed with sufficient accuracy. The axial part of the metal member to be corrected is pre-bent to one of the axial bending angle ranges with respect to the bending standard angle, so the correction data can be easily set, and the correction data can also be used to change the target value. By moving it in parallel in a positive or negative direction, it can be partially used as correction data for other objects to be corrected, ie, metal members, so that work efficiency can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the axially bent shape of a metal member to be straightened by the method according to the present invention, FIG. 2 is a bar graph showing the distribution of the super-extended axially bent metal member,
Fig. 5 is an explanatory diagram of a correction device that implements the method according to the present invention, Fig. 6 is an explanatory diagram showing in a diagram the setting conditions of correction data used in the method according to the present invention, and Fig. 7 is an explanatory diagram based on the correction data. A line graph showing the amount of correction several times in succession, Fig. 8 is an explanatory diagram showing a flowchart of the calculation operation based on the same data, Fig. 9, 1
Figure 0 is an explanatory diagram showing the amount of deformation due to correction in a minute range in strokes, Figure 11 is an operation system diagram showing only the expansion part when the CV value comparison part is expanded, and Figure 12 is an illustration of the operation system shown in Figure 11. An explanatory diagram that graphically shows the AV, BV, BVD, DV, and CV values when using the operation system diagram shown in Figure 13. Figure 13 is a modified example of the CV value comparison section for the purpose of improving accuracy. Fig. 14 is an explanatory diagram that graphically shows the DV and CV values (assuming no change in other relationships) when the operating system diagram shown in Fig. 13 is used, and Fig. 15 is a long diagram. 16 is an explanatory diagram showing the axial bending shape of the metal member corrected by the conventional method, and FIG. 17 is a bar showing the uneven distribution of axial bending that occurs in the same metal member. It is a line graph. S: Metal member, S ₁ : Axis line part to be set for positioning, S ₂ , S ₃ : Axis line part to be corrected and bent, α: Bending reference angle, β ₁ , β ₂ ...: Bending angle within the range exceeding or not reaching the reference angle .

Claims (1)

[Scope of Claims] 1.A long straight metal material is bent with respect to the reference angle, and the axis is either within a small range of bending angles exceeding the reference angle or within a large range of bending angles that do not reach the reference angle. The bent metal member is fixed at a predetermined portion that is not straightened, and the shaft end side in the extension direction is set so as to be freely deflectable, and the initial set position and bending standard are determined according to the bending angle of either axis of this metal member. When starting the first straightening operation based on the division, the straightening part that supports the extending direction of the metal member is divided into a plurality of sections between the predetermined position of the angle and the initial set position of the metal member, which is the machine origin. The position is confirmed, and in accordance with this confirmed position, a first comparison unit compares it with a correction target value which is a desired bending reference angle, and determines the initial correction amount and the accompanying addition amount of the correction amount with respect to the correction target value, Furthermore, when starting the second and subsequent straightening operations, the straightening section confirms the position from the machine origin, which is the initial set position of the metal member, and compares it with the straightening target value in multiple series starting from the second comparison section. Comparison with the prepared rough aim value and determining the addition amount of correction for each rough aim value, and bending the shaft end side extending from a fixed predetermined part of the metal member based on the determined value, one side facing the reference angle side. A method for correcting axial bending of a long metal member, characterized in that the axial line of the metal member is corrected and bent by moving and deforming the metal member several times. 2. A patent in which the axial portion of the metal member to which it is fixed is set above or below the set position of the other axial portions, and the surface shape is also corrected in accordance with the linear shape correction operation of the metal member. A method for correcting axial bending of a long metal member according to claim 1. 3. A patent claim in which a metal member whose axis has been bent to one of the above bending angles is fixed at the axis line portion serving as the intermediate side, and each of the shaft end sides extending left and right of the metal member is separately corrected. range 1
A method for straightening an axial line curve of a long metal member as described in 2. 4 A metal member whose axis is bent from a long straight metal material to either a small bending angle that exceeds the standard bending angle or a large bending angle that does not reach the standard angle. is fixed at a predetermined portion that is not corrected, and the shaft end side in the extension direction is set so as to be freely deflectable, and the initial set position and the predetermined position of the bending reference angle are determined according to the bending angle of either axis of this metal member. When starting the first straightening operation based on the division, the position of the straightening part that supports the extension direction of the metal member from the machine origin, which is the initial set position of the metal member, is confirmed, and this In accordance with the confirmation position, the first comparison section compares the correction target value, which is the desired bending reference angle, and determines the initial correction amount and the accompanying correction amount addition amount to the correction target value, and also determines the initial correction amount and the corresponding addition amount. Of the sum of the additional amount of correction amount and the amount of correction, at least the sum of the initial correction amount and the additional amount of correction amount accompanying it is stored in the storage unit as the total of the initial correction amount, and the second and subsequent correction operations are performed. When starting, the straightening section confirms the position from the machine origin, which is the initial set position of the metal member, and performs comparison with the straightening target value, comparison with the plurality of coarse target values, and each rough Determine the amount of addition of the correction amount to the target value, and compare it with the comparison setting condition set closest to the machine origin among the plural coarse target values set in the comparison units after the second comparison unit, and determine the condition. The addition amount of correction amount is added to the total amount of correction until the above condition is satisfied, and the addition amount of correction amount is added to the total amount of correction and is stored again in the storage unit. When the above condition is satisfied, the next condition set on the machine home side is The correction target value side is also compared with the comparison setting condition that is closest to the previous comparison setting condition, and until that condition is satisfied, an additional amount of correction amount that is smaller than the addition amount of the initial correction amount is set, and the total amount of correction is Add the additional amount of correction amount to and store it in the storage unit again as the total amount of correction, and add the additional amount of correction amount set in the first, second or subsequent comparison section to the initial amount of correction or the total amount of correction. is sequentially added to and stored in the storage unit, and the
Every time the addition of the correction amount after the comparison part satisfies the comparison condition, the shaft end side extending from the fixed axis line part of the metal member is bent at a small value that gradually approaches the correction target value to the standard angle. A method for correcting axial bending of a long metal member, characterized in that the axial line of the metal member is corrected and bent by moving and deforming the metal member several times from one side. 5. Set the increase or decrease in the correction amount due to variations in the material or characteristics of the metal member as a signed correction amount encoded with an external converter, thumb switch, etc.
5. A method for correcting axial bending of a long metal member as claimed in claim 4, wherein this is used as a calculation element when calculating the initial correction amount to correct changes in the correction amount. 6 A patent in which the axial portion of the metal member to which it is fixed is set above or below the set position of the other axial portions, and the surface shape is also corrected in accordance with the linear shape correction operation of the metal member. A method for correcting axial bending of a long metal member according to claim 4. 7. A patent claim in which a metal member whose axis has been bent to one of the above bending angles is fixed at the axis line portion that is the intermediate side, and each of the shaft end sides extending left and right of the metal member is separately corrected. range 4th
A method for correcting axial bending of a long metal member as described in 2.