JP4513240B2 - Shaft correction device for shaft workpiece - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for correcting distortion of an axial workpiece, and more particularly to an apparatus for correcting distortion of an axial workpiece by pressing.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is known a technique for correcting distortion by pressing with a press amount corresponding to the amount of distortion when distortion occurs in an axial work, for example, a power steering rack shaft of an automobile. For example, if distortion is found in the shaft-like workpiece, press with the amount of press specified by the amount of distortion, and if the correction is still insufficient even after pressing,
Next press amount = previous press amount × (100 + addition rate) / 100
A technique is known in which the next press amount is calculated and the distortion is corrected by pressing again with this press amount. If there is excessive correction after pressing, that is, distortion occurs in the reverse direction, generally the next press amount = the previous press amount × (100−subtraction ratio) / 100
The press amount is calculated by the above, and the press amount is corrected by pressing. Here, the addition rate and subtraction rate in the above equation are constants experimentally determined in advance.
[0003]
[Problems to be solved by the invention]
As described above, in the prior art, when the correction is insufficient or excessive, the addition rate and subtraction rate used to determine the next press amount are predetermined values, and the distortion of the shaft-shaped workpiece before and after pressing changes. Therefore, the shaft workpiece characteristics and correction history are not reflected in the next press amount, and as a result, the number of presses required to complete the correction by keeping the strain amount within the allowable range is not too small. was there.
[0004]
Of course, it is theoretically possible to obtain a relationship between the strain amount and the press amount in advance for each material and shape of the shaft work in which the strain has occurred, and press using this relationship. There is a problem in that it is necessary to collect data on the sample, and the memory capacity for storing all these relationships also increases.
[0005]
The present invention has been made in view of the above-described problems of the prior art, and its purpose is to reflect the work characteristics and correction history in the press amount, thereby determining the optimal press amount, and reducing the press. An object of the present invention is to provide an apparatus capable of correcting the distortion of an axial workpiece by the number of times.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides means for detecting a strain amount of a shaft-shaped workpiece, calculation means for calculating a press amount for correcting the strain according to the strain amount, and the calculated press amount. Means for pressing the shaft-shaped workpiece at a second press amount for the shaft-shaped workpiece, the amount of strain before and after the first press in the calculation means and a predetermined amount for the shaft-shaped workpiece. It is calculated by using the elastic deformation amount . By using the ratio of the strain amount before and after the press, it becomes possible to calculate the press amount in consideration of the characteristics of the shaft workpiece or the past correction history, and the strain can be corrected efficiently by performing a more appropriate press.
[0007]
Here, when the calculation means is insufficiently corrected after the first press,
[Expression 1]
Press amount = elastic deformation amount + [{ pre-press strain amount / (pre-press strain amount−post-press strain amount) } × (first press amount−elastic deformation amount) ] × constant (1)
It is preferable to calculate the next press amount using the calculation formula defined in (1). The amount of elastic deformation is a value unique to the shaft-like workpiece, and (the first press amount−the amount of elastic deformation) indicates the amount of deformation generated in the shaft-like workpiece beyond the elastic deformation, that is, the amount of plastic deformation. The amount of plastic deformation is corrected by the ratio before and after pressing, which is the ratio before and after pressing / (the amount of strain before pressing−the amount of strain after pressing). The amount that was insufficiently corrected can be further corrected with an appropriate press amount.
[0008]
Further, when the calculation means is insufficiently corrected after the second and subsequent presses,
[Expression 2]
Press amount = previous press amount × {100+ (addition rate × post-press strain amount / pre-press strain amount)} / 100 (2)
It is preferable to calculate the next press amount using the calculation formula defined in (1). By correcting the addition rate by the post-press strain rate / pre-press strain rate, which is the ratio before and after pressing, it becomes possible to press in consideration of the characteristics of the shaft workpiece or past correction history, and press until the correction is completed The number of times can be reduced as a result.
[0009]
Further, when the calculation means is overcorrected after the previous press,
[Equation 3]
Press amount = elastic deformation amount + [{ post strain amount / (pre press strain amount + post strain amount) } × (previous press amount−elastic deformation amount) ] × constant (3)
It is preferable to calculate the next press amount using the calculation formula defined in (1). The amount of elastic deformation is a value unique to the shaft-shaped workpiece, and (previous press amount−elastic deformation amount) indicates the deformation generated in the shaft-shaped workpiece beyond the elastic deformation, that is, the amount of plastic deformation. By correcting this plastic deformation amount by the post-press strain ratio ((pre-press strain amount + post-press strain amount), which is the ratio before and after pressing, and adjusting the increase / decrease by a constant and adding it to the elastic deformation amount, The excessive correction can be further corrected with an appropriate press amount.
[0010]
Further, the present invention provides means for detecting the amount of strain of the shaft-shaped workpiece, calculation means for calculating a press amount for correcting the strain in accordance with the strain amount, and the shaft-shaped workpiece with the calculated press amount. Means for pressing, and the amount of pressing is calculated using a workpiece hardness calculated from a distortion amount before and after pressing and a return amount from a lower end position to a spring-back position in the previous press. Features.
[0011]
As described above, by detecting the hardness of the workpiece and determining the press amount based on the workpiece hardness, an appropriate correction press can be performed even when the variation of the workpiece is large.
[0012]
Further, when the correction is insufficient after the previous press, the calculation means calculates the workpiece hardness = previous return amount = previous press amount− (current strain amount−previous strain amount) / 2, and the correction is excessive after the previous press. In some cases, it is preferable to calculate the workpiece hardness = the previous return amount = the previous press amount− (current distortion amount + previous distortion amount) / 2.
[0013]
Further, it is preferable that the calculating means calculates the next press amount by pressing amount = arbitrary constant × previous return amount + arbitrary constant × current distortion amount.
[0014]
Thus, by setting the workpiece hardness as the previous return amount, the workpiece hardness can be measured based on the amount of distortion caused by the previous press, and the next press amount can be determined according to the measurement result.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 shows the overall configuration of a distortion correcting device for a shaft-like workpiece according to this embodiment. An axial work 10 such as a power steering rack shaft is appropriately rotated around its central axis by a rotating mechanism 12 such as a roller. A press receiver 16 is disposed below the shaft-shaped workpiece 10, the shaft-shaped workpiece 10 is supported by the press receiver 16, and a predetermined portion is pressed by the press machine 14 to correct distortion. The amount of distortion of the shaft workpiece 10 is detected by the detector 20, and the detected amount of distortion is supplied to the CPU 22. The CPU 22 calculates the next press amount based on the strain amount supplied from the detector 20. Then, a drive signal is output to the press control unit 18 based on the calculated press amount. The press control unit 18 drives the press machine 14 based on the drive signal supplied from the CPU 22 and presses the shaft-shaped workpiece 10 with the instructed press amount.
[0017]
The CPU 22 may control the operation of the rotating mechanism 12 in addition to controlling the operation of the press control unit 18. The CPU 22 may rotate the shaft-shaped workpiece 10, detect the distortion amount by the detector 20, and the shaft-shaped workpiece by the press machine 14. It is preferable to collectively control the press to 10.
[0018]
FIG. 2 shows a processing flowchart in the present embodiment. First, the rotating workpiece 12 rotates the shaft-shaped workpiece 10 around the central axis at a predetermined speed, and the amount of distortion (amount of shake) at this time is detected by the detector 20. Hereinafter, an operation for measuring distortion (vibration) generated when the shaft-like workpiece 10 is rotationally driven is referred to as dynamic measurement (S101). The distortion amount detected by the detector 20 is supplied to the CPU 22, and the CPU 22 determines whether or not the detected distortion amount (shake amount) is within a predetermined allowable range (S102). When the detected distortion amount is within the predetermined allowable range, the distortion correction process is terminated with no problem in the shaft-like workpiece 10.
[0019]
On the other hand, if the detected distortion amount exceeds the allowable range, it is determined that distortion correction is necessary, and the process proceeds to the subsequent processing. That is, when it is determined that the strain exists, the CPU 22 outputs a drive signal to the press control unit 18 to perform the first press in a direction to reduce the strain, and the strain of the axial workpiece 10 is reduced. Correction is made to some extent (S103). This amount of press is obtained by, for example, pressing a plurality of axial workpieces having various amounts of distortion with various amounts of press, experimentally determining the amount of press with the smallest amount of strain, This relationship can be determined by storing the relationship in a table or the like and referring to this table.
[0020]
FIG. 3 shows the relationship between the strain amount and the press amount used when determining the first press amount. For example, if the distortion amount is α in the figure, the press amount for correcting this is determined to be β. Note that the relationship shown in FIG. 3 may be stored in the memory of the CPU 22 in a table format, or may be stored in the memory in a function format.
[0021]
Returning to FIG. 2 again, the pressing amount is determined as described above, and after the first pressing, the shaft-like workpiece 10 is rotated to perform dynamic measurement again (S104). In the dynamic measurement, the shaft-like workpiece 10 is rotated around the central axis by the rotation mechanism 12, and the amount of distortion (or the amount of deflection) at that time is measured. Then, the CPU 22 compares the measurement result with a predetermined allowable value (S105), and if it is within the allowable range, determines that the distortion has been corrected by the first press, that is, the press in S103, and ends the correction work. On the other hand, if it is determined as a result of the dynamic measurement that it is not within the predetermined allowable range, that is, the distortion is not corrected (if the table shown in FIG. 3 is accurate, the correction is completed in one press. However, the characteristics of the shaft-shaped workpiece are various, and therefore it is not uncommon for a limited table to fit within the allowable range with a single press. The CPU 22 uses the algorithm described later to determine the next press amount (indentation). Amount) is calculated (S106). And it presses with the calculated new press amount, repeats the process after S103 again, and finally puts the dynamic distortion amount in the predetermined tolerance.
[0022]
FIG. 4 shows a detailed flowchart of the press amount (push-in amount) calculation process in S106 of FIG. First, the CPU 22 determines whether the first press is under-corrected or over-corrected when the amount of dynamic distortion is outside the predetermined allowable range (S201). Specifically, this determination is determined as insufficient correction when the strain directions before and after pressing are the same direction, and excessive correction when the directions are opposite to each other. Then, in the case of insufficient correction, the CPU 22 determines whether or not it is the first correction after the next determination of insufficient correction or excessive correction (the second press if the press in S103 is included). (S202). In the case of the first correction press, that is, the second press, the next press amount is calculated based on the following formula (1).
[Expression 4]
Press amount = elastic deformation amount + [{ pre-press strain amount / (pre-press strain amount−post-press strain amount) } × (first press amount−elastic deformation amount) ] × constant (1)
Here, the elastic deformation amount is the elastic limit deformation amount of the shaft-like workpiece 10 and is determined experimentally. The amount of distortion before press is the amount of distortion that occurred in the shaft-like workpiece 10 before the previous press, that is, the first press performed in S103, and the strain after press is the axial shape that occurs immediately after the first press. The distortion amount and constant of the workpiece 10 are predetermined correction coefficients. The elastic modulus, pre-press strain amount, post-press strain amount, and constants are stored in the memory of the CPU 22, and the CPU 22 calculates the press amount using these.
[0023]
If it is not the first correction press, that is, if it is the second or subsequent correction press (including the press of S103, the number of presses is the third or subsequent press), the CPU 22 uses the following equation (2) to calculate the next time. Calculate the amount of press.
[Equation 5]
Press amount = previous press amount × {100+ (addition rate × post-press strain amount / pre-press strain amount)} / 100 (2)
Here, the addition rate is a predetermined value experimentally determined as in the prior art, the post-press strain amount is the strain amount of the shaft-like workpiece 10 generated immediately after the previous press, and the pre-press strain amount is that of the previous press. This is the amount of distortion of the shaft-like workpiece 10 that has occurred before performing. The previous press amount, addition rate, post-press strain amount, and pre-press strain amount are all stored in the memory of the CPU 22, and the CPU 22 reads these values from the memory and calculates the press amount according to the above equation.
[0024]
On the other hand, if it is determined in S201 that there is excessive correction, the CPU 22 calculates the next press amount by the following equation (3).
[Formula 6]
Press amount = elastic deformation amount + [{ post strain amount / (pre press strain amount + post strain amount) } × (previous press amount−elastic deformation amount) ] × constant (3)
Here, the amount of elastic deformation is the same as the equation (1), the amount of strain after pressing is the amount of strain of the shaft-like workpiece 10 that occurs immediately after the previous press, and the amount of strain before pressing occurs before the previous pressing. The distortion amount and the constant are predetermined correction coefficients.
[0025]
Comparing the formula (2), which is a corrected press amount calculation formula in the case of insufficient correction, with the conventional calculation formula, in the formula (2) in the present embodiment, the addition rate is corrected using the ratio of the strain amount before and after pressing. There is a feature in the point. That is, in the past, the addition rate is used as it is, but in the present embodiment, instead of using a fixed addition rate as in the past, the addition rate × post-press strain amount / pre-press strain amount The addition rate is adjusted in consideration of the correction history in the shaft-like workpiece 10, and the next press amount is calculated. As a result, for the shaft-like workpiece 10 whose distortion has been greatly improved after pressing, the next press amount is also reduced by that amount, and correction that matches the characteristics of the shaft-like workpiece 10 becomes possible.
[0026]
By the way, it is conceivable to use equation (2) for the first correction press amount calculation. However, when the distortion is corrected to a considerable extent by the process of S103 in FIG. 2, that is, the first press, the post-press distortion amount / pre-press distortion amount, which is the ratio of the distortion amount before and after the press, is minimized, and as a result There is a possibility that the addition rate will be greatly reduced and the value of the next press amount will become smaller, and sufficient correction cannot be made. Therefore, in the present embodiment, the expression (2) is used for the second and subsequent correction press calculations, and the expression (2) is used for the first correction press amount, that is, the press immediately after pressing in S103. Instead, the press amount is optimized by using the formula (1). In equation (1), the amount of elastic deformation is calculated experimentally, and (first press amount−elastic deformation amount) means the amount of plastic deformation caused by the first press. That is, equation (1) means that the next press amount is calculated as the amount of elastic deformation of the shaft-like workpiece 10 plus the amount of plastic deformation at a ratio that takes into account the past correction history. . The formula (3) is the same as the formula (1). However, the ratio representing the past history is the amount of distortion after pressing / (the amount of distortion before pressing + the amount of distortion after pressing) in consideration of the fact that the amount of distortion is reversed due to excessive correction. Note that the amount of distortion is an absolute value.
[0027]
FIG. 5 shows the result of correcting the distortion of the axial workpiece 10 by the algorithm described above. In the figure, the horizontal axis represents the number of presses, the vertical axis represents the number of data (%), and shows a histogram of the number of presses until the strain amount falls within a predetermined allowable range. In the figure, reference numeral 100 is a histogram when corrected by the algorithm according to the present embodiment, and reference numeral 200 is a histogram corrected by a conventional method. The conventional method may require about 15 presses, but with the algorithm of this embodiment, the correction is completed within 5 presses, which is more efficient with fewer presses than the conventional method. Indicates that a fix has been made.
[0028]
Thus, in this embodiment, since the next press amount is determined in consideration of the characteristics of the shaft-like workpiece 10 or the correction history, correction can be performed with a more appropriate press amount, and the number of presses can be reduced in a short time. In addition, the distortion of the shaft-like workpiece 10 can be corrected.
[0029]
In the present embodiment, the next press amount is calculated based on the above formulas (1) to (3), but the applicant of the present application also obtains a result of correction using another calculation algorithm. ing. For example, in addition to the formula (2) as a calculation formula used in the case of insufficient correction last time,
[Expression 7]
Press amount = previous press amount × (100 + addition rate) / 100 × post-press strain / pre-press strain (4)
Or [Equation 8]
Press amount = press amount of S103 × (100 + addition rate) / 100 × post-press strain amount / pre-press strain amount (5)
However, it has been confirmed that both are not as effective in reducing the number of presses as the formula (2).
In addition, in the case of excessive correction, in addition to equation (3),
Press amount = elastic deformation amount + [{ pre-press strain amount / (pre-press strain amount + post strain amount) } × (previous press amount−elastic deformation amount) ] × constant (6)
Or [Equation 10]
Press amount = elastic deformation amount + [{ pre-press strain amount / (pre-press strain amount + post-strain amount) }} × (press amount of S103−elastic deformation amount) ] × constant (7)
However, it has been confirmed that there is no effect of reducing the number of presses as much as the expression (3).
[0030]
Thus, in the above-described embodiment, efficient correction was performed by calculating the press amount based on the distortion rate before and after pressing.
[0031]
However, in such correction, there is a problem that it may take a long time to correct the press when the property of the workpiece deviates significantly from the correction curve. In the above-described embodiment, the variation of individual workpieces is expressed by separating the elastic deformation amount of the workpiece and the plastic deformation amount, but since elastic deformation is handled by a constant (set value), It is thought that the variation of the work is not fully expressed.
[0032]
In the present embodiment, the return amount in the previous press is obtained as the hardness of the workpiece, and the next press amount is determined based on the return amount, thereby providing a correction that can cope with a large variation in the workpiece.
[0033]
FIG. 6 shows a process flowchart in the present embodiment. First, the shaft-like workpiece 10 is rotated around the central axis at a predetermined speed by the rotating mechanism 12, and dynamic measurement is performed in which the detector 20 detects the amount of distortion (amount of shake) at this time (S201). The distortion amount detected by the detector 20 is supplied to the CPU 22, and the CPU 22 determines whether or not the detected distortion amount is within a predetermined allowable range (S202). When the detected distortion amount is within the predetermined allowable range, the distortion correction process is terminated with no problem in the shaft-like workpiece 10.
[0034]
On the other hand, if the detected distortion amount exceeds the allowable range, it is determined that distortion correction is necessary, and the process proceeds to the subsequent processing. That is, if it is determined that there is distortion, the CPU 22 performs a correction press based on the distortion amount and the correction press amount shown in FIG. 3 (S203). Then, the corrected distortion amount is dynamically measured (S204), and it is determined whether or not the distortion amount is within an allowable range (S205). If the determination in S205 is YES, the process ends.
[0035]
On the other hand, if the determination in S205 is NO, it is determined whether the number of presses is equal to or less than a preset set value (S206). If it is equal to or less than the set value, it is determined that the correction process is not performed well, it is determined that the correction cannot be performed (S207), and the process ends.
When it is determined that correction is not possible, it is preferable to output a message to that effect.
[0036]
If the determination in S206 is NO, the press amount is corrected (S208), and the correction press is performed with the corrected press amount by returning to S203.
[0037]
Thus, according to the present embodiment, in S208, the corrected press amount is corrected according to the hardness of the workpiece, and the next press amount is determined. This will be described below.
[0038]
First, when the amount of strain does not fall within a predetermined value (standard) at the previous press, the CPU 22 calculates the hardness of the workpiece from the amount of strain before and after the previous press and the previous press amount. And this work hardness is the last press shortage,
Work hardness = previous return amount = previous press amount-(current strain amount-previous strain amount) / 2
Calculated by
In case of excessive press at the previous time,
Work hardness = previous return amount = previous press amount-(current distortion amount + previous distortion amount) / 2
Calculate with
[0039]
That is, in FIG. 7, at the end of pressing, the workpiece springs back from the lower end of the press head 14 to the corrected position. This amount is the previous return amount, which is defined as the workpiece hardness. Then, at the next press, unless the press is performed with a stroke larger than the previous return amount (below the lower end of the press at the time of the previous correction), plastic deformation does not occur and the distortion is not corrected.
[0040]
Therefore, in consideration of the elastic deformation and plastic deformation of the workpiece, the press amount at the next press is determined using the following equation.
(When the previous press was insufficient)
Next press amount = α × previous return amount + β × current distortion amount (when the previous press is excessive)
Next press amount = γ × previous return amount + δ × current distortion amount Here, α, β, γ, and δ are arbitrary constants and differ depending on the vehicle type and shape. It is necessary.
[0041]
Thus, the press correction amount can be determined so as to obtain a desired plastic deformation in consideration of the work hardness (previous return amount). Therefore, even when the workpiece has a large variation, it is possible to perform an appropriate correction press on the workpiece and perform an effective correction press.
[0042]
FIG. 8 shows the results of the press count in the above-described embodiment and this embodiment.
In this example, four press counts were set as the maximum number, and the probability of completion of correction in the four presses could be increased from 81% to 97%. Also, the average number of places could be reduced from 2.5 to 2.0.
[0043]
Further, in the present embodiment, the description has been given by taking the rack shaft of the vehicle power steering as an example of the shaft-like workpiece 10, but the present invention is not limited to this, and for example, the rear shaft of the power steering rack shaft, pinion, and axle In addition, the present invention can be applied to distortion removal of an arbitrary shaft-like workpiece such as a front shaft, an intermediate shaft of CVJ (a constant velocity joint that transmits rotation at a constant angular velocity between a driving shaft and a driven shaft), an inboard, and the like.
[0044]
【The invention's effect】
As described above, according to the present invention, the distortion of the shaft-like workpiece can be corrected efficiently.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an embodiment.
FIG. 2 is an overall process flowchart of the embodiment.
FIG. 3 is a graph showing a relationship between a strain amount and a press amount.
4 is a flowchart of a press amount calculation process in FIG. 2. FIG.
FIG. 5 is a histogram of the number of presses in the embodiment and the conventional method.
FIG. 6 is a flowchart of processing according to another embodiment.
FIG. 7 is a diagram for explaining a press amount in another embodiment.
FIG. 8 is a diagram showing the number of presses according to another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Axis-shaped workpiece | work, 12 rotating mechanism, 14 press machine, 16 press receptacle, 18 press control part, 20 detector, 22 CPU.

Claims (7)

Means for detecting the amount of distortion of the shaft-shaped workpiece;
An arithmetic means for calculating a press amount for correcting the strain according to the strain amount;
Means for pressing the shaft-shaped workpiece with the calculated pressing amount;
Have
The second press amount for the shaft-like workpiece is calculated by using the strain amount before and after the first press and the elastic deformation amount predetermined for the shaft-like workpiece in the calculation means. A device for correcting distortion of an axial workpiece. The apparatus of claim 1.
When the calculation means is insufficiently corrected after the first press,
Press weight = the elastic deformation amount + [{before press strain amount / (before pressing strain amount - after pressing the distortion amount)} × (1 st press amount - the elastic deformation amount) of the calculation formula defined by × constant A distortion correcting device for a shaft-shaped workpiece, characterized in that the next press amount is calculated by using. The apparatus according to claim 1 or 2 ,
When the calculation means is insufficiently corrected after the second and subsequent presses,
Press amount = previous press amount × {100+ (addition rate × post-press strain amount / pre-press strain amount)} / 100
A distortion correction device for a shaft-like workpiece, characterized in that the next press amount is calculated using a calculation formula defined in 1. The apparatus of claim 1.
When the calculation means is overcorrected after the previous press,
Press weight = the elastic deformation amount + [{after pressing strain amount / (before pressing strain amount + press after the distortion amount)} × (previous Press weight - the elastic deformation amount) by using a calculation formula defined by × constant A distortion correction device for a shaft-like workpiece, characterized in that the next press amount is calculated. Means for detecting the amount of distortion of the shaft-shaped workpiece;
An arithmetic means for calculating a press amount for correcting the strain according to the strain amount;
Means for pressing the shaft-shaped workpiece with the calculated pressing amount;
The press amount is calculated using a workpiece hardness calculated from a strain amount before and after the press and a return amount from the lower end position to the spring-back position in the previous press. Work distortion correction device. The apparatus of claim 5.
When the calculation means is insufficiently corrected after the previous press,
Work hardness = Previous return amount = Previous press amount− (Current strain amount−Previous strain amount) / 2
If there are too many corrections after the last press,
Work hardness = previous return amount = previous press amount-(current distortion amount + previous distortion amount) / 2
An apparatus for correcting distortion of a shaft-like workpiece , characterized by: The device according to claim 5 or 6,
The computing means is
A distortion correction device for a shaft-shaped workpiece , characterized in that the next press amount is calculated by pressing amount = arbitrary constant × previous return amount + arbitrary constant × current strain amount.

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