Bending correction apparatus and correction program

Abstract

To solve such a problem that a conventional technique requires time and effort since it repeatedly pushes in a workpiece to ultimately correct bending.SOLUTION: A bending correction apparatus approximates a relationship between a deflection amount and a push-in amount using a cubic equation of a square root for each workpiece to be corrected. Constants for the equation are determined in a workpiece unit and stored in a storage part of a control unit. When correcting a specific workpiece, the cubic equation used for the workpiece is read out from the storage part by inputting information on the workpiece, and the deflection amount measured by a sensor is substituted into variables of the read-out cubic equation. Therefore the required push-in amount is calculated by a push-in amount calculation unit. A punch is controlled to push in the workpiece W by the push-in amount.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a bend straightening device and a straightening program for straightening a bend in a long workpiece. [Background technology]

[0002] Conventionally, a device for straightening a bend in a metal bar is known, as described in Patent Document 1. This bend straightening device is equipped with support rolls that support both ends of a long workpiece, and a pressure roll that presses the part of the workpiece between the support rolls. The workpiece is automatically fed and supported by the support rolls, and the pressure roll presses the intermediate position of the supported part to straighten the bend in the workpiece. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 1-278915 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, when straightening a workpiece, the amount of bending is measured and the workpiece is pressed in according to the amount of bending to cause plastic deformation. Specifically, the workpiece is pressed in more if the amount of bending is large, and pressed in less if the amount of bending is small, to cause plastic deformation within the targeted range and perform straightening. When a worker manually performs straightening, he or she first measures the runout of the workpiece and instantly determines the amount of pressing required based on the worker's experience.

[0005] The procedure for straightening a workpiece's bending can also be explained using the workpiece's stress-strain diagram. Figure 8 shows a typical stress-strain diagram. Straightening is performed by applying stress to the workpiece above its strength, causing it to plastically deform. If stress is first applied up to A and then released, the strain of line segment a will remain as plastic deformation. Similarly, if stress is applied up to B, the strain of line segment b will remain. Similarly, if the stress is increased, cracks will gradually appear near the workpiece's tensile strength, leading to fracture. As such, in the plastic deformation region the relationship between stress and strain is not linear, but is clearly nonlinear.

[0006] In such bending straightening, the amount of runout of the workpiece is measured, the amount of push-in is determined based on the result, and this is repeated to perform bending straightening of the workpiece, but since the appropriate amount of push-in for correcting the amount of runout of the workpiece is determined empirically or based on simple calculations, the workpiece is pushed in repeatedly until the bending is finally straightened, which is troublesome and time-consuming. The present invention has been made to solve such problems. [Means for solving the problem]

[0007] The bend straightening device of the present invention comprises a measuring means for placing both ends of a workpiece on a receiving seat and measuring the amount of runout of the workpiece, a push-in amount calculation means for calculating the amount of push-in of the workpiece relative to the amount of run-out measured by the measuring means using a calculation formula including a cubic expression of the square root set for each workpiece, a memory means for storing constants of the calculation formula for each workpiece, and a punch means for pushing the workpiece by the amount of push-in calculated by the push-in amount calculation means. [Brief description of the drawings]

[0008] [Figure 1] 1 is a configuration diagram showing a curve straightening device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a system configuration diagram of a curve straightening device. [Diagram 3] FIG. 2 is a configuration diagram showing the punch shown in FIG. [Figure 4]FIG. 4 is a partially enlarged view of FIG. [Diagram 5] 4 is a flowchart showing the operation of the bending straightening device. [Figure 6] 5 is an explanatory diagram showing the operation of the bend straightening device. FIG. [Figure 7] 5 is an explanatory diagram showing the operation of the bend straightening device. FIG. [Figure 8] 1 is a typical stress-strain diagram. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] FIG. 1 is a configuration diagram showing a bend straightening device according to a first embodiment of the present invention. FIG. 2 is a system configuration diagram of the bend straightening device. This bend straightening device 100 has a pair of core stocks 1 that rotatably support a long workpiece from the left and right, and a servo motor that rotates the core stock 1 together with the workpiece. A sensor 2 that detects the runout of the workpiece W is provided at the center position between the core stocks 1 on the bed 3. The sensor 2 is, for example, a touch probe or a reflective laser displacement meter. The core stock 1 has a conical tip and is inserted into the inside of the hollow pipe workpiece W to support the workpiece W substantially with its axis. The pair of core stocks 1 are provided on a core stock table on which the servo motor is arranged, and are fed manually or automatically in the axial direction of the workpiece W (not shown).

[0010] A pair of receiving seats 4 are arranged on the bed 3 to support the vicinities of both ends of the workpiece W. Furthermore, a punch 5 for pressing the workpiece W is provided at an upper position between the receiving seats 4 in the axial direction of the workpiece W. The curve straightening device 100 also has a control device 50 that controls servo motors and their drivers for moving the punch 5 and the workpiece W based on output signals from various encoders and sensors 2.

[0011] The control device 50 controls the driving of the sensor device that controls the movement and detection of the sensor 2, the core pusher servo motor, the punch servo motor, and the like.

[0012] The control device 50 also has a punch push amount calculation unit 60 that calculates the punch push amount relative to the deflection amount of the workpiece. The punch push amount calculation unit 60 approximates the relationship between the deflection amount of the workpiece W and the punch push amount using a square root cubic equation and stores this. Specifically, the cubic expression is defined as follows: y=a3√x+b√x+cx+d Conventionally, the correction of bending of a workpiece has been determined by empirical rule of thumb or by calculation using a linear equation. In contrast, in the present invention, attention is paid to the fact that the amount of push-in relative to the amount of run-out shows nonlinear characteristics, and the nonlinear shape is approximated by a cubic equation of the square root, reproducing the characteristics of the actual workpiece W.

[0013] Here, since the amount of push-in relative to the amount of runout differs for each work, the relationship between the amount of push-in relative to the amount of runout is approximated by a square root cubic equation for each work to be corrected. The values ​​of the constants a to d in the above equation are determined for each work, and are stored in the memory unit 61 of the control unit 50. When correcting a specific work W, the cubic equation used for the work W is read from the memory unit 61 by inputting information about the work W, and the amount of runout measured by the sensor 2 is substituted for the variable x of the read cubic equation. The variable x is automatically input from the output signal of the sensor 2. As a result, the necessary amount of push-in y is calculated in the push-in amount calculation unit 60. The punch is controlled to push the work W by this amount of push-in y.

[0014] Fig. 3 is a configuration diagram showing the punch shown in Fig. 1. This punch 5 is composed of a pressing unit 6 provided at the lower end for pressing the workpiece W, and a moving unit 7 to which the pressing unit 6 is attached and which moves it up and down. The moving unit 7 has a column 9 fixed to a block of a linear guide 8, and the pressing unit 6 is fixed to the column 9. The column 9 is controlled to move by a ball screw and a servo motor (not shown). The servo motor is controlled by the control device 50.

[0015] 4, the pressing part 6 is block-shaped and has a curved pressing surface 6a. The pressing part 6 has a separate pressing surface 6a so that the pressing surface 6a can be changed according to the diameter of the workpiece W. In addition, a protective layer 6b made of rubber or resin is provided on the pressing surface 6a.

[0016] Fig. 5 is a flow chart showing the operation of this bend straightening device. Fig. 6 is an explanatory diagram showing the operation of the bend straightening device. First, the workpiece W to be straightened is selected from the memory unit 61 (step S1). Next, while the workpiece W is fixed from both sides by the core stock 1 and rotated, the sensor 2 irradiates a laser to measure the surface of the workpiece W and obtains the bend of the workpiece W (step S2).

[0017] Next, the push-in amount calculation unit 60 calculates the push-in amount by the punch 5 from the calculation formula related to the selected workpiece W (step S3). The measurement signal of the deflection amount of the workpiece W from the sensor 2 is sent to the push-in amount calculation unit 60 and substituted for the variable x of the selected calculation formula. In this way, the required push-in amount y is calculated. Note that, as shown in FIG. 7, when the workpiece W is bent in one direction at the center position, the core stock 1 is rotated to position the workpiece W so that the crest side of the bend is on top.

[0018] Once the pushing amount y has been calculated, the punch 5 pushes the workpiece W by that pushing amount (step S4). When pushing, the receiving seat 4 is raised to support the workpiece W at both ends. With the workpiece W supported by the receiving seat 4, the pressing part 6 at the tip of the punch 5 is lowered, and the pressing part 6 presses the workpiece W by the pushing amount at the measurement position between the receiving seats 4 of the workpiece W.

[0019] By determining the indentation amount of the punch 5 using the cubic equation that approximates the actual characteristics, it is possible to perform the desired correction in one go, and as a result, the number of repeated indentations is reduced. Reducing the number of indentations reduces the number of times stress is applied to the workpiece W, preventing a deterioration in the mechanical characteristics of the workpiece W.

[0020] Next, after pressing the workpiece W by a predetermined amount with the punch 5, it is confirmed whether or not the bending of the entire workpiece W has been corrected (step S5). This confirmation is performed by measuring the bending with the sensor 2 while rotating the workpiece W with the core pusher 1, following the same procedure as described above. If bending is confirmed as a result of the remeasurement (step S6), the workpiece W is again supported by the receiving portion 41 and pressed by the punch 5 in order to correct the measured bending amount, and the bending is measured (steps S3 and S4). By repeating this process, the bending of the entire workpiece W is corrected. Finally, by confirming that the bending of the entire workpiece W has been corrected (step S6), the bending correction is completed.

[0021] As described above, according to the bend straightening device 100 of the present invention, when performing bend straightening, the nonlinear correlation between the amount of runout and the amount of push-in is approximately expressed by a cubic equation, and the measured amount of runout is substituted into this calculation formula to calculate the amount of push-in. As a result, the number of push-ins is reduced, so that straightening can be completed in a short time and fatigue of the workpiece is reduced.

[0022] The cubic square root equation can also be used to approximate the nonlinear shape of the displacement versus deflection amount using the following formula: y=a3√x+b2√x+c√x+d y=a3√x+b√x+d y=a3√x+c√x+d y=a3√x+d [Explanation of symbols]

[0023] 100 Curve straightening device 1 Tailstock 2 Sensors 4 Receiving seat 5 Punch 6 Pressing part 50 Control device 60 Push amount calculation section 61 Storage section

Claims

1. A measuring means for measuring the runout amount of the work by placing both ends of the work on a support seat; A push-in amount calculation means for calculating a push-in amount of the workpiece with respect to the runout amount measured by the measurement means using a calculation formula including a cubic expression of a square root set for each workpiece; A storage means for storing constants of the calculation formula for each workpiece; a punch means for pushing the workpiece by the push-in amount calculated by a push-in amount calculation means; A bending straightening device having the above structure.

2. The cubic equation of the square root is y=a3√x+b√x+cx+d 2. The bending straightening device according to claim 1,

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