JPS60231527A - Bending method of pipe - Google Patents

Abstract

PURPOSE:To enable bending of a pipe to an optional curved shape by tilting the pipe material between a straight plunger die and circular receiving die in the state of press contact therewith and controlling synchronously the movement of a gripper, the straight plunger die and the circular receiving die. CONSTITUTION:A pipe material P sandwiched between the stationary piece 2 and movable piece 3 of the gripper 1 is driven in X- and Y-axis directions by the screw shaft 5 of a table 8 and the screw shaft 6 of a table 10. The material P is set in the state of being sandwiched between the straight plunger die 25 and the circular receiving die 12 and is bent by the synchronous movement with the gripper 1 while the pipe material is titled around the die 12 which is driven and rotated by a pinion 20. The movement of the gripper 1, the die 25 and the die 12 is synchronously controlled by a computer 35 and a speed controller 34 outputs a command. The bending of the pipe to an optional shape such as arc, elliptical or parabolic shape is made possible by the above-mentioned mechanism.

Description

[Detailed description of the invention] <Industrial application field> This invention is applicable to straight pipes (tapered pipes, square pipes, round pipes, etc.)
The present invention relates to a method of bending υ into an arbitrary curved shape such as a circular arc, parabola, or ellipse, and particularly relates to a bending method that allows for highly accurate processing.

<Prior Art> Various methods for bending tubes have been known in the past. Typical examples are listed below.

1) Compression bending: As shown in Figure 1, a fixed bending die (4
) is a method of bending the pipe [F] by pressing it against the press die (g) so that it follows the curvature of the bending die.

11) Drawing bending: This is similar to changing the tilting of the press mold in compression bending to the rotation of the bending mold, and the bending shown in Figure 2 ((a) is the state before processing, (b) is the state in progress) As shown, bend 1fJJ (A) with the rotatable y and fix the pipe (■) with the fixed mold (b).In this state, rotate the bending mold (b), and then press the bending mold and its corresponding press. A method of bending by pulling out the tube one by one from between the mold (g).

Mandrel lv (to) is used if necessary.

1iQ press bending: As shown in Figure 3, a method of setting 't (p) across a pair of left and right catches (to) (g) and pressing the center part with a press die (t) to bend it.

lv) Roll bending: As shown in Fig. 4, a method of sequentially passing WCP) between three driving forming roll shafts in a staggered arrangement.

■) Tensile bending: As shown in Figure 5, the fixed bending type (A
) is pressed against the tube [F] and bent while pulling on both ends.

Vl) Hamburg bending: As shown in Fig. 6, a pipe of fixed size [F] is inserted from the proximal end into a pipe-shaped mandrel (c) with a thick tip, and the tip is passed through and bent.

However, each of the above methods has its own weight.

In particular, compression bending and press bending pose a problem in that the tube becomes flattened and wrinkles occur during processing. In all methods other than roll bending, the size of the mold (or mandrel for hanging bending) is changed each time the bending radius or other processing conditions change, and it is necessary to prepare many molds (mandrels). Changing setups takes time and effort. Moreover, the original aim of this type of method is circular bending,
Other methods, such as elliptical bending, are hardly considered. Regarding roll bending, although it is possible to adjust the bending radius by changing the mutual positional relationship of the forming rolls, the selection of the bending radius is limited to a relatively large range of values. In addition, Hamburg bending, in particular, can only be applied to short pipes that have been cut to a certain size in advance; for example, processing that only bends one end of a long pole cannot be performed at all. In fact, the method is used exclusively for the production of elbows.

<Purpose of the Invention> The present invention is capable of bending pipes along all kinds of curves, such as arcs, parabolas, and ellipses, using the same equipment without any setup changes such as changing molds. The purpose of the present invention is to provide a bending method that has good processing accuracy and is effective against flattening and wrinkles of the tube due to bending.

<Structure of the Invention> That is, the present invention grips a pipe to be bent at a position other than the part to be bent by a gripping device movable to any position on a specific plane, and holds the pipe to be bent at a position other than the part to be bent. It is set so as to be sandwiched between a circular receiving mold that rotates in a plane parallel to the plane of movement of the gripping device and a straight pressing mold paired with it, and the straight pressing mold is pressed against the circular receiving mold. The target bending shape is then gradually tilted along its outer periphery, and the speed control system of the drive device that controls this tilting motion, the rotating motion of the circular receiving mold, and the planar motion of the gripping device is controlled from the target bending shape to each drive. Input the speed value determined as the required command speed by taking into account the response delay of the device in advance as the command signal, and
The driving performance of each drive device is continuously detected, the error of the actual value with respect to the target value is sequentially determined, and the indicated speed is corrected by proportional-integral control.

The object of the present invention is to provide a method for bending a pipe, which is characterized in that the movements of the gripping devices are managed so that they match the target bending shape and are mutually synchronized before bending the pipe. The forming method of the present invention is basically a combination of so-called compression bending and roll bending. The method is to bend the pipe without giving any. In such a method, controlling the positions of the three members mentioned above during the molding process has an important meaning in terms of processing accuracy. Therefore, the present invention also specifies a method for synchronously controlling the positions of these three members.

<Example> Hereinafter, the method of the present invention will be explained specifically and in detail.

FIG. 7 is a plan view schematically showing an apparatus for carrying out the molding method of the present invention.

In the figure, (1) is a gripping device that grips a straight tube (round tube) to be bent, and this is a gripping device that is held between a fixed piece (2) and a movable piece (3) that moves forward and backward with respect to the fixed piece. The structure is such that the pipe is clamped and held between the two pieces by pressing the movable piece (3)' (i-) with the hydraulic cylinder (4). In the illustration, independent drive sources (7) and (9) are provided.
The structure is a combination of two tapes (5) and (6) with attached screw shafts (5) and (6).

That is, the gripping device (1) first screws into the screw shaft (5) of the tape/I/(8), is driven along the guides (8a) (8a) on the same table, and further holds the tape/I/(8). / (8) itself is fixed to the screw shaft (6) of another table αO arranged at right angles to it, and that table (
It is a structure that is driven along guides (10a) (10a) on 10. As the driving source (7) (9), a C motor is preferable because it has high controllability.

The same applies to all drive sources hereinafter.

(A) is a circular receiving mold located at an appropriate distance from the above-mentioned gripping device, and has a semicircular groove α frame on the outer periphery of a shape corresponding to the outer diameter of the part to be bent of the part to be bent (2). .

The illustration shows an example in which a tapered pipe is to be bent. This circular receiving mold has a larger diameter and is placed concentrically on a fixed bed αa equipped with gears (A) on its outer periphery, and is rotatable around an axis α fixed at the center of the bed. . This pivoting movement of the receiving mold is made to occur in a plane parallel to the plane of movement of the gripping device (1). This circular receiving mold has a circular gear (171) concentric with the outer circle, and a small gear (1) connected to a drive source (G) installed on the bed α through a reducer gear meshes with this circular gear (171). It is set up and driven.

c! Reference numeral D denotes a rotating mount that rotates coaxially with the circular mold (A), and is rotatably supported at its base end by the rotation center axis αQ of the circular mold (2). This frame (2]) il-j: A small-diameter drive gear (c) connected to a drive source (a) installed on it via a reducer (a) meshes with the large gear αO on the outer periphery of the fixed bed. A driving gear (c) is provided so as to rotate by moving around the bed along a large gear a$.

(c) `` is a straight die installed on the above-mentioned rotating frame (2]), and like the circular die, it has a semicircular groove (shaped) corresponding to the outer diameter of the part of the pipe to be bent (■) to be bent. ), and the semicircular grooves 03 (a) of the circular receiving mold α face each other. This straight die (c) is installed on the rotating pedestal (2]) via a support device @, and this support device (5) is attached to the pedestal 121) in the normal direction of the pivot trajectory of the pedestal. It is slidable along the guides (21a) (21a) provided in the circular receiving mold θ, that is, in the radial direction of the circular receiving mold θ,
In addition, for the straight die (c), a total of four support lobes (28a) (28a) corresponding to the upper and lower sides of the die are provided so that the die can slide along its own longitudinal direction. . In other words, the straight die (c) is the same as the circular receiving die (c).
It can move forward and backward in one radial direction and can slide in its own longitudinal direction.

On the back side of the straight die (to), rack teeth are provided along the longitudinal direction, and a small gear 0 connected to a drive source 0 on the rotating mount QD is meshed with this. 0
By driving 2, the straight mold (c) can be slid and positioned at any desired position.

The kiln is a suppressing mechanism that presses the straight mold (c) against the outer periphery of the circular receiving mold, and the loaf (c) incorporated in the support device (a)
28'b) (28-b) to press the back side of the straight mold (c). Needless to say, Laura (2
8b) is for making it possible to press the mold to such a degree that it remains slidable in the longitudinal direction. This suppression mechanism is hydraulically operated and is also used to separate the press die (C) from the circular receiving die (2) without creating any suppression.

In the tube bending method of the present invention, bending is performed in the following manner using the apparatus configured as described above.

■ First, the gripping device (1) set at a predetermined position grips the pipe [F] to be bent at a point other than the part to be bent, and at the same time, the pipe (F) is placed between the circular receiving mold 0 side and the straight pressing mold ( b) Set it by putting it in between. At this time, the outer periphery of the molding start position (goods) of the pipe opening is inscribed in the semicircular groove 03 of the circular receiving mold αη, and the semicircular groove (c) of the straight die (c) is inscribed in such a pipe [F]. It corresponds to the direction with a width, and its m1 surface touches the outer periphery of the circular receiving mold α. As shown in the figure, when the object to be bent is a tapered pipe, a semicircular groove a3 with an inner diameter matching the outer diameter at the same position is especially placed at the forming start position.
(c) It is important to match the parts accurately. The setting of the receiving mold and the pressing mold may be performed using the driving source 08)0υ.

After setting the positional relationship between the tube and each part of the device in this manner, the pressing mechanism is activated to press the straight mold (C) against the outer periphery of the circular receiving mold α with a predetermined force.

■ After completing the above set, turn mount C! υ is the driving source (c)
The straight mold (c) is held in pressure contact with the circular receiving mold Q21 and is gradually tilted along the outer periphery of the circular receiving mold Q21. At this time, the driving sources α81 and (7
) (9), and these movements, i.e., the tilting of the straight die (c), the rotation of the circular receiving die (6), 9 the gripping device (
1) Planar motion is managed according to the target bending shape.

FIGS. 8 and 9 show two specific examples of this management, with FIG. 8 showing arc bending and FIG. 9 showing elliptical bending. That is, in the figure, P7-P, 2... indicates the tilting movement of the straight mold (C) due to the transition of the contact point of the straight mold (C) onto the outer periphery of the circular receiving mold α, and Q/→Qν・・ is the transition of a point on the outer circumference of the circular receiving mold (1 point on the outer periphery of the gripping bag @ (1 ), respectively, and the same subscript numbers among P, Q, , M mean positions at the same time.

In this way, by managing the movements of the straight press die (c), the circular receiving die a4, and the gripping device (1) in synchronization with each other, it is possible to produce a bent shape that follows an arbitrary curve that matches the target. . In this case, it goes without saying that it is necessary to consider in advance the amount of nupling back of the tube after molding and to carry out the molding taking into account this amount.

In addition, in the above-mentioned forming process, the straight mold (c) is made to move 7 widths in the longitudinal direction in accordance with the rotational movement of the circular receiving mold αa which is in pressure contact with it, but the circular receiving mold It may be driven either by the movement of α gong or actively driven by the driving source 0υ. However, from the point of view of machining accuracy, it is preferable to use active drive so that the movement can be reliably synchronized with the movement of the circular receiving mold Q. Reliable synchronization between the rotation of the circular receiving mold α and the sliding movement of the straight pressing mold (c) can also be achieved by providing both molds with interlocking hook teeth.

By the way, in the above-mentioned molding method, the processing accuracy is controlled by the control accuracy of the movement of the device drive system during the molding process, that is, the straight pressing mold α4° circular receiving mold (c) 1 and the gripping device (1). However, it is actually very difficult to synchronize the movements of these three parties accurately with each other. In other words, ■ there is a delay in the response in the speed control of the drive sources (D and C motors) that govern each movement, and ■ the delay time between the actual carpet speed and the commanded speed varies because the moment of inertia differs for each drive system. This can be said to be caused by the fact that the ashing pattern of the commanded speed differs depending on the drive system.

The control method based on the present invention makes it possible to synchronously control the movement of such a device drive system with high precision.

The control will be explained in detail below.

Regarding the movement of the device drive system mentioned above, the tilting of the straight die (c) is the rotation angle (β) of the rotating frame (2), the circular receiving die σ
The turning motion of the wharf is determined by its own rotation angle (γ), the gripping device (
The plane motion of 1) is the screw axis (5) of two orthogonal trees (
Displacement (X) (Y) in the direction along 6) can be defined respectively. The bending shape of the tube can be specified by positional changes with respect to the four axes (β9γ, X, Y).

By the way, in general, in order to eliminate operational delays in mechanical devices, it is necessary to take into account the response delay characteristics of the drive system in advance and issue instructions to the control system early.

Therefore, when we actually measured and investigated the response characteristics of the drive system for the four axes β, γ, It has been found that sufficient control accuracy can be obtained by approximating it as a second-order lag system model.

Here, if the relationship between the speed instruction input and the response output is expressed mathematically, the T formula o (t) -1(t) X g (t) o (t)
: Output 1(t) at time t : Input g (t) at time t : A function indicating the relationship between input and output. If we convert this to Rapufnu, 0 (S) = Engineering (Sl x G (S) G (s)
: Expressed as a transfer function (specific to the equipment), and from this formula, to obtain the target output 0 (S), input crab (S) should be changed to O (→'0 (
It turns out that it is sufficient to do S). Therefore, 0 (S)
/ G (S) can be inversely transformed to obtain the target force by calculating the input 1(t) at time t in advance, and by giving this speed value as an input to the control system, basically The motor speed history matches the target and (X, Y, β, γ
) should match the target.

However, the rotational speed of a motor is generally determined by changes in voltage.

Some degree of variation is unavoidable due to unavoidable disturbances such as temperature changes, and therefore, in reality, sufficient results cannot be expected from the above predictive control alone.

However, based on the above predictive control and according to the method of so-called proportional-integral control, the following formula (% formula %) a, 'b: constant @ (adjustment parameter) △X: motor instruction based on the difference between the target position and the grand position pupil It is possible to obtain sufficient control accuracy for practical use by using the control a1 that increases the speed g t (correction sound 7Jl for ta).When proportional-integral control is applied, the actual value usually lags behind the change in the target value. In this sense, an error will remain, but since the response delay of the thread itself is taken into account in advance to the instructed speed, the actual value can almost match the target value. Sometimes, there are only minute errors originally caused by disturbances, and in this case, proportional-integral control can achieve highly accurate control.

That is, the control method according to the present invention is based on the above facts, and the specific method is as follows.

The equipment used for control is schematically shown in Figure 7 above. In the figure, (88/X83.2)... corresponds to the X, Y, β, and γ axes of the processing machine. A pulse generator connected to the drive motor generates a number of pulses corresponding to the actual rotation amount of the drive motor. The second one is the speed control system of each drive motor mentioned above. 0!51 is a computer that gives instructions to this speed control system. The contents of this computer d processing are shown in a block diagram in FIG.

During machining, the computer (c) uses information about the bending shape given in advance to give the instruction speed i: (t) to each drive system, taking into account the response delay of each drive system for machining. Calculate. That is, A in the block diagram of FIG.
Performs calculations on parts.

Next, the commanded speed 1(t) determined by this calculation is input to the control system (2) of each drive motor, and each drive motor is activated while controlling the speed. At this time, on the other hand, a pulse generator (33/) (33x) coupled to each drive motor
The output PALNU from ... is counted one by one according to the calculation method (c), the actual position of (X, Y, β, γ) is continuously detected, and the error of the actual value 1+- with respect to the target position is calculated. (△
X, △Y, △β, △γ), and the commanded speed 1(t) is corrected by proportional-integral control. This calculation is shown in part B of FIG.

This kind of speed control is continued until (X, Y, β, γ) reaches the final position of the target trajectory to perform the pipe bending.

The high accuracy of the control method based on the present invention described above can be shown by the following specific numerical values.

In other words, Fig. 12 shows the results of a simulation study of the accuracy when using only normal proportional-integral control, while Fig. 13 shows the results of applying the control based on the present invention to an actual machine and examining the control accuracy. The results are shown below. In the example using only proportional-integral control, the accuracy of β and γ was within ±2.3°, and the accuracy of , γ within 0.8°, X,
, Y was also recognized to be significantly improved to within 3 degrees, and sufficient accuracy was obtained for practical use.

As is clear from the above explanation, according to the method of the present invention,
It is possible to bend the pipe into any curved shape such as a circular arc, ellipse, parabola, etc. Moreover, the bending process can be performed with good precision. Because the shape is always completely enclosed between the circular receiving mold and the straight stamping mold, excellent effects can be expected, such as effectively preventing flattening and wrinkles of the tube during processing. be.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of compression stroke, and FIG. 2 is an explanatory diagram of four bends. The marks indicate the tube set state, and (0) indicates the state during processing. Fig. 3 is an explanatory diagram of plain bending, Fig. 4 is an explanatory diagram of roll bending, Fig. 5 is an explanatory diagram of tension 9 bending, Fig. 6 is an explanatory diagram of Hamburg bending, and Fig. 7 is an explanatory diagram of the method of the present invention. A schematic plan view of Sudame's bending device and a block diagram showing its control system, FIGS. 8 and 9, are based on the method of the present invention! FIG. 8 is an explanatory diagram showing how to manage each drive system of the same device when bending a pipe, FIG. 8 shows arc bending, and FIG. 9 shows elliptical bending. 10 is a diagram showing the response delay situation in speed control of the processing device shown in FIG. 7, FIG. 11 is a block diagram showing calculation-like processing based on the control method of the present invention,
Figures 2 and 13 show each drive system (β,
γ, X, Y);
The figure shows the case of only proportional-integral control, and Fig. 13 shows the case of applying predictive control + proportional-integral control based on the present invention. In both figures, (a) shows the γ-axis error, (b) shows the β-axis error, G /i represents the X-axis error, and ) represents the X-axis error. In the figure, l: gripping device, 5, 6: screw shaft, 7.9:
Drive source, 8, 10: Table, 12 Two circular receiving molds, 13 Two semicircular grooves, 14: Bed, 18: Drive source, 21: Swivel frame, 22: Drive source, 25: Straight press mold, 26: Semicircle ditch, 27
: Support mechanism, 29: Pressing mechanism, 31: Drive source, 3B: Parnu generator, 34: Speed controller, 35: Computer Applicant: Sumitomo Metal Industries, Ltd. Applicant: Sumikin Steel Industries, Ltd. Representative Patent Attorney Gen Kata Imao Heavy j II Figure 2 (A) (B) 6th (Support) Figure 7 Figure 10 Figure 132t

Claims (1)

[Claims] (1) A gripping device movable to any position on a specific plane grips the pipe to be bent at a position other than the portion to be bent, and the portion to be bent is placed on the plane of movement of the gripping device. The Cera F is inserted between a circular mold rotating in a plane parallel to the circular mold and a straight mold forming a pair with it, and the straight mold is pressed against the circular mold while maintaining its outer periphery. The speed control system of the driving device that controls this tilting movement, the rotational movement of the circular receiving mold, and the planar movement of the gripping device is controlled to control the response delay of each driving device from the target bending shape. Input the speed value calculated in advance as the required command speed as the command signal, and continuously detect the driving performance of each drive device and sequentially calculate the error of the actual value with respect to the target value and calculate the proportional value. The above commanded speed is corrected by integral control, and the small movements are managed so as to correspond to the target bending shape and to be synchronized with each other. A pipe bending method characterized by performing pipe bending from scratch.