JP2713773B2 - Control method of bending machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a control method of a bending machine.

(Conventional technology) In a bending machine, a work interposed between these dies is bent at a predetermined angle by relative movement of a punch or a die. Generally, a ram for moving a punch or a die with respect to the other mold is moved to a depth position set in advance to obtain a predetermined bending angle. The depth position at this time is determined using a data table of various conditions such as a work condition, a mold condition, and a machine frame condition in consideration of so-called springback.

However, in the bending process, since various factors such as variations in the thickness of the work are involved in the bending angle, it is difficult to determine an accurate depth position, and the tentative depth position is determined using the above data table. However, the fact is that the depth position is finely adjusted by trial and error every time the type of work is changed or for each lot.

(Problems to be Solved by the Invention) As described above, in the conventional bending machine control method, although the depth position of the ram is determined using the data table of various conditions, the thickness of the work varies. For this reason, uniform control could not be performed, and fine adjustment by trial and error was required.

Therefore, fine adjustment of the depth position requires much labor and time, and it is difficult to perform high-precision bending.

Therefore, an object of the present invention is to provide a method of controlling a bending machine capable of efficiently performing high-precision bending based on a depth position preset using a data table or the like. .

[Structure of the Invention] (Means for Solving the Problems) A method for controlling a bending machine according to the present invention for solving the above-mentioned problems, as shown in FIG. In a control method of a bending machine that bends a work interposed between these dies at a predetermined angle due to a short movement, a temporary operation is performed based on various conditions such as work conditions, die conditions, and frame conditions for a predetermined work. set the depth position D ₀ of moves the movable die up to the position D ₀ -d the set depth position D ₀ to the front of the temporary, then driven mold position D ₀ -d at that time as a reference up position Ds slightly front of the spring-back end point Pe is moved by a predetermined amount △ l, depth position in accordance with the difference △ F of the actual pressing force F and the pressure force F ₀ appointments from the correlation I for that position Ds Is calculated, and the provisional The correction value on the depth position D ₀ △ adding D to calculate an optimum depth position D ₀ ', characterized by re-driving the calculated optimal depth position D ₀ + △ said movable die to D.

(Operation) In the present invention, the actual pressurization is performed to the position or a position slightly short of the position as a temporary depth value using a depth value set in advance by table data or the like, and then the spring is backed up by a predetermined amount Δl. From the correlation between the predetermined pressure F and the actual pressure F, the correction value 補正 D
Is calculated.

Further, the correction value ΔD of the temporary depth position D ₀ is calculated by fuzzy inference.

Therefore, according to the present invention, a correction value ΔD of the depth position is obtained to automatically correct the condition deviation defining the data table and the like, and high-precision bending can be performed at a stretch.

(Example) Hereinafter, an example of the present invention will be described.

FIG. 2 is a front view of a bending machine embodying the present invention.

In the figure, a bending machine 1 has a fixed lower apron 2 and an upper apron (ram) 3 which is driven up and down with respect to the apron 2. A die 4 is placed above the lower apron 2 and a punch 5 is placed below the upper apron 3.
Is installed.

In order to detect the raising / lowering operation of the upper apron 3, encoders E for respectively detecting both end positions of the upper apron 3 are provided in a frame portion (not shown).

In order to drive the upper apron 3 up and down, cylinders 6 are provided at both ends of a frame portion (not shown). Both cylinders 6 have a hydraulic pump 7
Is connected to a servo valve 8 for supplying the pressure oil fed from the controller. The servo valve 8 is controlled by an NC device.

Further, wherein the upper chamber of the cylinder 6, the two pressure sensors P ₁ and P ₂ for detecting pressure is provided.
One pressure sensor P ₁ is a low pressure, the pressure sensor P ₂ of the other is intended for high pressure, both the pressure sensors P _1, P ₂ is adapted to be appropriately switched used in accordance with the pressure value to be detected I have.

Each of the aprons 2 and 3 is provided with a strain gauge 9 for detecting a strain state of each apron.

 FIG. 3 is an explanatory diagram of the depth position.

In the figure, a work W having a thickness t is interposed between a die 4 and a punch 5, and the work 5 is bent down by lowering the punch 5 to a predetermined height position and then spring back. It has become. The vertical axis of the punch 5 is called a depth (D) axis, and the position D is called a depth position. The lower side is the plus (+) direction. The illustrated die 4 has an R portion at the V-width shoulder, and the punch 5 has an R portion at the tip.

In general, setting the final depth position D ₀ is a work condition,
It is set using table data on mold conditions, machine (frame) conditions, and the like.

For example, D ₁ geometrically group Me is D value, the δ condition variable, determined by D ₀ = D ₁ - [delta.

δ = δ ₁ + δ ₂ + δ ₃ + δ ₄ δ ₁ : Deflection of the mechanical meter δ ₂ : Property of the material δ ₃ : Springback required δ ₄ : Others FIG. The block diagram is shown.

Although the figure shows only the control portion for driving the D axis, the NC device including the present control device controls not only the D axis but also auxiliary devices such as a hydraulic pump and a robot for a work supply service. It has become.

In the figure, a data input unit 10 is for inputting processing conditions such as the shape and bending angle of a work and the type of a die.

The D ₀ value setting unit 11 uses the database 12 to
It is for setting a depth device D ₀ of the temporary.

D-axis control portion 13, based on the set D ₀ value, the punch 5
It is intended to approximate the depth position D ₀ to at a predetermined speed pattern and a predetermined sequence.

The D-axis drive unit 14 outputs a valve drive signal to the servo valve 8 to drive the punch 5.

In this example, further, a correction operation control unit 15 shown separately from the D-axis control unit 13, a springback pressure detection unit 16 connected to the control unit 15, and a pressure detected by the detection unit 16 And a correction value calculation unit 17 for correcting the provisional D ₀ value to the optimum depth value D ₀ ′.

The operation of the control device having the above configuration is shown in the flowchart of FIG.

In step 501, when processing conditions such as sheet quality, sheet thickness, and bending angle θ ₀ are input, a temporary depth value D ₀ is obtained using the database 12 in step 502. Further, in order to set a bit position of the front of the depth value D _0, D ₀ -d is set using a small value d as 0.1 to 0.2 mm.

Next, the punch 5 is lowered in accordance with the control diagram shown in FIG. 1, reaches the position D ₀ -d in step 503, then rises by a preset value Δl in step 504, and is spring-backed.

At this time, in step 505, the pressing force F and the oil temperature are detected.

In step 506, it calculates the correction value of the depth value D ₀ (error) △ D by fuzzy inference as described below.

Here, the reason why fuzzy inference is used is that there is considerable ambiguity in the relationship between the pressing force and the oil temperature, and there is ambiguity in the influence factor of the pressing force.

FIG. 6 is a flowchart of the fuzzy inference method, FIG. 7 is an explanatory diagram showing a fuzzy set of the difference ΔF in the pressing force, and FIG.
FIG. 9 is an explanatory diagram showing a fuzzy set of oil temperature, and FIG. 9 is an explanatory diagram of a fuzzy rule. In the figure, B is Big, M is Middle,
S indicates Small.

The fuzzy rule in FIG. 9 is described in the form of if △ F is F and T isT then △ D% = A (F, T) (3). However, ΔD% in this table is shown as a percentage (%) value of the plate thickness t (nominal value).

The correction value △ D% represented by% of the plate thickness t is given by the following equation.
Calculated as a weighted average of all rules.

As described above, ΔD% is obtained from the equation (2), and the correction value ΔD is obtained from ΔD = t · ΔD%.

For example, when pressure is applied to a workpiece having a nominal thickness of 1.6 mm, a predetermined pressing force F ₀ at the time of a predetermined springback is applied.
However, it is assumed that the pressing force actually exceeds 5 kg, and the oil temperature at this time is 55 ° C.

Then, in FIGS. 7 and 8, the membership values of + M and S are both 0.5, and △% is −
0.5%, and the correction value is -0.08 mm.

Therefore, in FIG. 5, in step 507, the optimum depth position D ₀ ′ is set to D ₀ −0.08 mm, and in step 508,
Re drive shaft, the bending angle of the workpiece W and the target angle theta _0.

As described above, in this example, the correction value △ D is obtained by using fuzzy inference, and the optimal depth position D ₀ ′ is controlled.

It should be noted here, as is clear from the rule in FIG. 9, that the maximum correction amount is set to 15% of the plate thickness. The reason is that it is difficult to perform perfect pressure control in a so-called air bend. In this example, too, the D-axis control is basically used, and this is based on the idea that the control is brought close to the original optimum position by measuring the pressing force.

Therefore, in this example, the depth position D ₀ set by the database or the like can be approximated to the optimum position D ₀ ′ by fuzzy control, and more accurate machining can be efficiently performed.

The present invention is not limited to the above embodiment, but can be implemented in an appropriate mode by making appropriate design changes.

[Effects of the Invention] As described above, since the present invention is a method for controlling a bending machine as described in the claims, a depth position preset using a data table or the like is changed to a more optimal depth position. And highly accurate bending can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is a view showing an outline of the present invention, FIG. 2 is a front view showing an example of a bending machine, FIG. 3 is an explanatory view showing a bending mode,
FIG. 4 is a block diagram of a control device according to an embodiment of the present invention,
FIG. 5 is a flowchart showing the control system, FIG. 6 is a flowchart of the fuzzy operation system, FIG. 7 is an explanatory diagram showing a fuzzy set of pressurizing force, FIG. FIG. 9 is an explanatory diagram of a fuzzy rule. D _{0: a} preset depth position D ₀ ': optimal depth position D: correction value F: pressure T: oil temperature

Claims (2)

(57) [Claims] 1. A method for controlling a bending machine for bending a work interposed between these dies by a relative movement of a punch or a die at a predetermined angle. The temporary depth position is set based on various conditions such as conditions, frame conditions, and the driving die is moved to the set temporary depth position or a position before the temporary depth position, and then the driving die is set based on the position at that time. It is moved by a predetermined amount to a position slightly before the spring back end point, and a correction value of the depth position is obtained in accordance with a difference between a predetermined pressing force and an actual pressing force at the position, and this correction is made to the temporary depth position. A method for controlling a bending machine, comprising: calculating an optimum depth position by adding a value; and re-driving the driving die to the calculated optimum depth position. 2. The control method for a bending machine according to claim 1, wherein the calculation of the optimum depth position is performed by a fuzzy set of a difference between the predetermined pressing force and an actual pressing force and a hydraulic pressure cylinder for driving a mold. A method for controlling a bending machine, wherein fuzzy inference is performed using a fuzzy set of oil temperature.