JP3447184B2 - Bending machine in bending machine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving die (punch) supported by a ram having three or more driving shafts, and both ends arranged opposite to the ram. The present invention relates to a bending device in a bending machine that bends a plate-shaped work in cooperation with a fixed die (die) supported on a table to which a part is fixed. 2. Description of the Related Art Conventionally, as a bending machine of this kind, FIG.
A press brake 51 as shown in FIG. In the press brake 51, the ram 52 and the fixed table 53 are opposed to each other, and a pair of side frames 54 and 55 are integrally provided at both ends of the fixed table 53. The hydraulic cylinders 56, 56 provided on the
Is configured to move up and down. And ram 5
An upper die (punch) 57 is provided at the lower end of the fixed table 5.
Lower dies (dies) 58 are respectively arranged on the upper surface of the upper die 3, and a plate-like work is inserted between the upper dies 57 and the lower dies 58 to operate the hydraulic cylinders 56, 56 so that these upper dies 58 are actuated. The work is pressed between the lower mold 57 and the lower mold 58 and bent at a required bending angle. In such a press brake, the set pressure of the machine is usually set to a value obtained by adding a margin to the pressure required for bending, whereby the gap between the punch and the die is not properly set. Based on the above, the mold is prevented from being damaged due to an excessive pressing force acting on the work. In the case of a press brake having a total of two ram drive shafts, one on each side, as shown in FIG.
No. 16716 proposes this. In the press brake described in this publication, in the case of so-called eccentric bending, in which the bending center of the work is deviated in the right or left direction from the center of the machine, even if the pressing force required for bending is the same, the force generated by each drive shaft depends on the bending position. Is configured to change the limit value. [0005] However, in a press brake having three or more ram drive shafts, for example, a work having a small plate thickness and a long bending length, and a work having a large plate thickness and a long bending length are used. Even if the pressure required for bending is the same for workpieces with a short length, the pressure applied to each drive shaft is limited by the magnitude of the bending length even if the pressure required for bending is the same. Since the values are different, it is necessary to change the limit value of the applied pressure of each drive shaft according to not only the bending position of the work but also the bending length. If the limit value of the generated pressing force is not set to an appropriate value, for example, if the maximum pressing force can always be generated, there is a possibility that the mold will be damaged if there is a defective bending position. However, if only the required bending pressure is set to the limit value regardless of the bending position and bending length, on the other hand, the bending force may become insufficient depending on the bending position, leading to poor bending accuracy or bending. When the length is short, there is a problem that the pressing force is too large, which leads to breakage of the mold. SUMMARY OF THE INVENTION An object of the present invention is to provide a bending machine having three or more ram drive shafts to set the limit value of the applied pressure of each drive shaft to an appropriate value. Accordingly, it is an object of the present invention to provide a bending device in a bending machine capable of performing a bending process with high accuracy while avoiding the risk of mold breakage. [0008] In order to achieve the above-mentioned object, a bending device in a bending machine according to the present invention is supported by a ram having three or more drive shafts. A bending die device for bending a plate-shaped work by cooperation of a driving die to be driven and a fixed die supported on a table having both ends fixed to the ram. (A) input means for inputting bending data for controlling driving of each drive shaft; (b) whether bending data input by the input means;
Pressure required for bending processing from the
The work bending length and
Value calculating means for calculating a limit value of the generated pressurizing force for each drive shaft according to the bending position, and (c) a ram for driving the ram for each drive shaft based on a calculation result of the limit value calculating means. It is characterized by comprising a driving means. In the present invention, bending data for controlling the driving of each driving shaft of a ram having three or more driving shafts (eg, V width dimension of fixed die, work plate thickness, work bending length) , The work tension, etc.), the limit value of the generated pressing force for each drive shaft is calculated, and the ram is driven for each drive shaft so as not to exceed the limit value. Here, the generation
The pressure limit value is calculated from the input bending data.
The pressure required for machining is required, and this pressure
Work bending length and bending
It is calculated for each drive shaft according to the deflection position. According to the present invention, in a bending machine having three or more drive shafts, it is possible to obtain a necessary generated pressure per axis due to a difference in bending length and bending position. Even if the required bending force is the same and the bending length is different, or if the bending is performed in one of the left and right directions, the mold may be damaged due to the incorrect setting of the bending position. Can be suppressed as much as possible, and it is possible to realize high-precision bending by avoiding occurrence of bending angle accuracy failure due to insufficient set pressure. Next, a specific embodiment of a bending apparatus in a bending machine according to the present invention will be described with reference to the drawings. FIG. 1 is a front view of a press brake according to an embodiment of the present invention, FIG. 2 is a side view of the press brake, and FIG.
FIG. 2 is a block diagram showing a control system configuration of the present embodiment. The press brake according to the present embodiment includes a fixed table 1 and a ram 2 which is driven to move up and down opposite to the table 1. A die (lower die) 4 having a V-shaped mold groove is held, and a punch (upper die) 5 is attached to a lower portion of the ram 2 so as to face the die 4 via a punch holding device 6. . A pair of side frames 7 and 8 are integrally provided at both ends of the table 1, and a support frame 9 is provided so as to connect the upper ends of the side frames 7 and 8. A plurality of (four in this embodiment) ram driving devices 10a, 10b, 10c, 1
0d is attached, and these ram driving devices 10a
The ram 2 is swingably connected to the lower ends of 10 to 10d. Thus, the work inserted between the punch 5 and the die 4 is bent by raising and lowering the ram 2 by the operation of the ram driving devices 10a to 10d. Each of the ram driving devices 10a to 10d uses an AC servo motor 11a to 11d provided at the rear as a driving source and transmits the driving force to the ram 2 via a timing belt 12.
Are transmitted to a ball screw 13 connected to the servo motors 11a to 11
The rotational driving force d is converted into a vertical moving force to generate a pressing force on the work. The vertical position of the ram 2 is determined by linear encoders (incremental encoders) 14a to 14d provided corresponding to the driving shaft positions of the ram driving devices 10a to 10d.
14d, and the detection data is
9a, the respective servo motors 11a to 11a through the servo amplifiers 15a to 15d in accordance with the respective axis positions.
11d is feedback-controlled, and brakes 16a to 16d attached to the motor shafts of the servomotors 11a to 11d are controlled by a machine control device. Here, the linear encoder 14a
14d is a correction bracket 1 composed of two side plates provided along the side frames 7, 8 and a beam connecting the left and right side plates.
7 supported. With such a configuration, these linear encoders 14a to 14d
8, the absolute position of each axis of the ram 2 can be measured without being affected by the deformation due to the load change.
An encoder (absolute encoder) 18 for detecting the current position of each of the servomotors 11a to 11d is provided on the motor shaft of each of the servomotors 11a to 11d.
a to 18d are attached to these encoders 18a to 18d.
d, each servo amplifier 15a-
15d is controlled. A control unit 20 including an NC unit 19a and a machine control unit (sequencer) 19b for controlling the above-mentioned ram drive units 10a to 10d is mounted on the side of the main frame of the press brake. Operation panel 24 including a keyboard 21 for inputting data, a display 22 for displaying various data, and various switches 23.
Is suspended from the support frame 9 via a swingable arm 25. Further, a foot switch 26 for stepping operation is provided below the side of the body frame. In the press brake having such a configuration, the closest approach distance between the punch 5 and the die 4 is determined based on the bending data inputted from the operation panel 24 so that the bending angle of the work becomes the target bending angle. The target lower limit position of the ram 2 is calculated based on the calculation result for each drive shaft position.
The axes are simultaneously approached and separated by 1a to 11d, and whether or not the axes have reached the target position is monitored and controlled for each axis by a feedback signal of the ram position in each axis. In the press brake having the above-described structure, when the work W is bent at the center of the machine, as schematically shown in FIG.
_Since the workpieces are driven by ₁ , P ₂ , P ₃ , and P ₄ , the bending load applied to each axis changes according to the bending length L of the work W as shown in FIG. That is, in FIG.
When the bending length L is short, the central two axes P ₂ and P ₃ bear most of the bending load, but as the bending length L increases, the burden on the two axes P ₁ and P ₄ at both ends increases. come. When the bending length L is close to the machine length, the load is evenly distributed on four axes. Further, the axis position of each axis is set so that such a load can be obtained. For example, the load ratio Sp per axis borne by the central axes P ₂ and P ₃ can be approximated by a quadratic equation such as the following equation. Sp = C1 × L ² + C2 where C1 and C2 are constants. Next, as shown in FIG. 6, the bending position of the workpiece W is shifted from the center of the machine by the amount of eccentricity x in the horizontal direction. In the case of eccentric bending where processing is performed, FIG.
(B) As shown in (c), the bending length L and the eccentricity x
The load borne by each shaft changes according to the above. As is evident from FIG. 7, when focusing on the axis having a large load burden,
When bending length L is short (when below 1800mm in this embodiment), the eccentricity x is between 0 and the intersection position x ₁ is the axis P ₃ is most burden is large, the amount of eccentricity x is the intersection position x ₁
Most burden is large axis P ₄ is a larger area. Also,
When the bending length L is increased to some extent (180 in this embodiment).
Above 0 mm), but it may not take a large amount of eccentricity x, larger it is not the axis P ₃ regardless eccentricity x. Here, the intersection point x ₁ can be approximated to the bending length L by a quadratic equation as shown in the following equation (see FIG. 8). x ₁ = C3 × L ² + C4 The load ratio Sp can be approximated to the eccentricity x by the following equation (see FIG. 9). (1) 0 ≦ x <When _{x 1 Sp = sin ((x} / Pc11 + 1 / Pc12) × π) + C5 ··· (2) when _{x ≧ x 1 Sp = Pc13 ×} x + Pc14 ··· However, C3～ C5: constants Pc11 to Pc14: values using the bending length L as a variable. In the equation, when x = 0, the value is equivalent to the above equation. When the load ratio Sp is obtained as described above, the set pressing force per axis due to the difference in the bending length L and the bending position (the amount of eccentricity x) becomes the pressing force B required for bending.
It is obtained as a value obtained by multiplying F (including a machine-specific margin increase) by the obtained load ratio Sp. In this way, by limiting the pressing force of each axis so as not to exceed the set pressing force during the pressing operation of the work W in the bending operation, it is possible to prevent the generation of the pressing force more than necessary, and to reduce the bending length. Even if a workpiece having a short length L is bent or eccentrically bent, the pressing force does not become insufficient, and accurate bending can be realized. The setting of the pressing force as described above is performed according to the procedure shown in the flowchart of FIG. Next, this procedure will be described sequentially. S1 to S2: operation panel 24 as input means
, The bending data (the V width of the die 4, the work plate thickness, the work tensile strength, etc.) for controlling the driving of each drive shaft are input, and the bending length L and the eccentricity x of the work W are input. S3: The maximum pressurizing capacity of the machine is obtained from the maximum pressurizing force generated by one axis by the difference in the bending length L. The change in the maximum load of the machine according to the bending length is as shown in FIG. In addition, based on the pressing force BF obtained in this way, it is also possible to determine from the input bending conditions whether or not the bending operation is possible with the mechanical ability by the following equation. PF = Pax / (BF × Sp) where PF: Pressing capacity value Pax: Maximum generated pressing force of one axis BF: Pressing force required for bending S4 to S5: When pressing force is input from the operation panel 24 In the NC device 19a, it is determined whether or not the input pressing force is equal to or less than the maximum pressurizing capability. If the input pressurizing force is equal to or lower than the maximum pressurizing capability, the setting is completed, and the numerical value exceeds the maximum pressurizing capability. In this case, the display 22 indicates the fact.
When this display is made, the operator re-inputs the pressing force (S4) or returns to step S1 again. Next, the bending operation is performed according to the procedure shown in FIG. T1 to T2: It is determined whether or not the applied pressure per axis during the bending operation, in other words, during the operation of the ram 2, exceeds the set pressure (limit load) set as described above. Judgment is made, and if it is not exceeded and there is no other abnormality, the bending operation is terminated. Where 1
The generated pressure per axis is the servo motors 11a to 11d
Is proportional to the current value required to generate the torque, so that the current value of the servo motor of each axis falls within the current value per axis corresponding to the pressing force set by the operation panel 24. A command is issued to each of the servo amplifiers 15a to 15d by the NC device 19a so that the current can be settled, and each of the servo amplifiers 15a to 15d performs control so as to limit the current value. T3 to T4: If the generated pressing force per axis exceeds the set pressing force or if there is another abnormality even if the set pressing force does not exceed the set pressing force, the operation is interrupted, and After the factor is removed, the flow returns to the flow again. In the actual bending operation, when the operation pedal of the foot switch 26 is depressed, the punch 5 suddenly approaches the work W, and then the generated pressure is limited to lower the work pressure by a low-speed lowering operation (pressing operation). After performing the bending process of W and descending to an arbitrary bending angle, a high-speed ascent operation is performed and the operation is stopped at the upper limit, thereby completing the operation of one process. In this embodiment, the description has been given of the case where the generated pressing force of all the axes is set in accordance with the axis having the largest load ratio Sp among the four axes. However, the bending length and the bending position of each axis are described. May be used to control the generated pressing force separately for each axis. In this embodiment, a so-called overdrive type press brake in which an upper mold is attached to a ram (movable member) and a lower mold is attached to a table (fixed member) has been described. It goes without saying that the present invention can also be applied to a so-called under-drive type press brake in which a lower mold is attached to the (movable member) and an upper mold is attached to the table (fixed member). In the present embodiment, the one using an AC servomotor and a ball screw as the driving source of the ram has been described. However, as the driving source, a hydraulic unit and a cylinder may be used. In this embodiment, the case where the number of drive shafts of the ram is four has been described. However, the number of drive shafts may be three, five or more.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of a press brake according to one embodiment of the present invention. FIG. 2 is a side view of the press brake of the present embodiment. FIG. 3 is a block diagram illustrating a configuration of a control system of the press brake according to the present embodiment. FIG. 4 is a schematic diagram when a workpiece is bent at the center of a machine. FIG. 5 is a graph showing a relationship between a bending length and a load ratio per axis. FIG. 6 is a schematic diagram when eccentric bending is performed. FIGS. 7A, 7B, and 7C are graphs showing the relationship between the amount of eccentricity in eccentric bending and the load ratio per axis. FIG. 8 is a graph showing the relationship between the intersection length and the bending length. FIG. 9 is a graph showing a relationship between a load ratio and an eccentric amount. FIG. 10 is a flowchart illustrating a setting procedure of a pressing force. FIG. 11 is a graph showing a change in a maximum load of a machine depending on a bending length. FIG. 12 is a flowchart illustrating a bending operation procedure; FIG. 13 is a view showing a conventional press brake. [Description of Signs] 1 Table 2 Ram 4 Die (lower mold) 5 Punch (upper mold) 7, 8 Side frame 10a to 10d Ram drive device 11a to 11d Servo motor 12 Timing belt 13 Ball screw 14a to 14d Linear encoder 15a to 15d Servo amplifier 16a to 16d Brake 17 Correction bracket 18a to 18d Encoder 19a NC unit 19b Machine control unit (sequencer) 21 Keyboard 22 Display 24 Operation panel 26 Foot switch

Claims (1)

(57) Claims 1. A driving die supported by a ram having three or more driving shafts, and a table which is opposed to the ram and is fixed at both ends. A bending device in a bending machine that bends a plate-shaped work in cooperation with a fixed mold, comprising: (a) input means for inputting bending data for controlling driving of each drive shaft; (b) ) or bending data inputted by the input means
Pressure required for bending processing from the
The work bending length and
Value calculating means for calculating a limit value of the generated pressurizing force for each drive shaft according to the bending position, and (c) a ram for driving the ram for each drive shaft based on a calculation result of the limit value calculating means. A bending device in a bending machine, comprising a driving means.