JP4450939B2 - Press brake - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention The Less brakes, especially in press brakes, can reduce the bending force when bending a workpiece. Rupu It relates to the less brake.
[0002]
[Prior art]
Conventionally, press brakes are frequently used for bending plate-shaped workpieces, and there is a strong demand for high-precision bending when manufacturing high-quality processed products. Incidentally, high precision means the accuracy of the bending angle and flange dimensions of the workpiece after bending.
[0003]
In actual bending, for example, when the workpiece is bent by the cooperation of the punch and the die attached to the lower table by reciprocating the upper table on which the punch is mounted, the press brake is applied by the reaction force of the bending force. Deflection occurs in the frame. The deflection of the frame causes a drum-shaped opening at the distance between the punch and the die. Also, since the workpieces have the same production lot, there are variations in the plate thickness and tensile strength. This variation will cause variations in the opening between the punch and the die. Will lead to variations.
[0004]
Therefore, various methods have been devised in consideration of the deflection of the frame in order to obtain a highly accurate bending angle.
[0005]
For example, the “crowning method”, in which a hydraulic cylinder called a crowning cylinder is incorporated in the lower table and the lower table itself is bent so that the distance between the punch and the die is uniform even when bending force is applied, is a typical example. .
[0006]
There is also a “three-point method” in which the width dimension of the punch is divided into short pieces and an evenly distributed load is applied over the entire bending length (longitudinal direction of the punch) using hydraulic pressure.
[0007]
[Problems to be solved by the invention]
By the way, the former “crowning method” requires a very high level of control, and the latter “three-point method” has a problem in that the mold-related structure is complicated and the components are expensive. Therefore, in order to solve these conventional problems, it is only necessary to essentially reduce the bending force.
[0008]
This is because, as described above, the cause of the deterioration of the work bending angle quality is the amount of bending of the frame when bending force is applied during bending, so if the bending force can be reduced, the amount of bending of the frame will also decrease. This is because high-precision bending can be realized without the need for the above-described conventional sophisticated and complicated correction mechanism / structure.
[0009]
The present invention has been made to solve the above-mentioned problems, and its object is to reduce bending force by giving micro vibrations to a punch or die mold mounted on an upper or lower table, particularly in a press brake. It is an object of the present invention to provide a bending method and a press brake capable of performing a low-precision and high-precision bending as possible.
[0010]
[Means for Solving the Problems]
The present invention has been made in view of the above-described problems. The workpiece is bent by reciprocating either one of an upper table mounted with a punch and a lower table mounted with a die by a table driving device. In a press brake, a table position detecting device for detecting a displacement amount of a reciprocating table, a pressure detecting device for detecting a bending pressure of a reciprocating table, and a minute vibration with respect to a punch or die mounted on the table The micro-vibration generation device that gives the vibration, the data obtained from the table position detection device and the pressure detection device are used to determine the background during bending and to derive a preset micro-vibration start point. Microvibration command that gives a microvibration generator a command to add microvibration to the punch or die from the start point to the end of bending A first fluid pressure cylinder that reciprocates the table, and the minute vibration generator is provided at a tip of a piston rod of the first fluid pressure cylinder. A vibration transmitting member comprising two fluid pressure cylinders for transmitting minute vibrations of the piston of the second fluid pressure cylinder to a die at the tip of the table is provided penetrating the inside of the table, and the first fluid pressure cylinder has a fluid pressure. Is provided with a fluid pressure circuit for controlling the piston of the second fluid pressure cylinder to reciprocate minutely while operating the table to be bent. .
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a bending method and a press brake 1 according to the present invention will be described below with reference to the drawings.
[0027]
Referring to FIG. 1, a basic system block of a bending method according to the first embodiment is shown. In the press brake 1 according to the present embodiment, the lowering press brake 1 driven by hydraulic pressure is the control target. The punch P is mounted on the upper table 5 via the punch holder 3, while the die D is mounted on the lower table 9 which is a part of the frame 7. As the upper table 5 is lowered, the punch P is lowered, and the workpiece W is sandwiched between the punch P and the die D, whereby bending is performed.
[0028]
The upper table 5 is displaced by a reciprocating motion of a piston 13 incorporated in, for example, a first hydraulic cylinder 11 as a table driving device.
[0029]
The press brake 1 is provided with a control device 15 for controlling the operation of the machine, and this control device 15 is used for inputting various data to the CPU 17 as a central processing unit as shown in FIG. For example, an input device 19 such as a keyboard as an input means and a display device 21 such as a CRT for displaying various data are connected.
[0030]
In addition, the CPU 17 inputs data on bending work conditions such as bending length, bending angle, flange length, work material / plate thickness / tensile strength, specification mold type, etc. as work W bending information. A memory 23 which is input from 19 and stored therein is connected.
[0031]
Further, the CPU 17 gives a command for determining the stroke of the upper table 5 based on the bending information in the memory 23 and controlling the stroke operation of the first hydraulic cylinder 11, in other words, the displacement amount of the upper table 5. As will be described in detail later with reference to the table drive command unit 25, a minute vibration start point is derived by judging the circumstances at the time of bending, and minute vibration is added to the mold from this minute vibration start point until the end of bending. A minute vibration command unit 27 for giving a command to a minute vibration generator described later is connected.
[0032]
Referring again to FIG. 1 and FIG. 2 again, when a displacement command for the upper table 5 is output from the table drive command unit 25 of the control device 15 to the first hydraulic cylinder 11, this signal is sent to the servo amplifier 29. For example, a rotary hydraulic servo valve 31 (referred to as “first RDV” in the present embodiment) as a first switching valve that is converted into an analog signal and constitutes a part of the first hydraulic circuit as the first fluid pressure circuit, for example. It is input as an operation command. The pressure flow rate corresponding to this input signal is controlled by the first RDV 31 so that the displacement speed of the upper table 5 is controlled and automatic positioning is performed.
[0033]
The amount of displacement of the table is detected by, for example, a position sensor 33 as a table position detecting device that detects the amount of displacement of the upper table 5 (the lower table in the ascending press brake) that is mounted on the frame 7 of the press brake 1 and reciprocates. The detected value is input to the control device 15 as a displacement feedback signal.
[0034]
Referring to FIG. 3, the first RDV 31 is referred to as a “multi-port rotary valve” and generally moves a piston of a hydraulic cylinder as an example of a driving device up and down with a high or low fluid pressure. In the present embodiment, the pressure oil is supplied and controlled using the flow path on one side of the high pressure or low pressure of the “multi-port rotary valve”.
[0035]
The first RDV 31 is provided with a valve body 37 having a sliding groove 35 in the left-right direction in FIG. 3 at the center, and a spool 39 that can rotate and slide in the left-right direction in FIG.
[0036]
Also, a direct acting motor 41 as an example of a reciprocating mechanism for moving the spool 39 along the sliding groove 35 in the left-right direction in FIG. 3 is attached to the right end surface in FIG. The motor 41 is connected by a bearing 43 that allows only rotation.
[0037]
On the other hand, a rotary motor 45 as an example of a turning mechanism for rotating the spool 39 is attached to the left end surface in FIG. 3 of the valve body 37 via a motor holding block 47, and the rotary motor 45 is connected to the spool 39. It is configured to transmit rotation while allowing left and right reciprocation.
[0038]
On the side surface (lower side surface in FIG. 3) of the valve body 37, a low pressure port hole 49 as a low pressure pressure fluid inlet, a high pressure port hole 51 as a high pressure fluid intake, and the first hydraulic cylinder 11. A port hole 57 as a supply port connected by a pipe 55 to supply pressure fluid to the upper chamber 53 and a supply connected by a pipe 61 to supply pressure fluid to the lower chamber 59 of the first hydraulic cylinder 11. A B port hole 63 is provided as a mouth.
[0039]
Further, a TB port hole 67 connected by a pipe 65 for discharging the pressure fluid from the lower chamber 59 of the first hydraulic cylinder 11 and a pipe 69 for discharging the pressure fluid from the upper chamber 53 of the first hydraulic cylinder 11 are connected. A TA port hole 71 connected to the tank 73 by a pipe 75 is provided to return the pressure fluid discharged from the first hydraulic cylinder 11 to the tank 73.
[0040]
In the present embodiment, the pressure oil in the tank 73 is supplied using the flow path on the high pressure side, and the hydraulic pump 81 is driven by the hydraulic motor 79 to supply the pressure oil in the tank 73. Is connected to the high-pressure port hole 51 by a pipe 83.
[0041]
The inside of the spool 39 is basically hollow, and the thick portion 85 is provided with notches having various shapes at predetermined positions. A thick portion 85 of the right hollow portion 87 provided near the right end portion of the spool 39 in FIG. 3 is provided with a pair of upper and lower rectangular supply holes 89 facing each other.
[0042]
Further, a thick elongated portion 85 of the central hollow portion 91 provided on the left side of the right hollow portion 87 in FIG. Further, a pair of symmetrical thin notches 97 are provided in the right thick portion 85 of the left hollow portion 95 adjacent to the left in FIG. 3 of the central hollow portion 91, and the meat on the left side of the notch 97 is provided. The thick portion 85 is provided with a wide notch 99.
[0043]
The lengths of the notches 93, 97, and 99 are long enough to prevent a later-described hole from being removed even when the spool 39 is moved left and right by the direct acting motor 41.
[0044]
Various passages are provided in the valve body 37. When the spool 39 is moved to the right position by the direct acting motor 41, a low pressure opening 101 is provided on the lower inner surface of the sliding groove 35 corresponding to the position of the lower supply hole 89. A passage 103 connecting 101 and the low pressure port hole 49 is provided.
[0045]
Further, when the spool 39 is moved to the left position by the direct acting motor 41, a high pressure opening 105 is provided on the lower inner surface of the sliding groove 35 corresponding to the position of the lower supply hole 89. A passage 107 connecting the high-pressure opening 105 and the high-pressure port hole 51 is provided.
[0046]
The low pressure opening 101 and the high pressure opening 105 are provided in such a size that the supply hole 89 of the spool 39 does not deviate from the low pressure opening 101 or the high pressure opening 105 even when the spool 39 moves to a predetermined position on the left and right and rotates by a predetermined angle. ing.
[0047]
The valve body 37 is provided with two A port outlets 109 and two B port outlets 111 facing each other. The two A port outlets 109 are one inside the valve body 37 and are connected to the A port hole 57 via the passage 113. Similarly, two B port outlets 111 are also formed inside the valve body 37 and are connected to the B port hole 63 via the passage 115.
[0048]
Further, the valve body 37 is located on the left side of the A port outlet 109, and a pair of TB openings 119 communicated with the TB port hole 67 through the passage 117 and a pair of TA communicated with the TA port hole 71 through the passage 121. An opening 123 is provided.
[0049]
Further, the valve body 37 is provided with a T port outlet 125 on the upper and lower surfaces of the sliding groove 35 in the vicinity of the left end portion in FIG. The T port outlet 125 is provided in such a size that it does not come off from the notch 99 of the spool 39 even when the spool 39 rotates by a predetermined angle. A passage 127 connecting the T port outlet 125 and the T port hole 77 is provided.
[0050]
Hereinafter, the operation of the first RDV 31 will be described.
[0051]
First, the case where the piston 13 of the 1st hydraulic cylinder 11 is raised is demonstrated. In the present embodiment, the pressure oil in the tank 73 is supplied using the flow path on the high pressure side, so the spool 39 is moved to the left side by the direct acting motor 41 and set to high pressure supply. At the same time (the state shown in FIG. 3), the spool 39 is rotated counterclockwise by the rotary motor 45. In this state, the supply hole 89 of the spool 39 is positioned immediately above the high-pressure opening 105, and the low-pressure opening 101 is closed by the outer peripheral surface of the spool 39.
[0052]
The pressure oil in the tank 73 is supplied from the hydraulic pump 81 through the pipe 83, the high pressure port hole 51, and the passage 107, enters the central hollow portion 91 of the spool 39 from the high pressure opening 105 through the supply hole 89, and enters from the notch 93. The piston 13 is raised by being supplied to the lower chamber 59 of the first hydraulic cylinder 11 through the B port outlet 111 and the passage, the B port hole 63 and the pipe 61.
[0053]
At this time, in the central hollow portion 91 of the spool 39, the A port outlet 109 is closed by the outer peripheral surface of the spool 39. Therefore, the pressure oil filled in the upper chamber 53 of the first hydraulic cylinder 11 by the rise of the piston 13 flows to the left of the spool 39 through the pipe 69, the TA port hole 71, the passage 121, the TA opening 123, and the notch 97. It is discharged to the hollow portion 95 and further discharged to the tank 73 through the notch 99, the T port outlet 125, the passage 127, the T port hole 77, and the pipe 75.
[0054]
Next, the case where the piston 13 is lowered will be described. The spool 39 is rotated clockwise by the rotary motor 45. Even in this state, the supply hole 89 of the spool 39 is located immediately above the high pressure opening 105 and the low pressure opening 101 is closed by the outer peripheral surface of the spool 39, so that the pressure oil is supplied to the central hollow portion 91 of the spool 39. This is exactly the same as when the piston 13 is raised.
[0055]
The pressure oil supplied to the central hollow portion 91 passes through the notch 93, exits from the A port outlet 109, and is supplied to the upper chamber 53 of the first hydraulic cylinder 11 through the passage 113, the A port hole 57, and the pipe 55. As a result, the piston 13 is lowered.
[0056]
At this time, since the B port outlet 111 is closed by the outer peripheral surface of the spool 39 in the central hollow portion 91 of the spool 39, the pressure filled in the lower chamber 59 of the first hydraulic cylinder 11 as the piston 13 descends. The oil is discharged to the left hollow portion 95 of the spool 39 through the pipe 65, the TB port hole 67, the passage 117, the TB opening 119, and the notch 97, and further, the notch 99, the T port outlet 125, the passage 127, and the T port. It is discharged to the tank 73 through the hole 77 and the pipe 75.
[0057]
When the low pressure side flow path is used, the spool 39 is moved to the right by the direct acting motor 41 and set to low pressure supply. In this state, the spool 39 is rotated clockwise and counterclockwise by the rotary motor 45 in the same manner as in the case where the high-pressure side flow path is used. The piston 13 is moved up and down by being supplied to the upper chamber 53 or the lower chamber 59.
[0058]
Referring to FIG. 1 again, on the piston head side of the first hydraulic cylinder 11, for example, a pressure sensor as a pressure detection device for detecting the bending pressure of the reciprocating upper table 5 (lower table in the ascending press brake). 129 is mounted so that the hydraulic pressure during bending can be detected.
[0059]
When the bending process is started, the bending pressure is constantly detected by the pressure sensor 129, and the detected value is fed back to the control device 15, and the minute vibration command unit 27 of the control device 15 receives the detection signal of the pressure sensor 129 and will be described later. A minute vibration start point is derived.
[0060]
Hereinafter, the minute vibration starting point will be described in more detail. FIGS. 4A, 4B, and 4C show the positional relationship between the punch P and the die D when bending is performed. FIG. 5 shows the relationship between the amount of displacement of the upper table 5 during bending and the bending pressure.
[0061]
When the bending process starts, the punch P descends as the upper table 5 descends, and when the workpiece W is clamped between the punch P and the die D as shown in FIG. The bending force begins to increase as indicated by point S in FIG.
[0062]
The bending process proceeds as shown in FIG. 4 (B), passes through the point H in the air bending area as shown in FIG. 5, and bottoming as shown in FIG. 4 (C). It becomes. The point I in FIG. 5 is the bottoming pressurization start point. Since this bottoming is a process of pressing the workpiece W by the inclined surface of the punch tip and the V groove surface of the die D, the bending force rapidly increases from point I to point J in FIG. The bending process ends when the target bending angle is obtained.
[0063]
In the embodiment of the present invention, the final bending force is reduced by applying minute vibrations to the mold during bending. Since the deflection of the frame 7 of the press brake 1 due to the reaction force of the bending force is reduced by reducing the magnitude of the final bending force at the point J in FIG. 5, the variation in the bending angle of the workpiece W is reduced, and the processed product The accuracy of the bending angle can be improved.
[0064]
Below, the process of applying vibration during bending and the results will be described.
[0065]
In the system according to the first embodiment, the bending pressure is constantly detected by the pressure sensor 129. The bending process is depicted by the bending pressure detected by the pressure sensor 129 and the amount of displacement of the upper table 5 by the position sensor 33 as shown in FIG.
[0066]
When the bending process proceeds and the bottoming start point is reached as shown at point I in FIG. 5, the bending pressure increases from a decreasing tendency to an increasing tendency. 5) is determined and derived by the minute vibration command unit 27 of the control device 15. In the first embodiment, the bottoming start point is the minute vibration start point.
[0067]
Referring again to FIG. 1, when a micro-vibration generation command is output from the micro-vibration command unit 27 of the control device 15 when the bottoming start point is detected, this signal is converted into an analog signal via the servo amplifier 131. For example, a rotary hydraulic servo valve 133 (referred to as “second RDV” in the present embodiment) as a second switching valve constituting a part of a second hydraulic circuit as a second fluid pressure circuit, for example. A rotation command for reciprocal operation (sine wave) is output. In the present embodiment, the second RDV 133 is a switching valve having a mechanism similar to that of the first RDV 31 described above.
[0068]
For example, a second hydraulic cylinder 135 as a minute vibration generating device that applies minute vibration to the punch P is embedded in the punch holder 3 on the lower surface of the upper table 5, and the piston 137 of the second hydraulic cylinder 135 is operated by the operation of the second RDV 133. A minute vibration is generated by repeating a minute displacement in the vertical direction. Since the punch P is coupled to the tip of the piston 137, the minute vibration of the piston 137 is transmitted to the punch P.
[0069]
The operation of the second RDV 133 is basically the same as that of the first RDV 31. The difference is that the spool 39 is alternately switched clockwise and counterclockwise by the rotary motor 45 so as to reciprocate (sinusoidal). By rotating with a wave), the pressure oil is alternately supplied to the upper chamber 139 and the lower chamber 141 in small increments, and the piston 137 moves up and down with a minute displacement.
[0070]
As described above, the bending process is continued while the minute vibration is applied from the bottom point of the bottoming to the end of the bending process by the fluid pressure servo mechanism.
[0071]
As a result, the bending force when bending is performed while the punch P is slightly vibrated in the vertical direction has a locus of D, H, I, and K in order from the point S in FIG. From this, it can be understood that the bending force can be reduced from the point I at the bottom of the first embodiment to the point K at the end of the bending process from the point I at the end of the bending process from the point I at the end of the bending process. .
[0072]
In the first embodiment described above, the minute vibration start point is set in advance to the bottoming start point. However, even when other timings are set in advance as the minute vibration start point in the bending process. good.
[0073]
In the second embodiment of the present invention, as shown in FIG. 1, a position sensor 33 for detecting the amount of displacement of the upper table 5 is used to derive the minute vibration start point. That is, by using the detection signal from the position sensor 33, it is also possible to set the minute vibration start point in advance based on the displacement position of the upper table 5.
[0074]
For example, when bending a thick material, the bending force increases when a pressure is applied to the workpiece W (at the start of bending), so the amount of deflection of the frame 7 increases. In this case, if the bending force is reduced by applying minute vibrations from the air bending region from the point S to the point I in FIG. 5 to the point I, the amount of deflection of the frame 7 of the press brake 1 decreases. This is very effective in obtaining a highly accurate bending angle.
[0075]
In this case, the position of the upper table 5 when the bending process is started is previously detected by the position sensor 33, and minute vibration is applied from the time when the upper table 5 reaches this position during the actual bending process. It ’s good to start.
[0076]
A third embodiment of the present invention will be described. Referring to FIG. 6, a double cylinder 143 including a first hydraulic cylinder 11 and a second hydraulic cylinder 135 is used as a table driving device in the press brake 1A. It has been. As in the case of the first embodiment described above, the first hydraulic cylinder 11 performs vertical displacement of the upper table 5 itself according to the control by the first RDV 31, and the second hydraulic cylinder 135 is minute by the second RDV 133. It is in charge of vibration operation.
[0077]
Since the upper table 5 is displaced with respect to the sliding surface, the minute vibrations of the second hydraulic cylinder 135 are actually absorbed during the sliding, so that it is difficult to generate the targeted minute vibrations. Therefore, in FIG. 6, a hole 145 is formed in the upper table 5 on the extension of the central axis of the piston 137 of the second hydraulic cylinder 135 for the purpose of reliably transmitting the minute vibration of the second hydraulic cylinder 135 to the punch P. In this hole 145, for example, a core metal called a soul pillar 147 as a vibration transmitting member is inserted.
[0078]
The soul column 147 has one end connected to the piston 137 and the other end connected to the punch P via the punch holder 3. By adopting this structure, the minute vibration generated from the second hydraulic cylinder 135 is directly transmitted to the punch P, so that the same effect as the first embodiment described above can be obtained.
[0079]
The control mechanism is the same as that of the first embodiment, and is omitted in FIG.
[0080]
As described above, the method and mechanism for reducing the bending force by minutely vibrating the punch P in FIGS. 1 to 6 have been described. However, the minute vibration generating mechanism itself is not limited to the method shown in the present embodiment. Various methods are conceivable. However, since the main component of the embodiment of the present invention is to apply micro vibrations during bending, the basic principle of the bending method of the present embodiment can be applied to any other similar vibration generating mechanism.
[0081]
For example, as an application to a lift press brake, an actuator for driving a table that drives an upper table with a punch mounted with minute vibrations is provided, and the upper table is entirely moved by reciprocating the actuator itself. It may be a bending method that vibrates.
[0082]
In addition, a method of vibrating the lower table itself on which the die D is mounted by an actuator for driving the table is effective for the descending press brake.
[0083]
Further, a method of minutely vibrating a piston of a crowning cylinder incorporated in the upper table or the lower table at a high frequency may be used.
[0084]
The fourth embodiment will be described. In the press brake 1B shown in FIG. 7, the upper table 5 to which the punch P is attached is fixed to the frame 7, and the lower table 9 to which the die D is attached is the third hydraulic cylinder. 149 is a lifting press brake that moves up and down by 149. Two crowning cylinders 151 are provided at the center of the lower table 9, and the pressure of the piston 153 of the crowning cylinder 151 is controlled to control the lower table 9 The amount of deflection at the center is adjusted.
[0085]
As shown in FIG. 8, the third hydraulic cylinder 149 is displaced in the vertical direction of the lower table 9 itself according to the control by the first RDV 31 similar to the first embodiment described above, and the position sensor, pressure sensor, control Since it is almost the same including the mechanism, the same reference numerals are used in FIGS. 7 and 8, and a detailed description thereof is also omitted. In FIG. 7, the first RDV 31 is not shown. In this case, the minute vibration command unit 27 of the control device 15 gives the crowning cylinder 151 a command to add minute vibrations to the punch or die from the derived minute vibration start point until the end of the bending process. This is different from the case of the first embodiment.
[0086]
As shown in FIGS. 7 and 8, the two crowning cylinders 151 also perform the crowning operation of the lower table 9 in accordance with the control by the third RDV 155 having the same structure as the second RDV 133 of the first embodiment described above. It is. When the workpiece W is bent after the lower table 9 is pushed up to a predetermined position, it is derived from the minute vibration start point derived in the same manner as in the first embodiment to the end of bending. In the meantime, the piston 153 of the crowning cylinder 151 is repeatedly displaced slightly in the vertical direction by the operation of the third RDV 155 to generate minute vibrations.
[0087]
The fifth embodiment of the present invention will be described. This bending method is a method of setting the amplitude and frequency of the vibration waveform by a program.
[0088]
In the fifth embodiment, the description will be made assuming that the present invention is applied to a descending press brake as shown in FIGS. 10 and 11, but this is not restrictive. 10 and 11, the mechanism for driving the upper table 5 up and down is the same as that in FIG. Note that the control for raising and lowering the upper table 5 is the same as that in FIG.
[0089]
In the press brake 1C of FIG. 10, an actuator 157 that directly applies minute vibrations to the die D mounted on the lower table 9 is provided, and this actuator 157 itself is reciprocally displaced. The actuator 157 can be applied in any form as long as it gives minute vibrations such as an ultrasonic vibration device.
[0090]
Further, in the press brake 1D of FIG. 11, the entire lower table 9 on which the die D is mounted is minutely vibrated by an actuator 157 similar to the case of FIG. Since the entire lower table 9 vibrates, the die D also vibrates, so that the same effects as those of the above-described embodiment can be obtained.
[0091]
Referring to FIG. 9, there is shown a block diagram of a vibration wave generating device 159 for giving a vibration wave for driving the actuator 157 to generate a minute vibration. As the vibration wave generator 159, a reference waveform generation circuit 161 generates a sine wave as a reference of the vibration wave. This sine wave is input to the frequency dividing circuit 163, where it is divided based on the sampling clock to extract the sampling frequency.
[0092]
On the other hand, since the sampling clock itself has a correlation with the frequency of the vibration wave, when the frequency command value is output from the control device 15A, the vibration frequency generation circuit 165 generates an arbitrary vibration frequency from the sampling frequency. It will be.
[0093]
The vibration wave having a set frequency is input to the amplifier circuit 167. When the amplitude command value is output from the control device 15A as described above, this command is D / A converted by the D / A converter 169. Amplification command voltage. The vibration wave is amplified in proportion to the command voltage. That is, the amplitude is set by the control device 15A, and the desired vibration wave (actual vibration waveform) for actually driving the actuator 157 is obtained.
[0094]
Since the above frequency command value and amplification command command value can be set by an input operation to the control device 15A, the bending length B, the material of the workpiece, the thickness t, the tensile strength σ, the bending type of the specification mold, etc. Corresponding to the processing conditions, waveform parameters such as the frequency and amplitude of the vibration wave to be added can be optimally set. That is, when the bending process described above is input to the control device 15A in advance, it corresponds to the bending process from the relational expression of frequency (or amplitude) = (B, material, t, σ, punch P, die D). Since the frequency command value and the amplitude command value are optimally set and output to the frequency dividing circuit 163 and the amplifier circuit 167 as described above, the bending force can be reduced in any bending process, and a highly accurate bending angle can be obtained. It becomes possible.
[0095]
10 and 11, the case of the lift press brake has been described, but the present invention can also be applied to a processing press brake.
[0096]
9 may be provided as a substitute for the second hydraulic cylinder 135 in the press brake 1 in FIGS.
[0097]
In addition, this invention is not limited to embodiment mentioned above, It can implement in another aspect by making an appropriate change.
[0098]
In this embodiment, the descent press brake by hydraulic drive is controlled, and the minute vibration is controlled using a rotary hydraulic servo valve (RDV). The basic principle of the bending method can be applied to all types of press brakes regardless of whether hydraulic drive / electrical drive or ascending / descending drive. Also, the control of minute vibrations can be applied by using a general servo valve such as a nozzle flapper type hydraulic servo valve.
[0099]
【The invention's effect】
As can be understood from the description of the embodiments of the invention as described above, According to the present invention, by detecting the amount of displacement of the reciprocating table using the table position detecting device and detecting the bending pressure of the reciprocating table using the pressure detecting device, Since the history of bending can be easily determined from the correlation data with the amount of displacement of the table, a preset minute vibration start point can be reliably derived. In addition, since a minute vibration is applied to the mold mounted on the upper or lower table in the process of bending the workpiece, the bending force can be reduced, and the bending process can be performed with high accuracy at low cost. The fluid pressure servomechanism supplies the fluid pressure to the first fluid pressure cylinder to control the bending stroke, while the fluid pressure servomechanism supplies the fluid pressure to the second fluid pressure cylinder and the second fluid pressure cylinder. A minute vibration can be generated by controlling the stroke of the cylinder minutely. Therefore, a minute vibration can be given to the die mounted on the table during the bending process in the bending direction from the second fluid pressure cylinder via the vibration transmitting member. .
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view of a press brake according to an embodiment of the present invention.
FIG. 2 is a block diagram of a control device.
FIG. 3 is a cross-sectional view of a multi-port rotary valve used in the embodiment of the present invention.
FIGS. 4A, 4B, and 4C are schematic explanatory diagrams illustrating a bending process according to an embodiment of the present invention.
FIG. 5 is a relationship diagram between an upper table displacement amount and a bending force.
FIG. 6 is a schematic explanatory view of a press brake showing another embodiment of the present invention.
FIG. 7 is a schematic front view of a press brake showing another embodiment of the present invention.
8 is a right side surface of FIG.
FIG. 9 is a block diagram of vibration wave generation according to another embodiment of the present invention.
FIG. 10 is a schematic side view of a press brake showing another embodiment of the present invention.
FIG. 11 is a schematic side view of a press brake showing another embodiment of the present invention.
[Explanation of symbols]
1 Press brake
3 Punch holder
5 Upper table
7 frames
9 Lower table
11 First hydraulic cylinder (table drive mechanism)
15 Control device
27 Micro vibration command section
31 1st RDV (rotary servo valve; 1st switching valve)
33 Position sensor (table position detector)
129 Pressure sensor (pressure detector)
133 2nd RDV (rotary servo valve; 2nd switching valve)
135 Second hydraulic cylinder (micro vibration generator)
147 Soul pillar (vibration transmission member)
151 Crowning cylinder
155 3rd RDV
157 Actuator
159 Vibration wave generator
161 Reference waveform generation circuit
163 Frequency divider
165 Vibration frequency generation circuit
167 Amplifier circuit

Claims (1)

In a press brake that bends a workpiece by reciprocating one of the upper table with a punch and the lower table with a die by a table driving device,
A table position detecting device for detecting the amount of displacement of the reciprocating table;
A pressure detection device for detecting the bending pressure of the reciprocating table;
A micro-vibration generator that applies micro-vibration to a punch or die mounted on the table;
From the data obtained from the table position detecting device and the pressure detecting device, the process at the time of bending is judged to derive a preset minute vibration starting point, and from this derived minute vibration starting point to the end of bending. A control device having a minute vibration command unit for giving a minute vibration generating device a command to apply a minute vibration to the punch or die, and
The table driving device comprises a first fluid pressure cylinder for reciprocating the table, and the minute vibration generating device comprises a second fluid pressure cylinder provided at the tip of a piston rod of the first fluid pressure cylinder. A vibration transmitting member for transmitting minute vibrations of the piston of the fluid pressure cylinder to the mold at the tip of the table is provided through the inside of the table, and the table is to be bent by supplying fluid pressure to the first fluid pressure cylinder. A press brake comprising a fluid pressure circuit that controls the piston of the second fluid pressure cylinder to reciprocate minutely while operating.

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