JP6101595B2 - Press brake and crowning control method - Google Patents

Description

  The present invention relates to a press brake having a crowning mechanism for crowning a lower table and a crowning control method.

  The press brake includes an upper table to which a die holder for attaching a punch die is attached and a lower table to which a die holder for attaching a die die is attached. When bending a plate material, an operator attaches a punch die and a die die to each die holder. The press brake lowers the upper table to the lower table and bends the plate material between the punch die and the die die.

  When the upper table applies pressure in the direction of the lower table to bend the plate material, the lower table is slightly bent. If the plate material is processed with the lower table bent, an accurate angle cannot be obtained, resulting in a product with poor accuracy. Some materials may not even be processed.

  Therefore, as described in Patent Documents 1 and 2, the press brake includes a crowning mechanism that pushes up the lower table toward the upper table so as to correct the deflection of the lower table.

JP 2004-243345 A JP-A-8-155553

  In the conventional press brake, it is common to change the pressure of the lower table in accordance with the pressure of the upper table. However, with conventional press brakes, accuracy may not be obtained as desired, and improvements are required.

  In order to meet such a demand, an object of the present invention is to provide a press brake and a crowning control method capable of improving accuracy as described above.

  The present invention solves the above-described problems of the prior art by an upper table for holding a punch die, a main cylinder for moving the upper table up and down, and a lower portion for holding a die die. A table, a crowning cylinder for crowning the lower table in the direction of the upper table, and multiplying a first applied pressure over the entire area of the main cylinder by a first coefficient, A theoretical bending load value when the plate material is bent by the first multiplier that generates a second pressing force for the crowning cylinder proportional to the pressing force, and the punch die and the die die is set to a second value. A second multiplier that generates a third pressure force that offsets the second pressure force, and the second pressure force and the third pressure force. An adder that calculates a fourth pressure force, and releases the pressurization from a pressure state in which the upper table is pressurized to the first pressure force by pressing the upper table with the first pressure force. The third coefficient calculated by the ratio of the actual fifth pressing force over the entire area of the main cylinder and the actual sixth pressing force over the entire area of the crowning cylinder at the start point of release By multiplying, a third multiplier for generating a seventh applied pressure for the crowning cylinder used after the release start time is selected, and the fourth applied pressure is selected in the pressurized state, and the release start A first selection unit that selects the seventh applied pressure after the time point, a conversion unit that converts the applied pressure selected by the first selection unit into a pressure per unit area of the crowning cylinder, and the crowning Siri Providing a press brake in which the pressure of da is characterized in that it comprises a control unit for controlling so as to convert pressure by the conversion unit.

  In the press brake described above, a second pressure is selected when the first pressure is greater than or equal to a threshold, and a pressure of 0 is selected when the first pressure is less than the threshold. A selector, and the adder outputs the second pressure when the first pressure is less than the threshold, and the first selector is configured to output the second pressure in the pressurized state. It is preferable to select a pressing force of 2.

  In order to solve the above-described problems of the prior art, the present invention multiplies the first pressurizing force over the entire area of the main cylinder for moving the upper table up and down by a first coefficient, thereby reducing the lower table. For the crowning cylinder for crowning in the direction of the upper table, a second pressurization force proportional to the first pressurization force is generated and held in the punch mold held by the upper table and the lower table. By multiplying a theoretical bending load value when the plate material is bent by the die mold thus formed by a second coefficient, a third pressing force for offsetting the second pressing force is generated, and the second pressing force is generated. And the third pressure are added to generate a fourth pressure, and the first pressure is applied to pressurize the upper table with the first pressure. Pressure state It is calculated by the ratio of the actual fifth pressing force over the entire area of the main cylinder and the actual sixth pressing force over the entire area of the crowning cylinder at the time of starting the release of pressurization. A seventh pressure force for the crowning cylinder used after the release start time is generated by selecting the fourth pressure force in the pressurized state, and the release start is performed. After the time point, select the seventh pressing force, convert the selected pressing force into a pressure per unit area of the crowning cylinder, and control the crowning cylinder pressure to become the converted pressure, A crowning control method is provided, wherein the lower table is crowned toward the upper table.

  According to the press brake and crowning control method of the present invention, the accuracy can be improved.

It is a block diagram which shows the press brake of one Embodiment. It is a block diagram which shows the functional internal structure of the crowning control part 22 in FIG. It is a timing diagram for demonstrating operation | movement of the press brake and crowning control method of one Embodiment. It is a figure for demonstrating the effect by the press brake and crowning control method of one Embodiment.

  Hereinafter, a press brake and crowning control method according to an embodiment will be described with reference to the accompanying drawings. The press brake according to the embodiment shown in FIG. 1 schematically includes an input device 10, a press brake control device 20, an upper table 30, and a lower table 40. The press brake control device 20 can be configured by an NC device.

  The upper table 30 is moved up and down by main cylinders 35L and 35R provided on the left and right. The position of the upper table 30 is controlled so as to approach the lower table 40 and away from the lower table 40. In the lower table 40, crowning in the direction of the upper table 30 is controlled by crowning cylinders 45L and 45R provided on the left and right.

  In FIG. 1, the number of cylinders for driving each of the upper table 30 and the lower table 40 is two, but the present invention is not limited to this.

  An upper mold holder (not shown) is attached to the upper table 30, and a lower mold holder (not shown) is attached to the lower table 40. A punch die 31 is attached to the upper die holder, and a die die 41 is attached to the lower die holder. The punch mold 31 and the die mold 41 may be held by the upper table 30 and the lower table 40 directly or indirectly, respectively. The plate material W that is the object of processing (bending) is sandwiched between the punch die 31 and the die die 41 and bent.

  The specific configuration and operation of the press brake according to one embodiment are as follows. In FIG. 1, the operator inputs the plate thickness, material, bending position, bending length, and die information of the punch die 31 and the die die 41 using the input device 10. The mold information is the width and angle of the V-shaped tip.

  The operator instructs the start of processing of the plate material W by the input device 10. The press brake control device 20 controls the main cylinders 35L and 35R and the crowning cylinders 45L and 45R in response to an instruction to start processing from the input device 10.

  The press brake control device 20 includes a bending information calculation unit 21 and a crowning control unit 22 as functional configurations. The press brake control device 20 includes D / A converters 23, 25L, and 25R, counter input units 24L and 24R, and an A / D converter 26. The D / A converters 23, 25L, 25R and the A / D converter 26 may be provided outside the press brake control device 20.

  The press brake control device 20 generates control data composed of digital values for controlling the position when the upper table 30 is lowered or raised. The D / A converters 25L and 25R convert the control data into control values composed of analog values. The amplifiers 32L and 32R amplify the control value and supply it to the motors 33L and 33R. The motors 33L and 33R cause the bidirectional rotary pumps 34L and 34R to rotate forward or backward.

  The main cylinders 35L and 35R can be lowered by rotating the bidirectional rotary pumps 34L and 34R in the normal direction. The main cylinders 35L and 35R can be raised by reversing the bidirectional rotary pumps 34L and 34R.

  Pressure sensors 36L and 36R are connected to the hydraulic chambers above the main cylinders 35L and 35R. Pressure sensors 37L and 37R are connected to the hydraulic chambers below the main cylinders 35L and 35R. The pressure sensors 36L, 36R, 37L, and 37R supply the detected pressure value per unit area to the A / D converter 26.

  The A / D converter 26 converts the detection values of the pressure sensors 36L, 36R, 37L, and 37R into digital values.

  The pressure applied to the main cylinder 35L is obtained by multiplying the detected value (digital value) of the pressure sensor 36L by the area of the main cylinder 35L on the pressure sensor 36L side and the detected value (digital value) of the pressure sensor 37L. This is the difference from the applied pressure multiplied by the area of the main cylinder 35L on the 37L side.

  The pressure applied to the main cylinder 35R is obtained by multiplying the detected value (digital value) of the pressure sensor 36R by the area of the main cylinder 35R on the pressure sensor 36R side and the detected value (digital value) of the pressure sensor 37R. This is the difference from the applied pressure multiplied by the area of the main cylinder 35R on the 37R side.

  The area of the main cylinders 35L and 35R or the crowning cylinders 45L and 45R is the total area of the two cylinders. If there is one cylinder, it is the area of one cylinder, and when there are a plurality of cylinders, it is the total area of the cylinders.

  The A / D converter 26 supplies the pressure F1 of the main cylinder 35L and the pressure F2 of the main cylinder 35R to the crowning control unit 22. Strictly speaking, as will be described later, the press brake control device 20 supplies the added value of the pressurizing forces F1 and F2 to the crowning control unit 22. The applied pressures F1 and F2 here are the applied pressures of the main cylinders 35L and 35R.

  The position detectors 38L and 38R detect the vertical position of the upper table 30. The position detectors 38L and 38R can detect the position of the upper table 30 as a counter value. The position detectors 38L and 38R supply position detection values (count values) to the counter input units 24L and 24R. Thereby, the press brake control device 20 can know the position of the upper table 30 in the vertical direction.

  The bending information calculation unit 21 calculates the crowning proportionality coefficient α based on the bending position and the bending length among the information input from the input device 10. The bending information calculation unit 21 calculates the theoretical bending load value BF based on the above information. The crowning proportionality coefficient α and the theoretical bending load value BF are input to the crowning control unit 22.

  The crowning proportionality coefficient α is the ratio of the upward crowning pressure by the lower table 40 to the downward pressure by the upper table 30. For example, if the pressure by the upper table 30 is 10 tons and the crowning proportionality coefficient α is 200%, the crowning pressure by the lower table 40 is 20 tons.

  The crowning proportionality coefficient α can be automatically calculated by the NC device. The theoretical bending load value BF can be obtained as described in Patent Documents 1 and 2, and similarly, can be automatically calculated by the NC apparatus.

  The crowning proportionality coefficient α and the theoretical bending load value BF are input to the crowning control unit 22. The crowning control unit 22 outputs crowning control data Dcc composed of a digital value as described later. The D / A converter 23 converts the crowning control data Dcc into a control value composed of an analog value.

  The amplifier 42 amplifies the control value output from the D / A converter 23 and supplies it to the motor 43. The motor 43 rotates the bidirectional rotary pump 44 forward or backward. A tank 46 is connected to the bidirectional rotary pump 44.

  By rotating the bidirectional rotary pump 44 in the forward direction, the crowning cylinders 45L and 45R can be raised. By rotating the bidirectional rotary pump 44 in the reverse direction, the crowning cylinders 45L and 45R can be lowered.

  A pressure sensor 47 is connected to the crowning cylinders 45L and 45R. The pressure sensor 47 supplies the detected pressure value per unit area to the A / D converter 26. The A / D converter 26 converts the detection value of the pressure sensor 47 into a digital value.

  The A / D converter 26 supplies the pressure (crowning pressure) Fc1 of the crowning cylinders 45L and 45R to the crowning control unit 22. The crowning pressure Fc1 here is a pressure per unit area of the crowning cylinders 45L and 45R.

  The functional internal configuration and operation of the crowning control unit 22 will be described with reference to FIG. The operation of the crowning control unit 22 indicates a crowning control method according to an embodiment. The crowning control unit 22 includes multipliers 221 to 223, 227, and 229, selection units 224 and 226, an adder 225, and a subtractor 228.

  In FIG. 2, the added pressure (F1 + F2), which is an added value of the pressure F1 of the main cylinder 35L and the pressure F2 of the main cylinder 35R, is input to the multipliers 221 and 222. The multiplier 223 receives the theoretical bending load value BF. The added pressure (F1 + F2) is set as the first pressure.

  The multiplier 221 multiplies the added pressure (F1 + F2) by a coefficient αd (third coefficient). The coefficient αd is calculated based on the formula (1).

  αd = Fc10 / (F1 + F2) (1)

  The coefficient αd is determined when the release of the pressurization of the lower table 40 by the crowning cylinders 45L and 45R, that is, the pressurization force (the fifth pressurization) of the main cylinders 35L and 35R at the start of so-called depressurization, and the crowning cylinders 45L and 45L, A ratio with a pressing force of 45R (sixth pressing force) is shown. Fc10 indicates the applied pressure obtained by multiplying the crowning pressure Fc1 by the area of the crowning cylinders 45L and 45R.

  The coefficient αd is a pressure ratio that is actually generated, and is a variable value because the pressure ratio varies depending on the pressure release timing. The multiplier 221 outputs the crowning pressure Fc10 (seventh pressure) over the entire area of the crowning cylinders 45L and 45R from the equation (1).

The multiplier 222 multiplies the added pressure (F1 + F2) by a coefficient αp (first coefficient). The multiplier 223 multiplies the theoretical bending load value BF by a coefficient αo. The coefficients αp and αo are set as follows. _Let α _{Lmt be} the limit value of the crowning proportionality coefficient α that does not diverge. The limit value α _Lmt can be obtained by experiment. The coefficient αo is calculated based on the formula (2).

_αo = α−α _Lmt (2)

When αo ≦ 0, the coefficient αo is set to 0, and the coefficient αp is set to the coefficient α. When αo> 0, the coefficient αp is set to the limit value α _Lmt .

  The multiplier 222 multiplies the added pressure (F1 + F2) by a coefficient αp and outputs a crowning proportional pressure command value Fcp (second pressure). The multiplier 223 multiplies the theoretical bending load value BF by a coefficient αo (second coefficient) and outputs a crowning offset pressure command value Fco (third pressure).

  The crowning offset pressure command value Fco is input to the terminal ta of the selection unit 224, and the value 0 indicating the pressure 0 is input to the terminal tb. The selection unit 224 is set with a threshold value Th for determining whether the offset based on the crowning offset pressure command value Fco is valid or invalid. The selection unit 224 refers to the additional pressure (F1 + F2) as indicated by a broken line, selects the terminal ta when (F1 + F2) ≧ Tho is satisfied, and selects the terminal tb when (F1 + F2) <Tho is satisfied. To do.

  If the added pressure (F1 + F2), which is the pressure applied to the main cylinders 35L and 35R, is equal to or greater than the threshold value Tho, the offset based on the crowning offset pressure command value Fco is valid. Accordingly, the crowning cylinders 45L and 45R can be prevented from operating before the plate material W is sandwiched between the punch die 31 and the die die 41.

  The adder 225 adds the crowning proportional pressure command value Fcp and the output of the selection unit 224, and outputs a crowning pressure command value Fc (fourth pressure).

  The selection unit 226 is connected to the terminal ta when the upper table 30 is pressurized by the main cylinders 35L and 35R, and is connected to the terminal tb when the pressure is released. The selection unit 226 outputs a crowning pressure command value Fc during pressurization, and outputs a crowning pressure Fc10 during pressure relief.

  The output of the selection unit 226 is input to the multiplier 227. The multiplier 227 multiplies the output of the selection unit 226 by 1 / Ac and outputs the result. Ac is the area of the crowning cylinders 45L, 45R. Therefore, the multiplier 227 outputs the pressure per unit area of the crowning pressure command value Fc during pressurization, and outputs the pressure per unit area of the crowning pressure Fc10 during pressure release.

  The multiplier 227 operates as a conversion unit that converts the applied pressure selected by the selection unit 226 into a pressure per unit area of the crowning cylinders 45L and 45R.

  The subtractor 228 subtracts the crowning pressure Fc1 from the output of the multiplier 227. The subtractor 228 outputs an error between the pressure per unit area of the crowning pressure command value Fc and the crowning pressure Fc1 during pressurization, and the pressure per unit area of the crowning pressure Fc10 and the crowning pressure Fc1 during decompression. Error is output.

  The output of the subtracter 228 is input to the multiplier 229. The multiplier 229 multiplies the output of the subtractor 228 by the crowning pressure loop gain Kp, and outputs the result as crowning control data Dcc.

  A range from the subtractor 228 to the crowning cylinders 45L and 45R and a range from the crowning cylinders 45L and 45R to the subtractor 228 constitute a control loop CLP for controlling the crowning pressure Fc1.

  The crowning pressure Fc1 is controlled so that the error output from the subtractor 228 is eliminated by the action of the control loop CLP. The control loop CLP operates as a control unit that controls the crowning pressure Fc1 to be the pressure output from the multiplier 227.

  Therefore, at the time of pressurization, the crowning pressure Fc1 is controlled to be the crowning command pressure obtained from the crowning pressure command value Fc, and at the time of depressurization, the crowning pressure Fc1 matches the crowning pressure obtained from the crowning pressure Fc10. To be controlled.

  The operation of the press brake and the crowning control method of the embodiment will be further described with reference to the timing chart shown in FIG. FIG. 3A shows the position of the upper table 30. As described above, the position of the upper table 30 is detected by the position detectors 38L and 38R. The upper table 30 starts pressurizing the lower table 40 at timing T1, and starts depressurizing at timing T2.

  FIG. 3B shows the pressure applied by the upper table 30, that is, the additional pressure (F1 + F2). FIG. 3C shows the crowning proportional pressure command value Fcp described in FIG. The crowning proportional pressure command value Fcp is a value proportional to the additional pressure (F1 + F2). FIG. 3D shows the crowning offset pressure command value Fco described in FIG.

  FIG. 3E shows the crowning pressure command value Fc described in FIG. In a state where the selection unit 224 selects the terminal ta, the crowning pressure command value Fc includes the crowning proportional pressure command value Fcp shown in FIG. 3C and the crowning offset pressure shown in FIG. A value obtained by adding the command value Fco.

  If the crowning pressure command value Fc shown in (e) of FIG. 3 is used, it is compared with the case where the crowning pressure command value Fcp shown in (c) of FIG. 3 is simply made proportional to the added pressure (F1 + F2). Thus, the ratio of the applied pressure of the crowning cylinders 45L and 45R to the applied pressure of the main cylinders 35L and 35R can be increased. Therefore, the amount of correction of the deflection of the lower table 40 is not insufficient, and the accuracy can be improved.

  When the crowning pressure command value Fc is used, the pressure is rapidly reduced at the timing T2 when the pressure release is started, as indicated by the broken circle. Therefore, the balance between the added pressure (F1 + F2) by the upper table 30 and the crowning pressure command value Fc by the lower table 40 may be lost, and the accuracy may deteriorate.

  Therefore, in the press brake and crowning control method of an embodiment, a multiplier 221 and a selection unit 226 are provided as a preferable configuration, and the crowning pressure Fc10 is selected at timing T2. As described above, the crowning pressure Fc10 is a pressure obtained by multiplying the additional pressure (F1 + F2) by the coefficient αd.

  As a result, the output of the selection unit 226 becomes a pressing force as shown in FIG. As shown by being surrounded by a broken-line circle, the applied pressure does not rapidly decrease at the timing T2. Therefore, the balance between the added pressure (F1 + F2) by the upper table 30 and the crowning pressure by the lower table 40 is not easily lost.

  By switching to the crowning pressure Fc10 at timing T2, the accuracy can be improved as compared with the case where the crowning pressure command value Fc shown in (e) of FIG. 3 is also used after timing T2.

  As described above, the coefficient αd is a coefficient calculated by the ratio between the actual pressurizing force of the main cylinders 35L and 35R and the pressurizing force of the crowning cylinders 45L and 45R at the timing T2 when the depressurization is started. Therefore, the balance between the pressurizing force by the upper table 30 and the crowning pressurizing force by the lower table 40 is not easily lost, and the accuracy can be improved.

  The effect by the press brake and crowning control method of one Embodiment is typically demonstrated using FIG. In FIG. 4, the bending state of the upper table 30 and the lower table 40 is exaggerated.

  FIG. 4A shows the case where the crowning pressure shown in FIG. 3F is used. If the balance between the pressurizing force by the upper table 30 and the crowning pressurizing force by the lower table 40 is not lost, the distance between the upper table 30 and the lower table 40 is maintained in an appropriate state even after the start of pressure release.

  On the other hand, FIG. 4B shows a state in which the balance between the pressure applied by the upper table 30 and the crowning pressure applied by the lower table 40 is lost. When the balance between the pressing force by the upper table 30 and the crowning pressing force by the lower table 40 is lost, the distance between the upper table 30 and the lower table 40 at the left and right ends of the upper table 30 is reduced. The space between the upper table 30 and the lower table 40 is in an inappropriate state.

  The present invention is not limited to the embodiment described above, and various modifications can be made without departing from the scope of the present invention.

30 Upper table 35L, 35R Main cylinder 40 Lower table 45L, 45R Crowning cylinder 221-223,229 Multiplier 225 Adder 227 Multiplier (conversion unit)
224, 226 selection unit CLP control loop (control unit)

Claims (3)

An upper table for holding the punch mold,
A main cylinder for vertically moving the upper table;
A lower table for holding the die mold,
A crowning cylinder for crowning the lower table in the direction of the upper table;
A first multiplication that generates a second pressure force for the crowning cylinder proportional to the first pressure force by multiplying the first pressure force over the entire area of the main cylinder by a first coefficient. And
By multiplying a theoretical bending load value when the plate material is bent by the punch die and the die die by a second coefficient, a third pressure force that offsets the second pressure force is generated. A second multiplier;
An adder for adding the second applied pressure and the third applied pressure to generate a fourth applied pressure;
The actual area over the entire area of the main cylinder at the time of starting to release the pressure from the pressurizing state in which the upper table is pressurized to the first table with the first pressing force. The crowning cylinder used after the release start time is multiplied by a third coefficient calculated by the ratio of the fifth applied pressure to the actual sixth applied pressure over the entire area of the crowning cylinder. A third multiplier for generating a seventh applied pressure for
A first selection unit that selects the fourth pressure in the pressurization state, and selects the seventh pressure after the release start time;
A converter that converts the applied pressure selected by the first selector into a pressure per unit area of the crowning cylinder;
A control unit that controls the pressure of the crowning cylinder to be the pressure converted by the conversion unit;
A press brake characterized by comprising: A second selection unit that selects the third pressing force when the first pressing force is equal to or greater than a threshold value, and selects the pressing force zero when the first pressing force is less than the threshold value;
The adder outputs the second pressure when the first pressure is less than the threshold,
The press brake according to claim 1, wherein the first selection unit selects the second pressurizing force in the pressurized state. For a crowning cylinder for crowning the lower table in the direction of the upper table by multiplying the first applied force over the entire area of the main cylinder for moving the upper table up and down by a first coefficient, Generating a second pressure proportional to the first pressure,
By multiplying the theoretical bending load value when the plate material is bent by the punch die held by the upper table and the die die held by the lower table by the second coefficient, Generating a third pressure force that offsets the pressure;
Adding the second pressing force and the third pressing force to generate a fourth pressing force;
The actual area over the entire area of the main cylinder at the time of starting to release the pressure from the pressurizing state in which the upper table is pressurized to the first table with the first pressing force. The crowning cylinder used after the release start time is multiplied by a third coefficient calculated by the ratio of the fifth applied pressure to the actual sixth applied pressure over the entire area of the crowning cylinder. A seventh pressurizing force for
In the pressurized state, the fourth pressure is selected, and after the release start time, the seventh pressure is selected.
Converting the selected applied pressure into a pressure per unit area of the crowning cylinder;
A crowning control method comprising: controlling the pressure of the crowning cylinder to be a converted pressure to crown the lower table toward the upper table.

Images