JPH0112568B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for bending a plate material using a press brake, and more particularly to a method for performing a plurality of bending processes from one end side and the other end side of a plate material. Generally, when folding a sheet metal work, the dimensions in the drawing of the folded product are specified on the outside. However, sheet metal has a thickness, and as a result of bending, the outer side will expand and the inner side will shrink. Therefore, in order to finish the outside to the specified dimensions, a stopper called a back gauge (also called a back gauge) is used. , The elongation of the sheet metal must be calculated in advance from the engagement line of the upper and lower molds, and the parts must be placed close to each other by the elongation. Also, it is relatively easy if all the bending angles are 90 degrees, but there are also cases where the bending angles are obtuse or acute angles. There are cases where it is not possible to sequentially bend from one end because the part (also called the rising flange) interferes with the upper mold, lower mold, etc. In this case, it is necessary to calculate the abutting position by returning to the developed view obtained by subtracting the bending elongation from the product drawing dimensions. Also, as mentioned above, there is no problem when the sheet metal is bent sequentially from one end and the final edge can be trimmed, but in many cases, the sheet metal is folded by hitting one end and starting the bending, and then cutting the sheet metal from the opposite end halfway. If it is necessary to press and bend the
After the final bending, the dimensions of the product may not match in the middle, which cannot be trimmed. To deal with this, it is necessary to plan and add the trimming portion to the new abutting side from the time of changing the abutting end at the trial bending stage. Regarding the preparation for the work described above, conventionally, the elongation was estimated by feeling, and the product was bent after repeated trial bending. There was also a problem. Examples of the present invention will be described below.
First, a press brake that can implement the present invention will be described in detail based on the drawings. 1 to 3 show a front view, a side view, and a plan view of the press brake main body 1. The press brake main body 1 has a long upper apron 5 fixed above a frame 3 erected on the left and right sides. , the lower apron 7 is raised and lowered by a hydraulic cylinder (not shown) while processing is performed using a punch 5a and a die 7a. For the convenience of the following explanation, the left and right in Figures 1 and 3 are called the left and right of the machine, the top and bottom of Figures 1 and 2 are called the top and bottom of the machine, and the left and right of Figure 2 are the rear, front, and rear of the machine. I will call it. The lower apron 7 is provided with supports 9 fixed on the left and right in the front-rear direction, and the stretch 13 is moved forward and backward by rotation of a ball screw 11 (see Fig. 4) provided on this support. . In addition, a plurality of abutments 15 are provided on the front surface of the stretch 13 so as to be movable and fixed in the left and right directions. The dimensions are determined by matching. To explain the abutment 15 in more detail based on FIG. 4, the stretch 13 is attached to the left and right supports 4 via guides 17 and ball screws 11 so as to be movable back and forth. The ball screw 11 is rotated by a motor 19 fixed to the frame 3 via a spline shaft 21 and a gear 23. Further, the amount of rotation of the ball screw 11, that is, the moving distance of the abutment, is detected by an encoder 25 attached to the rear end of the ball screw 11, and the rotation of the motor 19 is controlled. In addition, when the height of the die 7a attached to the lower apron 7 is changed, the stretcher 13 is moved vertically by rotating the handle 27 provided on the stretcher 13, and the abutment 15 is adjusted to the set height. Move up to the bottom. Next, FIG. 5 shows a control mechanism for controlling the raising and lowering operation of the lower apron 7, and this control mechanism consists of a locking piece 29 provided at the longitudinal center of the lower apron 7.
There is a lever 31 that can be freely engaged and detached, and this lever is
The rotating body 3
5. It is rotatably provided by a shaft 37. In addition, a lower apron 7 is attached to the frame (not shown).
An upper limit valve 39 is fixed, and a spool 41 of the upper limit valve 39 is engaged with one end of the lever 31 via a leaf spring 43 fixed to a frame (not shown). The rotating body 35 is connected to one end of a feed screw 49 via a pin 45 and a lever 47, and the feed screw 49 is rotatably supported by a case 51 fixed to the frame 3. A clutch 55 such as a spline is connected to the other end of the feed screw 49 via a gear 53, and a lever 57 is connected to the connecting portion of the clutch 55.
A manual handle 59 is connected thereto. The lever 57 is used to switch the clutch 55, and when transmitting the rotation of the manual handle 59 to the feed screw 49, the lever 57 is used to switch the clutch 55.
9 side, the clutch 55 is moved rightward in FIG. 5, and rotation of the manual handle 59 is transmitted through spline engagement. The gear 53 provided on the feed screw 49 includes:
An endless belt 61 is wound around a shaft 65a of a detector 63 such as an encoder rotatably supported by the case 51. A belt 69 is attached to the detector 63 via a gear 67, and this belt 69 connects to the shaft 7 of a clutch 71 rotatably supported by the case 51.
The gear 75 is integrally fixed to the main body 3. A shaft 79 of a motor 77 attached to the case 51 is connected to one end of the clutch 71, and a tachogenerator 81 is fixed to one end of the motor 77. As described above, the manual handle 59 or the motor 7
7 rotates the feed screw 49, which rotates the rotating body 35 about the shaft 37 to control the engagement distance between the lever 31 and the locking piece 29, that is, the upward stroke of the lower apron 5. When raising the lower apron 5, pump 8
When pressure oil is supplied from 3 to the cylinder 85, the lower apron 5 rises, but the locking pieces 29 also rise as one body. When the lever 31 is engaged, the lever 31 rotates counterclockwise around the shaft 33 in FIG.
The supply of pressure oil to is released from the upper limit valve 39 to the tank T side, and the rising of the lower apron 5 is stopped. According to the above description, when bending a sheet metal material using a press brake, the abutment 15 on the stretch 13 is connected to the motor 19 and the encoder 25.
The engaging distance between the lever 31 and the locking piece 29 is controlled by the tachometer generator 81, the motor 77, the detector 63, etc., and as a result, the distance between the punch 5a and the die is controlled. 7a
It is clear that the distance of engagement can be controlled. Next, one example of folding will be described based on FIGS. 6 and 7. FIG. 6 is a product drawing, and the dimensions and bending angles from the outside of the bending are designated by H ₁ to _{H 7} . First, number the bending positions on the drawing, starting from the left end, for example, and call them P ₁ , P ₂ , P ₃ , P ₄ , P ₅ , and P ₆ . The bending angles at each processing position are A ₁ , A ₂ , A ₃ ,
A ₄ , A ₅ , A ₆ are determined. With the press brake, a worker can support the sheet metal workpiece at the front of the machine, and a support stand is provided, so there is no problem even if it extends for a long time, but the abutment 15 cannot be positioned as far back as possible. It is difficult to achieve dimensional accuracy if you hit the end far away at the back, so start work by hitting one end (in this case, the E end), and then place the end near the center of the length on the other side (in this case). In this case, it is necessary to change to F end). Therefore, the plan is to bend P ₁ to _{P 4} based on the E end, and bend P ₅ and P ₆ based on the F end. This is called the process order and is indicated by ~. Table 1 shows this planning, and FIG. 7 schematically shows the actual work. In the table, _V1 indicates the shoulder width dimension of the V groove of the die, and the same die was used during the six processing operations. T ₁ is the thickness of the sheet metal workpiece and naturally does not change. A ₁ to _{A 6} were the specified bending angles, and A ₂ , A ₃ , and A ₆ were right angles. The elongation α due to the bending angle is generally α=(V/6+T) ta _o 180−A/2 −π(180−A)/360(V/6+λT) λ=k ₁ (V/T) +k ₂ k ₁ and k ₂ are expressed as constants, but the numerical value of the calculation result of the above formula can be calculated by simply providing V, T, and A since the formula is stored in the built-in computer in advance. Real numbers have been obtained, and Table 1 shows α ₁ to α ₆ . In addition, in the second, third, and fourth steps, the material contacts the abutment obliquely, so at the input point, (180−A ₁ ),
There is an expression called (A ₁ − 90), and to convert H ₁ in the horizontal direction, cos (180 − A ₁ ), cos (A ₁ −
90) is an input to the computer. Note that the L-axis value represents the dimension from the engagement line of the punch and die to the abutment, and the D-axis value represents the approach distance between the punch and die when bending at a specified angle. In this example, the abutting end was changed midway, but
The process order moves in one direction from the E end to the F end. However, in general, the order is often reversed on the way, for example in this example, even if you bend _P6 first and then _P5 , if the F end does not interfere with the structure above the punch of the press brake (H (if ₆ is shorter) is possible. In that case, the input, L-axis value, and D-axis value will change.

【table】

[Table] In Table 1, there is a symbol called ++. This is a command to the computer that means that when bending at right angles, subtract twice the plate thickness instead of twice the bending elongation. Now, if you look at Figures 6, 7, and Table 1, what anyone will notice is that the data H ₇ is not used anywhere. The data for _H7 was not used because the abutting end was changed from E to F during several stages of bending, and although such a phenomenon always occurs in multi-stage bending,
If the H ₇ is not exactly the specified size, it will not be possible to trim it, and the work will be a failure and the product will be weak. One of the features of the present invention, as mentioned above, is that if a large amount of data is input into the computer built into the press brake, the press brake will automatically operate according to the instructions.
In addition to the fact that the worker only has to switch hands and butt the sheet metal work according to the plan, it also shows the unfolded length. The developed length of the product shown in Figure 6 is the developed length.
Assuming DP, DP=(H ₁ −2α ₁ )+(H ₂ −2α ₂ )+(H ₃ −2α ₃ )+(
It is expressed as H ₄ −2α ₄ ) + (H ₅ −2α ₅ ) + (H ₆ −2α ₆ ) + H ₇ , and since A ₂ , A ₃ , and A ₆ are right angles, 2α ₂ ,
It is also possible to use the plate thickness of T ₁ instead of 2α ₃ and 2α ₆ . As a side note, subtracting twice the elongation at each bending position is because the sheet metal work has a thickness, and the outside of the bend stretches and shrinks on the inside, but the specified dimensions of the product are on the outside. This is because the bending elongation defines only one side from the bending center. As is clear from the above, in the case of the product shown in Figure 6, _an accurate H ₇ product can be obtained with a workpiece of shorter dimensions than the workpiece of length H ₁ +H ₂ +H ₃ +H ₄ +H ₅ +H 6 +H ₇ . Therefore, at the time of trial bending, it is possible to increase the number _H6 by the difference between the trial bending work length and the developed length and leave the trimmed part at the F end, so that the sheet metal workpiece can be adjusted to the developed length. If you cut it to the appropriate length and fold it, the length of _H7 will be the required dimension. The reference numeral 87 in Figure 1 is a control panel with a built-in computer that automatically indicates the approach distance between the punch and die, automatically controls the position of the abutment, and also displays the unfolded length. It also has the function of As already understood, the present invention is applicable to the finished external dimensions H ₁ to H _o between each bending point of the plate material and the respective The developed length DP is calculated based on the elongation α ₁ to _{α o} corresponding to the bending angle of the bending point, and the plate material is sheared to a long open length DP in advance, and the finished external dimensions H ₁ to H between each bending point are calculated. _o , the position of the back gauge in the press brake (L-axis value) is calculated and positioned in the process order of each bending point based on the bending angle of each bending point and the elongation α ₁ to _{α o} , and The approach distance (D-axis value) between the punch and die in the press brake is calculated according to the bending angle of Control is performed based on the calculation results to bend each bending location of the plate material to a desired angle in the order of steps. That is, in the present invention, the elongation α ₁ to α _o of each bending point and the finished external dimension H ₁ between each bending point are
Since the developed length DP is calculated based on ~H _o and the plate material is sheared to the developed length DP in advance, the plate material is sequentially bent from one end side, and then multiple steps are performed from the other end side of the plate material. Even if the bending process causes elongation at each bending point, the final finished dimensions will match the desired dimensions, and accurate folding will not be possible. It is possible to obtain bent products. In addition, when bending each bending point of a plate material, although the control of the approach distance between the punch and die (D-axis value) in the press brake remains the same as before, the position of the back gauge (L-axis value) Since the calculation is based on the finished external dimensions H ₁ to H _o between locations, the bending angle, and the elongation α ₁ to α _o ,
The elongation in the previous process is also taken into consideration, which further improves the dimensional accuracy between each bending point after the plate material is brought into contact with the back gauge, positioned, and bent.

[Brief explanation of drawings]

FIG. 1 is a front view of a press brake equipped with the present invention. FIG. 2 is a side view of the same as above. FIG. 3 is a plan view of the same as above. FIG. 4 is a perspective view illustrating the abutting portion of the same machine. FIG. 5 is a perspective view showing a mechanism for controlling the approach distance of the die with respect to the punch for obtaining a designated bending angle of the same machine. Figure 6 is a product drawing. 7th
The figure is a conceptual diagram of the work process, particularly showing the relationship with abutment among the processing steps for the same. Explanation of symbols representing main parts of the drawings, 4...Support, 13...Stretch, 15...Abutment, 1
7...Guide, 19...Motor, 25...Encoder.

Claims (1)

[Claims] 1 Using a press brake to bend multiple parts of the plate material at desired angles,
Finished external dimensions H ₁ to _{H o} between each bending point of the plate material and elongation α ₁ corresponding to the bending angle of each bending point
The developed length DP is calculated based on ~α _o , the plate material is sheared to the developed length DP in advance, and the finished external dimensions H ₁ ~ _{H o} between each bending point, the bending angle of each bending point, and the elongation α The position of the back gauge (L-axis value) in the press brake is calculated and positioned in the process order of each bending point based on ₁ ~ α _o , and the punch and die position in the press brake is determined according to the bending angle of each bending point. The approach distance (D-axis value) of the plate material is calculated, and after selectively contacting both ends of the plate material with the back gauge, the approach distance between the punch and the die is controlled based on the above calculation result, and each bending point of the plate material is A method for bending plate materials using a press brake, which is characterized by bending sheets to a desired angle in the order of steps.