JPH08192227A - Bending method and device therefor - Google Patents

Abstract

PURPOSE: To prevent the occurrence vibration or noise by once stopping a lower table at a specific point just before bending, detecting the vibration frequency, etc., by a sensor, setting a waiting time based on a specific data table and changing the bending speed to a 2nd bending speed. CONSTITUTION: When it is detected that a lower table TL is reached at a specific position, the lower table TL is stopped and the frequency or the amplitude, etc., is detected by a vibration detecting sensor S. The frequency, etc., is compared with a specific threshold value, and at the time within an allowable normal value, the process is shifted to a low velocity bending process by a speed changing valve 2. Besides, at the time of being over than the value, after a timer set time to be waited decided based on the value of experience, etc., is read out from a data table 6 and set, after the set time is passed, the vibration is again detected, after confirming that the prescribed vibration level is obtained, the speed changing valve 2 is changed, the operation is executed so that bending is completed in the 2nd bending speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for bending sheet metal work, and more particularly to a method and apparatus for reducing vibration when switching the processing speed.

[0002]

2. Description of the Related Art A typical example of a conventional bending apparatus of this type is a press brake. As is well known, this apparatus has a sheet metal work inserted between an upper table and a lower table vertically opposed to each other as shown in FIG. Bending die (punch P and die D) attached to each table by raising
The work W is bent by a predetermined working line.

In this case, conventionally, as shown in FIG. 6 (a), an example of a moving speed diagram of a movable table, a lower table T
_L is moved up at a relatively high speed V ₁ , and the punch P comes into contact with the work W on the die D, and at the same time, it is switched to a low speed V ₂ for bending to generate a pressing force.

The above two speeds V ₁ and V ₂ are the amount of oil flowing into the main cylinder C for driving the lower table T _L and the area of the cylinder (piston), as shown in the schematic view of the drive unit in FIG. Determined by

FIG. 8 shows an example of an actual table drive hydraulic circuit. To explain its outline, C is the main cylinder for driving the lower table (only one of the plurality is shown), and a small diameter high-speed cylinder (piston) C ₁ for moving the work and work machining. It has a double structure with a large diameter low speed cylinder (piston) C ₂ . This drive oil pressure is sent from the hydraulic pump PP driven by the motor M to the main cylinder C via the operation direction switching solenoid valve 1 and the speed switching solenoid valve 2. In addition, 3 indicates the upper limit detection relief valve, and 4 indicates a relief / one-way valve.

However, the above-mentioned 2 by the speed switching valve 2
The speed switching is automatically and rapidly performed from a relatively high moving speed V ₁ to a low speed V ₂ for machining in a state where pressure is applied to the hydraulic circuit, which causes vibration and noise, and this vibration When the work W is relatively large, as shown in FIG. 7, the contact portion of the work W with respect to the back cage B is displaced, the regular bending line position of the work W is displaced, and there is a risk of defective machining. there were.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems in the conventional machining method. Vibration / noise generated when the drive speed of the drive table is switched during bending of a workpiece. The purpose is to provide a means for reducing.

[0008]

For this reason, in the present invention, (1) sheet metal work folding having table driving means having first and second speeds for rapid movement and bending of the sheet metal work. In the bending apparatus, when the bending process is started, the movement of the table at the first speed is temporarily stopped at the same time, and at the same time, the vibration of the table is detected, and a predetermined vibration value-timer setting is performed according to the detected vibration value. A waiting method until the start of the next bending operation is set in the timer means by the time table, and after the set time elapses, the table is driven at the second speed, and the bending method, and (2) ) Table driving means having two speeds for rapid movement and bending of the sheet metal work, vibration detecting means for the driving table, and a predetermined data table based on the vibration detected value. Further, there is provided a timer setting means for setting a switching standby time from the first speed to the second speed, and a speed switching valve control device for switching the speed after the set time has elapsed. An object of the present invention is to achieve the above object by providing a bending device.

[0009]

By the method and apparatus of the present invention as described above,
At the start of bending work, the work is first moved at the first speed, temporarily stopped at a predetermined point immediately before entering the bending process, and at the same time, vibration of the table (for example, frequency) is measured, and the value is measured. , For example, after waiting for a set time by a predetermined frequency vs. timer set time table (chart) based on empirical values,
Since the drive is configured to be switched to the second speed, vibration, noise and the like at the time of speed switching are not substantially generated unlike the conventional example, and the risk of processing defects and the like due to these is prevented. be able to.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments; (Structure) FIG. 1 is a structural block diagram of an embodiment of vibration reducing means in a bending apparatus such as a press brake according to the present invention. Show. Reference numeral 1 is a table operation direction switching valve shown in the hydraulic drive circuit diagram of FIG. 8 and 2 is the same speed switching valve, and S is a drive table provided by the present invention (also in this embodiment, a lower table drive type). A vibration detection sensor having a vibration frequency of, for example, Hz disposed in a part of T _L , and an example of its layout in FIG. 2 is shown.

Reference numeral 5 denotes an NC device for controlling the operation timing of the speed switching valve 2, which displays each standby time by the output data of the vibration detection sensor S, such as frequency Hz, and sets timer time setting means 7. A predetermined data table 6 based on experience values and the like for instructing
FIG. 3 shows an example thereof. Further, 8 is a table position detecting means such as a linear scale for inputting the table moving position to the NC device 5.

(Operation) Next, the operation sequence is
This will be described with reference to the flowchart of FIG. Also in this case, an example of the lower table T _L lifting drive type press brake shown in FIGS. 6 and 7 will be described.

At the start of the bending operation of the work W placed on the bending fitting die D fixed to the lower table T _L , first, at step S1, the NC device 5 of FIG. And the speed switching valve 2 enables the table _TL
Is moved up at a predetermined first high speed V ₁ . Then,
In step S2, when the hydraulic pressure reaches the predetermined pressure, and when it is detected by the linear scale 8 or the like in FIG. 1 that the table T _L reaches the predetermined position, the lower table T _L is temporarily stopped in step S3. At the same time, in step S4, the vibration detection sensor S detects the frequency or amplitude of the vibration.

Next, in step S5, the frequency (Hz) and the like are compared with a predetermined threshold value, and if this is within an allowable normal value, the flow jumps to step S10 and the speed switching valve 2 is directly operated. The process is changed to a low speed V ₂ ,
On the other hand, when the time exceeds this, in step S6, the timer set time (s) to be waited, which is determined based on the experience value or the like, is read out from the data table 6 shown in FIG. After this set time has passed, the vibration is detected again in step S8, and it is confirmed in step S9 that the predetermined vibration value level is reached, and then in step S1.
The speed switching valve 2 is switched at 0 to drive at the _second processing speed V ₂ , the speed switching is completed at step S11, and the bending process is completed at step S12.

By the operation of the present embodiment as described above, the conventional stroke-rise speed diagram of the lower table T _L shown in FIG. 6A becomes as shown in FIG. By setting, vibration at the time of speed switching is substantially eliminated, and accurate bending can be secured. For comparison, FIG.
The diagram of FIG. 6 (a) is shown in duplicate.

By properly selecting the time constant for the slope of acceleration / deceleration when the first speed V ₁ is temporarily stopped, the vibration at the time of stopping can be effectively alleviated.

Although all of the above embodiments have been described with respect to the lower table T _L drive type press brake, the present invention is not limited to this, and in the case of the upper table T _U drive type. Of course, it is applicable and the same effect can be obtained.

[0018]

As described above, according to the present invention, in the bending apparatus, the vibration and noise associated with the speed change during movement / processing during bending of the work are substantially reduced, resulting in defective processing. The risk of causing

[Brief description of drawings]

FIG. 1 is a configuration block diagram of an embodiment of vibration reducing means.

[Fig. 2] Example of arrangement of vibration detection sensors

FIG. 3 Data table of vibration frequency timer set time

FIG. 4 is an operation sequence flowchart of the embodiment.

FIG. 5: Stroke-up speed diagram of lower table

FIG. 6 is a schematic view of a conventional press brake.

FIG. 7 is a schematic diagram of a lower table drive unit.

FIG. 8 is an example of a lower table drive hydraulic circuit diagram

[Explanation of symbols]

1 Operation direction switching valve 2 Speed switching valve 3 Upper limit detection relief valve 4 Relief / one-way valve 5 NC device 6 Data table 7 Timer time setting means 8 Table position detection means C Main cylinder C ₁ / C ₂ High speed / low speed cylinder P / D punch / die S vibration detection sensor T _U / T _L upper / lower table

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Claims (2)

[Claims] 1. A sheet metal work bending apparatus having table driving means having first and second speeds for rapid movement and bending of a sheet metal work, and at the start of bending, the first of the tables At the same time as stopping the movement of the speed at a predetermined point, the vibration of this table is detected, and the waiting time until the start of the next bending drive is determined by the predetermined vibration value-timer setting time table according to the detected vibration value. A bending method, comprising setting in a timer means, and driving the table at the second speed after a lapse of the set time. 2. A table driving means having two speeds for rapid movement and bending of a sheet metal work, vibration detecting means for this driving table, and a predetermined data table based on this vibration detection value, which is higher than the first speed. A folding apparatus comprising: a timer setting means for setting a second speed switching standby time; and a speed switching valve control device for switching the speed after the setting time has elapsed.