JPH0576939A - Press - Google Patents

Abstract

PURPOSE:To always pressurize and work a material to be worked at a fixed state even when each part of a machine is extended or contracted or thermally transformed due to the change of room temperature and the generation of heat in a press driving part. CONSTITUTION:A ram 8 is moved by a reciprocating mechanism 13 to a target position to bend a material to be worked between an upper die 3 and a lower die 2. A range finder is mounted under the lower end of the ram 8 and a relative positional relation or a range between the upper die 3 and the lower die 2 is measured by this range finder 22. A control box 6 incorporates a controller having a CPU and an RAM and when the upper die 3 reaches the target position, the CPU fetches the measured value of the range from the range finder and the difference between the measured value and the reference value of the range stored in the RAM is calculated as the corrected value of the target value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press machine such as a press brake used for pressurizing a work piece between upper and lower dies.

[0002]

2. Description of the Related Art In a conventional press brake, a lower mold 2 having a V-shaped groove 1 as shown in FIG. 8 is arranged on a table installed on a bed, and an upper mold is mounted on a ram via a holder. Three
It is configured by attaching. A work piece 4 is supported on the lower die 2, and a ram reciprocates with respect to the work piece 4 to move the upper die 3 up and down.

During the lowering operation of the upper die 3, the pressing force of the upper die 3 acts on the workpiece 4, and the workpiece 4 is pushed into the V-shaped groove 1 to be bent at a desired angle α. .. In this case, the target position for lowering the upper die 3 is predetermined for each type of the workpiece 4, and if the upper die 3 is lowered to the target position, the workpiece 4 is always bent at a desired bending angle α. Can only be folded.

[0004]

If the lowering operation of the upper mold 3 is controlled based on the target position, the lowering end position P of the lower mold 2 should theoretically always be the same, but in reality, at room temperature. When the press brake is operated for a long time, the upper die 3 is moved to a target position because the machine body, the ram, the bed and the like expand and contract according to the change of, and the respective parts of the machine are deformed by the heat generated by the press drive section. Even if you lower the
In the figure, the lower end position of the upper die 3 is not always constant as indicated by P '. For this reason, an error occurs in the bending angle of the workpiece 4, and it is difficult to perform highly accurate bending.

The present invention has been made in view of the above problems. Even when each part of the machine expands or contracts or is thermally deformed due to a change in room temperature or generation of heat in the press drive part, the workpiece is always kept constant. An object of the present invention is to provide a press machine that can be pressed into a state.

[0006]

SUMMARY OF THE INVENTION The present invention is a press machine for moving an upper die or a lower die to a target position and pressurizing a workpiece between upper and lower dies, which comprises a measuring means, a storage means and a computing means. Have and. The measuring means measures the relative positional relationship between the upper die and the lower die, and a reference value of the relative positional relationship is preset in the storage means. When the upper die or the lower die reaches the target position, the arithmetic means takes in the measured value of the relative positional relationship from the measuring means and calculates the difference from the reference value as the correction value of the target position.

[0007]

[Function] When each part of the machine expands or contracts or thermally deforms due to a change in room temperature or generation of heat in the press drive unit, the relative positional relationship between the upper die and the lower die changes, so the relative position measured by the measuring means. A difference occurs between the measured value of the relationship and the reference value of the relative positional relationship set in the storage means, and the calculation means calculates the difference as a correction value for the target position.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a press brake according to an embodiment of the present invention, which is a machine body 5 installed on a floor surface.
A control box 6 is integrally attached to the side surface of the.

The machine body 5 includes both side frames 5A and 5A.
B and a bed 5C at the lower front surface are integrally formed, and a table 7 for mounting the lower mold 1 is mounted on the bed 5C. A ram 8 is arranged between the two side frames 5A and 5B so as to be able to move up and down so as to face the table 7. A foot switch 9 for lowering the ram 8 is provided at a lower position on the front surface of the bed 5C. The ram 8
The upper die 3 is set on the lower end edge of the via the holder 10.

The ram 8 is connected to a reciprocating mechanism 13 which uses an AC servomotor 12 as a drive source. The reciprocating mechanism 13 is a guide 1 provided on both side frames 5A and 5B.
This is for reciprocating up and down the ram 8 along 4, 4, and the feed screw shaft 15 is connected to the AC servomotor 12 via a power transmission mechanism 17 such as a belt mechanism or a gear mechanism. The shaft 15 is screwed onto a lead nut 16 integrated with the ram 8. Feed screw shaft 1
The bearing 5 is rotatably supported by a bearing 18, and the feed screw shaft 15 is rotated forward and backward by the driving of the AC servomotor 12, and the ram 8 reciprocates up and down according to the rotation direction.

The control box 6 has an operation section 19 and a display section 20 on the front surface, and a control unit 21 (shown in FIG. 5) for controlling the operation of the reciprocating mechanism 13 is incorporated inside the box. The operation unit 19 is provided with various switches, function keys, ten keys, etc. used for mechanical operations and data input.

At the lower end of the ram 8, there is provided a distance measuring device 22 for measuring the relative positional relationship between the upper mold 3 and the lower mold 2 (in this case, the distance L described later).
A reflection table 24, whose upper surface is a diffuse reflection surface 23, is set on the table 7 facing the table 2.

FIG. 2 shows the construction of the distance measuring device 22, which comprises a light projector 25 and a light receiver 26. Floodlight 2
The light projection beam 27 from 5 is focused on the reflection table 24 by the light projection lens 28. The projection beam 27 is diffusely reflected and diffused on the surface of the reflection table 24, and the reflected light is imaged by the light receiving lens 29 at the image forming position X1 on the light receiver 26 such as PSD. Now, temporarily, the reflection table 24
When is displaced from the solid line position to the broken line position, an image is formed on the light receiving device 26 at the image forming position X2, and the light receiving device 26 outputs different signals corresponding to the respective image forming positions X1 and X2.
By inputting this signal to the CPU of the microcomputer to be described later, the distance measuring device 22 of the reflection table 24 is
The distance L from is measured. In the figure, 30 is the projector 2
And a case for housing the light receiver.

The distance measuring device 22 may be of the intensity modulation type shown in FIG. 3 in addition to the above-mentioned type using the PSD, and is not limited to these optical and non-contact type, and may be a mechanical type. A contact type can also be used.

The intensity modulation type distance measuring device is a type that measures the distance to the object by detecting the phase delay with respect to the propagation distance of the modulated light, and its circuit configuration is shown in FIG. The time charts are shown in 1) and (2) respectively.

The projector 31 drives the laser light source with the oscillation output of a constant frequency (modulation frequency f ₁ ) and projects the intensity-modulated light on the reflection table 24. Figure 4 (1) shows the extracted intensity-modulated component of the projected light.
Is a reference signal of. The light receiver 32 includes a light receiving element such as a photodiode, receives the light reflected by the reflection table 24, and obtains a measurement signal (shown in FIG. 4 (1)). The reference signal and the measurement signal are given to the measurement processing circuit 33, and the distance to the reflection table 24 is calculated from the phase difference φ of both signals.

One multiplier 34 of the measurement processing circuit 33 has a reference signal and an oscillation output of the local oscillator 35 (oscillation frequency f ₂ ).
And the other multiplier 36 multiplies the measurement signal by the oscillation output of the local oscillator 35 to obtain a low frequency (f
A reference signal or a measurement signal of _1- f ₂ frequency) is obtained. The binarization circuits 37 and 38 binarize the input signal to generate a reference signal and a measurement signal as shown in FIG. 4 (2). These signals are given to the phase difference counter circuit 39, and the phase difference φ between them is φ.
A gate signal (shown in FIG. 4 (2)) having a pulse width corresponding to is generated. The gate signal opens the gate to allow the clock to pass, and the phase difference φ is measured by counting the clock.

FIG. 5 shows an example of the circuit configuration of the control device 21 incorporated in the control box 6. CP in the figure
The U40 constitutes a microcomputer together with the ROM 41 and the RAM 42 and executes instruction analysis and various calculations. The ROM 41 stores a program for machine control and the like, and the RAM 42 stores data such as a target value, a reference value L ₀ , and a calculation result described later.

Further, the CPU 40 gives the output to the AC servo motor 12 to the servo amplifier 43, and the servo amplifier 43 amplifies this and gives it to the AC servo motor 12. An absolute type rotary encoder 44 is connected to the AC servo motor 12. The encoder 44 detects the rotation angle of the AC servomotor 12, that is, the current movement position of the ram 8 (upper die 3) and outputs the value to the CPU 40. Further, the CPU 40 has the distance measuring device 22,
Input / output units such as the display unit 20 and the operation unit 19 are connected, and C
The PU 40 controls the input / output operation of these input / output units.

FIG. 6 shows the control procedure of the CPU 40. The operation of the press brake will be described below with reference to FIG. First, step 1 in the figure (indicated by "ST1" in the figure)
In the above, the target position of the upper die 3 and the reference value of the relative positional relationship between the upper die 3 and the lower die 2, that is, the reference value L ₀ (shown in FIG. 7) of the distance between the distance measuring device 22 and the reflection table 24 are set. When input by the operation unit 19, these data are stored in the RAM 42 of the microcomputer.

Next, after setting the work piece 4 on the lower die 2, when the foot switch 9 is operated in step 2, the reciprocating mechanism 13 moves the ram 8 downward (step 3).
In this descending operation, the CPU 40 takes in the current movement position of the ram 8 (upper die 3) from the rotary encoder 44 and determines whether or not the current movement position has reached the target position (step 4).

When the upper die 3 contacts the workpiece 4 and continues to descend, the workpiece 4 is pressed and bent. When the current movement position coincides with the target position, the determination in step 4 becomes "YES", and the reciprocating mechanism 13 stops the descent of the ram 8 in step 5 (step 5).

Next, at step 6, the distance L between the distance measuring device 22 and the reflection table 24 is measured by the distance measuring device 22.
Is measured, the CPU 40 takes in the measured distance L, calculates the absolute value of the difference from the reference value L _0, and determines whether or not the value is equal to or less than a threshold value TH close to zero.

If the absolute value of the difference ΔL between the distance L and the reference value L ₀ is less than or equal to the threshold value TH, the determination in step 7 is “YES” and the following step 8 is skipped. If the absolute value of the difference ΔL is larger than the reference value L ₀ , step 7 becomes “NO” and the process proceeds to step 8.
A new target position is calculated by adding the difference ΔL between the distance L and the reference value L ₀ to the current target position, and R is calculated according to the calculated value.
The value of AM42 is updated.

In the next step 9, the ram 8 moves up,
When the current movement position of the ram 8 reaches the rising end of the ram 8, step 10 becomes "YES", and the reciprocating mechanism 13 stops the rising of the ram 8 in step 11.

[0026]

As described above, the present invention is provided with the measuring means for measuring the relative positional relationship between the upper die and the lower die, and the storage means for presetting the reference value of the relative positional relationship. When the lower die reaches the target position, the calculating means takes in the measured value of the relative positional relationship from the measuring means and calculates the difference from the reference value as the correction value of the target position. Even if each part of the machine expands or contracts or thermally deforms due to changes or generation of heat in the press drive unit, the target position correction value can be calculated and the target position can be corrected using the correction value, and the workpiece will always remain constant. A remarkable effect that pressure processing can be performed in a state is achieved.

[Brief description of drawings]

FIG. 1 is a front view showing the appearance of a press brake according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a distance measuring device.

FIG. 3 is a circuit block diagram showing another specific example of the distance measuring device.

FIG. 4 is a time chart of the embodiment of FIG.

FIG. 5 is a block diagram showing a circuit configuration of a control device.

FIG. 6 is a flowchart showing a control procedure of machine operation.

FIG. 7 is an explanatory diagram showing a method of correcting a target position.

[Explanation of symbols]

 2 Lower mold 3 Upper mold 5 Machine body 6 Control box 13 Reciprocating mechanism 19 Operation part 21 Control device 22 Distance measuring device 42 RAM 44 Rotary encoder

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[Procedure amendment]

[Submission date] September 17, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief explanation of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a front view showing the appearance of a press brake according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a distance measuring device.

FIG. 3 is a circuit block diagram showing another specific example of the distance measuring device.

FIG. 4 is a time chart of the embodiment of FIG.

FIG. 5 is a block diagram showing a circuit configuration of a control device.

FIG. 6 is a flowchart showing a control procedure of machine operation.

FIG. 7 is an explanatory diagram showing a method of correcting a target position.

FIG. 8 is a front view showing a bending state of a workpiece.

[Explanation of Codes] 2 Lower mold 3 Upper mold 5 Machine body 6 Control box 13 Reciprocating mechanism 19 Operating part 21 Control device 22 Distance measuring device 42 RAM 44 Rotary encoder

Claims (1)

[Claims] 1. In a press machine for moving an upper die or a lower die to a target position and pressing a workpiece between the upper die and the lower die, a measuring means for measuring a relative positional relationship between the upper die and the lower die, When the upper mold or the lower mold reaches a target position with a storage unit in which a reference value of the relative positional relationship is preset, the measured value of the relative positional relationship is taken in from the measuring unit, and the difference between the reference value and the target value is acquired. A press machine comprising a calculation means for calculating a position correction value.