JPH0829440B2 - Press machine - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a press machine capable of highly accurate press working.

[Technical background of the invention and its problems] Generally, in a press machine, since there are always some connecting portions for converting rotational power into reciprocating linear motion, the total clearance including all the clearances (playing spaces) is It has a great influence on press accuracy. For example, in punching, if a press with a large total clearance is used, the punch enters the die hole due to the so-called breakthrough in which the elastic deformation of the frame part returns to the original when the material is separated. It may cause wear or damage to the mold. This phenomenon remarkably occurs especially when the bottom dead center position is at an inappropriate position. By the way, this bottom dead center position is
As shown in the figure, it changes depending on the operating time. That is, at the beginning of operation, the slide portion of the press machine locally generates heat, and as a result, the ram portion thermally expands, so that the bottom dead center drops. However, after a certain amount of operating time, the heat of the slide portion diffuses to the surroundings and the frame portion expands thermally, so that the bottom dead center rises. The fact that the bottom dead center changes with the passage of operating time in this manner indicates that the pressing accuracy also varies with the passage of operating time.

Therefore, various methods have been conventionally used to maintain the bottom dead center at a constant position. The main ones are (a) providing a mechanism for changing the ram position during the press operation, (b) keeping the temperature of the lubricating oil constant and stabilizing the temperature of the press machine. However, the former method (a) causes a decrease in rigidity of the press machine and shortens the life of the mold. Further, the latter method (b) has problems that a large-scale device is required for heating and cooling oil, and that it takes 1 to 2 hours until the temperature of the press machine is stabilized. In particular, in the case of high-speed press processing, at first, break-in processing is performed at a low press speed. Then, the process shifts to high-speed continuous press working, in which case the bottom dead center drops due to the inertial force due to the weight of the slide part and the upper die. In the case of low speed pressing, the bottom dead center is set to the upper side by the bottom dead center drop amount obtained from experience. However, in the case of high-speed press working, it takes time (for example, 0.3 to 1 second) to increase the speed. Therefore, if the bottom dead center is set to the upper side by the amount of the bottom dead center descending amount, the bottom dead center becomes lower than the set position until the speed increases, which causes wear trouble. Therefore, in the conventional high-speed press working, the bottom dead center is lower than the proper position (500 μm to 1000 μm).
There is no choice but to set it to m). As a result, the cost and time for re-grinding the punch are increased, and the die life is inevitably shortened.

[Object of the Invention]

An object of the present invention is to provide a press machine having a bottom dead center position control function and capable of maintaining the bottom dead center of a slide portion at an appropriate position without interrupting operation during press working. .

[Outline of Invention]

The bottom dead center position of the slide part is controlled to a constant position by adjusting the press speed.

Example of Invention

 An embodiment of the present invention will be described below in detail with reference to the drawings.

1 and 2 show the press machine of this embodiment. The press machine includes a frame (1) as a main body, a slide (3) attached to the frame (1) and moving up and down in the direction of an arrow (2), and a lower mold (4).
A bed part (5) to which the above is attached, a bottom dead center position detection part (6) for detecting the bottom dead center position of the slide part (3), and a slide drive part (7) for moving the slide part (3) up and down. , And an arithmetic control unit (8) for controlling the slide drive unit (7) based on the output signal SA from the bottom dead center position detection unit (6). The frame part (1) has a pair of mutually parallel columns (9) and (9). Inside surfaces (9a), (9a) facing each other to the columns (9), (9)
Is a guide surface of the slide portion (3). further,
A ram (10) slidably mounted on the columns (9), (9) in the direction of the arrow (2);
It consists of an upper mold (11) fixed to this ram (10). The upper die (11) has a punch, and is punched together with the die of the lower die (4). Further, the slide driving part (7) is connected to the motor part (12) built in the frame part (1) and one end of the slide part (3) to convert the rotation of the motor part (12) into reciprocating motion. It consists of a crank mechanism (13). The bed portion (5) is provided adjacent to the frame portion (1), and a bolster (14) for positioning the lower die (4) is fixedly mounted on the upper surface. On the other hand, the bottom dead center position detection unit (6) includes a proximity body (1) attached to the lower end of the ram (10).
5) and a position detection sensor (16) such as a high frequency type proximity switch fixed to the bolster (14) so as to face the proximity body (15). Above proximity body (15)
Is an L-shaped fixture (17) protruding from the ram (10)
And a rod-like body (18) hung vertically on this fixed mold (17),
The rod-shaped body (18) is provided with a proximity plate (19) made of metal and continuously connected to the lower end of the rod-shaped body (18) so that its main surface is a horizontal plane. The proximity plate (19) is arranged so as to face the position detection sensor (16) at a distance of, for example, 10 mm when the ram (10) is at the bottom dead center position. Position detection sensor (16)
Has a detection coil that generates a magnetic field that induces an eddy current in the proximity plate (19) and a high-frequency oscillator circuit that supplies a high-frequency current to this detection coil. The eddy current when the proximity plate (19) approaches The distance between the proximity plate (19) and the position detection sensor (16), that is, the ram (1
The output signal SA indicating the bottom dead center (0) is output. Further, the arithmetic control unit (8) holds an amplifier (20) connected to the output side of the position detection sensor (16) and a peak value indicating the bottom dead center connected to the output side of the amplifier (20). Peak value hold circuit (21) and analog-connected to the output side of this peak value hold circuit (21)
Digital (A / D) converter (22) and this A / D converter (2
It is composed of a microcomputer (23) which is connected to the output side of 2) and outputs a control signal SM to the motor section (12). The microcomputer (23) stores an arithmetic program described later.

Then, in the press machine having the above structure, the ram (10)
When the bottom dead center is at the proper position, the value held by the peak value hold circuit (21), that is, the reference bottom dead center position P ₀
Are stored in the microcomputer (23). Then, a work piece (not shown) is placed on the lower mold (4), the motor part (12) is started, and the slide part (3) is lowered through the crank mechanism (13) to move the upper mold. The work piece is sheared by the punch of (11) and the die of the lower die (4).
At this time, the position detection sensor (16) senses the approaching proximity plate (19), and the detection signal SA is output to the peak value hold circuit (21) via the amplifier (20). Then, the peak value hold circuit (21) holds the peak value indicating the bottom dead center, and the signal SB indicating the peak value is output to the A / D converter (22). With this A / D converter (22),
The signal SB is A / D converted, and the digital signal SC is output to the microcomputer (23). This digital signal SC
Are temporarily stored in the microcomputer (23) as bottom dead center position P data. By the way, FIG. 3 shows that the bottom dead center changes depending on the pressing speed (strokes per minute: Spm). That is, it is shown that the bottom dead center change amount (about 100 μm in FIG. 4) with the lapse of the press operation time can be controlled by adjusting the press speed in the range of 150 spm. Therefore, the microcomputer (23) calculates the difference ΔP between the bottom dead center position P and the reference bottom dead center position P ₀ . If the difference ΔP is positive, that is, if the bottom dead center shows an increasing tendency, when the difference is ΔP is increased by about 30 μm, the empirical formula based on FIG.
A control signal SM for increasing the spm pressing speed is applied to the motor section (12). On the contrary, if the difference ΔP is negative, that is, if the bottom dead center shows a downward trend, the control signal SM for decreasing the 30 spm pressing speed by a motor unit ( 12). Then, in the motor section (12) to which the control signal SM is input, the rotation speed thereof is increased or decreased according to the control signal SM. Then, the press working shifts to the next stroke process, and the slide portion (3) is lowered again to press the work piece. At this time, the processing speed of the slide part (3), that is, the pressing speed is increased or decreased in accordance with the increase or decrease in the rotation speed of the motor part (12). Therefore, the bottom dead center of the slide portion (3) moves up and down according to the press speed-bottom dead center position curve shown in FIG. 3, and approaches the reference bottom dead center position P ₀ . Then, in the same manner as before, the bottom dead center position P at this time is detected, and based on the difference ΔP between the bottom dead center position P and the reference bottom dead center position P ₀ , the same motor unit (12 ) Controls the number of rotations and shifts to the next press stroke. Hereinafter, the same adjustment of the bottom dead center position is repeated for each stroke. Further, when ΔP is outside the upper and lower limit values P _U and P _L , that is, when the bottom dead center change suddenly occurs, it is determined that an abnormality has occurred and an alarm signal for temporarily stopping the press working. To an alarm device (not shown) to generate an alarm sound.

Thus, the press machine of this embodiment has the following special effects. That is, [1] the bottom dead center position can be adjusted to an appropriate position in real time without interrupting the press working, and the change in the bottom dead center caused by inertial force or thermal deformation can be made zero. Every time, it is not necessary to stop the press work to adjust the bottom dead center, and productivity is greatly improved. [2] By determining whether or not the bottom dead center is abnormally displaced from the proper position,
Since the abnormal press working is judged at the same time as the adjustment of the bottom dead center, it is possible to prevent the accident from happening in advance, and as a result of the synergistic effect produced in combination with the effect [1], The safety and reliability of press working can be significantly improved. [3] In the case of high-speed press working, it is possible to position the bottom dead center position at the proper position in real time without interrupting the press working, so it is not necessary to set the bottom dead center lower than the proper position. . This makes it possible to reduce the re-grinding time by one to three hours. In addition, the life of the punch, which has conventionally been re-ground by regrinding 5 to 6 times, can be extended to 10 to 12 times.

The position detecting sensor may be of a capacitive type, a magnetic type (using a reed switch), or the like. Alternatively, a contact type sensor such as a differential transformer may be used.
Further, the proximity body (15) may be attached to the upper mold (11). Further, even if the peak value hold circuit in the above embodiment is omitted, the detection signal SA is once stored in the data memory unit via the A / D converter, and the bottom dead center is determined by the software of the microcomputer. Good.

〔The invention's effect〕

The press machine of the present invention has the following special effects. That is, [1] the bottom dead center position can be adjusted to an appropriate position in real time without interrupting the press working, and the change in the bottom dead center caused by inertial force or thermal deformation can be made zero. Every time, it is not necessary to stop the press work to adjust the bottom dead center, and productivity is greatly improved. [2] By determining whether or not the bottom dead center is abnormally displaced from the proper position, it is possible to determine the abnormal press working simultaneously with the bottom dead center adjustment.
It is possible to prevent accidental accidents from occurring, and as a result of the synergistic effect produced in combination with the effect [1], it is possible to significantly improve the safety and reliability of press working. [3] In the case of high-speed press working, it is possible to position the bottom dead center position at the proper position in real time without interrupting the press working, so there is no need to set the bottom dead center lower than the proper position. . This makes it possible to reduce the re-grinding time by one to three hours.
In addition, the life of the punch, which has conventionally been re-ground by regrinding 5 to 6 times, can be extended to 10 to 12 times.

[Brief description of drawings]

FIG. 1 is a side view of a press machine according to an embodiment of the present invention, FIG. 2 is a front view of the same, FIG. 3 is a graph showing the relationship between press speed and bottom dead center, and FIG. 4 is a press operating time. It is a graph which shows the relationship between and a bottom dead center. (1) …… Frame part, (3) …… Slide part, (4)
...... Lower mold, (5) ...... Bed part, (6) ...... Bottom dead center position detection unit, (7) ...... Slide drive unit, (8) ...... Operation control unit, (11) ...... Upper mold .

Claims (1)

[Claims] 1. A press machine comprising the following constitutions (a) to (f): (A) Slide part with the upper die attached. (B) A slide drive unit that supports the slide unit and drives it up and down. (C) a frame section supporting the slide drive section. (D) A bed to which a lower die for press working is mounted together with the upper die. (E) A bottom dead center position detection unit that detects the bottom dead center position of the slide unit. (F) While the press working by the upper die and the lower die is continued, the bottom dead center position of the slide part is detected based on the detection signal output from the bottom dead center position detection part for each stroke period. Is detected and the amount of deviation between the detected bottom dead center position and the preset reference position is determined.If this amount of deviation is outside the preset normal range, press working on the slide drive section is performed. In addition to outputting a stop signal, when the amount of the deviation is within a preset normal range and when the deviation is shifted to the lower mold side, a control signal for decreasing the moving speed of the slide portion is set as described above. An arithmetic control unit that outputs to the slide drive unit, and outputs a control signal for increasing the moving speed of the slide unit to the slide drive unit when the shift is shifted to the upper mold side.