JP3788568B2 - Servo press bottom dead center search device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bottom dead center search device for a servo press. The servo press means a press machine that uses a servo motor as a drive source and moves up and down a ram (corresponding to a slide) with a screw mechanism. The bottom dead center search device means a device that searches for the actual bottom dead center position of the ram for the purpose of making the actual bottom dead center position of the ram as accurate as possible, and keeps the bottom dead center position within an allowable value. .
[0002]
[Prior art]
In order to improve the dimensional accuracy of the pressed product, the bottom dead center position must be accurate. As a prior art for solving this problem, Japanese Patent Application No. 2000-27655 of the same applicant can be cited. In this application, as means for detecting the position of the ram, a ram position detector is provided in the column portion of the servo press main body, and a bottom dead center sensor is provided in the mold portion. That is, the bottom dead center sensor is used to detect the bottom dead center at a position that is not affected by various deformations of the servo press main body and the die mounting member.
[0003]
In the conventional example, the bottom dead center can be detected without being affected by the deformation of the servo press body or the like. However, it is impossible to raise the ram at the same time that the bottom dead center sensor detects the bottom dead center because of a control delay. That is, the detected bottom dead center does not match the actual bottom dead center.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-described problem, and is to make the actual bottom dead center fall within the set allowable value of the bottom dead center.
[0005]
[Means for Solving the Problems]
In this invention, it was set as the structure which raises the ram 3 in the step which lowers the ram 3 intermittently by the fixed amount from the short time before reaching a bottom dead center, and the bottom dead center was confirmed by the bottom dead center sensor 11 . More specifically, the invention of claim 1 detects the position of the ram 3 in a screw press in which the ram 3 is driven by a servo motor 5 via a screw mechanism, and the position of the ram 3 is controlled by this signal. A ram position detector 9 and a bottom dead center sensor 11 for detecting the relative positions of the upper and lower molds are provided, and the ram 3 is intermittently lowered by a certain amount from before reaching the set bottom dead center. a ram 3 each of descent of the ram 3 checks whether the host vehicle has reached the bottom dead center at the bottom dead center sensor 11, after the ram 3 in the bottom dead center sensor 11 detects the arrival at the bottom dead center The ram 3 is raised from the bottom dead center . A second aspect of the present invention, in addition to the first aspect, the bottom dead center sensor 11 when the bottom dead center of the ram 3 is detected, the end of the intermittent lowering the number of ram 3 which is set in advance In the case of aggregation, the intermittent lowering start position of the ram 3 from before reaching the set bottom dead center is changed to reduce the intermittent lowering of the ram 3 until reaching the bottom dead center .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 2, a servo motor 5 is fixed to the frame 2 of the servo press main body 1, and a pulley is fixed to the output shaft of the servo motor 5. On the other hand, a screw rod 4 is rotatably provided on the frame 2, and a pulley is fixed to the upper end portion of the screw rod 4. Belts are hung on both pulleys, and the rotational force of the servo motor 5 is transmitted to the screw rod 4. That is, if the servo motor 5 rotates, the screw rod 4 also rotates accordingly.
[0007]
A ram 3 is provided on the frame 2 so as to be movable up and down, and a lower end portion of the screw rod 4 is screwed into a nut portion of the ram 3. When the screw rod 4 is rotated forward and backward, the ram 3 moves up and down. A screw mechanism is constituted by the screw rod 4 and the nut portion of the ram 3. The upper mold 10 is fixed to the lower surface of the ram 3, and the lower mold 12 is fixed to the upper surface of the bed of the frame 2 or the upper surface of a bolster (not shown) fixed to the frame 2. The material supplied between the upper mold 10 and the lower mold 12 is pressed along with the up and down movement of the ram 3.
[0008]
A ram position detector 9 is provided on the frame 2, and a bottom dead center sensor 11 is provided on the lower mold 12. The ram position detector 9 uses a linear scale with a detection unit of about 0.5 micrometer, and the bottom dead center sensor 11 has an eddy current sensor with a detection unit of about 0.1 micrometer, which is more accurate than the linear scale. Adopted.
[0009]
In this case, the ram position detector 9 detects the position of the ram 3 in the height direction, and the bottom dead center sensor 11 detects the relative position of the upper and lower molds. Don't worry about it.
[0010]
Since the ram position detector 9 is longer than the bottom dead center sensor 11, it is not practical to use a highly accurate sensor similar to the bottom dead center sensor 11. On the other hand, the bottom dead center sensor 11 is unsuitable for a long object due to the installation space. Therefore, it is impossible to detect the position of the ram 3 over the entire lifting and lowering stroke of the ram 3. Therefore, the ram position detector 9 detects the position of the ram 3 over the entire stroke of the ram 3, and the bottom dead center sensor 11 detects the position of the ram 3 only near the bottom dead center.
[0011]
In FIG. 2, the outputs of the ram position detector 9 and the bottom dead center sensor 11 are sent to the NC control device 6 together with the output of the current detector 8, calculated by the NC control device 6, and servoed by a signal from the NC control device 6. The motor 5 is controlled.
[0012]
In FIG. 1, the horizontal axis indicates time, and the vertical axis indicates the position of the ram 3 in the height direction. In FIG. 1, the example of the locus | trajectory through which the ram 3 passes A, B, Q, R, P, D is shown. A and D indicate top dead center, and P indicates bottom dead center. The ram 3 descends from the top dead center A, passes through a preset B, and returns to the top dead center D through Q, R, and P by the subsequent control.
[0013]
In the case of the present invention, the ram 3 is intermittently lowered by a certain amount from before reaching the set bottom dead center. The bottom dead center sensor 11 detects whether or not the ram 3 has reached the bottom dead center. That is, in FIG. 1, the ram 3 is intermittently lowered by a fixed amount a from the time when the ram 3 reaches Q. When the ram 3 reaches R, the bottom dead center is not detected, and the ram 3 is continuously lowered by the predetermined amount a. At this time, the bottom dead center P is detected, the ram 3 is raised, and the top dead center D is reached. In FIG. 1, the bottom dead center is detected at the lower end of the second time, but usually it is detected between the predetermined amounts .
[0014]
In the case of the present embodiment, the bottom dead center is searched for the second time by 1 micrometer. Number falling times has a structure that can be selected between 1 and 10. Material depending on factors such as the state small cities the number the falling times if each time the pressing is stable, when there is a variation is required to be large.
[0015]
For instance, the number of down times were set to 10, in every press working, if the time of bottom dead center is detected by the bottom dead center sensor 11 is integrated into the rear of the number of descending times, the time required for the exploration to save, it is desirable to reduce the number of descending times of that amount.
[0016]
In any case, as described above, since the ram 3 is raised after confirming the bottom dead center, the actual bottom dead center of the ram 3 does not change greatly. In the above embodiment, it can be seen that it falls within 1 micrometer.
[0017]
【The invention's effect】
According to the present invention, the ram is lowered by a certain amount, the bottom dead center is checked each time, and the ram 3 is raised after confirming that the bottom dead center has been reached. No more than a certain amount will go mad. Therefore, a highly accurate press processed product can be obtained.
[Brief description of drawings]
FIG. 1 is an explanatory diagram showing the trajectory of a ram. FIG. 2 is an explanatory diagram showing the overall configuration.
1 is a servo press main body, 2 is a frame, 3 is a ram, 4 is a screw rod, 5 is a servo motor, 6 is an NC controller, 7 is a power current circuit, 8 is a current detector, 9 is a ram position detector, 10 Is an upper mold, 11 is a bottom dead center sensor, and 12 is a lower mold.

Claims (2)

In the screw press for driving a ram (3) through a screw mechanism with a servo motor (5), wherein the detecting the position of the ram (3), the ram position detector for controlling the position of the ram (3) in this signal (9) and a bottom dead center sensor (11) for detecting the relative positions of the upper and lower molds, and the ram (3) is intermittently lowered by a certain amount from before reaching the set bottom dead center, Each time the intermittent ram (3) descends, the bottom dead center sensor (11) checks whether the ram (3) has reached the bottom dead center, and the ram (3) is checked by the bottom dead center sensor (11 ). There after detecting the arrival at the bottom dead center, bottom dead center locator of the servo press, characterized in that it has a configuration to raise the ram (3) from the lower dead point. When the time point at which the bottom dead center of the ram (3) is detected by the bottom dead center sensor (11) is collected in the final stage of the intermittent number of descending times of the ram (3) set in advance, The intermittent lowering start position of the ram (3) from before reaching the bottom dead center is changed to reduce the number of intermittent lowering of the ram (3) until reaching the bottom dead center. Item 2. A bottom dead center search device for a servo press according to item 1.

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