JP2698040B2 - Hydraulic servo controlled bottom knockout device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bottom knockout device of a hydraulic servo control type in a forging transfer press on which stable transfer of a molded product (work) is fundamental.

[0002]

2. Description of the Related Art A bottom knockout device in a forging press mainly has a constant stroke in the greatest common denominator due to the mechanical connection of a cam, a lever and the like from the movement of a crankshaft or a connecting rod. In some cases, a mechanism that can change the knockout stroke according to the work or a mechanism that can change the timing of the start of knockout is used to suppress the inertia given to the work, but such a mechanism is supported. Inevitably, the structure of the apparatus becomes complicated, and if the rigidity of the entire apparatus is not sufficiently secured, there is a possibility that an adverse effect may occur. Hydraulic knockout devices have also been proposed in order to avoid the influence of inertia of mechanical knockout devices.However, since they also have a constant stroke, the shape, especially the fitting depth to the lower mold, is extremely low. In the case of a work that has become smaller, the play stroke between the knockout pin of the knockout device and the knockout pin in the lower mold has increased, giving unnecessary inertia to the work. For this reason, there is a problem that the work jumps up.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and makes it possible to obtain a required stroke accurately in a required time without complicating the apparatus. It is an object of the present invention to provide a hydraulic servo-controlled bottom knockout device that can cope with various works by eliminating the jumping-up phenomenon.

[0004]

According to a first aspect of the present invention, there is provided a bottom knockout apparatus as described above, comprising: a detecting means for detecting an up / down stroke of a rod of a hydraulic cylinder; A plurality of rod up / down strokes are selectable corresponding to the type of the work, and a hydraulic cylinder of the hydraulic cylinder is compared with a signal set corresponding to an arbitrary up / down stroke and a detection signal from the detection means. Hydraulic servo control means for controlling the operation. According to a second aspect of the present invention, in the bottom knockout device as described above, a displacement sensor that detects a vertical stroke of a rod of a hydraulic cylinder, and receives a detection signal from the displacement sensor and converts the detected vertical stroke of the rod into a voltage. A displacement controller for converting and sending the servo valve to the servo amplifier; changing the opening of the servo valve until the voltage from the displacement controller reaches a predetermined voltage to be sent from the control means in accordance with the elevating stroke of the rod of the hydraulic cylinder; And a control means that sets a plurality of switchable lift strokes of the rod of the hydraulic cylinder in accordance with the type of work. According to a third aspect of the present invention, in the first or second aspect, a pair of hydraulic cylinders are provided on the knockout lever, and a synchronous deviation detector for detecting a synchronous deviation of the operation of these cylinders is provided in connection with the displacement controller. .

[0005]

According to the operation control of the hydraulic cylinder by the hydraulic servo control means as described above, the knockout pin can accurately obtain a necessary stroke in a required time to suppress the inertia of the work. In addition, the stop position can be easily changed to any selected position.

[0006]

FIG. 1 is a perspective view showing a forged transfer press according to an embodiment of the present invention, in which a center is cut. In the forging transfer press, a die holder having a plurality of lower dies mounted on a bed frame 1 provided on the left and right columns 11 is omitted in the drawing. When the work is press-formed between a pair of upper and lower dies, it is transferred to the next pair of dies. At the time of this press molding, the work is the bed frame 1
It is formed into a complex predetermined shape by being grasped by a pair of fingers 31 attached to the front and rear mounted on the transfer beam 3 that moves three-dimensionally and sequentially moving in a pair of upper and lower molds in the next molding process. Is done. Since the work formed between one set of dies is closely attached to the lower mold, the work must be separated from the lower mold when grasped by one set of fingers 31. For this purpose, a hole is provided through the die holder and the lower mold, and the work is separated from the lower mold by utilizing the movement of the knockout pin 25 which penetrates the hole of the bed frame 1 and moves up and down.

A plurality of knock-out pins 25 are mounted on a knock-out lever 24 laid under the bed frame 1, and both ends of the knock-out lever 24 extending from the inside of the bed frame 1 to the outside are formed by a pair of hydraulic cylinders 2. Each is supported by a rod 21. That is, the knockout pin 25 moves up and down as the rods 21 of both cylinders 2 move up and down, separating the work from the lower mold. A bottom knockout is constituted by the two cylinders 2 provided below the bed frame 1, the knockout lever 24 and the knockout pin 25. As shown in FIG. 2, the rod 21 of both cylinders 2 has
18 is provided, and the detected part 18 is a non-contact type displacement sensor.
By being detected at 22, the lifting stroke of the rod 21 is detected. Reference numeral 23 denotes a displacement controller corresponding to the sensor 22, which receives a detection signal from the sensor 22 and detects the rod.
The ascending / descending stroke 21 is converted into a feedback voltage Ef and sent to the servo amplifier 52. Reference numeral 51 denotes a servo valve operating current I which is provided on an oil pipe connecting the hydraulic pressure generating device 53 and the two cylinders 2.
Servo valve controlled by servo amplifier 52 by s, 5
4 is a linear function command voltage Ei to the servo amplifier 52 during automatic operation.
This is a transfer control device that sends a CPU, and has a CPU built inside. 55 is an input voltage setting device that sends a constant command voltage Ei 'to the servo amplifier 52 during manual operation, 56 is a sequencer, 5
7 is the operation panel. Reference numeral 58 denotes a synchronization shift detector for detecting a synchronization shift between the operations of the two cylinders 2, and is provided to be connected to the controller 23. In FIG. 2, reference numeral 61 denotes a detecting means, and 62 denotes a hydraulic servo control means.

The operation will be described with reference to the bottom knockout flowchart of FIG. There are three types of bottom stroke stroke length, for example, 10mm, 30mm, 50mm.
It is input to the CPU of the transfer control device 54 in advance, and the length of an arbitrary elevating stroke can be selected from the set strokes by a changeover switch provided on the operation panel 57. Therefore, in order to select a necessary knockout stroke by the changeover switch of the operation panel 57, for example, when a data write button for selecting a vertical stroke length of 50 mm is turned on, data is written into the sequencer 56, and then a data save button Is turned on, data is saved in the CPU of the transfer control device 54. Next, when the automatic press operation button is turned on, the automatic operation starts, and the timing of raising and lowering the knockout pin 25, that is, the command voltage Ei (= + 2.5
V) is output from the transfer controller 54. The form of the command voltage Ei is not a simple one-shot (ON-OFF) output, but a linear function command voltage that gradually increases the output voltage over time. As a result, both cylinders 2 of the bottom knockout are transferred to the transfer control device 54.
The operation is controlled in accordance with the length of the up / down stroke inputted to the CPU. That is, by changing the servo voltage with time according to a predetermined function, the two cylinders 2 operate smoothly according to the transfer device, so that the work is not jumped up by the knockout pin 25.

The above-mentioned command voltage Ei (= + 2.5 V) is
+ 10V output at 200mm displacement by 22
V × 50 mm / 200 mm = + 2.5 V. Similarly, when the vertical stroke length is 30 mm, +1.5 V is obtained, and when the vertical stroke length is 10 mm, +0.5 V is obtained. On the other hand, the actual elevating stroke of the rods 21 of the two cylinders 2 is detected by the sensor 22 and the voltage Ef (= −2.5
V) is input as feedback. The command voltage Ei (= + 2.5 V) output from the transfer control device 54
And the feedback voltage E output from the controller 23
amplifies the difference voltage ± ε from f (= − 2.5V)
The current 51 is converted to a current Is for operation. That is, it is determined whether the two voltages match or not, and if Ef−Ei = ± ε = 0, the command to the servo valve 51 is turned off, thereby stopping the operation of the servo valve 51.

In the above description, the synchronization deviation detector 58 continuously checks the synchronization deviation between the two cylinders 2. If the synchronization deviation is large, an abnormal signal is issued to protect the device and the operation is stopped. This prevents the risk of damaging the components of the knockout device and serves as a safety device.

[0011] By changing the work to be formed, the length of the vertical stroke of the bottom knockout is changed from 10 mm to 30 mm or
To change it to 50 mm, the changeover switch on the operation panel 57 is selected, and the voltage Ei sent from the CPU in the transfer control device 54 to the servo amplifier 52 is changed. The above description is about the automatic operation, but the knockout pin is used to check the presence or absence of the work in the mold after the work is completed or before the work is started
Manual operation as a single operation of only 25 is also possible. The operation flowchart is shown in the left column of FIG.

[0012]

According to the first and second aspects of the present invention, the stop position of the knockout pin can be easily changed, and the knockout pin can be gently stopped at the stop position. Bouncing can be reliably prevented. In addition, the work can be reliably gripped because the timing of raising and lowering the cylinder is linked to the movement of the transfer beam. Moreover,
The structure is also simplified, and the productivity and quality of a workpiece having a complicated shape in a forging transfer press can be improved. The invention of claim 3 has an effect that the synchronization can be effectively achieved when a plurality of hydraulic cylinders are used, and the safety of the device can be enhanced.

[Brief description of the drawings]

FIG. 1 is a perspective view in which a center of a forged transfer press according to an embodiment of the present invention is cut.

FIG. 2 is a block diagram showing a hydraulic operation control mechanism for bottom knockout.

FIG. 3 is a flowchart of bottom knockout.

[Explanation of symbols]

 1 Bed frame 2 Hydraulic cylinder 3 Transfer beam 18 Detected part 21 Rod 22 Displacement sensor 23 Displacement controller 24 Knockout lever 25 Knockout pin 51 Servo valve 52 Servo amplifier 53 Hydraulic pressure generator 54 Transfer control device 55 Input voltage setting device 56 Sequencer 58 Synchronization Misalignment detector

Claims (3)

(57) [Claims] 1. A plurality of knock-out pins supported by a lever provided on a bed frame of a press machine and being supported by a rod thereof by operating a hydraulic cylinder through a knock-out lever. In the bottom knockout device that knocks out from inside,
Detecting means for detecting the lifting / lowering stroke of the rod of the hydraulic cylinder, and a plurality of lifting / lowering strokes of the rod of the hydraulic cylinder corresponding to the type of the work, which can be switched, corresponding to any of the lifting / lowering strokes A hydraulic servo-controlled bottom knockout device, comprising: hydraulic servo control means for controlling the operation of a hydraulic cylinder while comparing a set signal with a detection signal from the detection means. 2. A plurality of knockout pins supported by a lever provided on a bed frame of a press machine, which are supported by a rod of the hydraulic cylinder when the hydraulic cylinder is actuated. In the bottom knockout device that knocks out from inside,
A displacement sensor that detects a lifting stroke of the rod of the hydraulic cylinder, a displacement controller that receives a detection signal from the displacement sensor, converts the detected lifting stroke of the rod into a voltage, and sends the voltage to a servo amplifier; A servo amplifier that changes the degree of opening of the servo valve until the voltage reaches a predetermined voltage sent from the control means in accordance with the lifting stroke of the rod of the hydraulic cylinder, and stops the servo valve when the voltage reaches the predetermined voltage; A hydraulic servo-controlled bottom knockout apparatus, comprising: a plurality of control means for setting a plurality of switchable strokes of a rod of a cylinder in accordance with a type of a work. 3. The hydraulic cylinder is provided with a knockout lever.
3. The hydraulic servo-controlled bottom knockout device according to claim 1, wherein a pair of synchronous detectors for detecting a synchronous deviation of the operation of the cylinders are connected to the displacement controller.