JPH0367000B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a slide control device for a hydraulic press that controls a slide to move up and down parallel to a bolster.

Conventionally, in hydraulic presses that use multiple hydraulic cylinders to move the slide up and down, each cylinder is synchronized and controlled so that the slide moves up and down parallel to the bolster. For example, as shown in Fig. 1, stroke detectors b such as rotary encoders are provided on both ends of the slide a, and the electric signals detected by these detectors are used to control the electro-hydraulic servo mechanism d of the hydraulic pump c. A method in which both ends of the slide a are stroked by the same amount by each hydraulic cylinder e, or a guide rod that is stronger than the slide is provided upward and is passed through the cylinder frame, A known method is to mechanically control the parallel slide by having the cylinder frame guide the guide rod.

However, the former method requires a hydraulic pump with an electro-hydraulic servo control mechanism and a complicated control system, so it is generally expensive, and the latter mechanical method has the disadvantage of being structurally difficult to handle eccentric loads. There were drawbacks such as limitations.

The present invention was made with the aim of improving the conventional drawbacks, and is a slide control device for a hydraulic press that does not require a complicated control system or an expensive hydraulic pump with an electro-hydraulic servo mechanism, and has no restrictions on eccentric loads. This is what we are trying to provide.

An embodiment of the present invention will be described below in detail with reference to an embodiment shown in FIG. 2. In the figure, 1 is a hydraulic press main body, 2 is a bed thereof, and a bolster 3 is attached to the bed 2. At the same time, a cylinder frame 4 is erected from a corner of the bed 2, a plurality of hydraulic cylinders 5, 5' are provided in the upper part of the cylinder frame 4, and an oil tank 6 is provided on the cylinder frame 4. ing. A piston 5a is accommodated in each of the hydraulic cylinders 5, 5', and the piston 5a divides the inside of the cylinder 5 into an upper chamber ₅₁ and a lower chamber _{52 .}
is connected to the oil tank 6 through full oil valves 7 and 7', and a piston rod 5b is provided downwardly protruding from the piston 5a, and a slide 8 is provided between the tips of these piston rods 5b. The slide 8 is attached to the hydraulic cylinder 5 and
can be moved up and down.

Further, 10, 10' are two hydraulic pumps driven by electric motors (not shown), and servo mechanisms 11,
11' makes it possible to adjust the flow rate, and the oil discharged from one hydraulic pump 10 is sent to the upper chamber 51 of one hydraulic cylinder ₅ through a pipe 12 or to the lower chamber of the hydraulic cylinder 5 through a pipe 12'. The oil discharged from the other hydraulic pump 10 _' is supplied to the upper chamber ₅₁ of the other hydraulic cylinder 5' through a pipe 13, or the lower chamber 52 of the hydraulic cylinder 5' through a pipe _13'. The oil discharged from the auxiliary pump 14, which is provided separately from the hydraulic pumps 10 and 10', is supplied to the pipes 15 and 1, respectively.
5' and electromagnetic flow rate regulating valves 16, 16' and 17, 1 provided in the middle of these pipes 15, 15'.
7' to conduits 12, 12' and conduits 13, 13'.
The high pressure side of the

On the other hand, 20 is a variable speed motor installed in the center of the slide 8, and 21 is a speed reducer. 22,2
2' to a bracket 8a protruding from both ends of the slide 8. The bracket 8a is provided with threaded rods 23, 23' supported in a direction perpendicular to the respective rotating shafts 22, 22', and a nut 22a is rotatably screwed into the threaded portion 23a of these threaded rods 23, 23'. A worm gear 22b is provided on the outer periphery of the nut 22a, and the worm gear 22b meshes with worms 22c, 22c' provided at the ends of the rotating shafts 22, 22'.

Further, since the threaded rods 23, 23' are provided with appropriate means so that they can freely move up and down and their rotation is restrained, the threaded rods 23, 23' can be moved up and down without rotating by the rotation of the nut 22a.

An L-shaped lever 2 whose bent portion is supported on the press body 1 side is attached to the upper end side of each screw rod 23, 23'.
One end side of the lever 24, 24' is engaged, and the other end side of the lever 24, 24' is connected to the servo mechanism 11 of the hydraulic pump 10, 10' via a link 25, 25'.
11'. Servo mechanism 11,1
1' is the swash plate of the hydraulic pump 10, 10' (not shown)
One end of an operating rod 11c centered by a spring 11b is brought into contact with the servo valve 11a, and the operating rod 11c is pressed in the direction of arrow A by the links 25, 25'. When pressed, hydraulic pressure is discharged to the pipe lines 12 and 13, and when pressed in the direction of arrow B, hydraulic pressure is discharged to the pipe lines 12' and 13'.

Further, 26 and 26' are racks that protrude downward from the brackets 8a that protrude from both ends of the slide 8.
Pinions 28, 28' attached to rotating shafts 27a of slide stroke detectors 27, 27', such as rotary encoders, provided on the bed 2 are meshed with the racks 26, 26'. The position signal detected by one of these slide stroke detectors 27, 27' is compared with the signal detected by the other slide stroke detector 27, 27' as a reference, and the difference signal is used to control each electromagnetic flow rate regulating valve 16, 16' and 17, 17'. Control as follows.

Therefore, when the press body 1 slides up and down parallel to the bolster 3 regardless of the eccentric load, when the start switch (not shown) is first turned on, the variable speed motor 20 rotates at high speed (this motor The rotation speed of the rotary shafts 22, 2 can be set in advance), and
2' is rotated in the same direction. As a result, the worm 22 provided at the end of each rotating shaft 22, 22'
Since the nut 22a is rotated via the levers 24, 24' and the links 25, 25' to push the screw rods 23, 23' upward, the operating rod 11c of the servo mechanism 11 is rotated in the direction of the arrow. As a result, hydraulic pressure is discharged from each hydraulic pump 10, 10' to the pipe line 12, 13 side, and oil is supplied to the upper chamber ₅₁ side of the hydraulic cylinder 5, 5'. As a result, each hydraulic cylinder 5, 5' lowers the slide 8, and the lower chamber 5 ₂ of each hydraulic cylinder 5, 5'
The oil is supplied to the hydraulic pump 10,
10', and the insufficient oil is replenished from the oil tank 6 via the open oil fill valves 7, 7'. As the slide 8 descends, the bracket 8a also descends, so the nut 22a mounted on the bracket 8a also descends by the same amount, and the screw rod 2
3 and 23' also descend at the same time, attempting to return the operating rod 11c in the direction of arrow B. At that time, hydraulic pump 1
At 0 and 10', the state where the pump was discharging at the maximum discharge amount is about to change to a neutral state (the discharge amount from the pump is zero).

However, since the variable speed motor 20 is continuously rotating at high speed, even if the slide 8 is lowered, the screw rod 2
3, 23' continues to be pushed up, a constant amount of oil always flows from the left and right hydraulic pumps 10, 10' into the upper chamber ₅₁ of the hydraulic cylinders 5, 5', and therefore the nut 2
The slide 8 continues to descend at a speed corresponding to the rotational speed of the slide 2a.

Just before the slide 8 enters the pressurizing stroke, the variable speed motor 20 decelerates (the deceleration position is determined in advance by actuating a limit switch with a cam taken out from the slide 8 or by electric signals sent from the slide stroke detectors 27, 27'). (You can preset it using a digital switch, etc.)

When the slide 8 enters the pressurizing stroke, the full oil valves 7, 7' are automatically closed, the piston 5a is pressurized only with the oil discharged from the auxiliary pump 14, and the auxiliary pump 14 changes to maximum discharge. Note that the flow rate of the auxiliary pump 14 can be adjusted.

When pressurization is completed, the variable speed motor 20, which has been rotating in one direction, will rotate in the reverse direction (the position may be preset in advance, or it may be automatically reversed when the hydraulic pressure reaches a constant pressure using a pressure switch). (Good.) As a result, the screw rods 23, 23' are pulled down, and the operating rods 11c of the servo mechanisms 11, 11' are then moved in the direction of arrow B, so the hydraulic pumps 10, 10' , 11' convert the discharge, and the discharged oil is discharged to pipes 12', 13' and sucked in from pipes 12, 13.

Therefore, hydraulic pressure flows into the lower chambers ₅₂ of the hydraulic cylinders 5, 5', and the slide 8 rises. At this time, the full oil valves 7 and 7' are open, and most of the oil in the upper chamber ₅₁ is returned to the tank 6. When the slide 8 reaches the preset position, the variable speed motor 20 stops rotating and the slide 8 also stops rising.

As mentioned above, the slide 8 is connected to the rotating shafts 22, 22'.
By simultaneously rotating the worms 22c, 22c' and moving the screw rods 23, 23' up and down synchronously via the nut 22a, the same amount of discharge from the hydraulic pumps 10, 10' is sent to both the left and right cylinders.
Thereby, the slide 8 can be moved up and down parallel to the bolster 3 at all times.

However, in reality, it is difficult to make the discharge amounts of the hydraulic pumps 10, 10' exactly the same, and the amount of oil leaking from the gap between the hydraulic cylinders 5, 5' and the piston 5a is also not exactly the same. Parallel vertical movement of the slide 8 is not possible using only the control described above. Therefore, the amount of oil discharged from the auxiliary pump 14 is controlled by the electric signals sent from the slide stroke detectors 27, 27', by the electromagnetic flow rate adjustment valves 16, 16' (for lowering and pressurizing)
17' (for lifting) to enable parallel movement of the slides. That is, the signal detected by one of the slide position detectors 27, 27' is compared with the signal detected by the other detector 27', and the difference signal is used to synchronize the flow rate regulating valve 16' with the reference side. By adjusting the aperture to
Parallel vertical movement of the slide 8 becomes possible for the first time.

Note that the flow rate adjustment valves 16 and 1 on the reference side
7 is required when constant speed operation of the slide 8 is required, but when it is acceptable to have slight variations in slide downward pressurization and rising speed (normally, the variation in speed is not required to be too large and parallel control is preferable) (strongly required), the flow rate regulating valves 16' and 17' may be deleted and the flow rate may be controlled so that the right side is used as a reference and the left side (the reference may be reversed) to match the right side reference.

Also, even if there are two or more cylinders 5, 5',
It is sufficient to control the left and right halves separately. For example, in the case of four cylinders, the two on the right side and the two on the left side are controlled separately. Furthermore, it is also possible to install a slide control device for each press and simultaneously control the slides 8 of a plurality of presses in parallel.

As described in detail above, this invention divides a plurality of hydraulic cylinders that move the slide up and down into two equal parts, right and left, and provides slide stroke detectors at the left and right ends of the slide to detect the stroke position of the slide. Then, the signal detected by one of these position detectors is used as a reference to compare the value detected by the other detector, and the obtained difference signal controls the flow rate adjustment valve installed between the auxiliary pump and the hydraulic cylinder. Since the slides are controlled to move up and down while keeping them parallel to the bolster using each of the hydraulic cylinders, conventional hydraulic pumps with complicated control systems and expensive electro-hydraulic servo mechanisms are no longer required. Parallel control of the slide is possible without the use of mechanical means, and there is no problem of being restricted by the allowable eccentric load unlike when parallel movement is performed using mechanical means.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a conventional device, FIG. 2 is a configuration diagram showing an embodiment of the present invention, and FIG. 3 is a sectional view taken along the line shown in FIG. 2. 1 is the hydraulic press body, 3 is the bolster, 5, 5'
is a hydraulic cylinder, 8 is a slide, 10, 10' is a hydraulic pump, 11, 11' is a servo mechanism, 14 is an auxiliary pump, 16, 16', 17, 17' are flow rate adjustment valves, 27, 27' are slide strokes Detector.

Claims (1)

[Claims] 1. A slide 8 is provided above the bolster 3 of the hydraulic press body 1, and is movable up and down by a plurality of hydraulic cylinders 5, 5'. A hydraulic pump 10, 10' is connected to each of the divided hydraulic cylinders 5, 5', and flow regulating valves 16, 16', 1 are connected to these hydraulic pumps 10, 10'.
The auxiliary pump 14 is connected in parallel via 7, 17',
The servo mechanisms 11 and 11' that control the discharge amount of each of the hydraulic pumps 10 and 10' are synchronously controlled by a variable speed motor 20 so that the same amount of flow is discharged from each hydraulic pump 10 and 10', Slide stroke detectors 27, 27' are provided at both ends of the bed 2 of the hydraulic press body 1, and the signal detected by one of these detectors 27, 27' is used as a reference to compare the value detected by the other detector. , according to the obtained values, the flow rate regulating valves 16, 16', 17,
17', each hydraulic cylinder 5,
A slide control device for a hydraulic press in which a slide 8 is moved up and down parallel to a bolster 3 by means of a slide control device 5'.