JP7601655B2 - Press forming machine and control method thereof - Google Patents

Description

The present invention relates to a press molding machine that drives a hydraulic cylinder to raise and lower a pressing body to mold a workpiece, and performs LFT-D (Long Fiber Thermoplastic-Direct) molding, prepreg molding, metal bending, metal deep drawing, RTM (Resin Transfer Molding) molding, etc., and a control method for the same.

Conventionally, press molding machines are known that drive hydraulic cylinders to raise and lower a pressing body to mold a workpiece, and a piston pump capable of discharging in both directions is used for servo control of these press molding machines (for example, Patent Document 1).

JP 2000-312929 A

In press molding machines such as that described in Patent Document 1, a single bidirectional pump controls the supply and discharge of hydraulic oil to the head side pressure chamber and rod side pressure chamber, which have different pressure receiving areas of the double-acting hydraulic cylinder, making it difficult to perform precise speed control such as high speed depression and low speed depression. In addition, bidirectional pumps that can discharge hydraulic oil from both sides, such as piston pumps, are special pumps and there are only a limited number of types. For this reason, a fairly large bidirectional pump is required to control a large press, and pumps of the required size may not exist or may be very expensive.

On the other hand, when using a gear pump, the discharge volume of the gear pump is determined by the size of the gear. Therefore, in order to increase the speed of the press molding machine, it is necessary to either increase the size of the gear pump or to increase the number of units used.

However, if the gear pump becomes larger and the pump capacity increases, or if the number of gear pumps increases, the control accuracy decreases and the press forming machine cannot be operated stably.

The present invention was made in consideration of these points, and its purpose is to enable stable operation of a press molding machine without using a large-capacity pump.

To achieve the above object, the first invention is based on a press molding machine that drives a hydraulic cylinder to raise and lower a pressing body to mold a workpiece.

And, the press molding machine is
a push-down side pump that sends hydraulic fluid to the hydraulic cylinder to push down the pressing body, and a pull-up side pump that sends hydraulic fluid to the hydraulic cylinder to pull up the pressing body,
At least one of the push-down side pump and the pull-up side pump is composed of three or more gear pumps,
The three or more gear pumps are connected to a rotating shaft of the electric motor so as to rotate integrally with each other, with the gear phases being shifted from each other by a predetermined angle.

According to the above configuration, three or more gear pumps can be driven simultaneously by the rotating shaft of one electric motor, making it easy to control and eliminating the need to use a large-capacity pump. In addition, the multiple gear pumps are connected to the rotating shaft of the electric motor so that the gear phases are mechanically shifted from each other, increasing the apparent number of teeth, reducing the pulsation of the oil discharged from the gear pumps and improving the accuracy of position or pressure control.

In a second invention, a press forming machine is provided that drives a hydraulic cylinder to raise and lower a pressing body to form a workpiece,
a push-down side pump including a plurality of gear pumps for feeding hydraulic fluid to the hydraulic cylinder to push down the pressing body;
a push-down-side electric motor for independently driving each of the push-down-side pumps including the plurality of gear pumps;
a lifting side pump including a plurality of gear pumps for pumping hydraulic fluid into the hydraulic cylinder to lift the pressing body;
and a pull-up side electric motor for independently driving each of the pull-up side pumps including the plurality of gear pumps,
The push-down side pumps, which are made up of a plurality of gear pumps, are configured to be controllable by the corresponding push-down side electric motors so that the gear phases are shifted from each other by a predetermined angle,
The pull-up side pumps, which are made up of a plurality of gear pumps, are configured so that the gear phases can be controlled by the corresponding pull-up side electric motors so as to be shifted from each other by a predetermined angle.

With the above configuration, multiple gear pumps can be driven simultaneously by the rotating shafts of their corresponding electric motors, making it easy to control and eliminating the need to use large-capacity pumps. In addition, multiple gear pumps are controlled to be driven by corresponding electric motors so that the gear phases are intentionally shifted, increasing the apparent number of teeth, reducing pulsation of the oil discharged from the gear pumps and improving control accuracy.

In a third aspect of the present invention, the hydraulic cylinder includes at least one of a push-down side pump that sends hydraulic fluid to the hydraulic cylinder to push down the pressing body and a pull-up side pump that sends hydraulic fluid to the hydraulic cylinder to pull up the pressing body,
At least one of the push-down side pump and the pull-up side pump is composed of three or more gear pumps that are connected to a rotating shaft of a corresponding electric motor so as to rotate together in such a manner that the gear phases are shifted from each other by a predetermined angle, and the present invention is directed to a control method for a press molding machine that drives a hydraulic cylinder to raise and lower a pressing body to mold a workpiece,
The control method includes:
The three or more gear pumps are driven so that the gear phases are shifted from each other by a predetermined angle.

With the above configuration, three or more gear pumps can be driven simultaneously by the rotating shaft of a single electric motor, making it easy to control and eliminating the need to use a large-capacity pump. In addition, the gear phases of the multiple gear pumps are mechanically shifted from each other, increasing the apparent number of teeth, reducing the pulsation of the oil discharged from the gear pumps and improving the accuracy of position or pressure control.

In a fourth aspect of the present invention, the hydraulic cylinder includes at least one of a push-down side pump that sends hydraulic fluid to the hydraulic cylinder to push down the pressing body and a pull-up side pump that sends hydraulic fluid to the hydraulic cylinder to pull up the pressing body,
At least one of the push-down side pump and the pull-up side pump is composed of a plurality of gear pumps, and the method is based on a control method for a press molding machine that drives a hydraulic cylinder to raise and lower a pressing body to mold a workpiece,
A push-down side pump, which is made up of a plurality of gear pumps, is controlled by a corresponding push-down side electric motor so that the gear phases are shifted from each other by a predetermined angle,
The pull-up side pumps, which are made up of a plurality of gear pumps, are controlled by the corresponding pull-up side electric motors so that the gear phases are shifted from each other by a predetermined angle.

With the above configuration, multiple gear pumps can be driven simultaneously by the rotating shafts of their corresponding electric motors, making it easy to control and eliminating the need to use large-capacity pumps. In addition, multiple gear pumps are controlled to be driven by corresponding electric motors so that the gear phases are intentionally shifted, increasing the apparent number of teeth, reducing pulsation of the oil discharged from the gear pumps and improving control accuracy.

As described above, according to the present invention, multiple gear pumps are driven so that the gear phases are shifted from each other by a predetermined angle, so that the press forming machine can be operated stably without using a large-capacity pump.

1 is a hydraulic circuit diagram showing an overview of a press forming machine according to a first embodiment of the present invention. FIG. FIG. 1 is a schematic diagram showing one cycle of a press forming machine according to a first embodiment of the present invention. FIG. 6 is a hydraulic circuit diagram showing an overview of a press forming machine according to a second embodiment of the present invention.

The following describes an embodiment of the present invention with reference to the drawings.

(Embodiment 1)
1 shows a hydraulic circuit diagram 1 of a hydraulic press 2 as a press molding machine according to a first embodiment of the present invention, and although not shown in detail, this hydraulic press 2 drives a hydraulic cylinder 3 as a double-acting hydraulic cylinder to press down a slide 4 as a pressing body to mold a workpiece. The workpiece is not particularly limited to a forged product, carbon fiber reinforced plastic (CFRP), etc.

Specifically, the hydraulic cylinder 3 is a double-acting hydraulic cylinder having a piston 3a and a piston rod 3b, and a slide 4 acting as a pressing body is connected to the piston rod 3b. The movement of the piston 3a raises and lowers the slide 4 to form the workpiece. The hydraulic cylinder 3 is provided above the slide 4, and a relatively large double-acting hydraulic cylinder is required to ensure the pressing force.

The hydraulic press 2 is equipped with multiple push-down pumps 5 that pump hydraulic oil as a hydraulic fluid into the hydraulic cylinder 3 to push down the slide 4. In this embodiment, the multiple push-down pumps 5 are composed of three gear pumps.

As shown enlarged in FIG. 2, these three push-down side pumps 5 are rotatably connected to one rotating shaft 6a of a push-down side electric motor 6 such as a servo motor. As a feature of this embodiment, the three gear pumps are connected to the rotating shaft 6a of the push-down side electric motor 6 so that the gear phases are shifted from each other by a predetermined angle. For example, as shown in FIG. 2, the input shaft 5a of each push-down side pump 5 is connected to the same shaft, and for example, two suction ports 5b and three discharge ports 5c are provided.

In this way, the push-down electric motor 6 is driven in the forward direction to suck up hydraulic oil from the hydraulic oil tank 7 and send pressurized hydraulic oil to the head side hydraulic chamber 3c of the hydraulic cylinder 3, pushing down the piston 3a. When the piston 3a is pulled up, the hydraulic oil in the head side hydraulic chamber 3c flows into the push-down pump 5, and the hydraulic oil returns to the hydraulic oil tank 7 while rotating the push-down electric motor 6 in the reverse direction.

In this embodiment, the push-down electric motor 6 may be precisely controlled by the controller 10 for rotation and may be configured to be capable of regenerative braking. However, this is not necessarily limited to this. The push-down electric motor 6 is connected to the power storage device 9 via the controller 10 or via a separate charge controller. The power storage device 9 may be a lead-acid battery, a nickel-metal hydride battery, a lithium-ion battery, a capacitor, or the like, but is not limited to this. A relief valve 8 is provided on each of the rod side and head side of the hydraulic cylinder 3. Unless the pressure in the piping rises above the set pressure, hydraulic oil will not flow into the hydraulic oil tank 7 through this relief valve 8.

On the other hand, multiple lifting side pumps 15 are connected to the rod side of the hydraulic cylinder 3, which pump pressurized hydraulic oil from the hydraulic oil tank 7 into the rod side hydraulic chamber 3d to raise the piston 3a and lift the slide 4. The multiple lifting side pumps 15 are composed of three gear pumps.

A single rotating shaft 16a of a regeneratively braking-capable pulling-side electric motor 16 is connected to these three pulling-side pumps 15 so that they rotate together. Although not shown, the input shafts 15a of these three pulling-side pumps 15 are also connected to the rotating shaft 16a of the pulling-side electric motor 16 so that the gear phases are shifted from each other by a predetermined angle, as shown in FIG. 2.

When the piston 3a is pushed down, hydraulic oil in the rod-side hydraulic chamber 3d flows into the input shaft 15a of the lifting-side pump 15, and the hydraulic oil returns to the hydraulic oil tank 7 while rotating the lifting-side electric motor 16 in the reverse direction. The lifting-side electric motor 16 is also made of a servo motor or the like, and is precisely controlled for rotation by the controller 10, and is connected to the power storage device 9 via the controller 10 or via a separate charge controller. In other words, when the slide 4 is pushed down, the speed or pressure is controlled by the lifting-side electric motor 16, which rotates in the reverse direction, without speed or pressure control by a valve.

The head side hydraulic chamber 3c of the hydraulic cylinder 3 is connected to the hydraulic oil tank 7 via a suction valve 11 that includes a piloted check valve.

The position of the slide 4 is measured in real time by a position sensor 12 and sent to the controller 10. In addition, a push-down side pressure sensor 17 is provided on the discharge side of the push-down side pump 5, and a pull-up side pressure sensor 18 is provided on the discharge side of the pull-up side pump 15. Information obtained by these sensors 12, 17, and 18 is sent to the controller 10.

- Hydraulic press operation -
Next, the operation of the hydraulic press 2 according to this embodiment will be described with reference to FIG.

First, in the high-speed lowering process as the lowering process, the weight of the slide 4 is used to reversely rotate the lifting-side pump 15 while controlling the rotation of the lifting-side electric motor 16 to lower the slide 4 at high speed. At this time, the suction valve 11 is open, the head-side pressure A is (back pressure-pressure corresponding to mass load W) x rod-side area/head-side area, and the rod-side pressure B is back pressure. Since the suction valve 11 is open, the oil supplied to the head-side hydraulic chamber 3c of the hydraulic cylinder 3 flows in from the hydraulic oil tank 7. At this time, the head-side push-down electric motor 6 is free. Then, the discharge oil from the rod-side hydraulic chamber 3d of the hydraulic cylinder 3 is discharged by the rotational braking of the lifting-side electric motor 16 while performing speed feedback (possible position feedback as well). At this time, the power generated by regenerative braking is stored in the power storage device 9 or used as it is in another process. By weakening the degree of this regenerative braking, the slide 4 can be lowered at a higher speed.

Next, in the pressurization process, first, in the pressurization lowering process, the rotation of the push-down side electric motor 6 is controlled to send hydraulic oil from the push-down side pump 5 to the hydraulic cylinder 3 to push down the slide 4 and mold the workpiece. At this time, the suction valve 11 is closed, the head side pressure A is the back pressure x rod side area / head side area plus the molding pressure, and the rod side pressure B is the back pressure. At this time, the head side operates the push-down side electric motor 6 in power running by speed feedback (possibly with position feedback), and the oil supplied to the head side hydraulic chamber 3c is sent from the push-down side pump 5 driven by the push-down side electric motor 6. Then, the discharge oil from the rod side hydraulic chamber 3d is discharged from the pull-up side pump 15 by the pull-up side electric motor 16, which rotates in the reverse direction while providing speed feedback, and regenerative braking is performed in some cases. The electricity generated at this time is stored in the storage device 9 or used as is in another process.

Next, in the holding process, the suction valve 11 is closed and the workpiece is pressed while regenerative braking of the pushing-down electric motor 6 is performed on the head side using position (pressure) feedback.

Next, in the depressurization process, the suction valve 11 is closed and depressurization is performed while regenerative braking of the push-down side electric motor 6 is performed on the head side using pressure feedback.

Next, in the ascending process, first, in the load ascending process, the rotation of the lifting side electric motor 16 is controlled to send hydraulic oil from the lifting side pump 15 to the hydraulic cylinder 3 to raise the slide 4. At this time, the suction valve 11 is closed, the head side pressure A is the back pressure, and the rod side pressure B is the pressure corresponding to the mass load W including the slide 4 plus the back pressure x head side area / rod side area. At this time, the oil supplied to the rod side hydraulic chamber 3d of the hydraulic cylinder 3 is sent from the lifting side pump 15 by the power operation of the lifting side electric motor 16 by speed feedback. Then, while performing regenerative braking of the push-down side electric motor 6 by speed feedback, the discharge oil on the head side of the hydraulic cylinder 3 is discharged by the push-down side pump 5, and the electricity generated by the regenerative braking at this time is stored in the power storage device 9 or used as it is in another process.

Next, in the high-speed ascent process, the suction valve 11 opens, and the lifting side electric motor 16 is powered by speed feedback to send pressurized hydraulic oil from the lifting side pump 15 to the hydraulic cylinder 3, causing the slide 4 to rise at high speed.

When the hydraulic press 2 is stopped, the suction valve 11 is closed, the head side pressure A is 0, and the rod side pressure B is a pressure corresponding to the mass load W including the slide 4.

In addition, during the pressurizing process and the load increasing process, speed control and pressure control may be switched or combined as appropriate depending on the material being processed and the processed shape.

Here, the discharge volume of the gear pump is determined by the size of the gear. Therefore, in order to increase the speed, it is necessary to increase the size or the number of pumps used. In this embodiment, by connecting the three pump input shafts 5a, 15a to a single rotating shaft 6a, 16a, respectively, it is possible to control the position or pressure with a single servo motor 6, 16, respectively.

And, if the pump capacity is P cc/rev, the rotation speed is N r/m, and the cylinder volume is A ^cm2 ,
Speed V cm/m=P×N/A
It becomes.

However, the accuracy deteriorates as the number of pumps increases. In other words, if the number of pumps is Y and the number of pump teeth is W,
Control accuracy Q cm = (P x Y) / (A x W)
It becomes.

As can be seen from this formula, increasing the number of teeth increases accuracy, but this is not practical as it significantly affects pump performance. However, in this embodiment, the gear phase of each pump can be shifted by, for example, half a pitch or one-third of a pitch, thereby increasing the apparent number of teeth and improving accuracy.

In addition, by shifting the gear phase, the pulsation of the oil discharged from the pump is reduced, allowing the hydraulic press 2 to operate stably.

Therefore, with the hydraulic press 2 according to this embodiment, multiple gear pumps are driven so that the gear phases are shifted from each other by a predetermined angle, so that the press forming machine 1 can be operated stably without using a large-capacity pump.

--Modification of the first embodiment--
As a modified example of the first embodiment of the present invention, although not shown in detail, multiple sets of the hydraulic cylinders 3, push-down side pump 5, pull-up side pump 15, etc. shown in FIG. 1 may be provided so that multiple hydraulic cylinders 3 are used to control the push-down and pull-up of one slide 4.

(Embodiment 2)
3 shows a hydraulic circuit diagram 101 according to a second embodiment of the present invention, which differs from the first embodiment in that the pump configuration is different. In the following embodiments, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals and detailed description thereof will be omitted.

Specifically, in the hydraulic press 102 according to this embodiment, the push-down side pump 105 is composed of two gear pumps, and two push-down side electric motors 106 are provided, each of which is a servo motor that drives the push-down side pump 105 independently. Unlike the first embodiment, the input shafts 105a of the two push-down side pumps 105 are not connected to each other, but are connected to the corresponding push-down side electric motors 106 so as to rotate together. The two push-down side electric motors 106 may be provided at locations separated from each other. There may be three or more push-down side pumps 105 and push-down side electric motors 106. The controller 10 always accurately grasps the gear positions of the gears of each gear pump during operation, so that the gear phases of the gears can be shifted by a predetermined pitch.

Similarly, the hydraulic press 102 is equipped with a pull-up side electric motor 116 consisting of two gear pumps, and two pull-up side electric motors 116 that independently drive the pull-up side pumps 115 consisting of these two gear pumps. The rotating shafts 116a of the two push-up side electric motors 116 are connected to the input shafts 115a of the corresponding pull-up side pumps 115 in a rotating integral manner, and the input shafts 115a are not connected to each other. The two push-up side electric motors 116 may be provided in locations separated from each other. There may be three or more push-up side electric motors 116 and push-up side electric motors 116. The controller 10 always accurately grasps the gear positions of each gear pump during operation, so that the gear phases of the two gear pumps can be shifted by a predetermined pitch.

These two push-down side pumps 105 are configured so that their gear phases can be intentionally controlled by the corresponding push-down side electric motors 106 so that they are shifted from each other by a predetermined angle. The two pull-up side electric motors 116 are also configured so that their gear phases can be controlled by the corresponding pull-up side electric motors 106 so that they are shifted from each other by a predetermined angle.

Unlike the first embodiment above, where a single electric motor 106, 116 rotates multiple pumps on a single rotating shaft 106a, 116a, each electric motor 106, 116 must be controlled. However, if a servo motor is used, the gear phase of each pump can be precisely controlled to always be shifted by half a pitch, 1/3 pitch, etc. from each other.

Therefore, in this embodiment, multiple gear pumps are driven so that the gear phases are shifted from each other by a predetermined angle, so the press molding machine can be operated stably without using a large-capacity pump.

Other Embodiments
The present invention may be configured as follows with respect to the above embodiment.

In other words, in the above embodiment, an example of a hydraulic press 2, 102 was shown as a press molding machine, but the present invention can be applied to press molding machines that perform LFT-D (Long Fiber Thermoplastic-Direct) molding, prepreg molding, metal bending, metal deep drawing, RTM (Resin Transfer Molding) molding, etc., and in which the pump is directly controlled by an electric motor such as a servo motor.

In addition, the push-down side pumps 5, 105 and the pull-up side pumps 15, 115 are pumps that can discharge pressurized hydraulic oil in only one direction, but they may also be bidirectional pumps that can discharge pressurized hydraulic oil in both directions.

In addition, in each embodiment, the slide 4 is pushed down to form the workpiece, but the slide 4 may also be pushed up to form the workpiece. In that case, the hydraulic cylinder 3, the push-down hydraulic cylinder 103, etc. can be embedded in the ground, etc., to save space. The direction of the weight will be reversed, but basically the configuration and control of each of the above embodiments can be turned upside down accordingly.

In each of the above embodiments, a hydraulic cylinder using hydraulic oil as the hydraulic fluid is used as the hydraulic cylinder, but a water hydraulic cylinder using water as the hydraulic fluid may also be used. In that case, a water hydraulic pump should be used instead of a hydraulic pump.

Note that the above embodiments are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or uses.

1,101 Hydraulic circuit diagram
2,102 Hydraulic press (press molding machine)
3. Hydraulic cylinder (hydraulic cylinder)
3a Piston
3b Piston rod
3c Head side hydraulic chamber
3d Rod side hydraulic chamber
4 Slide (pressure body)
5,105 Push-down pump
5a, 15a, 105a, 115a Input shaft
6,106 Push-down electric motor
7 Hydraulic oil tank (hydraulic fluid tank)
8 Relief valve
9. Electricity storage device
10 Controller
11 Suction valve
12 Position sensor
15,115 Pull-up pump
16, 116 Pulling side electric motor

Claims (2)

In a press molding machine that drives a hydraulic cylinder to raise and lower a pressing body to mold a workpiece,
a push-down side pump including a plurality of gear pumps for feeding hydraulic fluid to the hydraulic cylinder to push down the pressing body;
a push-down-side electric motor for independently driving each of the push-down-side pumps including the plurality of gear pumps;
a lifting side pump including a plurality of gear pumps for pumping hydraulic fluid into the hydraulic cylinder to lift the pressing body;
and a pull-up side electric motor for independently driving each of the pull-up side pumps including the plurality of gear pumps,
The push-down side pumps, which are made up of a plurality of gear pumps, are configured to be controllable by the corresponding push-down side electric motors so that the gear phases are shifted from each other by a predetermined angle,
A press forming machine characterized in that the pull-up side pumps consisting of a plurality of gear pumps are configured to be controllable by the corresponding pull-up side electric motors so that the gear phases are shifted from each other by a predetermined angle. a push-down side pump that pushes down a pressing body by feeding hydraulic fluid into a hydraulic cylinder, and at least one of a pull-up side pump that pulls up the pressing body by feeding hydraulic fluid into the hydraulic cylinder,
At least one of the push-down side pump and the pull-up side pump is composed of a plurality of gear pumps, and a control method for a press forming machine that drives a hydraulic cylinder to raise and lower a pressing body to form a workpiece, comprising:
A push-down side pump, which is made up of a plurality of gear pumps, is controlled by a corresponding push-down side electric motor so that the gear phases are shifted from each other by a predetermined angle,
A control method for a press forming machine, comprising the step of controlling a pull-up side pump consisting of a plurality of gear pumps so that the gear phases are shifted from each other by a predetermined angle by the corresponding pull-up side electric motors.

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