JP7543099B2 - Hydroforming System - Google Patents

Description

The present invention relates to a hydroforming system.

There is a known hydroforming system in which a forming liquid is filled inside a tube and the tube is plastically deformed by the liquid pressure. For example, Patent Document 1 discloses a bulge processing device in which a material is inserted into a cavity formed by upper and lower dies, and high-pressure liquid is supplied from an internal pressure supply mechanism into the material to process it to the shape of the cavity. Patent Document 2 discloses a similar hydroforming device in which the clamping force that holds the upper and lower dies in close contact can be increased or decreased.

JP 2000-84624 A JP 2002-172433 A

In order to be able to process shapes that are difficult to process with conventional machines, it is possible to consider increasing the hydraulic pressure to ultra-high pressure. However, when the hydraulic pressure is increased to ultra-high pressure, the flow path of the forming liquid becomes complicated, and the device tends to become larger. Therefore, the object of the present invention is to provide a hydroforming system that can configure a compact flow path for the forming liquid.

The hydroforming system according to one aspect of the present invention comprises a press machine capable of servo-controlling the slide motion, a die attached to the press machine, a pressure booster that plastically deforms the tubular material by boosting the pressure of the forming liquid filled inside the tubular material fixed to the die, and a valve that can open and close a flow path for discharging the forming liquid from the tubular material, the valve being disposed within the die.

According to this embodiment, the flow path can be shortened by placing the valve inside the mold. Since the flow path can be made compact, for example, an air hydro booster that has a small flow rate but high boosting capacity can be selected. For example, parts that are subject to high pressure can be concentrated inside the press machine and these parts can be surrounded by a cover to create an explosion-proof device.

In the above embodiment, the slide motion may be a multi-stage motion that includes multiple stops during one step.

According to this embodiment, the slide is stopped multiple times during one process of processing the pipe material into a pipe material molded product, so that, for example, the inside of the pipe material can be filled with molding liquid while the slide is stopped, thereby ensuring that air is removed.

In the above embodiment, the pressure booster is an air hydrobooster that is driven by air pressure to boost the molding liquid, and may be disposed within the press machine.

According to this embodiment, the hydroforming system can be made more compact by adopting an air hydro booster that has a small flow rate but high boosting capacity. In addition, using air as the driving source for the booster makes it easier to configure the device with an explosion-proof structure because, unlike electric types, no sparks are produced. It becomes possible to select flammable oil as well as water as the forming liquid.

In the above embodiment, there may be multiple air-hydro boosters, including a main booster that can boost the hydraulic pressure to a predetermined level that plastically deforms the pipe material, and an auxiliary booster that can boost the hydraulic pressure faster than the main booster in a pressure range lower than the predetermined hydraulic pressure.

According to this embodiment, when the pressure is low, a booster with a low corresponding pressure but a high flow rate is used, and once the pressure rises, a booster with a low flow rate but capable of boosting to high pressure is used, thereby shortening the boost time.

In the above embodiment, the valve may be connected to a transmission mechanism capable of converting the movement of the press machine into the movement of the valve closing the flow path.

According to this embodiment, there is no need to add a drive source such as a motor to open and close the valve inside the mold. Since the number of parts required to change the valve position is small, the valve can be placed inside the mold without making the mold excessively large.

In the above aspect, the press machine includes a bolster, a slide whose distance from the bolster can be changed by a servo-controlled motion, and at least one of a first buffer material and a second buffer material, the first buffer material is disposed between the bolster and the die and is compressible from a first thickness to a second thickness thinner than the first thickness in response to movement of the slide, the second buffer material is disposed between the slide and the die and is compressible from a third thickness to a fourth thickness thinner than the third thickness, and the transmission mechanism may convert at least one of the motion of closing the die until the first buffer material is compressed to the second thickness and the motion of closing the die until the second buffer material is compressed to the fourth thickness into a motion of the valve closing the flow path.

According to this embodiment, the tube can be temporarily fixed in a position where the mold is not completely closed by supporting it with a cushioning material such as a urethane spring or a gas cylinder. For example, when the tube is supported by the cushioning material, the valve is still open, so air can be expelled from inside the tube. When the cushioning material is further compressed to a position where the valve is closed, the inside of the tube can be closed and the liquid pressure of the molding liquid can be increased. The timing of opening and closing the valve can be adjusted by the position of the slide of the press machine, which is capable of multi-stage motion.

In the above embodiment, the tubular material is a rotor shaft that constitutes a motor, and may be fixed to a mold while being inserted into a rotor core, and fastened to the rotor core by plastic deformation.

This aspect allows the motor rotor to be manufactured efficiently.

The present invention provides a hydroforming system that allows for a compact flow path for the forming liquid.

FIG. 1 is a diagram showing a schematic configuration of a hydroforming system according to one embodiment of the present invention. FIG. 2 is a cross-sectional view showing an example of the press machine and the die shown in FIG. FIG. 3 is an enlarged cross-sectional view of an example of the valve shown in FIG. FIG. 4 is a diagram for explaining the position of the slide in the molding cycle and the opening and closing of the valve according to the position. FIG. 5 is a cross-sectional view showing the slide in the second position shown in FIG. FIG. 6 is a cross-sectional view showing the slide in the third position shown in FIG. FIG. 7 is a flow chart illustrating an example of a method for manufacturing a rotor using a hydroforming system.

A preferred embodiment of the present invention will be described with reference to the attached drawings. In each drawing, parts with the same reference numerals have the same or similar configuration. One of the features of the hydroforming system 1 according to one embodiment of the present invention is that a valve 9 capable of opening and closing a flow path 200 for discharging the forming liquid from the pipe material P is disposed in the die 3. The present invention will be described in detail below with reference to the drawings.

Figure 1 is a diagram showing a schematic configuration of a hydroforming system 1 according to one embodiment of the present invention. The hydroforming system 1 is a manufacturing device that fills the inside of a tube material P with a forming liquid and plastically deforms the tube material P using the hydraulic pressure of the forming liquid to produce a formed product of the tube material P.

As shown in FIG. 1, the hydroforming system 1 includes a press machine 2 that can accelerate and decelerate the slide motion during one process by servo control, a die 3 attached to the press machine 2, a pressure booster 4 that can fill the inside of a tube material P fixed to the die 3 with molding liquid to boost the liquid pressure of the molding liquid, and a valve 9 that can open and close a flow path 100 that discharges the molding liquid from the tube material P.

Free motion, which accelerates and decelerates the slide motion during one process, is, for example, a multi-stage motion in which the slide 26 stops multiple times during one process. One example of a press machine 2 capable of such slide motion is a mechanical servo press, which transmits the power of a servo motor to the slide 26 via a rotary mechanism such as a crank or a linear mechanism such as a ball screw. Note that the press machine 2 is not limited to mechanical servo presses, and may be a hydraulic servo press driven by hydraulic pressure controlled by a servo system, or another type of press machine, as long as free motion such as multi-stage motion is possible.

The press machine 2 includes a bolster 21, a slide 26 that can change the distance from the bolster 21 with free motion such as multi-stage motion, and cushioning materials 23, 24 such as urethane springs or gas cylinders. The lower cushioning material 23 is fixed to the bolster 21. The upper cushioning material 24 is fixed to the slide 26. Either one of the cushioning materials 23, 24 may be omitted, or common plates 22, 25, which will be described later, may be further included. In the illustrated example, the slide 26 is configured to be able to reciprocate up and down. The slide 26 may also be configured to be able to reciprocate left and right.

The mold 3 is composed of a fixed plate and a movable plate that faces the fixed plate. In the illustrated example, the mold 3 is composed of a pair of upper and lower dies, a lower die 31 and an upper die 32. The lower die 31 is fixed to the bolster 21 via the buffer material 23. The upper die 32 is fixed to the slide 26 via the buffer material 24. In the following description, the lower buffer material 23 may be referred to as the first buffer material 23, and the upper buffer material 24 may be referred to as the second buffer material 24.

The pipe material P can be fixed between the lower die 31 and the upper die 32. Inside the die 3, a flow path 100 for filling the fixed pipe material P with molding liquid and a flow path 200 for discharging the molding liquid from the pipe material P are formed. The molding liquid may be water or oil. The flow paths 100 and 200 are connected to a tank 5 capable of storing the molding liquid via pipes 110 and 210. The tank 5 may be disposed outside the press machine 2.

The booster 4 is connected between the flow path 100 and the tank 5. The booster 4 is, for example, an air-hydro booster that is driven by air pressure and converts the air pressure into amplified hydraulic pressure, and is disposed within the press machine 2. In the illustrated example, the booster 4 includes a first booster 41 fixed to the lower die 31 and a second booster 42 fixed to the upper die 32.

Either the first or second booster 41, 42 may be omitted. The first and second booster 41, 42 may be the same type of booster or different types of boosters. When different types of boosters are combined, either the first or second booster 41, 42 may be configured as a main booster and the other may be configured as an auxiliary booster.

The boost time can be shortened by switching between a main booster (e.g., first booster 41) that boosts the pressure to a predetermined hydraulic pressure that causes plastic deformation of the pipe material P, and an auxiliary booster (e.g., second booster 42) that boosts the pressure faster than the main booster in a pressure range lower than the predetermined hydraulic pressure.

The valve (relief valve) 9 is provided between the flow path 200 and the tank 5. The valve 9 is disposed in the die 3, and is connected to a transmission mechanism 8 that can convert the multi-stage motion of the press machine 2 into a motion in which the valve 9 closes the flow path 100. In the illustrated example, the valve 9 and the transmission mechanism 8 attached to the valve are disposed in each of the lower die 31 and the upper die 32.

In the following description, the valve 9 arranged in the lower mold 31 and the transmission mechanism 8 attached to the valve are referred to as the first valve 91 and the first transmission mechanism 81, respectively, and the valve 9 arranged in the upper mold 32 and the transmission mechanism 8 attached to the valve are referred to as the second valve 92 and the second transmission mechanism 82, respectively.

Figure 2 is a cross-sectional view showing an example of the press machine 2 and die 3 shown in Figure 1. In the illustrated example, the press machine 2 further includes upper and lower common plates 22, 25. The lower common plate 22 is configured to be detachable from the bolster 21. The lower cushioning material 23 and lower die 31 described above are fixed to the bolster 21 via the common plate 22. The upper common plate 25 is configured to be detachable from the slide 26. The upper cushioning material 24 and upper die 32 described above are fixed to the slide 26 via the common plate 25.

As described above, the pressure booster 4 is disposed within the press machine 2. In the illustrated example, the first and second pressure boosters 41, 42 are disposed between the upper and lower common plates 22, 25. The press machine 2 may be provided with a cover 27 that protects the operator from flying fragments in the unlikely event that a part or pipe material P to which high pressure is applied breaks. In the illustrated example, the cover 27 is disposed in a position opposite the first and second valves 91, 92.

Figure 3 is an enlarged cross-sectional view of an example of the valve 9 and the transmission mechanism 8 attached to the valve shown in Figure 2. The first and second valves 91, 92 have substantially the same shape and function. Therefore, the second valve 92 will be described in detail as a representative, and a duplicated description of the first valve 91 will be omitted. Similarly, the first and second transmission mechanisms 81, 82 have substantially the same shape and function. Therefore, the second transmission mechanism 82 will be described in detail as a representative, and a duplicated description of the first transmission mechanism 81 will be omitted.

In the illustrated example, the valve 9 (second valve 92) is configured as a needle valve and includes an elongated conical valve body 93 and a partition block 94 on which a valve seat surface 94 against which the valve body 93 abuts is formed. The configuration of the valve 9 is not limited to the illustrated example, and any known configuration can be appropriately selected. When the tip of the valve body 93 abuts against the valve seat surface, the flow path 200 is closed. When the tip of the valve body 93 moves away from the valve seat surface, the flow path 200 is opened.

If the valve 9 is a needle valve, the flow rate of the forming liquid can be smoothly adjusted according to the gap between the valve body 93 and the valve seat surface. By gradually opening the needle valve using the multi-stage motion of the press machine 2 described below, the water hammer phenomenon, cavitation, and shock wave generation in the die 3 can be suppressed, and damage to the hydroforming system 1 and the pipe material P can be minimized.

In the illustrated example, the transmission mechanism 8 (second transmission mechanism 82) is configured as a wedge mechanism. The transmission mechanism 8 includes a drive member 83, at least a portion of which is formed in a wedge shape and has a wedge surface 83A inclined with respect to the sliding motion, and a driven member 84, which has a wedge surface 84B that slides against the wedge surface 83A of the drive member 83 and moves when pressed against the wedge surface 84B. The drive member 83 may be configured to be detachable from another member, or may be configured as an integral structure with another member. The driven member 84 is fixed to the valve body 93 of the valve 9.

The configuration of the transmission mechanism 8 is not limited to the example shown in the figure, and may be a cam mechanism, a lever mechanism, or a link mechanism. Any known configuration may be selected as appropriate as long as it can convert the movement of the press machine 2 to clamp the die 3 into the movement to close the valve 9 inside the die 3.

The driving member 83 moves in a direction pressing the driven member 84 in response to the clamping of the mold 3 by the press machine 2. For example, in the case of a transmission mechanism 8 arranged on the slide 26 side, the driving member 83 descends from the slide 26 toward the bolster 21. In the case of a transmission mechanism 8 arranged on the bolster 21 side, the driving member 83 ascends from the bolster 21 toward the slide 26. In other words, the driving member 8 arranged on either the lower mold 31 or the upper mold 32 moves from one of the lower mold 31 and the upper mold 32 to the other.

The driving member 83 is formed in a wedge shape whose width changes in the left-right direction in which the valve 9 closes the flow path 200. Therefore, when the driving member 83 moves in the mold clamping direction (e.g., downward), the driven member 84 is pressed in the direction in which the valve 9 closes the flow path 200 (e.g., leftward).

A biasing member such as a spring may be provided to bias the valve body 93 in a direction that opens the valve 9. According to this embodiment, when the driving member 83 presses the driven member 84, the driven member 84 moves against the biasing force, and the valve 9 closes. When the driving member 83 is not pressing the driven member 84, the biasing force moves the driven member 84, and the valve 9 opens.

Figure 4 is a diagram explaining the position of the slide 26 and the opening and closing of the valve 9 according to that position in a molding cycle using the hydroforming system 1. As shown in Figure 4, the press machine 2 according to this embodiment is capable of multi-stage motion, and can be stopped midway at the second position B or at another position, and can be accelerated, decelerated, and stopped freely. In the example shown, when clamping from the first position A to the second position B, the slide 26 is decelerated just before the second position B, avoiding a sudden stop and suppressing shock.

By stopping the slide 26 at the second position B, one of the cushioning materials 23, 24 is compressed, one of the first and second valves 91, 92 is closed, and the other is kept open, as described below, and molding liquid is filled inside the tube material P to remove air. The mold is then clamped from the second position B to the third position C, and the slide 26 is stopped again at the third position C, which is the bottom dead center, and pressure is maintained to plastically deform the tube material P.

The slide 26 is slowly raised from the third position C to the fourth position B, gradually opening the valve 9 to suppress the occurrence of water hammer, cavitation, and shock waves within the mold 3. The process is again temporarily stopped at the second position B, and the molding liquid inside the tubular product is drained. The mold is opened again to the first position A, and the tubular product is removed and prepared for the next process.

The cushioning materials 23, 24 shown in Figures 1 and 2 are configured to be compressible in response to the movement of the slide 26. The lower cushioning material 23 arranged between the bolster 21 and the lower die 31 can be compressed from a first thickness t1 to a second thickness t2 that is thinner than the first thickness t1 in response to the movement of the slide 26. The cushioning material 24 arranged between the slide 26 and the upper die 32 can be compressed from a third thickness t3 to a fourth thickness t4 that is thinner than the third thickness t3.

Figures 5 and 6 show the position of the slide 26 and the thickness of the cushioning materials 23, 24 when the lower cushioning material 23 has a smaller elastic force than the upper cushioning material 24. Figure 2, which was previously explained, is a cross-sectional view showing the slide 26 in the first position A shown in Figure 4. Figure 5 is a cross-sectional view showing the slide 26 in the second position B shown in Figure 4, and Figure 6 is a cross-sectional view showing the slide 26 in the third position C shown in Figure 4.

When the slide 26 is in the first position A, as shown in FIG. 2, the thickness of the lower cushioning material 23 is t1, and the thickness of the upper cushioning material 24 is t3. When the slide 26 moves, the lower cushioning material 23 is compressed before the upper cushioning material 24, which has a greater elastic force. When the slide 26 is in the second position B, as shown in FIG. 5, the lower cushioning material 23 is compressed to a second thickness t2.

When the slide 26 moves from position B to position C, in addition to the lower cushioning material 23, the upper cushioning material 24 is also compressed. When the slide 26 is located at the third position C, as shown in FIG. 6, the upper cushioning material 24 is compressed to a fourth thickness t4.

The second transmission mechanism 82 shown in FIG. 2 converts the movement of closing the mold 3 until the second cushioning material 24 is compressed from the third thickness t3 to the fourth thickness t4 into the movement of the second valve 92 closing the flow path 200. Similarly, the first transmission mechanism 81 converts the movement of closing the mold 3 until the first cushioning material 23 is compressed from the first thickness t1 to the second thickness t2 into the movement of the first valve 91 closing the flow path 200.

Figure 7 is a flow chart explaining an example of a method for manufacturing a rotor using the hydroforming system 1. As shown in Figure 7, one of the features of the method for manufacturing a tube formed product using the hydroforming system 1 is that it includes all of steps S1, S3, S4, S6, and S7, and also includes at least one of steps S2 and S5. As will be described later, it is also possible to omit one of steps S2 and S5 by using a multi-axis servo press.

In step S1, the rotor shaft, which is an example of the tubular material P, is inserted into the through hole of the rotor core R and set in the mold 3. In step S2, the movement of closing the mold 3 until the first cushioning material 23 is compressed from the first thickness t1 to the second thickness t2 is converted into a movement of closing the first valve 91 by the first transmission mechanism 81. In step S3, the first valve 91 is closed.

In step S4, one of the first and second valves 91, 92 (e.g., the first valve 91) is closed and the other (e.g., the second valve 92) is open, and the molding liquid is filled into the tube material P and air is discharged from the tube material P.

In step S5, the movement of closing the mold 3 until the second cushioning material 24 is compressed from the third thickness t3 to the fourth thickness t4 is converted into a movement of closing the second valve 92 by the second transmission mechanism 82. In step S6, the second valve 92 is closed. Note that the order of the steps may be such that step S3 precedes step S6 or may follow step S6.

In step S7, with both the first and second valves 91, 92 closed, the molding liquid filled in the pipe material P is pressurized, and the liquid pressure of the molding liquid causes plastic deformation of the rotor shaft, which is an example of the pipe material P. The expanded rotor shaft (pipe material P) bites into the rotor core R, which is made of laminated electromagnetic steel sheets or the like, and the two are fastened together, thereby producing a motor rotor, which is an example of a pipe material molded product.

According to the hydroforming system 1 of this embodiment configured as described above, the flow path 200 can be shortened by disposing the valve 9 inside the die 3. For example, an air hydrobooster, which has a small flow rate but a high boosting capacity, can be used as the booster 4 to make the hydroforming system 1 more compact. In this case, unlike an electric booster, no sparks are produced, so it becomes possible to select flammable oil as well as water as the forming liquid.

In this embodiment, the valve 9 is connected to a transmission mechanism 8 that transmits the movement of the press machine 2, so there is no need to add a drive source such as a motor inside the die 3. Since the number of parts required to change the position of the valve 9 is small, the valve 9 can be placed inside the die 3 without making the die 3 excessively large.

The above-described embodiments are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The elements of the embodiments, as well as their arrangement, materials, conditions, shapes, and sizes, are not limited to those exemplified, and may be modified as appropriate. In addition, configurations shown in different embodiments may be partially substituted or combined.

For example, a multi-axis servo press having a master axis that moves the slide 26 and a slave axis that can be controlled independently of the master axis may be used as the press machine 2, and one of the first and second transmission mechanisms 81, 82 may be omitted, with the valve 9 corresponding to the omitted transmission mechanism 8 being opened and closed by the slave axis.

According to this embodiment, when the press machine 2 comes to an emergency stop due to some kind of trouble, even if the master axis that moves the slide 26 cannot be moved, the slave axis can be operated to open the valve 9. Even if the press machine 2 stops while the inside of the pipe material P and the flow paths 100 and 200 are in a state of ultra-high pressure, the valve 9 can be opened to safely reduce the pressure.

The pipe material P that can be molded in the present invention is not limited to a cylindrical shape. The shape of the pipe material P may be, for example, a polygonal square tube with a cross section perpendicular to the axial direction, a bow-shaped tube composed of arcs and chords, a truncated cone or pyramid whose cross-sectional area gradually changes in the axial direction, or another shape. The mold structure of the present invention is not limited to a rotor. For example, the structure of the mold 3 of the present invention may be applied to hydroforming when manufacturing an assembled camshaft in which a hollow shaft is inserted into an egg-shaped cam, or a multi-stage hollow shaft having an enlarged diameter portion and a reduced diameter portion. The booster device 4 constituting the present invention is not limited to an air hydrobooster. For example, it may be a pump with an electric motor, or another type of pump. Even in these cases, the flow path 200 of the molding liquid can be compactly configured in the hydroforming system 1, as in the embodiment described above.

The present invention provides a hydroforming system that allows for a compact flow path for the forming liquid.

1...hydroforming system, 2...pressure booster, 3...die, 4...pressure booster, 5...tank, 8...transmission mechanism, 9...valve, 21...bolster, 22, 25...common plate, 23, 24...cushion material, 26...slide, cover 27, 31...lower die, 32...upper die, 41...first pressure booster, 42...second pressure booster, 81...first transmission mechanism, 82...second transmission mechanism, 83...driving member, 84...driven member, 91...first valve, 92...second valve, 100, 200...flow path, 110, 210...piping, A, B, C...position of slide, P...pipe, R...rotor core, S1 to S7...manufacturing method of pipe material molded product, t1, t2, t3, t4...thickness of cushioning material.

Claims (7)

a press machine capable of servo-controlling a slide motion; a die attached to the press machine; a pressure booster device for boosting a molding liquid filled inside a tubular material fixed to the die, thereby plastically deforming the tubular material; and a valve for opening and closing a flow path for discharging the molding liquid from the tubular material,
the valve is disposed in the die and is connected to a transmission mechanism capable of converting a movement of the press machine into a movement of the valve for closing the flow path .
Hydroforming system. the press machine includes a bolster, a slide capable of changing a distance between the bolster and the slide by the slide motion, and at least one of a first buffer material and a second buffer material,
the first cushioning material is disposed between the bolster and the mold and is compressible from a first thickness to a second thickness smaller than the first thickness in response to movement of the slide; the second cushioning material is disposed between the slide and the mold and is compressible from a third thickness to a fourth thickness smaller than the third thickness;
the transmission mechanism converts at least one of a movement of closing the mold until the first cushioning material is compressed to the second thickness and a movement of closing the mold until the second cushioning material is compressed to the fourth thickness into a movement of the valve closing the flow path.
The hydroforming system of claim 1 . The slide motion is a multi-stage motion including multiple stops during one step.
3. The hydroforming system according to claim 1 or 2 . The pressure booster is disposed in the press machine, directly fixed to the die, and connected to the flow path formed in the die.
6. The hydroforming system according to any one of claims 1 to 5. The pressure booster is an air-hydro booster that is driven by air pressure to boost the pressure of the molding liquid, and is disposed within the press machine.
5. The hydroforming system according to claim 1 . The air-hydro booster includes a main booster capable of boosting the hydraulic pressure to a predetermined hydraulic pressure that causes plastic deformation of the pipe material, and an auxiliary booster capable of boosting the hydraulic pressure at a higher speed than the main booster in a pressure range lower than the predetermined hydraulic pressure.
The hydroforming system of claim 5 . The tubular material is a rotor shaft constituting a motor, and is fixed to the die in a state where it is inserted into a rotor core, and is fastened to the rotor core by the plastic deformation.
7. The hydroforming system according to any one of claims 1 to 6.

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