JP3298112B2 - Pressing force holding device for mechanical press - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressing force holding device for holding a pressing force by holding a slide of a mechanical press at a bottom dead center position, and is suitable for use in press forming of a material having a large springback. is there.

[0002]

2. Description of the Related Art A mechanical press using mechanical force as a driving source is used for drawing, forging, etc. of various small and medium-sized parts manufactured in large quantities, and a hydraulic press using hydraulic pressure or hydraulic pressure. There is a feature that the bottom dead center position of the slide can be fixed as compared with the press. Various materials are used for forming by such a mechanical press, and recently, press working of aluminum or high-tensile steel has also been performed. Such aluminum and high-tensile steel have a large springback as compared with a normal steel plate, and therefore have a problem that the product shape after forming has a large variation and the quality is deteriorated. As a method of eliminating the uneven forming when press-working such a material having a large springback, it is effective to hold the pressing force near the bottom dead center of the slide. However, in a normal mechanical press, a crankshaft and a connecting rod are required. Depending on the specifications, the stroke curve of the slide is determined to be a sine curve or the like, and the slide cannot be held in a constant stroke state, or the operation cannot be performed with the applied pressure maintained near the bottom dead center.

Therefore, a press device capable of changing the shape of a stroke curve by improving the structure of a mechanical press has been developed.
Japanese Patent Publication No. 1396 discloses a crankshaft driving device for a crank press. As shown in FIG. 4, the crankshaft driving device of this crank press has a lever 3 provided with a guide groove 2 at an end of a crankshaft 1 and a sliding member 4 reciprocating in the guide groove 2 of the lever 3. Is mounted on a side surface of a drive gear 5 for driving a crankshaft via a pin 6.
And a pinion 8 driven by a motor 7 is rotated. Therefore, by changing the ratio (e / R) of the distance R from the center of the drive gear 5 to the pin 6 and the distance e from the center of the drive gear 5 to the center of the crankshaft 1, as shown in FIG. In addition, the stroke curve of the crank press can be changed as shown by a dashed line d and a solid line e, thereby reducing the speed near the bottom dead center of the slide connected to the crankshaft 1 via the connecting rod, although not shown. And increase the climbing speed.

[0004]

However, in such a crankshaft driving device for a crank press, if the mounting position of the sliding body 4 to the drive gear 5 does not change continuously during the operation of the press, the slide can be lowered. It is not possible to hold the material near the dead center, and there is a problem in that, due to its mechanism, it is not possible to eliminate the uneven molding by holding the material having a large springback under pressure. The present invention has been made in view of the problems of the related art, and makes use of the features of the mechanical press, and for a material having a large springback,
It is an object of the present invention to provide a pressing force holding device of a mechanical press which can apply a pressing force and can eliminate molding unevenness.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, a pressing force holding device for a mechanical press according to the present invention includes a fluid pressure cylinder interposed between a connecting rod and a slide of the mechanical press. , Slide position adjustment
Mechanisms and fluids controlling fluid pressure in hydraulic cylinders
A pressure control mechanism is provided.
Required to maintain the pressing force after molding against the work curve
Initially set the movement amount S1 of the bottom dead center of the
When the slide is at the top dead center position by the body pressure control mechanism
The piston relative to the cylinder part of the hydraulic cylinder
Change the relative position to allow the stroke of the piston
Required to prevent overload of the hydraulic cylinder.
From the start of descent of the slide from the trooke and top dead center
To make the stroke curve assumed until it touches the charge
The stroke is controlled by adding the correction stroke and
From the start of the descent of the ride until the upper mold hits the material
According to the assumed stroke curve during the descent of the slide
The syringe of the hydraulic cylinder relative to the piston
The piston part can be moved by moving the piston part relatively.
The stroke required to prevent overloading the range and the bottom death
One control is performed so as to be the movement amount S1 for moving the point.
On the other hand, it is necessary to prevent overload after the upper mold hits the material
Under the slide by a stroke other than
Control to maintain the pressing force while maintaining the dead center position
It is characterized by the following.

[0006]

According to the press-holding device of this mechanical press, a position adjusting mechanism for the fluid pressure cylinder and the slide is interposed between the connecting rod and the slide .
To maintain the pressing force after molding against the stroke curve
Initially set the amount of movement S1 of the bottom dead center of the slide required for
It said fluid pressure of working fluid supplying and discharging the hydraulic cylinder
When the slide is at the top dead center position,
Piston relative to cylinder part of hydraulic cylinder
Change the position to increase the stroke range of the piston.
Straws required to prevent overload of the hydraulic cylinder
Contact with the material from the start of descent of the slide from
Correction stroke to obtain the assumed stroke curve
The stroke is controlled by adding a trooke and the slide
From the start of the lowering of the mold until the upper mold hits the material.
During the descent, the pitch is adjusted to the expected stroke curve.
The cylinder part of the hydraulic cylinder relative to the ston
Relative to each other to increase the strokeable range of the piston.
Movement of stroke and bottom dead center required to prevent overload
While controlling the amount of movement for movement to be S1.
After the upper mold hits the material,
Stroke at the bottom dead center of the slide
Is controlled so as to maintain the pressing force while maintaining the pressure, and despite the fact that the connecting rod moves by moving the stroke curve determined by the mechanical press by the position adjusting mechanism and controlling the relative movement between the connecting rod and the slide. Instead, the slide is maintained at a fixed position to maintain the pressing force near the bottom dead center. Therefore, it is possible to obtain a high-quality press-processed product with no molding unevenness even for a material having a large springback, and it is possible to expand a press-working range of a mechanical press.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram according to an embodiment of a pressing force holding device of a mechanical press according to the present invention. The pressure holding device 10 of the mechanical press is applied to a crank press 11 which is one of the mechanical presses. In the crank press 11, the other end of a connecting rod 12 having one end connected to a crankshaft (not shown). A ram 13 reciprocally driven in the up-down direction is connected to the (lower end). At the tip of the ram 13 of the mechanical press, a hydraulic cylinder 14 that constitutes a hydraulic cylinder is disposed.
Are formed in a slide 16, and a piston 17 is mounted in the cylinder portion 15.

A position adjusting mechanism 18 for adjusting the initial position of the slide 16 is interposed between the piston 17 of the hydraulic cylinder 14 and the ram 13 so as to be connected to each other. A position adjusting rod 19 having an external thread is connected. As a driving portion of the position adjusting mechanism 18, a worm wheel 20 having a female screw formed in the middle of the male screw of the position adjusting rod 19 is screw-coupled, and a retainer 20a is provided so as to surround the outside of the worm wheel 20. Hydraulic cylinder 14 with bolts
The worm wheel 20 is rotatable inside the retainer 20a.

A worm 21 meshing with the worm wheel 20 is driven by a motor mounted on a frame (not shown). Therefore, when the worm 21 is driven by a motor (not shown) in a state where the hydraulic oil is supplied to the cylinder portion 15 of the hydraulic cylinder 14 and the oil is sealed, the worm wheel 20 moves up and down along the position adjusting rod 19 screwed. The movement of the worm wheel 20 causes the piston 17 and the cylinder portion 15 of the hydraulic cylinder 14 connected via the retainer 20a to move as one, and changes the initial position of the slide 16 on which the cylinder portion 15 is formed. Can be.

An upper die 22 is mounted on the slide 16, and a lower die 24 is mounted on a bolster 23 to face the upper die 22, and a material 25 supplied between the upper and lower dies 22, 24 is formed into a predetermined shape. Press working. Further, a hydraulic control mechanism 26 as a hydraulic control mechanism for controlling a working fluid to be supplied and discharged is connected to the hydraulic cylinder 14 constituting the hydraulic cylinder via a hydraulic pipe 27 to the cylinder portion 15. In this hydraulic control mechanism 26, a relief valve 28 functioning as a safety valve for preventing an overload state in which the pressure in the hydraulic cylinder 14 abnormally increases is provided by branching to a portion of the hydraulic pipe 27 closest to the hydraulic cylinder 14. The overload is prevented by preventing the oil pressure from becoming higher than a predetermined oil pressure.

The hydraulic control mechanism 26 is provided with an oil tank 29 which is pressurized with air in order to control and supply the pressure and amount of hydraulic oil to the hydraulic cylinder 14, an electromagnetic control valve 30 and a throttle valve 31. And a hydraulic valve 27 via a check valve 32. In addition, an electromagnetic control valve 33 having a function of a throttle valve branched to a hydraulic pipe 27 for controlling discharge of hydraulic oil from the hydraulic cylinder 14 is interposed and connected to the oil tank 29. Therefore, the hydraulic cylinder 1
By controlling the supply and discharge of the working oil to the hydraulic cylinder 4 by the hydraulic control mechanism 26, the slide 16 can be relatively moved with respect to the movement of the ram 13 that moves up and down via the connecting rod 12.

The control of the pressing force holding by the pressing force holding device 10 of the mechanical press configured as described above will be described with reference to FIG. 2 and FIG. FIG. 2 is a stroke curve of the pressurizing force holding device 10 of the mechanical press, and FIG. 3 is an explanatory diagram of a state of the hydraulic cylinder. In order to hold the pressing force at the end of molding by the pressing force holding device 10 of the mechanical press, it is necessary to create a state in which the slide 16 is held at the bottom dead center. Therefore, the solid line A in FIG.
The movement of the slide 16 follows a stroke curve as shown by. That is, the position of the bottom dead center is set to s1 (for example, s1) with respect to the sine curve of the broken line B which is a normal stroke curve.
= 40 mm) is used as the stroke curve A which is initially set to be lowered by the position adjusting mechanism 18 and falls between the stroke curves indicated by the two-dot chain line C in the figure.

First, the worm 2 of the position adjusting mechanism 18
1 is driven by a motor (not shown) to rotate the worm wheel 20 and screw the position adjustment rod 19
Moves up and down along the piston 17 and the cylinder portion component 15 of the hydraulic cylinder 14 through the retainer 20a in a state in which an integral initial position of the slide 16 only s1 the bottom dead center position for normal stroke curve B For example, the initial state is set to a state lowered by s1 = 40 mm. Furthermore, this slide 1
In the state of FIG. 3A in which the position 6 is at the top dead center position H, the hydraulic control mechanism 26 controls the cylinder portion 1 of the hydraulic cylinder 14.
Hydraulic oil is supplied into the cylinder 5, and the relative position of the piston 17 with respect to the cylinder portion 15 of the hydraulic cylinder 14 is changed to make the stroke possible range of the piston 17 s2. The stroke allowable range s2 of the piston 17 is equal to the stroke s3 required to prevent the hydraulic cylinder 14 from being overloaded and the slide 1
This is a value obtained by adding a correction stroke s4 for making the stroke curve from the start of descent of 6 to the contact of the material 25 with the solid line A, for example, s2 = s3 + s4 = 25 mm + 22 mm = 47.
mm. That is, in the state before the start of the operation, the slide 16 has a lower dead center with respect to the normal stroke curve B.
The descent is started along the stroke curve lowered by 22 mm, so that the hydraulic cylinder 14 has a 25 mm allowance to prevent overload.

Thereafter, for example, when the material 25 is supplied between the upper and lower molds 22 and 24 and the crankshaft of the crank press 11 is rotated to perform press working, the connecting rod 12
As a result, the ram 13 is lowered, and the position adjusting rod 19, the worm wheel 20 and the retainer 20 a, the piston 17 of the hydraulic cylinder 14, the hydraulic oil of the cylinder portion 15, and the upper mold 22 attached to the slide 16 via the cylinder portion 15 are moved. Descended.

[0015] Then, in FIG. 3 descending the slide 16 to the state of (b) the upper die 22 strikes the material 25, and supplies hydraulic fluid to the cylinder portion 15 of the hydraulic cylinder 14 by the hydraulic control mechanism 26, 2 points The cylinder portion 15 is relatively moved with respect to the piston 17 so as to follow the stroke curve indicated by the dashed line C, thereby lowering the ram 13 at a speed higher than the lowering speed. As a result, the stroke possible range of the piston 17 is changed from s2 to s5, and the value s5 is a stroke curve obtained by lowering the stroke s3 necessary for preventing the overload of the hydraulic cylinder 14 and the bottom dead center position s1 of the slide 16 by 40 mm. A value obtained by adding the correction stroke s1 to be placed on C, for example, s5 = s3 + s1 = 25 mm + 40 mm = 65 mm. Therefore, after the upper die 22 of the material 25 hits, the slide 16 descends along the stroke curve C, and the slide 16 is moved to the bottom dead center (stroke becomes zero) before the rotation angle of the crankshaft becomes 180 degrees. If the slide 16 is lowered as it is, an overload condition occurs, which may cause damage to each part of the mechanical press 11 and damage to the material 25.

Therefore, the electromagnetic control valve 33 on the hydraulic oil discharge side of the hydraulic control mechanism 26 is switched to discharge the hydraulic oil from the cylinder portion 15 of the hydraulic cylinder 14 to the oil tank 29 while adjusting the discharge speed by the function of a throttle valve. . Then, although the ram 13 is lowered by the rotation of the crankshaft,
The remaining s1 = 40 mm excluding the s3 = 25 mm necessary for preventing overload in the stroke possible range s5 formed between the cylinder portion 15 of the hydraulic cylinder 14 and the piston 17.
, The slide 16 is held at the bottom dead center position, and at the same time, the state where the pressing force is applied is maintained. In the state of FIG. 3 that the crankshaft is 180 degrees (c), and in a state where each part of the state of the crank press 11 matches the bottom dead center position of the normal stroke curve B, the piston of the hydraulic cylinder 14 17 and cylinder part 1
Between 5 and 5, the stroke s3 necessary to prevent overload
= 25mm exists.

After press forming is performed while holding the pressing force in this manner, in the upward stroke of the slide 16, the hydraulic oil is supplied from the hydraulic control mechanism 26 to the hydraulic cylinder 14 until the crankshaft reaches 360 degrees. The same stroke possible range s2 as in the state before the start of operation is given between the piston 17 and the cylinder portion 15, for example, s2 = s3
+ S4 = 25 mm + 22 mm = 47 mm.

After that, the same control is repeated, and the press working is continued.

By controlling the hydraulic oil supplied to and discharged from the hydraulic cylinder 14 provided between the slide 16 and the ram 13 by the hydraulic control mechanism 26 during the drawing stroke of the mechanical press 11 as described above, the final pressurization is performed. Holding (body sticking) becomes possible, sufficient molding holding force can be given to the product, and molding unevenness due to springback of the material 25 can be eliminated. Therefore, it is particularly effective for pressing a material having a large springback, such as aluminum or high-tensile steel, which is required to have high precision by press working.

In the above embodiment, the relative movement of the slide is controlled by the hydraulic cylinder and the hydraulic control mechanism. However, the slide is controlled by a hydraulic cylinder using another working fluid or a hydraulic pressure control mechanism. May be. Further, the rotation angle range of the crankshaft and the magnitude of the pressing force for holding the pressing force may be appropriately determined according to the pressing conditions such as the material. Further, it goes without saying that each component may be changed without departing from the scope of the present invention.

[0021]

As described above in detail with one embodiment, according to the pressurizing device for a mechanical press of the present invention, a fluid pressure cylinder and a slide position adjusting mechanism are provided between a connecting rod and a slide. With this position adjustment mechanism ,
Holds the pressing force after molding against the normal stroke curve
Initially set the amount of movement S1 of the bottom dead center of the slide required for
Constant, and said working fluid supplying and discharging the fluid pressure cylinder
When the slide is at the top dead center position by the fluid pressure control mechanism,
Piston for the cylinder part of said hydraulic cylinder
Range of the piston by changing the relative position of
Required to prevent overload of the hydraulic cylinder.
From the start of descent of the slide from the trooke and top dead center
To make the stroke curve assumed until it touches the charge
The stroke is controlled by adding the correction stroke and
From the start of the descent of the ride until the upper mold hits the material
According to the assumed stroke curve during the descent of the slide
The syringe of the hydraulic cylinder relative to the piston
The piston part can be moved by moving the piston part relatively.
The stroke required to prevent overloading the range and the bottom death
One control is performed so as to be the movement amount S1 for moving the point.
On the other hand, it is necessary to prevent overload after the upper mold hits the material
Under the slide by a stroke other than
Since the pressing force is controlled to be maintained while the dead center position is maintained , the pressing force can be maintained in the vicinity of the bottom dead center by maintaining the slide at a fixed position despite the movement of the connecting rod.
Therefore, it is possible to obtain a high-quality press-processed product with no molding unevenness even for a material having a large springback, and it is possible to expand a press-working range of a mechanical press.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram according to an embodiment of a pressing force holding device of a mechanical press according to the present invention.

FIG. 2 is a stroke curve of the pressing force holding device of the mechanical press according to the present invention.

FIG. 3 is an explanatory diagram of a state of a hydraulic cylinder of the pressurizing force holding device of the mechanical press according to the present invention.

FIG. 4 is a schematic perspective view of a conventional crank press.

FIG. 5 is a stroke curve of a conventional crank press.

[Description of Signs] 10 Pressing force holding device for mechanical press 11 Crank press 12 Connecting rod 14 Hydraulic cylinder 15 Cylinder part 16 Slide 17 Piston 18 Position adjustment mechanism 20 Warm wheel 20a Retainer 26 Hydraulic control mechanism 27 Hydraulic piping 28 Relief valve 30 Electromagnetic control Valve 33 Electromagnetic control valve s1 to s5 Stroke range

Claims (1)

(57) [Claims] A fluid pressure cylinder is interposed between a connecting rod of a mechanical press and a slide, and a slide position is provided.
Control the fluid pressure in the pressure adjustment mechanism and the fluid pressure cylinder.
A fluid pressure control mechanism is provided, and the position adjustment
Bottom dead center of the slide required to maintain the applied pressure after shaping
Initially, the moving amount S1 of the slide is set at the top dead center position by the fluid pressure control mechanism.
When the hydraulic cylinder is
Ton stroke can be changed by changing the relative position of the ton
Range is needed to prevent overloading of the hydraulic cylinder
Of the slide from lower stroke and top dead center
To the assumed stroke curve until it comes into contact with the material
Control stroke and the correction stroke
From the start of the slide lowering until the upper die hits the material
During the descent of the slide,
The piston of the fluid pressure cylinder with respect to the piston.
Relative movement of the Linda part to move the piston stroke
The stroke required to prevent overload and the
Control is performed so as to be the movement amount S1 for moving the bottom dead center.
On the other hand, after the upper mold hits the material, it is necessary to prevent overload.
A stroke other than the necessary stroke
Control to maintain the pressing force while maintaining the bottom dead center position
A pressure holding device for a mechanical press.