JPH0744400Y2 - Die cushion preliminary lowering device - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a preliminary lowering device for dicing provided in a press.

[Conventional technology]

The die cushion provided in the conventional press has a structure that elastically supports the lower die cushion pad provided in the vicinity of the lower die via a plurality of die die pin,
When the upper mold that descends with the slide comes into contact with the lower die pad and the press load acts on the lower die pad, the pressure in the cushion cylinder that supports the lower die pad is discharged. As a result, the lower mold cushion pad as well as the upper mold is lowered by the cushion stroke.

[Problems to be solved by the device]

However, when press molding is performed using the above-mentioned die cushion, when the upper die lowered along with the slide collides with the lower die cushion pad, the lower die cushion pad and the die die pin collide with each other, and a large pinch noise is generated, which causes noise. There was a problem that became. In order to improve such a problem, for example, in Japanese Patent Laid-Open No. 63-63536, a pin detector position is detected by a position detector such as a limit switch, and pressure oil is supplied to the upper oil chamber of the hydraulic cushion cylinder by a signal from the detector. A die cushion device has been proposed in which the noise at the time of collision is reduced by supplying and pushing down the cushion pad.

However, in the die cushion device of the above publication, the cushioning effect is obtained by relieving the hydraulic pressure in the lower oil chamber from the relief valve connected to the lower oil chamber of the cushion cylinder, so the upper mold is brought into contact with the material and the lower oil chamber is pressed. A so-called surge pressure is generated in which the hydraulic pressure in the chamber temporarily rises. As a result, indentations and scratches are generated on the molded product, resulting in a problem that product quality is significantly reduced.

This invention was made in order to improve the above-mentioned problems, and it is intended to provide a preliminary lowering device for dicing which reduces noise at impact by lowering the lower cushion pad preliminarily just before the upper mold collides with the lower cushion pad. It is what

[Means and Actions for Solving the Problems]

In order to achieve the above-mentioned object, the present invention provides a lower die cushion pad provided in the vicinity of a lower die installed on a bolster of a press body, which is elastically supported by a die cushion through a die cushion pin. The pin cradle that supports the cushion pin is raised to the upper limit position of the die cushion by the hydraulic pressure supplied to the chamber provided in the lower part of the locking device, and it is lowered together with the slide The upper die reaches the pin touch position where it collides with the lower die cushion pad Then, the servo valve connected to the chamber is energized with an electric signal necessary for the preset die cushion capacity to change from 0 to the set capacity, and the hydraulic pressure in the room is drained by supplying the electric signal for the set time of the die cushion set capacity. By doing so, the lower cushion pad is preliminarily lowered, and after the preliminary lowering, the hydraulic pressure in the chamber is reduced. The servo valve is controlled so that the pressure becomes almost equal to the die cushion capacity when the preliminary lowering is completed.When the upper die reaches the pin touch position, the lower die cushion pad is moved to the upper die. By preliminarily lowering at a speed corresponding to the lowering speed, it is possible to reduce the pin touch sound generated when the upper and lower mold cushion pads collide.

Also, the pressure in the chamber was gradually increased as the preliminary descent progressed so that the pressure became almost equal to the diction setting capacity when the preliminary descent was completed.Therefore, the transition from the preliminary descent to the diction operation is performed smoothly. You will be told.

〔Example〕

 An embodiment of the present invention will be described in detail with reference to the drawings.

In the figure, reference numeral 1 is a press body, and a lower die 2 is placed on a bolster 1a. Lower die cushion pads 2a provided in the peripheral portion of the lower die 2 are a plurality of die cushions provided in the bolster 1a. It is elastically supported by the diction 4 via the pin 3.

The dike 4 comprises a pin receiving base 5 for supporting the dicing pins 3 from below, and a cushion cylinder 6 for supporting the pin receiving base 5 via a die pad 4a. The locking device 8 whose cushion speed is controlled by NC control at the bottom of the
Is provided.

The locking device 8 has a piston rod 8c whose upper end is connected to the pin receiving base 5, and three chambers 8 ₁ divided by two pistons 8a and 8b provided on the piston rod 8c. , 8 ₂ and 8 ₃ are provided, and these chambers 8 ₁ to 8 ₃ are connected to the NC dicing unit 10 by a pipe line 9 and a logic valve from a charge pump 11 is provided in the chamber 8 ₃ .
By supplying hydraulic pressure via 12, the pin receiving base 5 is raised to the position indicated by the phantom line in FIG.

The pressure detector 13 to the conduit 9 leading to the chamber 8 ₃ for detecting the pressure in line 9, the servo valve to drain the pressure in the chamber 8 ₃
14 is connected, the servo valve 14 is controlled by the control device 15 as follows, and the preliminary lowering of the pin receiving base 5 is performed.

Next, referring to the flow chart shown in FIG. 2 and the diagram shown in FIG. 3, the operation will be described. Before starting the press, the hydraulic pressure is supplied from the charge pump 11 to the chamber 8 ₃ of the locking device 8 and the pin cradle is received. 5 is raised to the upper limit position shown by the phantom line in FIG.

When the press is started from this state, the rotation speed θ of the main motor is input to the control device 15 from the rotation detector 16 provided in the main motor (not shown). The controller 15 determines the slide speed V from the main motor rotation speed θ. Calculated from

Note that θm is the maximum main motor speed, and Vm is the slide speed at the maximum main motor speed.

Then, from the obtained slide speed, the upper limit stroke y of dicing, and the set capacity generation point yc, the set capacity generation time Δ
t Calculated from

The flow rate Q of the servo valve 14 is calculated as follows.

When the electric signal i of the servo valve 14 i, the inlet pressure p of the servo valve 14 p, and the pressure receiving area A of the chamber 8 ₃ , (K is a constant) In order to make the diction capability 0-F during the time Δt, the electric signal i is changed to You can In addition, F is a setting diction ability.

By controlling the servo valve 14 by the servo valve generation signal i calculated as described above, it is possible to reduce the pinch sound generated when the upper die 21 provided on the slide 20 collides with the lower die cushion pad 2a. Like

That is, when the slide 20 starts descending from the top dead center and the upper die 21 collides with the lower die cushion pad 2a, a current i calculated in advance is flown to the servo valve 14 for Δt time, and the servo valve 14 is driven.
Is opened according to the current i to drain the hydraulic pressure in the chamber 8 ₃ .

As a result, the pin cradle 5 is lowered in accordance with the lowering speed of the upper die 21 as shown by the curve B in FIG. 3, so that the impact at the time of the collision between the upper die 21 and the lower die cushion pad 2a is alleviated and the pin touch sound is generated. Noise will be reduced.

After that, when the Δt time elapses and the preliminary descent is completed, the room
Since the pressure in 8 ₃ has been increased to the dicing capability F ₀ , the pin pad 5 does not impact the dicing pad 4a, and it is possible to smoothly shift from the pre-descent to the dicing action. become.

The dicing operation is performed by the NC dicing unit 10 as shown by the curve B in FIG.

In the above embodiment, the pressure in the chamber 8 ₃ of the locking device 8 is controlled by the servo valve 14 to perform the preliminary lowering. However, as shown in FIG. The hydraulic cylinders 23 are provided, and the diction pin 3 is provided on the piston rods 23a of these hydraulic cylinders 23.
Similar effects can be obtained even if the pressure in the hydraulic cylinder 23 is controlled by the servo valve 14 as in the above embodiment.

[Effect of device]

As described in detail above, when the upper die and the lower cushion cushion that collide with the slide collide with each other at the pin-tatch position, the lower cushion pad is preliminarily lowered at a speed corresponding to the lowering speed of the upper mold. Since the pinching noise generated when the die and the lower die cushion pad collide with each other, noise due to the pinching noise can be reduced.

In addition, the pressure in the cylinder for preliminarily lowering the lower die was gradually increased to almost equal the dicing cylinder capacity when the preliminary lowering was completed. There is no risk of generating an impact sound at the end of the process, and there is no surge pressure that causes the hydraulic pressure in the room to suddenly rise after a pin touch, so there is no dent or scratch on the molded product, and product quality is improved. Inconveniences such as a significant decrease can also be resolved.

[Brief description of drawings]

The drawings show an embodiment of the present invention, FIG. 1 is a circuit diagram, FIG. 2 is a flow chart for explaining the operation, FIG. 3 is a diagram for the same, and FIG. 4 is an explanatory view showing another embodiment. is there. 1 is a press main body, 1a is a bolster, 2 is a lower mold, 2a is a lower mold dicing pad, 3 is a dicing pin, 4 is a dicing pin, 5 is a pin holder, 8 is a locking device,
8 ₃ is a chamber, 14 is a servo valve, 21 is an upper die, and 23 is a hydraulic cylinder.

Claims (2)

[Scope of utility model registration request] 1. A lower die cushion pad 2a provided near a lower die 2 installed on a bolster 1a of a press body 1 elastically supported by a die cushion 4 via a die cushion pin 3, wherein the die An upper die that raises the pin receiving base 5 supporting the cushion pin 3 to the upper limit position of the die cushion by the hydraulic pressure supplied to the chamber 8 ₃ provided in the lower portion of the locking device 8 and lowers it together with the slide 20.
21 Once reached Pintatchi position impinging on the lower die cushion pad 2a, the servo valve 14 connected to the chamber 8 _3, electrical signals necessary for the preset die cushion capability becomes setting capability F 0 i is energized for the set capacity generation time Δt of the die cushion to drain the hydraulic pressure in the chamber 8 ₃ to preliminarily lower the lower cushion pad 2a, and after preliminarily lowering the hydraulic pressure in the chamber 8 ₃ . A pre-lowering device for a die cushion, which is gradually increased to control the servo valve 14 so that the pressure becomes substantially equal to the die cushion capacity F when the pre-lowering is completed. 2. A hydraulic cylinder 23 for supporting the dike pin 3 is provided in the pin receiving base 5, and the pressure in the hydraulic cylinder 23 is controlled by a servo valve 14.
Preliminary lowering device as described.