JPH0133280Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an overload protection device for a press machine in which the overload protection device for the slide also serves as the overload protection device for the knockout device.

Generally, in a mechanical press, a slide 1 moves up and down relative to a bolster 3, as shown in FIGS. 1 and 2. When the upper die 5 attached under the slide 1 is fitted with the lower die attached to the bolster 3 (not shown), the material placed between the two dies is pressed. It is then shaped and processed into products.

Such a press is usually equipped with a knock-out device 7. The knock-out device 7 is slidably inserted into each of the knock-out columns 11 that are vertically installed on the frame 9 in a pair at the front and rear, and is fixed in an appropriate position with a nut 13. It is equipped with a knock out rod 15 that can be used for various purposes. Furthermore, there is provided a knockout bar 17 horizontally across the slide 1 and a knockout pin 19 provided from a mold at the center of the press relative to the knockout bar 17.

To explain the operation of the knockout device 7, first, the protrusion length of the knockout rod 15 with respect to the knockout support 11 is adjusted in relation to the product to be molded. As the slide 1 descends, the product is processed, and the slide rises again. As the slide 1 rises, the knockout bar 17 also rises and the knockout rod 1
It collides with the bottom edge of 5. Since the knockout rod 15 is fixed to the frame 9 and does not move, the knockout bar 17 is pushed down relative to the slide 1 as the slide 1 further rises. Due to this movement, the knockout pin 19 also descends relative to the slide 1, and its lower end pushes out the product 21 in the upper mold 5 from the upper mold 5.

Generally, a knockout device in a press machine operates as described above, but in the conventional knockout device, no consideration was given to an overload protection device. Therefore, if you incorrectly set the height of the knock out rod and lower it too much, the slide will continue to rise even after the drawn product has been pushed out, pushing the knock out rod up, causing the knock out rod and There was also a risk of damage to the bar and even the mold. Furthermore, there is a possibility that a similar situation may occur if the knockout ability exceeds the allowable knockout force.

This idea was made in view of these conventional problems, and it is an overload protection device for the slide used in general mechanical presses that can also be used as an overload protection device for the knockout device. It is an object of the present invention to provide an overload protection device for a press machine which prevents an excessive load from being applied to a knockout device.

The embodiment shown in the figures will be explained in detail below. Third
Referring to the figure, this figure shows the knockout strut 11.
and the knockout rod 15 shown in FIG. 1 in more detail. A pair of knock-out supports 11 are provided at the front and rear, and a required number of knock-out supports 11 are hung from the frame 9. The knockout support 11 includes a hollow cylindrical portion 23, into which the knockout rod 15 is inserted so as to be vertically slidable. A nozzle 25 is further provided in the upper part of the hollow cylindrical part 23 to introduce pressure oil into an oil chamber 27 formed between the upper end of the knock out rod 15 and the upper end of the hollow cylindrical part 23. It's getting old.

The lower end of the knock out rod 15 has a screw hole 2.
9 is provided, and a threaded rod 31 is screwed into this screw hole 29. When adjusting the protrusion length of the knockout rod 15 relative to the knockout post 11, first loosen the nut 13, screw in or loosen the threaded rod 31 into the threaded hole 29 to adjust the protrusion length of the threaded rod, and then tighten again. This is done by tightening the nut 13.

Furthermore, the knockout rod 15 is connected to the hollow cylindrical portion 23.
A key 33 is attached to the hollow cylindrical portion 23 so as not to rotate with respect to the lock, and this key 33 is engaged in a keyway 35 provided in the knock out rod 15.

FIG. 4 shows the hydraulic and pneumatic circuit. The slide 1 of the press machine described above is provided with a cylinder 37, and a piston 39 is installed inside the cylinder 37.
is embedded. The piston 39 is connected to the crankshaft via a connecting rod 41. An oil chamber 43 is formed between the cylinder 37 and the piston 39. Since the piston 39 presses the slide 1 in the pressurizing direction via the pressure oil in the oil chamber 43, by measuring the oil pressure in the oil chamber 43, the repulsive force acting on the slide 1, that is, the pressurizing force can be calculated. It can be measured.

An overload detector 45 for the oil chamber 43 consists of a main cylinder 47 and a balance piston 49 fitted into the main cylinder 47. One side of the balance piston 49 is used as an oil chamber 51, and the other side is used as an air chamber 53, so that the oil chamber 51 is the oil chamber 4 of the slide 1.
3, the air chambers 53 are each connected to an air pressure source 57 via a pressure regulating valve 55. Therefore, it is detected that the hydraulic pressure in the oil chamber 43 communicating with the oil chamber 51 is greater than the air pressure set by the pressure regulating valve 55, and the pressure oil in the oil chamber 51 is released to the oil tank 59. This allows the drive of the slide 1 to be stopped. Here, the pump 61 supplies pressurized oil to the oil chamber 51 from the pneumatic source 57 via the pressure regulating valve 63 and the electromagnetic control valve 65 at a pressure commensurate with the pneumatic pressure applied to the pump itself.

The oil chamber 51 of the overload detector 45 is also communicated with an oil chamber 27 provided between the knock-out column 11 and the knock-out rod 15 of the knock-out device 7. Here, the cross-sectional area of the oil chamber 27 perpendicular to the knock-out direction is determined by the allowable load of the knock-out rod 15, the allowable load of the slide 1, and the cross-sectional area of the oil chamber 43 provided in the cylinder 37 of the slide 1. . That is, the maximum allowable load A of the press machine, the cross-sectional area B of the oil chamber 43 of the cylinder 37
Then, the hydraulic pressure C at the maximum overload allowable to the slide 1 is as follows: C=A/B (1). Further, the overload generating oil pressure D in the knockout device 7 is also expressed by the following equation, where the knockout capacity is E and the cross-sectional area of the oil chamber 27 of the knockout device 7 is F.

D=E/F Therefore, the hydraulic pressure Dmax for the maximum permissible overload of the knockout device 7 is given by the following equation, where the maximum permissible knockout force is Emax.

Dmax=Emax/F (2) Therefore, if the cross-sectional area F of the oil chamber 27 of the knockout device 7 is designed so that Dmax in the above equation (2) matches C in the equation (1), the allowable knockout can be reduced. When a knock-out force greater than the knock-out force is generated, the same hydraulic pressure as when the overload protection device operates is generated against the slide 1, causing the balance between air pressure and hydraulic pressure in the overload detector 45 to collapse, and the hydraulic pressure to open. It will be done.

This invention aims to protect the knock-out device from overload by using the slide overload detection device used in ordinary press machines to also detect the overload of the knock-out device. There is no need to employ a more expensive detection mechanism for load protection, and the structure is simple, and damage to the knockout device and accidents can be prevented at low cost.

[Brief explanation of the drawing]

Fig. 1 is a front view showing the entire press machine using an embodiment of this invention, Fig. 2 is a side sectional view illustrating the operation of the above press machine, and Fig. 3 is a portion of the knockout device of the above press machine. Enlarged sectional view of 4th
The figure is a hydraulic and pneumatic circuit diagram of the same as above. 1...Slide, 7...Knockout device, 9
... Frame, 11 ... Knockout support, 15
... Knockout rod, 17 ... Knockout bar, 19 ... Knockout pin, 23 ... Hollow cylindrical section, 27 ... Oil chamber, 37 ... Cylinder, 39
... Piston, 43 ... Oil chamber, 45 ... Overload detector, 47 ... Main cylinder, 49 ... Balance piston, 51 ... Oil chamber, 53 ... Air chamber.

Claims (1)

[Claim for Utility Model Registration] If the pressure in the hydraulic cylinder 37 for overload protection provided in the slide 1 of the press machine and the oil chamber 43 of the cylinder 37 exceeds the hydraulic pressure C at the maximum overload, an overload occurs. An overload protection device for a press machine, comprising: an overload detector 45 for detecting pressure and releasing pressure in the oil chamber 43; , a hydraulic cylinder with a knockout rod 15 movable up and down is provided, and the oil chamber 27 of this hydraulic cylinder is connected to the oil chamber 43 provided in the slide 1, when the maximum allowable knockout force is applied. The cross-sectional area of the oil chamber 27 in the knock-out device 7 is adjusted so that the maximum oil pressure Dmax in the oil chamber 27 in the knock-out device 7 is equal to the oil pressure C at the maximum overload of the oil chamber 43 provided in the slide 1. An overload protection device for a press machine, which is characterized by the following: