Method of preventing crank-operated presses overload by force at slide

FIELD: process engineering.

SUBSTANCE: invention relates to press forging and may be used at crank-operated presses with composite foundation tied by studs. With force at press slide exceeding rated magnitude, reduced is rigidity of press power structure formed by press actuator, deforming tool and processed article. Note here that studs used to tie composite foundation feature central part diameter that provides reducing power structure rigidity to magnitude making 10-30% of press effective rigidity.

EFFECT: long-term inertialless protection against overloads at whatever deformation rates.

2 dwg, 1 tbl

 

The invention relates to mechanical engineering and can be used in the construction of the crank presses and other forging machines with reciprocating movement of the working element subjected to overloads associated with the peculiarities of the process of loading or other factors.

There is a method of protection of the crank presses against overload force on the slider (Forging and stamping equipment: a Textbook for engineering universities / Annankatu, Waarom, Nestorovski and others; Ed. by Annankatu, Engleskog. - 2 ed., revised and enlarged extra - M.: Mashinostroenie, 1982. - s, ri)based on integration into the power circuit created a processed product, the tool actuator and the frame spring-arm device that reduces the rigidity of the power circuit when excessive efforts on the slider nominal values. The disadvantages of the method - the complexity of implementing its devices and low response accuracy associated with the variability of the transfer function lever systems under various generalized coordinates of loading process, which limits its use horizontal forging machines and cold-landing guns for protection additional actuator (mechanism of grip).

There is a method of protection is of crank presses against overload force on the slider (USSR author's certificate No. 1639976, 1991), based on integration into the power circuit created a processed product, a tool actuating mechanism and the frame of non-metallic elastic elements, deformable when exceeding efforts on the slider nominal values. The disadvantages of the method is limited durability and low precision actuation implementing the method of the devices, reducing the effective stiffness of the presses, the inability to implement in the crank presses for die forging due to unacceptably high specific loads on the elastic elements.

There is a method of protection of the crank presses against overload force on the slider (mechanical sheet metal stamping presses. Rovinsky G.N., Zlotnikov S.L. - L: mechanical engineering, 1968. - s, ri)based on integration into the power circuit created a processed product, the tool actuator and the frame hydraulic or hydro-mechanical safety devices. The disadvantage of this method is the inertia of the implement actuation devices, limiting its use to low-speed medium and heavy sheet metal stamping presses. Another drawback is the inability to use in presses for die forging with high specific loads on the table and the slider, because the aggregate used in hydraulic presses us what the hardware is not designed to occur under these conditions the pressure.

The closest to the technical nature of the claimed is a method of protection of the crank presses against overload force on the slider (mechanical sheet metal stamping presses. Rovinsky G.N., Zlotnikov S.L. - L: mechanical engineering, 1968. - s, ri)based on integration into the power circuit created a processed product, a tool actuating mechanism and the frame of the safety device with decaying elements. The disadvantages of the method is the low accuracy of response associated with a gradual reduction efforts the fuse in the fatigue phenomena, no samovosstanavlivaemy.

The proposed method aims at providing durable and instantaneous protection crank presses overload force on the slider at all attainable speeds of deformation of the workpiece.

This technical result is achieved in that way protection overload force on the slider crank press having a detachable stand, a tight hairpins, is that when the excess effort on the press slide the nominal value reduces the rigidity of the power circuit, created the bed of the press, its Executive mechanism, deforming tool and a processed product, for tightening ashenai frame using pins, made with the diameter of the middle part, ensure the reduction of rigidity of the mentioned power circuit to the value component of 10-30% of the effective stiffness of the press.

The inventive method includes the following sequence of operations (1):

1. Detachable base shrinks coupling pins 2 so that when the excess effort on the slide of the nominal value of the junction of the tightened connection is revealed.

2. The diameter of the middle part of the tie rod 2 is chosen so that after the disclosure of the joint rigidity of the power circuit created a processed product 4, a tool actuating mechanism consisting of the slider 3, the connecting rod 5 and the main shaft 6 and the frame 1, was 10÷30 from the effective stiffness of the press.

3. When opening the junction mounted on a frame sensors efforts 7 off the press so that its working body comes in instrumentation with alarms about the fact overload.

4. Hydrogena 8 or other known device perestayut stud, restoring calculated force actuation in accordance with the measured deformation in the manual mode, remote or automatic control.

Read more the essence of the proposed method is illustrated by drawings:

- figure 1 shows a diagram of the method under the protection of the press;

- figure 2 shows the development of the overload is alsoone press. The development of the overload on the press slide describes figure 2.

Considered the ultimate option - schedule operation schedule is effective rigidity of the press. The vertical axis represents the current force on the press slide P, on the horizontal - does not slide s to the PKK. Point a corresponds to the beginning of deformation of the workpiece, the point b to force disclosure of the junction of the base point in the Central part of the pins 2 in the plastic region, the point g is the transition of the slide through the PKK. The angle α characterizes the effective stiffness of the press, the angle β is the linear stiffness of the press after the disclosure of the junction of the frame, the angle γ is the linear stiffness of the press when crossing the Central part of the pins in the plastic region. Depending on the ratios of parameters press studs plastic region in some cases may be missing (for example, for machines with small relative stroke of the slide).

Studs 2 have unlimited lifetime under normal operation, press and limited durability when the press under conditions of overload. In the latter case, the destruction of the pins is determined by the ductility resource exhaustion.

As an example, the implementation of the proposed method table 1 shows the results of overload crank die forging press nominal force of 5 MN, as well as sheet metal stamping machine with a nominal force of 1 MN.

Table 1
The results of applying the proposed method of protection crank presses force on the slider
№ p/pWithout protectionWith protection by using the proposed method
1Material studssteel 45 normalization, 230-250 NV
2sheet metal stamping machine with a nominal force of 1 MN
3PC/Pn1.2-1.80.932
4WithAF/SAF1.00.26
5Pmax/Pn2.91.18
6heat punching-press the nominal condition is Liem 25 MN
7PC/Pn1.2-1.80.86
8WithAF/SAF1.00.23
9Pmax/Pn2.71.10

In the table below:

PCthe torque rods;

WithAFeffective stiffness of the press before the opening of the joint housings;

WithAFeffective stiffness of the press after the disclosure of the junction of the base;

Pmax- maximum stress overload on the slider.

Way protection overload force on the slider crank press having a detachable stand, a tight hairpins, characterized in that when the excess effort on the press slide the nominal value reduces the rigidity of the power circuit, created the bed of the press, its Executive mechanism, deforming tool and a processed product, while torque split housings use studs made with the diameter of the middle part, ensure the reduction of rigidity of the mentioned power circuit to the value component of 10-30% of the effective stiffness of the press.



 

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