DD146160A1 - Device for hydraulic presses to prevent waste of the upper pressing table - Google Patents

Abstract

The invention relates to a device for hydraulic presses, in particular plastic presses, which should prevent the dropping of the upper press table in "stop" positions and when opening the press in case of disturbances. According to the invention, this object is achieved in that a toothed rack rigidly fixed to the upper press table cooperates with a pawl which can be engaged and disengaged by a compression spring and a hydraulically actuated control piston, and a pressure chamber of the hydraulic cylinder in which the control piston moves in front of the control piston Pressure line is connected to a known control valve, while a closable by the control piston control line leads from the lying behind the control piston chamber of the hydraulic cylinder to a known main-way valve.

Description

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Title of the invention ;

Device for hydraulic presses for preventing the top of the press table from falling off

Area of application of the invention

The invention relates to a device for hydraulic presses, in particular plastic presses, which should prevent the falling of the upper press table due to interference occurring when opening the press. 10

Characteristic of the known technical solutions

In commercial presses, it is known to prevent the fall of the press ram by a pipe break valve when the ülrücklaufleitung is defective. However, this solution is in the event of tearing of the upper press table, e.g. by ram breakage or leaking ram cuffs, ineffective, so that there is an acute risk to repairing or operating personnel.

By DD - PS 86 979 was therefore already proposed, parallel to the press ram a working cylinder whose cylinder is connected by a pressure line via a directional control valve with an oil reservoir, to be fixed to the press stand and the piston of the working cylinder on the upper press table.

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This solution is too complex overall, so carries sources of interference and is disadvantageous for subsequent attachment to the said hydraulic presses.

In addition, the excitation of the Ε-magnet of the pilot valve is maintained when driving the press, although the press table can be demolished. This has the consequence that the oil column in the cylinder can escape into the oil reservoir, d * h. the protective measure will only take effect when the machine is switched to "stop".

Finally, DE-OS 2 633 616 has proposed a mechanical safety device for the stamping of presses, consisting essentially of a locking rod fixed immovably on the press ram and a locking sleeve rotatably mounted on a fixed part of the press. The rod and sleeve have cooperating members which engage with each other in a first rotational position of the sleeve to lock the punch and are disjointed in a second rotational position of the sleeve to permit movement of the rod through the sleeve and thus movement of the punch allow.

However, this stamp fuse is only suitable for repair and set-up operations and can only by hand and in ^M Halt "position of the press and be disengaged.

Object of the invention

The purpose of the invention is to eliminate the disadvantages mentioned and to achieve greater safety against accidents, especially when driving up the presses.

Explanation of the essence of the invention

The invention has for its object to provide by simple means a permanently reliable device, the dropping of the upper press table in "stop" positions and when opening the press, with troubles occurring, e.g. Tearing off of the press table (stamp breakage), leaking piston collars and defects of the sleeve holding head, defective oil return line, prevented and, if necessary, can also be subsequently attached to hydraulic presses. Erf indungsgetnäß'diese this is achieved in that a rigidly fixed to the upper press table rack with a by a compression spring and a hydraulically operated control piston, which is arranged together with the compression spring in a hydraulic cylinder in a row, engageable and disengageable pawl and that a Pressure chamber of the hydraulic cylinder is connected in front of the control piston by a pressure line with a known control valve, while a closable by the control piston control line leads from the lying behind the control piston skirt of the hydraulic cylinder to a known main way valve.

embodiment

In one embodiment, the invention will be explained in more detail below. In the accompanying drawing shows the

Fig. 1: the schematic representation of the device with the hydraulic circuit diagram.

At the upper press table 1 a parallel to the press ram 2 extending rack 3 is rigidly attached, the

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interacts with a pawl 4. The pawl 4 is held by a compression spring 7 via a hydraulically actuated control piston 6 which is arranged together with the compression spring 7 in a hydraulic cylinder 5 in succession, as long as the press is in the "stop" or in the opening position. The hydraulic cylinder 5 is connected in a manner not shown fixed to the press stand.

The pressure chamber 5.1 in front of the hydraulic control piston 6 is connected by a pressure line 8 to the Yorsteuerventil 9 and the spring chamber 5.2 behind the control piston 6 through a control line 10 with the Haupttwegeventi]. 11 connected and included in this way in the usual hydraulic system. At the pilot valve 9, the control oil pressure is applied via the pressure line 12.

The operation of the device is the following: The rack 3 carries out the same lifting movement as the press ram 2. With the triggering of the upward movement of the press ram 2, e.g. by opening a protective grid, not shown in the drawing, the hydraulic control piston 6 are printed by the compression spring 7 in its front position and thus the pawl 4 in the form of a squeeze with the rack 3. The oil in the pressure chamber 5.1 of the hydraulic cylinder 5 flows through the pressure line 8 and the pilot valve 9 without pressure in the return 14. If the hydraulic press stopped in any position, the pawl 4 remains engaged with the rack 3 »aa the pilot valve 9 in its zero position, the pressure line 8 also without pressure with the return line 14 connects.

With the triggering of the downward movement of the control solenoid 13 is a pilot valve 9 is energized, thereby the pressure

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line 12 connected to the pressure line 8 and constructed in the pressure chamber 5.1 an oil pressure. The hydraulic control piston 6 overcomes the compression spring 7 and opens the pawl engagement on the rack 3. In its rear end position, the control piston 6 releases the connection between the pressure line 8 and the control line 10, so that the main way valve 11 is actuated and the downward movement of the press ram. 2 initiates.

If the downward movement stopped, the control solenoid 13 is de-energized »Thus, the pilot valve 9 again assumes the zero position, so that the pressure line 8 is connected without pressure to the return and the compression spring 7 engages the pawl 4 via the hydraulic control piston 6 back into the rack 3 ,

Claims (1)

1. claim

   Device for hydraulic presses, in particular plastic presses, which should prevent the falling of the upper press table due to interference occurring when opening the press, characterized in that a rigidly fixed to the upper press table (1) and parallel to the press ram (2) extending rack (3) a by a compression spring (7) via a hydraulically actuated control piston (6), which is arranged together with the compression spring in a hydraulic cylinder (5) arranged one behind the other, engageable and disengageable pawl (4) and that a pressure chamber (5.1) of the hydraulic cylinder (5.1) 5) in front of the control piston (6) by a pressure line (8) with a known pilot valve (9) is connected, while a control piston (6) closable control line (10) from a behind the control piston (6) spring chamber (5.2 ) of the hydraulic cylinder (5) leads to a known main way valve (11).

   For this purpose -7 page drawing