FR2568172A1 - Hydraulic device for balancing the clamping plate (platen) of a press - Google Patents

Abstract

The invention relates to a hydraulic device for balancing the clamping plate (platen) of a press. The device is characterised in that it comprises a certain number of vertical cylinders 9, 10 securely attached to the said clamping plate (platen) 7 which are each capable of sliding on a fixed inner piston 11, 12 securely attached to a vertical column 1, 2 connecting the two abovementioned fixed parts 5, 6 of the press, sealing means being provided between each column and its associated movable cylinder, each cylinder 9, 10 communicating with at least one another cylinder 10, 9, preferably an opposing cylinder, via two pipes 13, 14 each connecting the upper volume V1, V3 inside one of the cylinders 9, 10 with the lower volume V2 V4 inside the other cylinder 10, 9, each pipe 13, 14 being connected via a pipe 15, 16 and a non-return valve 17 to a common source of incompressible pressurised fluid. Application, in particular, to vertical hydraulic (hydrostatic) presses.

Description

HYDRAULIC BALANCING DEVICE
MOBILE PRESS TRAY
The present invention relates to a hydraulic device for balancing the movable platform, in particular a vertical hydraulic press.

 The devices currently used on this type of press to maintain the parallelism between the movable and fixed platen, use counter-thrust systems acting from bottom to top on the descending movable platen.

 This results in a significant consumption of energy, thereby reducing the actually available power of the press. These balancing thrusts are triggered by electrically or electronically controlled hydraulic components.

 The complexity of such systems increases the risk of errors and results in a high cost price.

 The invention aims to overcome these drawbacks by proposing a new fully hydraulic balancing device, simple and efficient, and at a particularly advantageous cost price.

 To this end, the subject of the invention is a hydraulic device for balancing the movable plate, in particular a vertical hydraulic press of the type comprising two superposed fixed parts between which a plate moves vertically, characterized in that it comprises a number of vertical cylinders secured to said plate, each capable of sliding on a fixed inner piston secured to a vertical column connecting the two above-mentioned fixed parts of the press, sealing means being provided between each column and its associated movable cylinder , each cylinder communicating with at least one other cylinder, preferably opposite, by two pipes each connecting the upper internal volume to one of the cylinders to the lower internal volume to the other cylinder, each pipe being connected by a pipe and a valve non-return to a common source of incompressible pressure fluid.

 According to a particular embodiment applied to a press with a rectangular movable plate, there is provided such a movable cylinder in each corner of the rectangular plate, the cylinders being connected in pairs diagonally.

 Furthermore, advantageously, the fluid under incompressible pressure is oil, which makes it possible to ensure self-lubrication of the pistons of the cylinders.

 Such a device makes it possible to correct almost instantaneously any initiation of offset of the movable plate during its descent by pressure compensation between the upper and lower volumes of the cylinders connected to each other. The parallelism between the two opposite plates of the press is thus maintained in a simple, efficient and reliable manner.

Other characteristics and advantages will emerge from the description which follows of an embodiment of the device according to the invention, description given by way of example only and with reference to the appended drawing in which:
- Figure 1 very schematically shows a top view
a vertical hydraulic press with four columns of
guidance, and
- Figure 2 shows a vertical diagonal section
along the line D1-D2 of the press of Figure 1 provided
of a device according to the invention.

 In FIG. 1, the fixed parts of a vertical hydraulic press are shown diagrammatically by a rectangle, joined in the four angles by vertical columns 1,2,3 and 4.

 These columns bring together the upper 5 and lower 6 parts (FIG. 2) and ensure the sliding and the vertical guidance of the rectangular movable plate 7 of the press, moved by an appropriate jack 8.

 The movable plate 7 is integral in its four cylinder angles (9 and 10 in FIG. 2) mounted to slide along said vertical columns.

 Each column is shaped so as to constitute a part of enlarged diameter forming a piston (11 and 12, FIG. 2) on which one of said cylinders slides.

 Each piston thus determines in each cylinder two chambers.

FIG. 2 shows the cylinder 9 with its two chambers V1 and V2 on either side of the piston 11 and the cylinder 10 diagonally arranged with its chambers V3 and
V4 on either side of the piston 12.

 The upper chamber -V1 of the cylinder 9 communicates by a pipe 13 with the lower chamber V4 of the diagonally opposite cylinder 10.

Similarly, the lower chamber V2 of the cylinder 9 communicates by a pipe 14 with the upper chamber
V3 of cylinder 10.

 Columns 3 and 4 also include pistons similar to 11 and 12 and on which cylinders similar to 9 and 10 slide and delimiting upper and lower chambers connected to each other in the same way as chambers V1 to V4 of columns 1 and 2 .

 The cylinders (9,10) are fitted with cable glands at their ends.

 Each pipe such as 13 and 14 in FIG. 2 is connected to a common source of pressurized hydraulic fluid by a pipe (15, 16) in which a non-return valve 17 is interposed. Said hydraulic fluid is advantageously oil in order to ensure self-lubrication of the fixed pistons 11, 12.

 With such a device, any initiation of offset of the movable descending plate 7 with respect to the lower fixed plate 6, along arrow A or B, that is to say any initiation of loss of parallelism between 7 and 6 will almost instantaneously generate a overpressure in at least one of the four upper chambers such as V1 and V3, which overpressure will have repercussions on the diagonally opposite lower chamber thereby ensuring automatic compensation maintaining rigorously and constantly the parallelism between the plates 7 and 6.

 This device can either be used as an integral part of a compression press, in which case columns 1 to 4 constitute the columns of the press, or as an auxiliary device on an existing press.

 The columns can be of variable number and arranged in other places than the angles of the movable plate according to the configuration and the mounting of the latter.

Claims (5)

 1. Hydraulic device for balancing the movable plate, in particular a hydraulic-vertical press of the type comprising two fixed parts (5,6) superimposed between which a plate (7) moves vertically, characterized in that it comprises a number of vertical cylinders (9,10) integral with said plate (7), each capable of sliding on a fixed internal piston (11,12) integral with a vertical column (1,2) connecting the two above-mentioned fixed parts ( 5,6) of the press, sealing means being provided between each column and its associated movable cylinder, each cylinder (9,10) communicating with at least one other cylinder (10,9), preferably opposite, by two lines (13,14) each connecting the upper volume (V1, V3) internal to one of the cylinders (9,10) to the lower volume (V2, V4) internal to the other cylinder (10,9), each line (13,14) being connected by a pipe (15,16) and a non-return valve (17) to a common source of sou fluid s incompressible pressure.  2. Device-according to claim 1, characterized in that said plate (7) is rectangular and comprises at each angle a cylinder associated with a fixed vertical column (1 to 4), the cylinders being connected in pairs diagonally.  3. Device according to claim 1 or 2, characterized in that the incompressible pressure fluid is oil.  4. Device according to one of claims 1 to 3, characterized in that said fixed columns (1 to 4) are the original elements of the press and shaped so as to constitute said fixed pistons (11,12).  5. Device according to one of claims 1 to 3, characterized in that said fixed columns (1 to 4) are elements added to an existing press independently of the original means provided for guiding said movable plate (7).