DE2606261A1 - Hydraulic press stroke limiting device - has valve for press cylinder operated by length adjustable rod - Google Patents

Abstract

The stroke limiting arrangement holds the press surfaces at a constant relative distance which is greater than the smallest distance between these surfaces during the press cycle. The arrangement consists of a hydraulic fluid supply (13) to each press cylinder (1) or each group of press cylinders, a valve (7) which is mounted near a press cylinder, and a valve operating rod (8), which engages with the valve as soon as the relative distance between the press surfaces has reached a certain distance. The arrangement further consists of a common valve (12) for several press cylinders which controls the supply and outlet of hydraulic fluid to and from the cylinders according to a pre-determined programme.

Description

Stroke limiting device in hydraulic presses with several press cylinders The present invention relates to a simple and reliable stroke limiting device with raw accuracy, which can be set in and out of function at will.

When pressing resilient material, loosely connected, resilient Mats between heated @@ e @ plates in hydraulic presses with several cylinders compressed, transforming them into stiff plates.

To achieve a uniform panel thickness even with varying thicknesses Weight of the mat s per surface unit are along between the press plates their nongues usually have intermediate strips, but there are others as well mechanically operating stroke-limiting device is known at.

The disadvantages of these various devices are the @ och-mann well known.

@ In certain contexts, e.g. if you are in a first Phase of pressing I would like to avoid squeezing a lot of water out of the battens the devices mentioned a compression down to a thinner mat thickness than the final plate thickness and thereby the water expulsion is limited.

There are also known presses in which several electrical cal devices, like limit switches / are arranged along the long sides of the press, the press movements sense and the hydraulic pressure in one or more cylinders in the area of the control the respective sensing device individually, so that a certain predetermined Stroke length is not exceeded. The available electrical organs with the desired Sensing accuracy, however, have such a weak output that it amplifies must be to the solenoid valve that makes the transition between the electrical and the hydraulic chain of the servo system forms to be able to operate. Often it can Solenoid valve then does not directly regulate the hydraulic pressure in the associated cylinder, but hydraulic reinforcement must also be used. The number at stages in the servo system affects the accuracy with which the stroke length of the cylinder is limited, a negative effect and increases the risk of malfunctions. This last-mentioned deficiency is particularly evident when eating with large ones Pressing areas, e.g. 2.5 x 20 m, where the number of cylinders and control systems 20 - 30 pieces can reach.

The present invention relates to a stroke limiting device with great accuracy which, thanks to its simplicity, is reliable and arbitrary in and out of function can be and the one limitation the stroke length to any number of fourths in any order during the pressing process allowed. The subject of the invention was with a press with 15,000 tons of pressing force was used and had a repeatability of less than +/- 0.05 mm.

The invention is now illustrated on a one-day press with only four cylinders are explained in more detail using the accompanying drawing, 1 shows a side view of a press, FIG. 2 shows an end view of the Press shows, Fig. 3 schematically a hydraulic circuit diagram for a cylinder Fig. 4 shows an alternative to that in kig. 3 shows the embodiment shown, and Fig. 5 ene embodiment of a pressure member adjustable during the pressing process length shows.

In Fig. 1 and 2 is a press with cylinders 1 and associated pistons 2, which act on a movable press table 3, while of the pressing process, the Iviaterial 4 to be pressed against a fixed press table 5 presses.

The reaction force from the cylinders 1 and the fixed table 5 becomes taken up by a press frame 6. In the area of each cylinder l is with a valve 7 is firmly connected to the lower press table 5. The valves 7 are through Pressure organs 8 opened mechanically, which are firmly connected to the movable press table 3 are and are arranged over the valves 7, u.zw. if a certain predetermined Value for the distance between the Iressenti tables 3, 5 is undershot, and they will closed as soon as this value is exceeded.

As soon as any valve 7 is opened, the associated cylinder 1 connected via pipes 9, 10 to a tank 11 which is common to all cylinders is. In the pipe 10 common to the cylinder 1, there is a shut-off valve 12 is provided, which interrupts the flow from the cylinders 1 to the tank 11 in the blocking position. The pressure members 8 have an adjustable length during the pressing process. For each individual cylinder is a device 13 for the continuous supply of liquid intended.

In Fig. 3, the hydraulic connection described above is in schematic form for a cylinder. It is also shown how the cylinder 1 each Via an actuatable valve 14 for the purpose of closing, pressure increase, pressure decrease and Opening of the rresse is connected to a common hydraulic system 15 of conventional type or, alternatively, is separate.

FIG. 4 shows an alternative to the embodiment shown in FIG. 3 shown. The cylinders are each connected to a check valve 16 here common pumping station 17 for closing and pressure increase as well as over each one second check valve 18 to a common valve system 19 to reduce pressure and opening connected.

In Fig. 5 is a guide form of the pressure element 8 with during the pressing process of adjustable length shown. The one on the movable press table 3 The attached cylinder body 20 contains a piston 21 with a piston rod 24 and together with this forms two spaces 22, 23, the alternate under pressure with the piston in one of two well-fixed positions.

Claims (5)

Patent claims: 1. Device with hydraulic single or multi-daylight presses several press cylinders for pressing resilient material between two pressing surfaces, which device to keep the mutual distance between the pressing surfaces constant is provided for a predetermined value which is greater than the smallest Value of the distance during the pressing process, characterized by a device (13) for supplying liquid to each press cylinder (1) or each group of press cylinders, a valve (7) in the area of the press cylinder for draining off liquid, a pressure element (8) for mechanical opening of the valve as much as the mutual distance between the pressing surfaces falls below a predetermined value in the working range of the cylinder, as well as for each press cylinder (1) or for several cylinders together a valve (12) which the liquid drainage from the cylinder or according to a predetermined program prevented or allowed by the cylinders (1). 2. Device according to claim 1, characterized by a check valve (16) for each press cylinder (1) or each cylinder group, which valve the liquid supply; of a hydraulic system common to several, preferably all, press cylinders (@ 7) allows. 3. Device according to claim 1, characterized by a check valve (18) for each press cylinder (1) or group of press cylinders, which valve is the fluid drain to a valve system (19) common to several, preferably all, press cylinders for lowering the pressure and opening the press. 4. Device according to claim 1, characterized by an actuatable Valve (14) for each press cylinder or group of price cylinders, which valve after a predetermined program the liquid flow to or from one for several, preferably all press cylinders allows common hydraulic system or alternatively prevented. 5. Device according to claim 1 to 4, characterized in that that the specified in claim 1 pressure member (8) one during the pressing process Has adjustable length.