EP0634253A2 - Press, in particular a platen press for woodworking - Google Patents

Abstract

A press (11), usable in particular as a platen press for woodworking, generates the pressing pressure by means of two superposed rows (20, 21) of flexible tubes (19) which are filled with compressed air. An intermediate plate (17) ensures pressure equalisation. The pressing surfaces are formed by heated platens (29), the bottom one of which can be partly pulled out beyond the press frame to facilitate charging and cleaning. <IMAGE>

Description

APPLICATION AREAS AND PRIOR ART

The invention relates to a press, in particular a plate press for woodworking or the processing of similar workpieces. The press is e.g. Designed for gluing plate-shaped materials under temperature and pressure, especially for the production of veneered or plastic-coated boards.

Plate presses are known from EP 141 801 B1 and EP 176 498 B1, in which the pressing force is applied by pneumatically inflatable hoses. Such plate presses manage with relatively little mechanical effort and are therefore particularly suitable for repair shops, etc.

TASK AND SOLUTION

The object of the invention is to further develop plate presses of this type and, in particular, to enlarge their area of use and thus to make them more universally applicable. This object is achieved according to the invention in that in a press with a press drive by pneumatically expandable Hoses at least two rows of hoses are provided one above the other.

In this way it is possible to obtain a fairly large stroke without the hoses having to be too large in diameter. This saves compressed air because e.g. Two hoses of half a diameter lying one above the other require a significantly smaller total volume of air than a hose with twice the diameter. Furthermore, the large hoses would be at a fairly large distance from one another, so that the press plate above them would be subjected to greater stresses.

A vertically movable rigid intermediate plate can be provided between the two rows of tubes, which has a mechanically compensating effect and thus promotes a uniform application of the pressing force.

The press can have a rigid frame-shaped press frame with a stiffened upper and lower support plate. Due to the large stroke, it is possible without any adjustment means, i.e. to capture a relatively large range of workable plate thicknesses with rigid carrier plates. The press is therefore very simple, since the upper and lower plates can be simple rigid structures, for example composed of double flange supports.

The upper of these carrier plates can each carry a pressing surface forming a pressing surface on its underside and the upper row of tubes on its upper side.

The heating plates can have a plate-shaped base body with electrical heating conductors inserted in grooves, which are covered by a cover plate, and with a high-pressure insulating plate are highlighted. This enables the electrical heating of the carrier plates to carry out hot working or pressing operations requiring heat.

The hoses of the rows of hoses can each lie vertically one above the other so that hardly any bending forces are applied to the intermediate plates and the force flow is introduced as directly as possible from the pressing surface into the lower carrier plate. If even larger strokes are required, more than two rows of hoses can be used. Although a horizontal arrangement (vacuum press) with a movable pressing surface underneath is preferred, other arrangements with several hose levels can also be implemented. Separate hoses should be used in the rows one above the other.

The hoses are preferably arranged in the longitudinal direction of the press. You get by with a smaller number of hoses and still ensure a tight occupancy.

The ends of the hoses, and in particular their end pneumatic connections, can be staggered in the longitudinal direction of the hose. In this way, the tubes can be arranged in a small space and with only a small thickness of the intermediate plate, despite certain thickenings at the ends and in particular the connections, because the end connections are then staggered. It is thus advantageously also possible to make the hoses of the two rows of hoses the same length in each case.

It is particularly preferred if the hoses of the two rows of hoses are supplied with compressed air from different sides, that is to say their end connections are in each case at opposite hose ends. This will not only ensures that the hose connections, which may take up space, can be better arranged, but also that the pressing process is evened out, particularly at the beginning of the pressing process. Although, of course, the pneumatic pressure in each hose is evenly adjusted at every point, due to various influences, e.g. the inflation characteristics of the hoses, certain restoring forces in the hose material itself, etc., the hose normally begins to inflate first and only then the pressure afterwards Forward over the entire length of the hose. Due to the opposing arrangement of the blowing sides, the press plate remains horizontal without further measures being necessary. A similar effect can be achieved if adjacent hoses of the same row are connected at different ends, although the intermediate plate may then be subjected to a more uneven load.

These and other features and configurations of the invention result from the claims and also from the description and the drawing, the individual features being realized individually and in groups in the form of sub-combinations in one embodiment of the invention and in other areas and being advantageous as well as representable protective versions for which protection is claimed here. An embodiment of the invention is shown in the drawing and is explained in more detail below. Show it:

FIGURE SHORT DESCRIPTION

Fig. 1

a partially sectioned front view of a press,

Fig. 2

a shortened side view of the plate press,

Fig. 3

2 shows a perspective sectional view of a detail of a heating plate,

4 and 5

Views corresponding to Figure 1 in two working positions, and

Figure 6

a schematic arrangement and circuit diagram of the pneumatic connections of the press hoses.

DESCRIPTION OF THE EMBODIMENT

The drawings show a press 11, seen from the end face 42. The right side is cut on the one hand and shown on the other hand in the closed state, while the left side of the drawing shown in view shows the plate in the open state.

A press frame 12 has an upper and a lower support plate 13, 14, which are each composed of wide-flange double-T supports running in the longitudinal direction of the plate and thus form a stiffened structure with individual longitudinal chambers. These carrier plates are so designed that they maintain their flatness even with the strongest achievable pressing pressures.

At their four corners, the long rectangular support plates 13, 14 are connected to one another by vertical supports 15, which protrude from the underside above the lower plate 14 and have rollers 16 there, so that the press can be moved easily.

Two rows of tubes 20, 21 are arranged on the lower carrier plate 14, each underlaid by intermediate plates 17, 18. They consist of hoses 19 made of flexible material, for example rubber or plastic, possibly with fabric inserts or the like, and extend over the entire length of the press (see FIG. 2). The hoses of the two rows of hoses are of equal length, but, as can be seen from FIG. 2, are offset from one another in such a way that their ends 22 and / or possibly connections 23 are offset from one another. Each hose has a pneumatic connection 23 which is supplied by one or more distributors 24 (in FIG. 6: two distributors) and a common compressed air connection 25. This is preceded by a single pneumatic circuit 26, not shown, which is supplied by a conventional compressed air network 27 or a compressor.

The pneumatic circuit 26 (FIG. 6) contains a pressure regulator 50, on which the desired pressing pressure can be set. This pressure can be read off a manometer 51. A switched in the pneumatic line 52 safety solenoid valve 53 ensures that the press can only be closed by pressurization when a switch 54 is closed, which is part of a protection against accidental contact, for example by a safety line running around the press. In conjunction with switch 54, it ensures that the press cannot be closed as long as an operator still has a hand in the press or the like.

The trigger pulse for closing the press is given via a valve 55 and a button 56. The pressure is released to open the press via a 3-way ball valve 57 with a large outlet cross section, which may discharge the compressed air from the hoses via a silencer 58.

A safety valve 59 secures the pneumatic system against excess pressure.

A pressure transfer valve 61 is provided in a pneumatic line 60 that branches off behind the pressure regulator, but upstream of the safety valve 53. This is a non-electrically operated, but exclusively pneumatically operated valve, which has a control feedback 62 in the press direction. It can be set so that it opens when the pressure falls below a set value and compensates for any pressure losses in the system.

Fig. 1 shows that the tubes of both rows are arranged parallel to each other and one above the other. Their spacing is to be chosen at least so large that the hoses can lie next to one another on the intermediate plates 17, 18 in the flat, ie unfilled state.

A heating plate 29 lies on an upper plate 28, which covers the upper row of tubes, and is vertically movable together with the latter. A corresponding heating plate 29 is also accommodated on the underside of the upper carrier plate 13. Their heating surfaces facing each other form the upper and lower pressing surfaces 30.

The structure of the heating plates 29 can be seen from FIG. 3. The base body 31 of the heating plate is plate-shaped and has grooves 32 on the top for receiving heating conductors 33. The base body is made of aluminum. The heating conductors 33 contain electrical heating resistors 34, which are surrounded by electrical insulation 35, for example by means of multiple glass fiber braiding and braiding with a protective film made of polytetrafluoroethylene (PTFE).

The grooves 32 are covered by a cover plate 36 in the form of a sheet made of a good heat-conducting alloy which is attached to the base body 31 by gluing.

The base body 31 is underlaid by an insulating layer 37 made of high-pressure mineral fiber, under which a high-pressure insulating plate 38 made of highly compressed fiber material (chipboard or the like), optionally with a phenol resin bond, is arranged. This heating plate has very good heat transfer properties towards the pressing surface 30, while the rear is provided with an effective insulation that can withstand the high pressing pressures.

2, 4 and 5 it can be seen that the lower heating plate 29 is displaceably guided relative to its substructure. For this purpose, the heating plate 29 has guide strips 65 on two of its outer longitudinal sides, which extend along the outer edges 66 of the insulating plate 38. This is firmly connected to the plate 28 covering the hoses 19 upwards, while the heating plate 29 rests on it only in a pressure-transmitting manner.

Using a handle 67 (FIGS. 4 and 5), the heating plate, sliding on the insulating plate 38, can in the example shown be pulled out of the press frame by about half until a stop 68 stops the further displacement and thus the heating plate 29 tilts prevented. With appropriate comprehensive guidance, however, further pulling out could also be permitted.

It can also be seen that the electrical connection of the lower heating plate takes place via a flexible cable 69 from a connecting device 70, so that the heating plate movement is possible is. The heating plate can thereby be partially pulled out of the press for easier loading and / or cleaning.

The heating conductors are provided with a heating control, which is not shown in detail and can also contain thermal control elements for heating.

FUNCTION

The press works as follows:
In the open state of the press (Fig. 1 left), the lower pressing surface 30 is loaded with the material to be pressed, the press gap 40 being quite large and allowing convenient loading. The pull-out of the heating plate 29 (FIG. 5) further facilitates the loading. The hoses 19 in the hose rows 20 and 21 are depressurized and emptied, so that they form two flat layers 41.

After loading, compressed air is admitted into the hoses 19, namely in both positions from two different end faces 42 of the press (FIGS. 2 and 3) via the pneumatic circuit 26 and the distributors 24 and the pneumatic connections 23. For this purpose, the pressure regulator 50 is set to the desired pressing pressure and the button 56 is actuated so that the valve 55 opens. The safety valve 53 stops the pressure build-up when it is closed by opening the safety switch. The hoses fill up, lifting the intermediate plates 17 and 28 and the heating plate 29 fastened thereon and the workpiece placed thereon, and finally pushing them against the underside of the upper one Heating plate 29. Both plates can be heated.

The uniform application of pressure to the entire pressing surface by the hoses results in a very uniform contact pressure without the need for major mechanical effort. It is only necessary to ensure that the intermediate plates 17 and 28 and the lower heating plate 29 can move vertically. By arranging, for example, eight tubes per row of tubes with a freely inflated diameter of, for example, 80 mm, which run parallel to each other at a mutual distance of about 130 mm over the entire press length of, for example, 2.5 m, a press stroke of about 120 mm is possible guarantee. The hoses are clamped at their ends between guide strips 43, which also ensure the necessary spacing of the hoses from one another.

The per se circular, flexible hoses 19 lie flat against the plates 17, 18, 28 and thus transmit the pressure well distributed. Since the valve 55 had closed again after the button 56 had been released, the pressure take-over valve 61 ensures that the pressure set there or at the pressure regulator 50 is not fallen below if a pressure loss occurs due to leakages.

After the machining time, the air is released from the hoses 19, specifically via the ball valve 57 and reducing the pressure on the regulator 50, as a result of which the lower pressing surface is lowered and the workpiece can be removed.

Claims (11)

Press, in particular plate press for woodworking, with press drive by pneumatically expandable hoses (19), characterized in that at least two rows (20, 21) of hoses (19) are provided one above the other. Press according to claim 1, characterized in that at least one vertically movable rigid intermediate plate (17) is provided between the rows of tubes (20, 21). Press, in particular according to claim 1 or 2, characterized in that it has a rigid, frame-shaped press frame (12) with a stiffened upper and lower support plate (13, 14), preferably the upper support plate (13) on its underside and / or the upper row of tubes (20) carries on its upper side a heating plate (29) forming a pressing surface (30), the heating plate (29) in particular having a plate-shaped base body (31) with electrical heating conductors (33) inserted in grooves (32) are covered by a cover plate (36) and is underlaid with a high-pressure insulating plate (38). Press according to one of the preceding claims, characterized in that the hoses (19) of the hose rows (20, 21) each lie vertically one above the other. Press according to one of the preceding claims, characterized in that the hoses (19) are arranged in the longitudinal direction of the press. Press, in particular according to one of the preceding claims, characterized in that the hoses (19) in one or more rows of hoses (20, 21) with their ends (22) and in particular with their end pneumatic connections (23) offset in the longitudinal direction of the hose arranged, and preferably the tubes (19) of the tube rows (20, 21) are each of the same length. Press according to one of the preceding claims, characterized in that the hoses (19) of different hose rows (20; 21) provided on one side with end pneumatic connections (23) have the end pneumatic connections (23) on different ends (22) of the hoses (19) exhibit. Press according to one of the preceding claims, characterized in that in a row of hoses (20, 21) adjacent hoses (19) alternately have end pneumatic connections (23) arranged at one or the other end (22). Press according to one of claims 3 to 8, characterized in that the lower heating plate (29) is guided substantially horizontally at least partially over a press frame. Press according to claim 9, characterized in that the heating plate is displaceably guided on the insulating plate which supports the heating plate. Press according to one of the preceding claims, characterized in that the pneumatic press drive has a pressure take-over valve which, after a preferably pulse-controlled pressure build-up in the hoses (19), keeps this pressure above a predetermined value.

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