EP0519414A2

EP0519414A2 - Pressing apparatus particularly for sheet-like elements such as hides, fabrics, leather and the like

Info

Publication number: EP0519414A2
Application number: EP92110200A
Authority: EP
Inventors: Carlo Bianchini
Original assignee: VIPA Srl Studio Progettazione Rappresentanze Conciarie
Current assignee: VIPA Srl Studio Progettazione Rappresentanze Conciarie
Priority date: 1991-06-19
Filing date: 1992-06-17
Publication date: 1992-12-23
Also published as: IT1248499B; EP0519414A3; ITMI911667A0; ITMI911667A1

Abstract

The pressing apparatus particularly for sheet-like elements such as hides, fabrics, leather and the like, comprises, inside a supporting frame (1), a fixed abutment plane (5) and a movable abutment plane (6) which can move with respect to the fixed abutment plane (5); the sheet-like element to be pressed can be interposed between the abutment planes (5,6). The pressing apparatus further comprises a movable base (10) which supports the movable abutment plane (6), by the interposition of piston means, and is connected to the frame (1) through translatory motion means (15) for positioning it in an upper or working position and in a lower or loading and unloading position. Supporting means (20) are interposed between the movable base (10) and the frame (1) and can engage the movable base (10) in the upper position in order to support the movable base (10) during the actuation of the piston means in order to press the sheet-like element interposed between the planes (5,6).

Description

The present invention relates to a pressing apparatus particularly for sheet-like elements such as hides, fabrics, leather and the like.
As is known, in many industrial fields it is necessary to have presses with a relatively large working surface in order to press sheet-like elements such as for example hides, fabrics, leather and the like.
The problem to be met with these types of process is constituted by the fact that it is necessary to perform the approach and spacing strokes of the press surface in an extremely short time, so as to reduce dead time, and to exert considerable high pressures.
The solutions of the known art teach hydraulic presses, having a hydraulic cylinder, arranged below the movable surface of the press, which during the initial approach step is raised by independent means, whereas the oil or working fluid is freely drawn into the chamber of the cylinder.
Due to the considerably large volumes, it is necessary to use very large inflow sections, with consequent constructive complications related to the closure and discharge valves.
Therefore, a compromise is generally resorted to, using cylinder cross-sections which are relatively large but definitely smaller than the surface of the press, so that it is necessary to significantly increase the pressure in the cylinder in order to exert the required pressures.
This fact introduces another mechanical problem, since it is difficult to maintain the perfect planarity of the abutment planes when subjected to load.
On the other hand, the conceptually ideal solution of having a cylinder with an extremely large cross-section is not practical due to the excessively large amounts of working fluid which would have to be fed and discharged from the cylinder in extremely short times.
Other types of press adopt a structure which can be defined mechanical, since the surfaces of the press are moved by means of systems with an eccentric element or the like, which offer the advantage of having very small movement times but, on the other hand, create great problems in adjusting the strokes, since even a small shift of the stroke of the surface entails difficult and very expensive operations for calibrating the eccentric element or the connecting rod systems which perform the movement.
Furthermore, these adaptations cannot be performed continuously during the normal production cycle.
The aim of the invention is indeed to solve the problems described above by providing a pressing apparatus particularly for sheet-like elements such as hides, fabrics, leather and the like, which allows to combine the typical advantages of hydraulic presses and mechanical presses without having their disadvantages.
Within the scope of the above aim, a particular object of the invention is to provide a pressing apparatus wherein it is possible to use, for the press surface, one or more cylinders having an extremely large cross-section without however having to control a considerable flow of incoming or outgoing oil.
Another object of the present invention is to provide a pressing apparatus wherein the time required to move the press surface is extremely short, thus significantly reducing the dead times of the process.
A further object of the present invention is to provide a pressing apparatus which allows to have a distribution of the load on the press surface which is extremely uniform so as to obtain the best treatments.
Not least object of the present invention is to provide a pressing apparatus which allows to obtain high working pressures without thereby having to use high pressures in the hydraulic circuit.
Not least object of the present invention is to provide a pressing apparatus particularly for sheet-like elements such as hides, fabrics, leather and the like which can be easily obtained starting from commonly commercially available elements and materials and is furthermore highly competitive from a merely economic point of view.
This aim, the objects mentioned and others which will become apparent hereinafter are achieved by a pressing apparatus particularly for sheet-like elements such as hides, fabrics, leather and the like, according to the invention, which comprises, inside a supporting frame, a fixed abutment plane and a movable abutment plane translatable with respect to said fixed abutment plane, the sheet-like element to be pressed being interposable between said abutment planes, characterized in that it comprises a movable base which supports said movable abutment plane, by the interposition of piston means, and is connected to said frame through translatory means for positioning it in an upper or working position and in a lower or loading and unloading position, supporting means being furthermore provided, said supporting means being interposed between said movable base and said frame and being engageable with said movable base in said upper position in order to support said movable base during the actuation of said piston means for pressing the sheet-like element interposed between said planes.
Further characteristics and advantages will become apparent from the description of a preferred but not exclusive embodiment of a pressing apparatus particularly for sheet-like elements such as hides, fabrics, leather and the like, illustrated only by way of non-limitative example in the accompanying drawings, wherein:

figure 1 is a partially sectional schematic view of the pressing apparatus according to the invention;
figure 2 is a sectional plan view of the pressing apparatus, taken along the plane II-II of figure 1;
figure 3 is a schematic sectional view of the pressing apparatus according to the invention, taken along a vertical plane;
figures 4 and 5 illustrate the supporting means respectively at the end of the movement of the movable base and during the actuation of the press;
figure 6 is a view of the detail of the sliding means of the supporting means;
figure 7 is a view of a particular embodiment of the piston means;
figure 8 is a diagram of the hydraulic layout of the press.

With reference to the above figures, the pressing apparatus particularly for sheet-like elements such as hides, fabrics, leather and the like, according to the invention, comprises a supporting frame, generally designated by the reference numeral 1, which is of a substantially conventional type and has a lower cross-member 2 which is joined by means of uprights 3 to an upper cross-member 4.
A fixed abutment plane 5 is supported inside the frame 1, is usually connected to the lower face of the upper cross-member 4 and generally supports a plate which bears the impression of the pattern or the like to be impressed on the sheet-like element being treated.
A movable abutment plane 6 is arranged opposite to the fixed abutment plane 5, can translate with respect to the fixed abutment plane and supports, as usual, a layer made of felt or the like on which the sheet-like element to be pressed is applied.
Advantageously but not necessarily, it is possible to provide an automatic conveyor-belt loader for moving the sheet-like element to be treated below the press planes.
The movable abutment plane 6 is supported by a movable base 10 with the interposition of piston means, generally designated by the reference numeral 11, which will be described in greater detail hereinafter.
The movable base 10 is supported by the frame 1 and more precisely by the lower cross-member 2 through translatory means constituted by hydraulic pistons 15. The pistons 15 are arranged so that one is located at each corner of the movable base and have the function of producing the stroke for the approach and spacing of the movable abutment plane 6 toward or away from the fixed abutment plane 5.
Supporting means are interposed between the movable base 10 and the frame 1 and are advantageously defined by an upper comb 20, which is connected to the lower face of the movable base, and by a lower comb 21, which is associated with the lower cross-member 2.
The combs 20 and 21 are mutually intercalatable, when the movable base is in its lower or loading and unloading position, whereas they can be mutually superimposed, thus constituting a mechanical supporting element for the movable base, when said movable base is in its upper or working position and the pressing action is in progress.
The lower comb 21 can move transversely with respect to the upper comb 20 in order to arrange it in its two different working positions.
More in detail, during the initial approach of the movable abutment plane toward the fixed abutment plane, the pistons 15 are actuated by means of a pump 30 for feeding oil or a working fluid which, by means of a first distribution unit 31, feeds the pressurized oil into the pistons 15 until the movable base moves the abutment plane 6 proximate to the fixed abutment plane 5.
An ascent sensor 32 is furthermore provided which detects the approach of the movable abutment plane to the fixed abutment plane and activates a brake so as to slow down the last step of approach.
A descent sensor 33 is also provided which detects the retraction or lowering of the movable base, activating a descent brake on the last distance.
The ascent of the pistons 15 occurs until a device for sensing the position of the movable base, which can be constituted by a photocell or by a microswitch, both designated by the reference numeral 40, indicates that the combs 20 and 21 have moved away from one another, i.e. that the upper comb 20 has exceeded the height of the lower comb.
Once the movable abutment plane is arranged proximate to the fixed abutment plane, the microswitch 40 intervenes and activates a second distribution unit 41 which feeds the pressurized fluid to a transverse translatory motion cylinder 42 which acts on the lower comb, translating it until the teeth of the comb 20 are located at the teeth of the comb 21.
When the teeth are positioned, a first transverse translatory motion sensor 43 is activated and stops the translatory motion.
In order to facilitate the translatory motion of the lower comb 21, the cross-member 50 for supporting the lower comb 21 is mounted on rollers 51 with a horizontal axis which are supported, below said cross-member, by pairs of vertical pivots 52 with the interposition of elastic means 53 constituted, for example, by Belleville springs which, when no pressure bears on the movable base, in practice allow the rollers 51, which act as sliding means, to protrude, whereas when pressure is present the rollers retract into the cross-member 50 which rests on the frame 1.
For the sake of completeness in description, it should be furthermore added that lateral guiding bearings, designated by the numeral 55, are provided and guide the translatory motion of the lower comb 21.
Once the lower comb 21 is positioned, the intervention of the first vertical translatory motion sensor 43 activates a third distribution unit 60 which feeds oil to the piston means interposed between the movable base and the movable abutment plane.
It should be noted first of all that the stroke which must be performed by the movable abutment plane is extremely short, since all the approach stroke has been performed by the pistons 15 which have raised the movable base, so that the amount of oil to be fed is the amount required in order to perform the last very short distance of the translatory motion and to exert the required pressure.
Furthermore, since the amounts of oil to be fed are very small, it is possible to use piston means which have an extremely large useful cross-section which approximately corresponds to the useful area of the movable abutment plane.
As schematically shown in figure 1, it is possible to provide two circular pistons, designated by the numeral 70, which are supported by the movable base and are sealingly movable within a cylindrical chamber 72 which is defined on the lower face of the movable abutment plane.
It is furthermore possible to use a piston with a rectangular cross-section which approximately matches the cross-section of the press surface, as schematically shown in figure 2, and furthermore, since the stroke to be performed is extremely short, it is possible, as illustrated in figure 7, to join the piston part 75, which is connected to the movable abutment plane, to the cylinder part 76, which is connected to the movable base, by means of a sealing membrane 77 which allows to avoid the execution of structurally complicated guides and of expensive machinings for surface treatments.
It is furthermore conceptually possible to provide a complete membrane in order to close the chamber where pressurized oil is fed; the piston part connected to the movable abutment plane may rest on said membrane, so as to exert the required pressure.
It should be noted that this solution is possible first of all because the strokes to be performed are extremely short, on the order of millimeters, and secondly because, since the useful cross-section of the piston arranged below the movable abutment plane is substantially equal to the useful cross-section of said movable abutment plane, it is possible to use oil pressures which are low and in any case approximately equal to the pressure values to be obtained between the press surfaces.
In practical operation, once the movable base has been positioned so as to move the movable abutment plane into contact with the fixed abutment plane, the fluid fed by means of the third distribution unit 60 is fed into the previously described piston means until the required pressure is reached.
Once the pressing time, which is normally set on the timer, has elapsed, the distribution unit 60 connects the piston means to the discharge until it is halted by the position detector, schematically designated by the reference numeral 40 in figure 7, and at this point the pumping means 30 deliver oil to the translatory motion cylinder 42 until its actuation is interrupted by the second translatory motion sensor 44.
In this manner it is possible to automatically adjust the amount of oil which remains in the piston means, thus adapting to the different thicknesses of the felts or impression plates.
As soon as they receive the enable signal from the second sensor 44, the single-action pistons 15, inside which pressure had been maintained, discharge their pressure, activating the first distribution unit 31 and allowing a fast spacing-apart of the movable abutment plane until the second descent sensor 33 intervenes and brakes the last portion of the stroke.
From what has been described above it can thus be seen that the invention achieves the aim and objects and in particular the fact is stressed that a press is provided which is able to combine the typical advantages of mechanical presses and of hydraulic presses, since it allows to perform extremely rapid approach and spacing, without having to use considerable amounts of fluid, since the translatory step is performed by means of the pistons 15.
Furthermore, by performing the pressing step with the help of the piston means, which are hydraulically actuated, it is very easy to perform calibration, with the possibility of exerting high pressures between the planes of the press without however having large amounts of oil that must enter the piston means or be discharged therefrom, since the stroke required to perform the pressing step is extremely small.
Furthermore, the use of a piston with a rectangular cross-section which is very close to the surface of the movable abutment plane allows to have oil pressures being substantially comparable to the pressures exerted between the press surface, with considerable uniformity in stress distribution.
To the above it should be added that the use of very small strokes for the piston means which perform the actual pressing step in the press allows to considerably simplify the structure, since it is possible to use a sealing membrane between the fixed part and the movable part of the piston means.
The invention thus conceived is susceptible to numerous modifications and variations, all of which are within the scope of the inventive concept.
All the details may furthermore be replaced with other technically equivalent elements.
In practice, the materials employed, as well as the contingent shapes and dimensions, may be any according to the requirements.
Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims

Pressing apparatus particularly for sheet-like elements such as hides, fabrics, leather and the like, comprising, inside a supporting frame (1), a fixed abutment plane (5) and a movable abutment plane (6) which is movable with respect to said fixed abutment plane (5), the sheet-like element to be pressed being interposable between said abutment planes (5,6), characterized in that it comprises a movable base (10) which supports said movable abutment plane (6), by the interposition of piston means (11), and is connected to said frame (11) through translatory means (15) for positioning it in an upper or working position and in a lower or loading and unloading position, supporting means (20,21) being furthermore provided, said supporting means (20,21) being interposed between said movable base (10) and said frame (11) and being engageable with said movable base (10) in said upper position in order to support said movable base (10) during the actuation of said piston means (11) for pressing the sheet-like element interposed between said planes (5,6).
Pressing apparatus according to claim 1, characterized in that said piston means (11) have a useful cross-section which is close to the useful area of said movable abutment plane (6).
Pressing apparatus according to the preceding claims, characterized in that said piston means (11) comprise at least one pair of circular pistons (70) which are associated with said movable base (10) and are sealingly movable in cylindrical chambers (72) defined below said movable abutment plane (6).
Pressing apparatus according to one or more of the preceding claims, characterized in that said piston means (11) comprise a piston with a rectangular cross-section which substantially corresponds to the useful area of said fixed abutment plane (5).
Pressing apparatus according to one or more of the preceding claims, characterized in that said piston means (11) comprise a piston-like part (75) which is connected to said movable abutment plane (6) and a cylinder-like part (76) which is connected to said movable base (10), said parts being mutually connected by a sealing membrane (77) which sealingly delimits the working fluid inflow chamber.
Pressing apparatus according to one or more of the preceding claims, characterized in that it comprises a complete membrane adapted for sealingly closing the chamber in which the working fluid can be introduced, a piston-like part (75) connected to said movable abutment plane (6) resting on said complete membrane.
Pressing apparatus according to one or more of the preceding claims, characterized in that said translatory means comprise a plurality of hydraulic pistons (15) which act between said movable base (10) and said frame (1).
Pressing apparatus according to one or more of the preceding claims, characterized in that said supporting means (20,21) comprise an upper comb (20) which is connected to the lower face of said movable base (10) and a lower comb (21) which is associated with said frame (1).
Pressing apparatus according to one or more of the preceding claims, characterized in that said lower comb (21) and said upper comb (20) can be mutually intercalated, when said movable base (10) is in said lower position, and can be mutually superimposed when said movable base (10) is in said upper position.
Pressing apparatus according to one or more of the preceding claims, characterized in that it comprises means (42) for transverse translatory motion which act on said lower comb (21) to make it translate transversely with respect to said upper comb (20).
Pressing apparatus according to one or more of the preceding claims, characterized in that it comprises a working fluid feed pump (30) which is connected to said hydraulic pistons (15) by the interposition of a first distribution unit (31), an ascent sensor (32) being furthermore provided for sensing the approach of said movable abutment plane (6) to the fixed abutment plane (5) in order to drive a brake for slowing down the last step of approach, a descent sensor (33) being furthermore provided for sensing the retraction or lowering of said movable base (6), and for activating a descent brake on the last portion.
Pressing apparatus according to one or more of the preceding claims, characterized in that it comprises a device (40) for sensing the position of the movable base for sensing that said upper comb (20) has exceeded the height of said lower comb (21), said position sensing device (40) driving a second distribution unit (41) which is connected to said supply pump (30) in order to drive a cylinder (42) for the transverse translatory motion of said transverse translatory motion means (42) for the translatory motion of said lower comb (21).
Pressing apparatus according to one or more of the preceding claims, characterized in that it comprises a first transverse translatory motion sensor (43) adapted for stopping the transverse translatory motion of said lower comb (21) and for driving a third distribution unit (60) for feeding pressurized working fluid into said piston means (42), a second transverse translatory motion sensor (44) being further provided, said second sensor (44) driving said first distribution unit (31) for the descent of said translatory motion means (15).
Pressing apparatus according to one or more of the preceding claims, characterized in that said lower comb (21) is supported by rollers (51) having a horizontal axis which are connected to a supporting cross-member (50) of said lower comb (21), said rollers (51) being supported by vertical pivots (52) with the interposition of elastic means (53) adapted for allowing the protrusion of said rollers (51) when no pressure bears on said movable base (10) and their retraction into said cross-member (50) when pressure is exerted.
Pressing apparatus according to one or more of the preceding claims, characterized in that it comprises lateral guiding bearings (55) which act on the lateral surfaces of said lower comb (21) for its transverse translatory motion.