FR2605931A1 - HYDRAULIC PRESS WITH FAST-RUNNING ARCADE FOR FORMING, LINING AND COMPRESSION OF LOW THICKNESS PARTS BASED ON PLASTIC MATERIAL - Google Patents

Abstract

HYDRAULIC PRESS INCLUDING A SLIDER 6 PERFORMING FIRST AN NO LOAD STROKE UNDER THE ACTION OF A QUICK MOVEMENT DRIVE SYSTEM 9, 10 HYDRAULIC BY BEING GUIDED FOR PUSH RODS 5 IN THE TANK 15 AND THEN A STROKE OF WORK UNDER THE ACTION OF HYDRAULIC CYLINDERS 4 WITH SHORT STROKE, THE PISTONS OF WHICH ARE IN ONE OF THE LOWER ENDS OF THE RODS 5 WHICH ARE THEN LOCKED SYNCHRONOUSLY ON THE CAP 15.

Description

FAST-RUN ARCADE HYDRAULIC PRESS FOR

  FORMATION DOUBLING AND COMPRESSION OF PARTS

  LOW THICKNESS BASED ON PLASTIC MATERIAL

  The present invention relates to a hydraulic press with a rapid stroke arch comprising a table, a marquee and a slide movable between the table and the marquee, for the forming, doubling and compression of large parts and thin thickness of wall, made of plastic or composite materials based on plastic or fiber mats impregnated with plastic, in the form of profiled parts, the upper half of the mold being carried by the slide which can be raised and lowered using a fast-moving hydraulic device for idling and a device

  hydraulic short stroke for working stroke.

  When forming, lining and compressing large parts and thin wall thickness, made of plastic, composite materials based on plastic or fiber mats impregnated with plastic, in the form of profiled parts, it is necessary to have extremely rigid, high precision and high pressure presses. In automobile construction, there is also a tendency to produce large-scale profiled parts produced hitherto in plastic or in plastic-based composite materials. sheet steel, such as doors, pavilions, etc. Numerous new plastics and combinations of plastics having the required characteristics have been developed for this purpose. As starting material, however, it is also possible to use fiber mats impregnated with plastics material or sheets of plastics material, which are compressed and shaped cold or hot in the press. In particular, the shaping of large body parts with extremely small wall thicknesses requires exact parallel guidance of the tool parts (mold) so as not to obtain differences in thickness on the part. Hydraulic presses are known according to patent application DE-32 07. 242 which meet these requirements. In order to meet the severe requirements mentioned above, such a press is composed of a very high upper bed (upper sole), movable on long lateral circular columns and serving as a press table, and a part lower press of great height, composed of a lower bed base (lower sole) on which are mounted press cylinders and a press table. On this press, the upper box spring first locked on the circular columns is unlocked and pulled * on the circular columns to the lower working position. The upper bed base is then again locked onto the circular columns, after which the lower half of the press tool is pushed with the lower bed base by the hydrostatic mounting cylinders up against the upper part of the tool in order to compression and shaping. By the large play necessarily necessary for the guiding of the upper box spring on the circular columns, a parallel guiding and an adjustment of the halves of press tool with the required precision

is hardly achievable.

  However, the processing of fiber-reinforced thermosetting and thermoplastic materials also imposes other requirements, namely: a) extremely short non-pressure rest times for the thermosetting material subjected to relatively strong acceleration (for example polyester resin for large profiled parts ) or also for preheated thermoplastic materials which are placed in the cold tool; b) short periods of pressure build-up in order to arrive, from the contact of the material with the mold parts up to the demolding, at a setting time

fit = <1 second.

  The conditions according to a) or b) must be satisfied in order to obtain qualitatively perfect parts in order to ensure, for example in the case of too rapid pre-hardening or cooling of the material not yet shaped or, in the case b) for fast-reacting materials, complete processing even with long flow paths and sections

narrow flow.

  Apart from these requirements imposed for shaping known as "plastic forging", it is necessary, in order to achieve high precision of the shaped parts as well as good form fidelity or also for the purpose of thin and uniform in the tool, that c) a parallel movement is ensured during the rapid descent of the slide and during the compression phase, within very narrow limits (measured

  on the four corners of the press table).

  The subject of the present invention is a fast-stroke hydraulic press which, by meeting the three requirements a), b) and c) above, allows cycles of

extremely short compression. -

  According to one embodiment of the invention, the slide is raised and lowered during the vacuum stroke by a hydraulic movement system with rapid movement, acting centrally in the marquee, and is guided sliding using rods pushing in the marquee; the push rods are coupled, after the idle stroke, passing through hydraulic locks with clamping sleeves, synchronously and by tightening with annular casings serving as guides for the push rods and anchored in the marquee; the working stroke is carried out by short-stroke cylinders which are fixed on the upper side of the slide and whose pistons are at the lower ends of the rods

  thrust, the pistons being prestressed under counter

  hydraulic pressure compared to small cylinders

stroke before locking.

  According to another embodiment of the invention, the slide is raised and lowered during the vacuum stroke by a hydraulic movement system with rapid movement, acting centrally in the marquee, and is guided using push rods in the marquee; the push rods are coupled, after the idle stroke, in

  passing through hydraulic locks with ..

  clamping, synchronously and by clamping with the annular pistons of differential cylinders anchored in the marquee; the working stroke is carried out by said differential cylinders, by means of annular pistons and push rods locked with these pistons, the pistons being prestressed under hydraulic back pressure by

  compared to differential cylinders before locking

age.

  The opposing force established in the cylinder pressure cushions is preferably maintained somewhat greater than the total weight of all

the push rods and pistons.

  Hydraulic locking by. clamping sleeves and the arrangement (s) of differential or short-stroke hydraulic cylinders and pistons preferably constitutes a construction unit with

the push rods.

  According to a preferred embodiment, continuously adjustable mechanical contacts in the slides of the press frame and high-sensitivity measurement systems advantageously control a common hydraulic control device for triggering in series the central pressure preload in the pressure cushions, hydraulic locking by clamping sleeves, pressure build-up in cylinders with simultaneous parallel running (synchronization) control of the slide by volumetric fluid control of the small cylinders

stroke or differential cylinders.

  Preferably, the fast-motion drive system for the idle stroke is controlled, up to proximity before the contact of the interpenetration edges of the tool, with a walking profile (speed and braking), exactly predetermined by a

  computer numerically controlled system.

  Preferably, for the purpose of parallel (synchronous) regulation, a proportional action servo valve is directly associated with each

  differential cylinder or short stroke cylinder.

  The advantages obtained by the invention reside in particular in the fact that with effective masses

  reduced, practically a coupling is obtained without

  blows and wear-free by synchronous locking by tightening the push rods, the technical realization being possible by hydraulic damping and automatic compensation of the masses added in the pre-stressed pressure cushions. The neutralization of the weight of the push rods and of the pistons favors, by the low residual masses, in an advantageous manner the obtaining of shorter braking times, of higher speeds on the path to be traveled in

  free travel, as well as high closing speeds.

  This results in extremely short rest times of the material to be shaped from the installation in the mold part until the start of the forming and therefore a better formability up to the extreme corners of the room. It is also advantageous that the control and regulation arrangements as well as the construction arrangements chosen ensure synchronous parallel running precision already when the female part of the mold (matrix) enters the slides and the edges of the mold. interpenetration of the male mold part (punch), before the start of contact with the

material to be shaped.

  Another advantage is that the hydraulic locking by clamping sleeves forms a construction assembly with the arrangement of short-stroke hydraulic piston cylinders for short periods of pressure build-up, the use of small cylinders. race allowing

  particularly high compression speeds.

  In the case of short-stroke piston cylinder arrangements, the energy consumption as well as the quantities of hydraulic fluid to be controlled and regulated are also particularly low and due to the small volume of hydraulic fluid in the cylinders, the duration d pressure build-up is very low due to the low compression volume of the fluid column, i.e. the quantity of hydraulic fluid to be compressed is approximately 20 times lower than in the case of a fully hydraulic system. Lower quantities of hydraulic fluid to be moved in turn favor high precision of the movement of the press plunger by numerical control, during the closing and compression stroke, within the narrow tolerance range of the deviation " setpoint-actual value "according to the speed, braking and pressure profiles

predetermined compression.

  Compared to other short stroke compression systems, the fast stroke press according to the invention does not require complicated controls for an uninterrupted movement of the pusher as well as for a synchronous movement between the pusher and the

  compression pressure system.

  The press in accordance with the invention with fast stroke thus provides a shorter compression cycle for the part to be produced, therefore a higher rate with better quality and a lower scrap rate, as well as an extended service life of the tools thanks to the fact that the interpenetration edges of the tool are located

  provided by synchronous parallel walking.

  Referring to the accompanying drawings, there will be described below in more detail two illustrative and nonlimiting exemplary embodiments of the subject of the invention; 1'0 in the drawings: FIG. 1 is a section of the hydraulic locking by clamping sleeves. And of an arrangement of piston-cylinder with short stroke of an embodiment of a * rapid stroke press according to invention; FIG. 2 is a section through the assembly of the fast-stroke press using the system of FIG. 1; O Figure 3 is a section of the hydraulic locking by clamping sleeves and a differential piston-cylinder arrangement of another embodiment of the rapid stroke press according to the invention; Figure 4 is a section through the entire press using the system of Figure 3;

  FIG. 5 represents a course diagram

  pressure time for the fast stroke press according to the

figure 2 or 4.

  FIG. 2 represents an exemplary embodiment of a fast-stroke hydraulic press of the arcade type, comprising a press frame 1, a marquee or upper base 15 and a table 14. Between the marquee and the table 14 is a slide 6 supporting the upper half of the mold or die 28 and capable of being raised or lowered using a rapid hydraulic drive system 9, 10. The rapid drive system comprises a pusher 9 fixed in the central position to the slide 6, and a hydraulic cylinder-piston arrangement 10 anchored in the marquee 15. The slide 6 is fixed to two (or four) push rods 5 guided in the bed base 15. A hydraulic locking device with clamping sleeves 2,3 , 7, 13 and a hydraulic arrangement of compression piston cylinders 4,8,11 and 12 which are in connection with the lock constitute a construction assembly

with push rods 5.

  It should be noted that the push rods 5

  are shaped as pistons 8 at their lower end

  better. Figure 1 is a sectional view of the arrangement of a push rod 5 of a hydraulic locking by clamping sleeve 2,3,7,13 and a short stroke hydraulic cylinder 4,8,11,12 for compression pressure. By sending pressurized fluid into the pipe 13 of an annular casing 2, the membrane 7 contained in the annular casing 2 exerts pressure on the clamping sleeve 3, the push rod 5 thus being locked by clamping relative to the annular casings. The annular casing 2 is anchored in the marquee 15, so that the push rod 5 is

  then also connected to the box spring 15.

  Already at the start or before the start of the lowering of the slide 6, pressurized fluid is sent from an accumulator into the pressure cushions 11 of the cylinders 4 in order to compensate for the weight of all the push rods 5 and all the pistons 8 relative to the bed base 15. The synchronous locking of the push rods 5 with the bed base 15 thus ensures shock-free damping of the moving masses. After locking, the additional sending of pressurized fluid through line 12 into the cylinders generates the compression pressure necessary for the compression operation, the pistons 8 pushing the slide 6 with the die 28 against the punch 29 and the table of

press 14.

  At the start of a compression cycle, the locking by clamping sleeves 2,3,7,13 is

  unlocked in the upper position of pusher 9.

  At the start of the rapid descent movement controlled by the hydraulic cylinder-piston arrangement 10, the push rods 5 descend with the slide 6 and the die 28. Nearby before the two tool halves come into contact (die 28 and punch 29), when the contact 18 reaches the hill 16, the downward movement of the slide 6 and the push rods 5 connected to the slide 6 is braked. During synchronous coupling, it suffices to accelerate the relatively small mass of the pistons 8 and therefore of the push rods 5 integral with these pistons, against the pressure cushions it slightly prestressed in

13 2605931

  depending on the dead weight, the life V = 0 rmm / sec at the braked running speed of the slide 6. Coupling using locking by clamping sleeves 2,3,7,13 can therefore take place in a damped manner , without interrupting the movement of the slide, without shock to the mass of the piston 8 and of the push rods 5. When the contact 18 touches the stop 17, the establishment of the compression pressure begins and the synchronous running regulation starts. To this end, a servo-valve having a reaction proportional to the volume of fluid under pressure introduced is associated directly with each cylinder 4. The mechanical abutments 16 and 17 are fixed in an adjustable manner in the slides 19 in order to allow the manufacture of parts 31 of different thicknesses. The movement of movement of the pusher 9 can be controlled and regulated also by a system

  central measurement as a function of time and / or route.

  The embodiment according to Figures 3 and 4 differs mainly from the embodiment of Figures 1 and 2 in that the push rods 5 'are fixed by their lower end to the slide 6 and are surrounded by an annular casing 2' comprising two 3.3 'clamping sleeves with two membranes 7 and 7'. At its lower part, the annular casing 2 'is shaped as an annular piston 8' sliding in a cylinder 4 'fixed to the marquee. 5. The cylinder 4 ′ is a differential cylinder delimiting with the annular piston 8 ′ a pressure cushion 11 ′ creating a pressure preload to compensate for the weight of the push rods 5 ′ and the annular pistons 2 ′ with respect to the cap 15, and a compartment 8 "supplied by the conduit 12 '. Apart from these structural differences, the operation of the embodiment of FIGS. 3 and 4 is comparable to that of the embodiment of the

Figures 1 and 2.

  FIG. 5 illustrates in the form of a path-time-pressure diagram, with. schematic representation of the mold parts 28 and 29, the progress of the shaping in accordance with the invention of a part 31 from the start of the pusher 9 at 21 until the end of the compression time at 33. On the abscissa, the stroke of the pusher has been represented and the closing speed on the ordinate. The speed profile curve shows at 22 the start and at 23 the end of the coupling between the annular pistons 2 (fig. 1 and 2) or the annular housings 2 '(fig. 3 and 4) and the push rods 5. At the same time, the synchronous running regulation begins at 23. Tandi: that contact with the material to be shaped begins at 25, the arrows indicate at 26 the short duration of pressure build-up due to the execution of the 4.4 'cylinders in the form of short stroke cylinders. After the pressure has been established at 26, the actual compression pressure begins at, as shown on the right as a pressure profile. The progress over time of a compression cycle is indicated at the bottom by the arrow parts "idle stroke" and "compression stroke with pressure build-up time", the time of 0.3 sec being the time of locking or coupling of the push rods 5. 27 designates the idle stroke necessary for

  allow access to the loading and removal robot.

  The rapid movement of the pusher (approximately 1000 mm / sec of closing speed) is carried out shortly before the contact of the interpenetration edges 20 with an exactly predetermined braked speed and walking profile. 24 designates in the example assumed the press stroke with synchronous regulation until the end of the shaping of the material or the part 31 to

thickness 32.

Claims (7)

  1. Hydraulic quick stroke arch press including a press table, one. marquee and a movable slide between the marquee and the press table for shaping, lining and compressing pieces of material of great extent and of small wall thickness, of plastic material or of composite materials based on plastic material or fiber mats impregnated with plastic, in the form of profiled parts, the upper half of the mold being carried by the slide which can be lowered and lifted using a hydraulic quick-moving device for the vacuum travel and a short stroke hydraulic device for the working stroke, characterized in that the slide (6) is raised and lowered during the unladen stroke by a hydraulic, fast-acting hydraulic drive system (9,10) central in the marquee (15), and is guided sliding using push rods (5) in the marquee (15), that after the idle stroke, the push rods (5) are synchronously coupled and by clamping, in steps sant by hydraulic locks with clamping sleeves (3,7, 13), with annular casings (2) serving as guides to the push rods (5) and anchored in the marquee (15), and that the working stroke is executed by short stroke cylinders (4) which are fixed on the upper side 1, of the slide (6), and whose pistons (8) are located at the lower ends of the push rods (5), said pistons (8) being, before locking, prestressed under hydraulic back pressure with respect to the short stroke cylinders (4). 2. Hydraulic quick-stroke arcade press comprising a press table, a marquee and a movable slide between the marquee and the press table for shaping, doubling and compressing large pieces of material and thin wall thickness , made of plastic or composite materials based on plastic or fiber mats impregnated with plastic, in the form of profiled parts, the upper half of the mold being carried by the slide which can be lowered and raised using of a fast-moving hydraulic device for the idle stroke and of a short-stroke hydraulic device for the working stroke, characterized in that the slide (6) is raised and lowered during the idle stroke by a system hydraulic movement drive (9,10) acting centrally in the marquee (15), and is guided sliding with push rods (5 ') in the marquee (15), only after the race to empty, the push rods (5 ') are synchronously and tightly coupled, passing through hydraulic locks with serrate bushings   (3,3'7 ', 13) with the annular pistons (2') -de.   differential cylinders (4 ') anchored in the marquee (15), and the working stroke is carried out by said differential cylinders (4') via the annular pistons (2 ') and push rods (5') locked with these pistons, said pistons (2 ')   being, before locking, prestressed under counter   hydraulic pressure in relation to the cylinders differentials (4 ').   3. Press according to claim 1 or 2, characterized in that the opposing force established in the pressure cushions (11) of the cylinders (4,4 ') is maintained somewhat greater than the total weight of all the push rods ( 5.5 ') and pistons (2,2 ').   4. Press according to any one of   Claims 1 to 3, characterized in that the   hydraulic locking by clamping sleeves (3.7, 13; 3.3 - ', 7', 13) and the hydraulic piston-cylinder arrangements form a construction assembly with the push rods (5,5 ').   5. Press according to any one of   previous claims, characterized in that   that mechanical contacts (16,17), continuously adjustable, in the slides (19) of the press frame and high-sensitivity measuring systems control a common hydraulic control device with a view to triggering the central prestressing in series of   pressure in the pressure cushions (11), of the lock   hydraulic lage by clamping sleeves (3,7,13; 3,3 ', 7', 13), of the establishment of pressure in the cylinders (4,4 '), with simultaneous parallel running regulation   (synchronization) of the slide (6) by volume control- cylinder fluid cover.   6. Press according to any one of   previous claims, characterized in that   that the fast motion drive for the idle stroke is carried out, up to proximity before the contact of the interpenetration edges (20) of the mold, with an exactly predetermined braked speed and walking profile   by a numerically controlled computer system.   7. Press according to any one of   previous claims, characterized in that   that for synchronous operation regulation, a proportional action servo valve is directly associated with each cylinder (4,4 ')