DE8629460U1 - Hydraulic quick lift press - Google Patents

Description

J. Dieffenbacher GmbH & Co.

Description ''

Hydraulic quick lift press

The invention relates to a hydraulic high-speed press according to the preamble of claim 1. When forming, coating and pressing large-area material parts with a low wall thickness made of plastic, plastic composites or fiber-reinforced plastic mats into molded parts, extremely rigid presses with high pressing precision and high pressing pressure are required. In automobile construction, too, the larger molded parts previously made of sheet steel, such as car doors, car roofs, etc., are now being made of plastic or plastic composites. Many new plastics and plastic combinations have been developed for this purpose that have the required properties. However, fiber-reinforced plastic mats or plastic sheets can also be used as starting materials, which are compressed and deformed in the press when cold or heated. In particular, the shaping of large-area body parts with extremely low wall thickness requires precise parallel guidance of the molded parts in order to avoid different thickness ranges in the workpiece.

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To meet these requirements, hydraulic fracturing machines according to SB-OS 32 &ogr;7 242 are known.

In order to meet the high requirements described above, such a milling machine consists of a high upper milling beam that is adjustable on long lateral round columns and serves as a press table and an unfavorably high lower milling beam with raised

; set press cylinders and feeding table existing press

'-, lower part. In this face the upper part is attached to the

i! lund columns initially jammed press beam unlocked

and pulled into the lower working position on the round columns. The upper press beam is then clamped again on the round columns, after which the lower mold half with the lower jaw beam is pressed upwards against the material part via the hydrostatically mounted press cylinders for compaction and deformation. Due to the large amount of play that must be specified for guiding the upper press beam on the round columns, parallel guidance and adjustment of the mold halves with the required accuracy is hardly achievable.

However, the process and material technology developments in the processing of thermosetting and thermoplastic fiber-reinforced materials require further

a) extremely short pressure-free lay times for the

relatively highly accelerated heat-curing materials (e.g. polyester resins for large SMC molded parts) or preheated thermoplastic materials that are placed in the cold tool,

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b) short pressure build-up times in order to get from material contact (between male and female molds) to forming with a forming time of = < 1 sec.

Fulfillment of the conditions according to a) and b) is the prerequisite for qualitatively perfect parts, e.g. in the case of pre-curing or too rapid cooling of the material that has not yet been formed or in the case of b) in the case of fast-reacting materials, to ensure formation even with long flow paths and narrow flow cross-sections.

In addition to this requirement profile for so-called "plastic forging", it is also necessary to ensure high molded part accuracy and uniform structural strength or a corresponding uniformly thin surface coating in the tool itself.

c) that an exact parallel control is ensured during the rapid descent of the press table and during the pressing process within very narrow limits (measured over the 4 corner points of the press table).

The invention is based on the object of creating a hydraulic high-speed press which, while fulfilling the above three requirements a) b) and c, enables extremely short pressing cycles.

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Are the measures and features listed in claims 2 to 6 advantageous further training?

6 and improvements of the % specified in claim 1

Quick lift press possible. j. §

The advantages achieved by the invention consist of

in particular in the fact that practically a shock- and wear - free coupling is achieved by the travel-synchronous and force-locking clamping of the pressure rods with small effective masses, whereby the technical implementation is made possible by the hydraulic damping and automatic compensation of the connected masses in the pre-tensioned pressure cushions. The neutralization of the weight of the pressure rods and the pistons advantageously promotes shorter braking times, greater speed for the idle stroke distance that can be traveled, and high closing speeds due to the remaining small masses. This results in extremely short rest times for the material to be formed from the time it is placed in the die to the start of forming and thus better formability right up to the outermost corners of the workpiece.

Another advantage is that the control and regulation measures as well as the structural design ensure that the parallel running accuracy is already ensured when the die is inserted into the guides and plunge edges of the die before the material contact begins.

Another advantage is the structural unity of the

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hydraulic clamping sleeve locking with the hydraulic short-stroke cylinder piston arrangement for short pressure build-up times, whereby the use of the short-stroke cylinders enables particularly high

Press speeds are possible. With short-stroke cylinder piston arrangements, the required energy consumption as well as the oil quantities to be controlled and regulated are very low and due to the low oil volume in the cylinders, the pressure build-up time is very short due to the low compression volume of the oil column, i.e. the oil quantity to be compressed is approx. 20 times less than in a fully hydraulic system. Smaller oil quantities moved again support an exact NC-controlled movement of the press ram during the closing and pressing stroke within a narrow tolerance range of the "target-actual deviation" according to the specified speed, braking and pressing pressure profile.

In comparison to other known short-stroke press systems, the quick-stroke press according to the invention does not require any complex controls for uninterrupted ram movement or for synchronous movement between ram and press pressure system.

As a result, the inventive high-speed press

a shorter pressing cycle for the workpiece to be produced and thus higher output with higher quality and less waste as well as a longer service life of the tools by protecting the plunge edges.

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An embodiment of the invention is shown in the drawing and is described in more detail below:

Show it:

Pig. 1 in elevation and section the

hydraulic clamping sleeve locking and the short-stroke cylinder piston arrangement of the quick-stroke press according to the invention,

fig. 2 the high-speed press according to the

Invention in elevation and section and

Fig. 3 is a path-time-pressure diagram for the high-speed press according to Fig. 2.

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The embodiment according to Figure 2 shows a hydraulic high-speed press in a frame construction, consisting of the press frame 1 with the upper crosshead 15 and the press table 14. Between the crosshead 15 and the press table 14 is the press ram 6, which carries the upper tool half or die 28 and can be raised and lowered by means of the hydraulic high-speed drive 9 and 10. The high-speed drive consists of the ram 9 attached centrally to the ram 6 and the hydraulic cylinder-piston arrangement 10 anchored in the crosshead 15. The press ram 6 is attached to two or four (depending on the press design) pressure rods guided in the crosshead 15, with the short-stroke cylinder arrangement 4, 8, 11 and 12 interposed. The hydraulic clamping sleeve lock 2, 3, 7 and 13 and the short-stroke cylinder arrangement 4, 8, 11 and 12 operatively connected to it form a structural unit with the pressure rods 5, whereby the pressure rods 5 are designed to form pistons 8 on their front side.

Pig. 1 shows in section the arrangement of a pressure rod with hydraulic clamping sleeve locking 2, 3, 7 and 13 and the hydraulic short-stroke cylinder arrangement 4, 8, 11 and 12 for the pressing pressure. By introducing pressure medium into the supply line 13, the diaphragm 7 generates pressure on the clamping sleeve 3 and the pressure rod 5 is non-positively locked to the cylinder 2. Since the cylinders are anchored in the crosshead 15, the pressure rods 5 are

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At the beginning of a pressing cycle, the clamping sleeve lock 2, 3, 7 and are unlocked in the upper position of the ram 9. With the start of the controlled downward movement by the hydraulic cylinder piston arrangement 1o, the pressure rods 5 are lowered with the press ram 6 and the die 28. Immediately before the two tool halves, die 28 and male die 29, come into contact, when counter-contact 18 hits stop 16, the downward movement of the press ram 6 and the pressure rods 5 connected to it in a form-fitting manner is braked. With the travel-synchronous coupling, only the relatively small mass of the pistons 8 and the pressure rods 5 connected to them in a form-fitting manner need to be accelerated against the pressure cushion 11, which is slightly pre-tensioned in accordance with its own weight, from speed V=0 mm/sec to the braking speed of the press ram 6. The force-fitting

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Coupling by means of the compression springs 3, 7 and 13 can thus take place without interrupting the movement of the press ram, without impact on the mass of the piston 8 and the pressure rods 5 in a dampened manner. When the stop is touched by the counter contact 18, the press pressure build-up is initiated and the parallel running control is started. A servo switching valve that reacts proportionally to the supplied pressure medium volume is directly assigned to each cylinder as an actuator. The mechanical stops 16 and 17 are adjustably attached to the guide rails 19 in order to be able to produce molded parts 31 of different thicknesses. The travel movement of the ram 9 can also be controlled and regulated via a central time and/or position measuring system.

Fig. 3 shows in a path-time-pressure diagram, with a schematic representation of the mold parts 28 and 29, the inventive manufacturing process of a workpiece 31 from the start of the ram 9 at 21 to the end of the compression time at 33. The ram stroke is shown on the abscissa and the closing speed on the ordinate. The speed profile curve shows the start at 22 and the end at 23 of the coupling between the cylinder 2 and the pressure rods 5. At the same time, the parallel running control begins at 23. While the material contact begins at 25, the arrows at 26 show the short pressure build-up time due to the short stroke design of the cylinders 4. After the pressure build-up 26, the actual

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Press pressure, :wie"hach, -rent's^u ₁ J&pressure profile drawn. The time sequence of a press cycle is shown at the bottom by the arrow limits "idle stroke" and "press stroke" with pressure build-up time, whereby the time for locking or coupling the pressure rods 5 is also drawn with &ogr;,3 sec.

^! is. With 27 the required idle stroke is the clearance

for the loading and unloading robot.

The fast ram movement of approx. 1ooo mm/sec.

Closing speed is briefly until the touch of the

'. leek edges 2o over a precisely specified speed

; and braking profile. With 24 the path in the

assumed example for a parallel controlled

ä Press stroke until the end of the forming of the pressing material

btw. molded part 31 is designated to thickness 32.

Claims (6)

Anton Hartdegen Patent Engineer. "*· · Geisenbtuh:ni* Angerfeldstr. 12, IeL 0.8105/8127 * Maschinenfabrik J. Dieffenbacher GmbH & Co. E &rgr; -p i &eegr; g e &eegr;&tgr;&ggr;-&Igr;&ggr; «nsprüch e 1. Hydraulic high-speed press in frame construction with press table, crosshead and press ram movable between them for forming, coating and pressing large-area material parts with low wall thickness made of plastic or plastic composites or of bevel-reinforced plastic mats into molded parts, with a press ram supporting the upper half of the mold, which can be raised and lowered by a hydraulic high-speed device for the idle stroke and a hydraulic short-stroke device for the working stroke, characterized in that the press ram (6) can be raised and lowered in the idle stroke by a hydraulic high-speed travel drive (9 and 10) acting centrally in the crosshead (15) and is guided in a sliding manner by means of pressure rods (5) in the crosshead (15), the pressure rods (5) after the idle stroke via a hydraulic clamp sleeve lock (3, 7 and 13) ■ · I· ··· ·· Il &bull; 1 I 1 ■ I » ) > ·· ·· ■ I > JJl. > 1 ■ » ·· can be coupled to the ring cylinders (2) anchored in the crosshead (15) in a synchronous and force-locking manner, the working stroke can be carried out via short-stroke cylinders (4) which are attached to the top of the press ram (6) and via pistons (8) on the front sides of the pressure rods (5), whereby the plunger pistons (8) are pre-tensioned against the short-stroke cylinders (4) under hydraulic counterpressure before locking. 2. Hydraulic quick-stroke press according to claim 1, characterized in that the counterforce built up in the pressure cushions (11) is kept slightly greater than the total weight of all pressure rods (5) and pistons (8). 3. Hydraulic quick-stroke press according to claim 1 and 2, characterized in that the hydraulic clamping sleeve lock (3, 7 and 13) and the hydraulic short-stroke cylinder piston arrangements (4 and 8) form a structural unit with the pressure rods (5). 4. Hydraulic high-speed press according to claims 1 to 3» characterized in that continuously adjustable mechanical contacts (16 and 17) in the guide rails (19) of the jaw frame and highly sensitive measuring systems control a common hydraulic switching device &bull; t f I I · if i ( i I « central pressure preload in the pressure cushions (11), the hydraulic clamping sleeve lock (3, 7 and 13)» the pressure build-up in the short-stroke cylinder (4); with simultaneous parallel running control of the press ram (6) by volumetric synchronization control of the contents of the short-stroke cylinder (4). 5. Hydraulic high-speed press according to claims 1 to 4, characterized in that the high-speed travel drive (9 and 10) for the idle stroke up to shortly before the plunge edge contact (20) is carried out by a numerically controlled computer system via an exactly specified speed and braking profile. 6. Hydraulic high-speed press according to claims 1 to 5» characterized in that a proportionally reacting servo switching valve is directly assigned to each short-stroke cylinder (4) as an actuator for parallel operation control.