DE102011057033A1 - Press tool e.g. sheet molding compound (SMC) press tool for manufacturing mold portion such as outer casing of motor vehicle, has die that is biased with ram in direction of pressing position, if tool is opened in advance position - Google Patents

Abstract

The press tool (1) has a punch that is relatively moved together with a die (4) so that a mold cavity for forming a planar mold portion is limited. The die is biased with ram in the direction of pressing position so that a portion of ram guided along the mold cavity is partially limited, if the press tool is opened in an advance position. The ram is moved in a lower cleaning position through a lifting cylinder, so that the punch is accessed. The ram is moved into an upper cleaning position through lifting cylinder, so that dipping edge portions of ram are accessed. An independent claim is included for mold portion.

Description

The invention relates to a pressing tool, in particular an SMC pressing tool according to the preamble of claim 1 and a molded part, which is produced with such a pressing tool.

From the DE 10 2007 050 951 A1 The applicant is known to form a sheet-like body component in plastic, an outer shell and an inner shell, which give the body component a stiffness that is comparable to that of a conventional steel body component, the body component has significantly less weight. The outer shell can be produced, for example, in the SMC (Sheet Molding Compound) or RTM (Resin Transfer Molding) or LFI (Long Fiber Injection) process. In all of these methods, the molding compound is pre-mixed with virtually all necessary components, such as resins and reinforcing fibers, and then processed by pressing (SMC) or injection molding (RTM, LFI) in a tool.

In the course of increasing lightweight construction in automotive engineering, more and more attempts are being made to replace sheet steel components with components made of plastic. In the production of flat, three-dimensionally curved plastic moldings, for example of body components, there is a problem in that due to the three-dimensional shape and the required adaptation to the surrounding body components often at least one peripheral edge is provided with a comparatively large circumferential radius, the tool technically relatively difficult to master is, since this rounded peripheral edge is usually in an SMC pressing tool in the region of a dipping edge gap between the die and punch, which dipping edge gap is then visible. However, such a marking is not allowed in the outer skin area by the car manufacturer, as there is a considerable Nachbearbeitungsbedarf to later produce a paint job with the required surface quality can.

In contrast, the invention has for its object to provide a pressing tool, which makes it possible to produce a molding with high surface quality. Another object of the invention is to provide a molded article with high surface quality.

This object is achieved with regard to the pressing tool by the feature combination of claim 1 and with regard to the molded part by the feature combination of the independent claim 14.

Advantageous developments of the invention are the subject of the dependent claims.

According to the invention, the pressing tool, in particular an SMC pressing tool, has a punch and a die movable relative thereto, which together define a cavity (cavity) for forming a flat shaped part. According to the invention, a preliminary stirrer is guided in the area of the punch, which delimits the cavity in sections and which, when the pressing tool is open, is prestressed into an advanced position and can be entrained in the direction of a pressing position when closing it.

Such a press tool construction makes it possible to place the critical rounded peripheral edge in the region of the override so that the rounded area is correspondingly formed essentially by the overroller. Since this is taken from the die during the pressing, the molding is formed in the critical peripheral edge region over a comparatively long stroke of the die, wherein the resulting in the pressing position of the vane edge intersection can be formed with such high surface quality that post-processing is no longer required ,

Accordingly, the molded part is designed such that the critical region, for example a rounded peripheral edge, is placed in the region which is essentially formed by the preliminary part. In other words, the molding is designed so that the marginal undercut is placed in the region of the leading edge of the pressing tool.

In one embodiment of the invention, the advance is in the broadest sense annular and surrounds this passing through the stamp at least in sections.

Relative positioning of die, punch and leader during the pressing operation is simplified when the die engages the leader in the press position.

The structure of the pressing tool is particularly simple if the preload of the override is hydraulic.

This bias can be done for example via one or more impression cylinder, which are preferably performed in a male.

In addition to the pressure cylinders, it is also possible to provide one or more lifting cylinders, by way of which the override can be moved for cleaning into at least one cleaning position, so that peripheral regions of the dipping edge gap are accessible for the cleaning process. It can be accessible in a lower cleaning position, the dipping edge of the punch and in an upper cleaning position, the dipping edge of the override.

In a variant of the invention, the lifting cylinders or the pressure cylinders are designed such that they can be moved into an ejection position, in which the molded part is lifted off the stamp after the pressing process. Since the override engages surface on the molding, usually resulting in the use of ejectors subscriptions can be avoided, so that the molding meets the highest demands on the surface quality.

According to the invention, it is preferred if the maximum stroke of the lifting cylinder is greater than that of the pressure cylinder.

The leader is preferably mounted floating on the stamp, wherein a punch-side stop is provided to limit the stroke of the override.

To further improve the surface quality, the tool can be designed with an injection port, for example an IMC port. This connection is preferably formed on the die.

In order to improve the guidance between the punch and the leader and the former and the encompassing die, guide plates made of wear-resistant and friction-minimizing materials can be provided in the overlapping areas of the respective components.

The molded part is preferably an outer shell of a trunk lid of a motor vehicle. In principle, however, other body components or other planar components can be formed with the pressing tool according to the invention.

Preferred embodiments of the invention are explained in more detail below with reference to schematic drawings. Show it:

1 an inventive SMC-pressing tool in the pressing position;

2 the pressing tool off 1 with the die removed;

3 an individual representation of a leading edge of the pressing tool with lifting and pressure cylinders;

4 a male of the pressing tool with removed leader;

5 to 13 Processing steps in the production of a molded part according to the invention with an SMC pressing tool according to the invention;

14 . 15 schematized sections through the SMC-pressing tool during compression of the molding;

16 a schematic diagram of a pressing tool in the region of a rounded peripheral edge of a molding;

17 a section transverse to the cutting plane in 16 and

18 and 19 the forerunner in two cleaning positions.

This in 1 illustrated SMC pressing tool 1 is used to produce an outer shell of a motor vehicle body component. The pressing tool 1 has in a conventional manner a clamp mounted on a tool table, not shown 2 , which together with a vertical direction (see arrows in 1 ) movably guided die 4 , a further below explained in more detail cavity (mold cavity) limited. At the patrix 2 are indicated clamping surfaces 6 trained for clamping on a table. The matrix 4 has a free-cutting on the side 8th in which a connection 10 for an IMC injection head, (Injection Mold Coating), through which an IMC material, such as pure resin can be injected to improve the surface quality of the curing molding. To reduce thermal losses is the pressing tool 1 with pressure-resistant insulating panels 7 dressed.

The patrix 2 as well as the matrix 4 are provided with a mold temperature control, wherein both in the die 4 as well as in the patrix 2 each three circuits are formed.

2 shows a detail of the patrix 2 , This has a Patrützockel 12 on which the matrix 4 facing end face a variety of stop plates 14 made of wear-resistant material on which the die 4 in the closed position rests. In the patron sock 12 are four column guides 16 formed in the corresponding guide recesses of the die 4 dive in, so that patrix 2 and die 4 are positioned relative to each other. In the middle area of the patrix 2 is the actual stamp 18 formed, via which the inner contour of the auszuformenden molding is formed. In the illustration according to 2 you can see the contour of the stamp 18 , via which a rear wall of the molded part with an embossed sink 20 is trained. In conventional tools, the cavity of the pressing tool 1 solely by the stamp and the template described below 4 limited. When pressing tool according to the invention 1 the stamp is so to speak two-part executed, whereby the actual stamp 18 from a trailblazer 20 is encompassed in the vertical direction (parallel to the column guides 16 ) is movable. Laterally on the advance 20 is a variety of guide plates 22 formed along the inner peripheral surface of the die 4 is guided. About the advance 20 is the tool technically quite difficult to be controlled rounded peripheral portion of the molding 38 educated.

3 shows the basic structure of the vane 20 , Accordingly, this is approximately frame-shaped and has a recess in the center 24 that from the actual stamp 18 is interspersed. In a manner known per se, both the punch side and the leading side hardened dipping edges are in this area 26 formed, which are profiled in a suitable manner. In the illustration according to 3 You can also see the side of the Voreiler 20 attached guide plates 22 , The closing movement of the forerunner 20 is about a variety of pressure cylinders 28 controlled in the patrix base 12 are stored and their piston rods 29 are extendable in the vertical direction and at the in 3 lower face 32 the forerunner 20 attack. These impression cylinders 28 are preferably hydraulic cylinders which are connected to a hydraulic system. In principle, however, electrically or pneumatically actuated pressure cylinder can be used. In the illustrated embodiment, ten impression cylinders 28 along the face 32 arranged distributed. These impression cylinders 28 serve the lead 20 during the pressing process and in abutment with the die 4 to keep. The preload pressure of the impression cylinder 28 For example, about one-fifth of the press force. This can be in a trunk lid about in the range of 1000 t, so that the on the impression cylinder 28 applied biasing force is 200 t. This bias voltage can be influenced by suitable throttles in the hydraulic circuit.

In the patron sock 12 Furthermore, there are four lifting cylinders 30a - 30d arranged, whose piston rods 31 also on the face 32 attack. The lifting cylinders 30 serve, as will be explained in more detail below, to the vendor 20 Adjust in cleaning positions, so that its peripheral contour can be cleaned. lifting cylinder 30 and impression cylinder 28 are on the perimeter of the face 32 arranged distributed.

The forerunner 20 is also still with two flush mounted air ejectors 34 , Also on the die side not shown air ejector can be provided.

4 shows the patrix 2 without an override on extended lifting cylinders 30 , of which in the illustration according to 4 only the piston rods 31a . 31b visible from the base of the patrick base 12 are extended and the lead 20 from the patrix base 12 take off.

The mold cavity contour of the die 4 is according to the outer contour of the molding 38 formed, wherein a part of the visible surface of the trunk lid is formed by the mold-side mold cavity. The mold cavity (cavity) forming areas of stamp 18 , Forerunner 20 and die 4 are polished, the polishing on the mold side is done with a finer grain size. The surface in this area is further chromed, the layer thickness is about 0.02 to 0.03 mm.

5 shows the patrix 2 in a position where the lift cylinders 30 are even further extended; One recognizes clearly in this representation that the visible piston rods 31a . 31b even further from the base of the patrick socket 12 cantilever and thus the lead 20 raise to an upper cleaning position, in which the accessibility inner peripheral edge of the vane 20 is still further improved - this is further explained below. In this upper cleaning position is the lead 20 according to 5 clearly above the stamp 18 out, leaving the dipping edge 26 the forerunner 20 can be cleaned.

Both in the illustration according to 4 as well as in the illustration according to 5 you can see that in the upper cleaning position, the piston rods 29 the impression cylinder 28 no longer on the bottom face 32 the forerunner 20 attack.

In 6 is the basic position of the open crimping tool 1 shown. The matrix 4 is from the patrix 2 lifted. The impression cylinder 28 and the lifting cylinders 30 are depressurized, so the lead 20 on the patrix base 12 rests, wherein in Auflageberelich also stop plate 24 are formed on which the forerunner 20 is applied. This position also corresponds to a lower cleaning position, in which the dipping edge of the punch 18 is accessible. This will be explained later.

At the beginning of the pressing process ( 7 ) become the impression cylinders 28 extended, leaving the trail ahead 20 over their piston rods 29 of the Patrizensockel 12 is lifted, this "lead" may be about 15-20 mm. That is, in this early position has the lead 20 opposite the stationary stamp 18 about the extent of the lead to the matrix 4 postponed.

According to 8th then gets into the open crimping tool 1 SMC material 36 inserted, this on the stamp 18 is hung up. The layer structure of the resin-added SMC material 36 meets the requirements of the respective molding 38 adapted and is known per se, so that further explanations are unnecessary.

The forerunner 20 is when inserting the SMC material 36 extended to his override. In a following step, the template is then 4 on the patrix 2 lowered. As explained in more detail below, while running the die 4 on the advance 20 on ( 9 ) and shifts it against the pressure of the printing cylinder 28 in the direction of his in the 10 shown pressing position. This is the SMC material 36 deforms and adapts to the contour of the mold cavity (cavity), wherein the shape due to the moving back into the pressing position precursor 20 in the area of the critical rounded peripheral edge continuously over a comparatively long distance, so that this area is performed with excellent surface quality.

9 shows the closing process in the stage where the die 4 on the advance 20 runs. In 10 is the pressing tool 1 completely closed.

With closed pressing tool 1 hardens the molding 38 during which this hardening process can be injected into the mold cavity via the IMC injection head mentioned in the introduction in order to increase the surface quality. The injection pressure can be chosen so that it causes a slight opening of the mold cavity to create space for the injected resin. Alternatively or additionally, the pressing tool 1 also be opened slightly controlled to facilitate the injection process.

After curing of the molding 38 is the pressing tool according to 11 opened, the impression cylinder 28 are then depressurized, so the lead 20 himself in his in 6 is shown depressurized position.

In a following step will be the lead 20 then by driving the impression cylinder 28 and / or the lifting cylinder 30 raised to an ejector position. Because the lead 20 the molding 38 circumferentially encompasses the entire area, this is also lifted off, so that the lead 20 practically as a flat ejector 21 acts. Because of this area concern are no marks on the molding 38 to fear. This ejection can be done via the air ejector 34 get supported.

As in 13 is shown after the procedure of the lead 20 in its ejector, the cured and optionally provided with the IMC layer molding 38 taken.

A significant advantage of the above-described tool design is that a post-processing of the molded part in the region of the rounded peripheral edges 40 ( 13 ) is not or only to a lesser extent than in a pressing with conventional pressing tools required.

For a better understanding, the above-described method steps are again based on some schematic sections through the pressing tool 1 explained.

14 shows the pressing tool 1 in its open position or home position. The matrix 4 with the die-side mold cavity contour 42 is above a suitable actuator, away from the patrix 2 method. The indicated advance 20 is about the printing cylinder 28 , more precisely, their piston rods 29 in its advanced position, in which he about 15 to 20 mm from the stamp 18 upwards, towards the matrix 4 is moved. This extension can be done by the lifting cylinder 30 and their piston rods 31 be supported. When closing the pressing tool 1 the matrix is running 4 with a stop surface 44 on the advance 20 on and pushes this against the pressure cylinders 28 applied bias in the direction of its pressing position ( 15 ), in which the die 4 on the stop tiles 14 or a separately provided stop rests, so that the stroke of the vane 20 is limited accordingly. In the pressing position is the lead 20 but not yet on the patrix base 12 on.

The matrix 4 is as shown in the 14 and 15 approximately cup-shaped, with Innenseitenwandungen 46 the matrix 4 with the outer peripheral walls of the vane 20 a downwardly widening dip edge gap 48 form. As shown in 15 grasps the matrix 4 in the closed position with a centering collar 50 the patron sock 12 , so that also an exact relative positioning of the mold halves is ensured.

The pressing, injection of the IMC resin layer and ejection then takes place in the manner described above. In the described molding 38 the IMC gating is preferably carried out in Area of the valley 21 , This Anspritzbereich is in 14 with the reference numerals 42 Mistake.

16 shows a highly schematic section through a pressing tool approximately transverse to the cut in 15 , Indicated in this illustration are a lateral region of the stamp 18 , a part of the trailers 20 , a printing cylinder 28 , its piston rod 29 who are at the fore 20 attacks and the stopper forming a stop 14 to which the forerunner 20 accumulates in the lower cleaning position. Recognizable is further a part of the matrix 4 , This, the stamp 18 and the lead 20 together form the mold nest 54 in which the component 38 is pressed. Is recognizable in 16 also a dipping edge gap 56 between the stamp 18 and the forerunner 20 , Circular indicated in this illustration Temperierkanäle 58 the temperature control circuits in the stamp 18 , the mold 4 and the forerunner 58 , The gap between the SMC molding 38 and the matrix 4 or the advance 20 are in the illustration according to 16 greatly exaggerated. Based on this presentation, only the location of the vane 20 be explained. One recognizes in 16 the rounded peripheral edge 40 of the molding 38 , where at the bottom of a Randhinterschneidung 60 is formed, which is difficult to control in a two-part press tool. In particular, the area of this Randhinterschneidung 60 becomes during the above-described pressing process with the help of the precursor 20 formed, wherein the pressing takes place along a comparatively long stroke, since the leader 20 according to the amount of advance from the die 4 is taken along and then continuously the Randhinterschneidung 60 formed. As explained, the pressed molding must 38 after removal from the pressing tool 1 practically no longer be reworked.

17 again shows a schematic section corresponding to the illustration in FIG 15 , One recognizes in this representation the one to the matrix 4 attached IMC injection head 62 , which dips in this variant obliquely from above into the mold. Dashed lines indicate an alternative position of the IMC injection head 62 that corresponds to the one in 1 is shown. In the sectional view you can clearly see the mold nest 54 that by the stamp 18 , the die-side mold cavity contour 42 and the lead 20 is limited. In dip gap between the advance 20 and the stamp 18 are the above guide plates 22 educated about the the forerunner 20 floating on the stamp 18 is stored. The matrix 4 embraces with its center collar 50 both the lead 20 as well as the patron sock 12 in which the stamp 18 is used. This takes place along the outer gap 64 between the outer circumference of the vane 20 and the centering collar no guide - but this is in the contact area between the centering collar 50 and the adjacent part of the Zentriersockels 12 in front. This a guide and centering ensuring peripheral region of the Zentriersockels 12 is in the representations according to the 17 and 2 with the reference numerals 66 characterized.

In 18 is the pressing tool 1 in a section corresponding to the sectional views of 14 and 15 presented in a position where the forerunner 20 over the lifting cylinders 30 (visible here 30g . 30b ) is moved to a lower cleaning position, in which the advance 20 on abutment on the patrix base 12 is lowered, so that the dipping edge gap 56 bounding area of the stamp 18 is accessible and thus can be cleaned. The pressing position of the lead 20 is above this lower cleaning position.

19 shows the lead 20 in its upper cleaning position, in which he by means of the lifting cylinder 30 up, over the dipping edge of the stamp 18 is moved out, so then for cleaning the dipping edge gap delimiting dipping edge surface section 68 the forerunner 20 is accessible. As explained, is the lead 20 extended in this upper cleaning position by about 70 mm.

The above-described pressing tool with punch, die and override can be used in principle for the design of sheet-like components in which it depends on a high surface quality in the peripheral edge region.

Disclosed is a pressing tool in which a peripheral edge portion of a molded part is formed with an adjustable leader, which also serves as an ejector.

LIST OF REFERENCE NUMBERS

1

 press tool

2

 punch

4

 die

6

 clamping surface

7

 insulation

8th

 relief cut

10

 connection

12

 Patrizensockel

14

 Coupling pad

16

 column guide

18

 stamp

20

 rams

21

 depression

22

 guide plate

24

 recess

26

 dipping edge

28

 pressure cylinder

29

 piston rod

30

 lifting cylinder

31

 piston rod

32

 face

34

 air ejector

36

 SMC material

38

 molding

40

 peripheral edge

42

 Mold cavity contour

44

 stop surface

46

 Innenseitenwandung

48

 Dipping edge gap

50

 centering collar

52

 IMC-gating

54

 cavity

56

 Dipping edge gap

58

 tempering

60

 Randhinterschneidung

62

 IMC injection head

64

 gap

66

 peripheral region

68

 Diving edge surface section

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007050951 A1 [0002]

Claims (15)

Pressing tool with a stamp ( 18 ) and a relative to this movable matrix ( 4 ), which together form a mold nest ( 54 ) for forming a flat molding ( 38 ), characterized by one in the area of the stamp ( 18 ) guided trailers ( 20 ), the mold nest ( 54 ) is limited in sections and which is biased when the die is open in an advanced position and when closing by the die ( 4 ) is entrained in the direction of a pressing position. Press tool according to claim 1, wherein the lead 20 ) is annular and the punch ( 18 ) engages in sections. Press tool according to one of the preceding claims, wherein the die ( 4 ) the advance ( 20 ) engages in the pressing position at a distance. Press tool according to one of the preceding claims, wherein the lead ( 20 ) is hydraulically biased. Press tool according to claim 4, wherein the bias voltage via at least one pressure cylinder ( 28 ) he follows. Press tool according to one of the preceding claims, wherein the lead ( 20 ) is movable in an ejector position. Press tool according to one of the preceding claims, with at least one lifting cylinder ( 30 ), over which the Voreiler ( 20 ) is movable in a lower cleaning position in which the stamp ( 18 ) is accessible. Press tool according to claim 7, wherein the lead ( 20 ) is moved over the lifting cylinder in an upper cleaning position, in the dipping edge sections ( 68 ) of the lead ( 20 ) are accessible. Press tool according to one of the preceding claims, wherein the maximum stroke of a lifting cylinder ( 30 ) larger than that of a printing cylinder ( 28 ). Press tool according to one of the preceding claims, with a stop for limiting the closing stroke of the overrun ( 20 ). Press tool according to one of the preceding claims, having an IMC connection ( 10 ) on the die ( 4 ). Press tool according to one of the preceding claims, with guide plates ( 22 ) in the contact area between the leader ( 20 ) and the stamp ( 18 ) and / or in the contact area between the die ( 4 ) and the vendor ( 20 ). Press tool according to one of the preceding claims, wherein the lead ( 20 ) together with the matrix ( 4 ) a rounded peripheral edge ( 40 ) forms the molding. Press tool according to one of the preceding claims, wherein the die ( 4 ) a patrix base ( 12 ) engages in the closed position. A molded part produced in a pressing tool according to any one of the preceding claims, wherein a portion of a rounded peripheral edge through the leader ( 20 ) is trained.

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