DE102006038727B4 - Mehrkomponentenspritzgieß turntable tool - Google Patents

Abstract

The invention relates to a turntable tool for the production of moldings by means of the multi-component injection molding process. A problem with the turntable technology of the prior art is that due to the material-specific shrinkage during cooling of the preform stands out from the turntable and creates a gap. This disadvantage is eliminated. The turntable tool for multi-component injection molding consists of a turntable with at least 2 casting cores and at least 2 dies, which are guided onto the cores. Each core on the turntable has a tracking device, which is in operative connection with a force device. These cause a tracking of the casting tool in shrinkage of the pre-molded part.

Description

The The invention relates to a multi-component injection molding turntable tool.

Multi-component injection molding move increasingly in the focus of the industry. They enable the integration of Sealing and damping functions in components in a single step. Likewise, optical functions, such as for example partially translucent buttons for automobiles, easy and inexpensive be introduced. By applying an elastomer layer can the feel (pleasant grip), especially in household appliances or Tools, to be improved.

in principle first becomes a pre-molded part in multi-component tooling techniques made of the first component in a cavity. Subsequently, will this by releasing volumes in the following cavities additional components added. Multi-component tooling techniques can be used in transfer, and divide slider techniques.

at the transfer technology, the injection process in several stations. First, the preform is molded in a station. Then done Transport to the final injection station, where the second component is applied. The procedure can be extended to more stations and expand more components. The transfer technology offers one huge Design flexibility, as well as changes the core contour possible are. Disadvantageous Turning and sliding techniques is the high technological effort for the Transport of the molded parts from one station to the next. To be an automated transport to avoid damage the injection molds high demands, as well as the precision at the dimensioning of the Fertigspritzkavität to a precise insertion and holding the pre-molded part. In addition, this is Technology costly due to the time-consuming transfer processes.

The Turning techniques are used by index plate tools or turntable tools realized. The present invention relates to a turntable tool.

at Turntable tools are located on the turntable at least 2 cores.

The Functional principle allows a simultaneous production of pre-and Finished molded part. A core is thereby first led into the die of the pre-injection station, while at the same time the other core, on which there is already a preform, led into the final spray station becomes. Then the finished spray is ejected. Subsequently, will a tool half rotated so that the pre-molded part in the final spray station and the core, which has ejected the Fertigspritzling, in the pre-injection station guided becomes. Thus, the use of a turntable tool due to the high effectiveness for the Producing large numbers suitable.

The 1a . 1b illustrate the known operating principle of a turntable tool. 1a shows the casting of the pre-molded part 7 (please refer 1b ) and 1b that of the finished syringe. The preform 7 gets to a core 1 injection-molded, which is in a die 2 for the pre-molded part 7 located. The die for the preform 7 has a material feed 3 , Between the core 1 and the die 2 for the pre-molded part 7 there is a cavity 4 for the pre-molded part 7 , After the preform 7 the die is cast 2 for the pre-molded part 7 from the pre-molded part 7 lifted, the turntable 9 turns so that the molded pre-molded part 7 under the die 6 for the finished injection 5 located. The die 6 for the ready-to-shoot 5 lowers on the pre-molded part 7 and forms the cavity for the Fertigspritzling 5 , Finally, about the material supply 3 of the die 6 for the finished injection 5 Material in the cavity of the finished injection 5 led and this poured. After a short cooling phase, the die 6 for the finished injection 5 lifted, ejected the Fertigspritzling and the process begins again.

The problem with this technology according to the prior art is that due to the material-specific shrinkage during cooling, the preform stands out from the turntable and a gap 8th (please refer 1b ) arises. This unwanted gap 8th is filled with the material for the finished syringe during casting of the finished syringe, resulting in an unwanted single-layer injection. This requires a complex and uneconomical post-processing of the finished injection molding, in which the single-layer injection is removed by suitable means.

To solve this problem, various solutions have been proposed in the past:
In the WO 2006/072366 A1 For example, there is proposed a method and a mold for forming and coating a substrate in a mold having at least two cavities. After forming the substrate in a first cavity and then introducing it into a second cavity, the substrate is coated there with a lacquer. The coating takes place under increased pressure. Among other things, this increased pressure ensures that the volume shrinkage during Aushär balanced. However, the method and the tool are only suitable for coating with lacquer with a maximum thickness of up to 3 mm.

In the DE 43 17 381 A1 discloses a method and an apparatus for the production of moldings, consisting of a first and a second part. In this case, the formation of sink marks is prevented by applying pressure by means of a press mandrel during the curing of the material of the second part and also ensures that the material propagates completely in the second cavity. However, the method and apparatus are not suitable for preventing the above-described sub-injections on turntable tools.

In the DE 10 2005 038 469 A1 For example, there is proposed a method for manufacturing an injection molded plastic component from two different plastic components for inside and outside. The outside should meet as a visual page particularly high quality standards, in particular, have no apparent sink marks. The plastic component is produced by means of an internal pressure injection molding process and / or an external pressure injection molding process. Also, this method is not suitable for use in conjunction with a turntable tool and thus to prevent the injections described above.

In the EP 0273769 A2 is a process for casting plastic components 1 proposed, wherein first a cavity is filled with plastic and then during cooling and curing of the plastic component, the volume of the cavity is reduced. With this method, only one-piece plastic components can be made, therefore, this method is not transferable for use on a turntable tool.

The Invention has the object of an injection of the first component, as a result of the reduction in volume due to fading, which no post-processing of the finished injection molds required.

According to the invention Task solved by the features of the main claim. Preferably developments are in retrospective dependent claims explained.

The inventive device for multi-component injection molding consists of a turntable with at least 2 casting cores and at least 2 dies, which are led to the cores. Each core on the turntable has a tracking device with a Force device is in operative connection. These cause a tracking in the Dwindling of the pre-molded part.

The production of a two-component injection-molded casting by means of the device according to the invention is described below:
The die 2 for the production of the preform 7 gets to a core 1 of the turntable 9 guided. The die presses 2 with the force F _G1, the tracking device in its zero position, against the, applied by the force means, upward force F _T. Thereafter, the injection of the first component via a material supply 3 in between the core 1 and the die 2 remaining cavity 4 , After a sufficient cooling of the pre-molded part 7 becomes the die 2 from the pre-molded part 7 lifted. Due to the shrinkage, the preform has 7 from the border of the core 1 or the tracking device N lifted and a gap 8th between pre-molded part 7 and border formed. To compensate for shrinkage, the tracking device is tracked in the direction of the pre-molded part. The force required for this purpose F _T is caused by the force of the tracking N, z. B. springs applied. By lifting the border of the core 1 or the tracking device N is the by the shrinkage of the pre-molded part 7 formed gap 8th eliminated. After rotation of the turntable 9 becomes the die 6 for spraying the finished syringe 5 to the core 1 guided and the second component in the between die 6 and preform 7 remaining cavity sprayed. By tracking the border of the core N by the amount of Schwindmaßes there is no gap between pre-molded part 7 and turntable 9 or the border N, so that no sub-injection can form. After ejection of the finished syringe no reworking is necessary.

Advantageously, the force device for applying the force F _T consists of mechanical springs. This variant is simple and inexpensive. Alternatively, for complicated applications, the force F _{T can} also be applied hydraulically, electromechanically or pneumatically. In addition, can be done by force or displacement sensors precise control of the movement of the border.

Based of the drawings 2 and 3, an embodiment will be explained.

there demonstrate:

2 the sectional view of the pre-injection station of the turntable tool and

3 the sectional view of the finish injection station of the turntable tool.

through the turntable tool, a housing half is made for a drill. The multi-component injection molding technique is used to create a thermoplastic elastomer (TPE) in the grip area Thin Apply, which in this area an improved feel is reached.

2 shows a schematic diagram of the pre-injection station of the turntable tool. The core 1 is on a turntable 9 with a tracking device N. Bin Gesenk 2 for casting a preform 7 got to the core 1 led, so that between the Gesenk 2 and the core 1 a cavity 4 forms for the pre-molded part.

The material for the preform 7 is through a material feed 3 fed. The tracking device N has a force device, which in the present case consists of mechanical springs, so that the tracking device with a force F _T in the direction of the die 2 is pressed. The force F _T counteracts the force F _GI , which is countered by the die 2 attacking, the die 2 and the tracking device presses in its zero position n ₀ .

In this zero position n ₀ has the cavity 4 the exact dimensions for the casting of the Fertigspritzlings on. The material for the pre-molded part 7 , a polyamide PAG GF 35, is fed through the material feed 3 pressed until the cavity 4 is filled.

After cooling the die 2 and the core 1 the preform 7 is sufficiently solidified, the die is 2 lifted off to the top. During solidification, the pre-molded part experiences 7 a shrinkage of about 0.5-0.55%.

By the force F _T is when lifting the Gesenkes 2 the tracking device N the die 2 tracked until the tracking device on the pre-molded part 7 is applied. The force F _T is chosen based on empirical values cast part-specific so that the tracking device N on the pre-molded part 7 rests without damaging or deforming it. The turntable tool is next rotated so that the core 1 with the pre-molded part 7 is guided into the final spray station.

3 shows a schematic diagram of the spray station. The die 6 for the pouring of the finished syringe is on the core 1 with the pre-molded part 7 led, so between both a cavity 5 for the second component remains. The force F _G2 , with the die 6 is pressed against the tracking device N is set so that the tracking device N continues to the pre-molded part 7 is applied. The tracking device N is in the position n _F , at a distance s _N from the zero position n ₀ .

The following is the second component about the material feed 3 into the designated cavity 5 injected. After the cooling process and the concomitant solidification of the workpiece, the die 6 lifted and the workpiece ejected. The turntable tool rotates, so that the core again to the pre-injection station ( 2 ) and the manufacturing process starts again.

1

core

2

die for pre-molded part

3

material supply

4

Cavity preform

5

Cavity finished injection and finished injection

6

die Finished molded part

7

Preform

8th

gap

9

turntable

N

tracking device

F _T

Force, the on tracking device in the direction of Gesenk attacks

^F G1

Force, the on the die for Pre-molded part in the direction of tracking device attacks

^F G2

Force, the on the die for Ready-injection mold in the direction of tracking device attacks

n ₀

zero position the tracking device

n _F

position the tracking device when applying the second component

s _N

Distance between n ₀ and n _F

Claims (4)

Multi-component injection molding turntable tool comprising a plurality of workstations, at least one workstation having a casting core ( 1 ) and at least two, in the direction of the casting core ( 1 ) movable dies ( 2 ) 6 ) and on or in the casting core ( 1 ) a tracking device (N) is arranged, which the dwindling preform ( 7 ) and when closing the Gesenkes ( 6 ) touched at least at the bottom. Multi-component injection-molding turntable tool according to claim 1, characterized in that the tracking device (N) by one or more adjustable springs in the direction of the dwindling Vorspitzlings ( 7 ) is movable. Multi-component injection molding turntable tool according to claim 1, characterized in that the tracking device (N) by pneumatic or hydraulic working cylinder is movable. Multi-component injection molding turntable tool according to one of claims 1 to 3, characterized in that the size of the shrinkage of the pre-molded part ( 7 ) or whose time course is detected by a measuring probe, in a data processing device the traversing speed or the Ver guideway (s _N ) of the tracking device (N) determined and passed on to electromotive actuators that move the tracking device (N).