DE3249426A1 - Negative mould for producing adapter blocks and process for their production - Google Patents

Abstract

Negative mould for producing an adapter block for applications in fluid technology. An expandable material is introduced into the negative mould, and a structural moulding is obtained by foaming and curing. The negative mould is produced by casting with a pourable plastic from a master positive of the adapter block to be foamed. To create connecting bores in the adapter block, the negative mould contains anchorable pins, which are embedded in the plastic by anchoring ends. Preferably, one negative mould serves for foaming a plurality of adapter blocks. The casting of the negative mould takes place under a vacuum, and casting compound may be filled into corners and edges of the master positive before pouring-in takes place.

Description

Negative mold for the production of adapter blocks

and method of making them. The invention relates to a negative mold for the production of adapter blocks for applications in fluid technology according to the preamble of claim 1 and a method for their production according to the preamble of claim 3.

Such a negative mold and such a method are from DE-PS 31 24 020 known. This describes a so-called universal form in which Shaped pins to create connecting bores in the adapter block use Find. The heads of the shaped pins are in counterbores of shaped pin receptacles supported, and the counterbores are through an overlying Support plate closed without play. With this arrangement, it is possible to use the form pins in one To arrange the standard grid and any counterbores for the shaped pin receptacles that are not required to be closed with dummy pins.

An advantage of this arrangement lies in its risk-free speed and in the precision of the hole positions present in the foamed panels. A disadvantage but is due to the relatively long changeover times and the increase in the cost of the press to see the elaborate perforated plate and the many pins. Furthermore, the well-known Negative shape due to the pre-determined hole pattern for the shaped pins in their design options limited, and finally it prepares additional troubles, if through holes with a larger cross-section than corresponds to the grid used should.

The object of the invention is to remedy these disadvantages and a Specify the negative form of the type mentioned at the beginning, which is simpler and less expensive Structure offers more versatile design options.

This object is achieved with a negative mold according to claim 1.

From EP patent application 62 70 is a foam mold for production known from objects made of structural foam.

A plastic material is injected into this foam mold foams and on the cooled walls of the mold a compact skin forms, while a foam body is created inside. To shorten the dwell time local cooling of the foamed material in the mold is proposed, which brought about for example by means of cooling fingers extending through the mold can be. In the area of these cold fingers, material bridges are made of solidified Material formed that stabilize the structural foam.

Furthermore, in the 'Kunststoff-Rundschau', issue 1o, October 1973, Page 435 - 443? Details of the mixing and sprue technology for the production of polyurethane structural foam specified.

In the negative form according to claim 1, form pins are used, one end of which is designed as an anchoring end. With such a measure the tolerance range increases in the preparatory work for production the mold. Originally there was a risk that the shaped pins, which later Connections in the adapter plate from the ducts to the levels below should cause either too much on the forming of the channels of the negative mold existing ribs or did not touch the latter. In the latter case this means the formation of separating skins, which in a separate operation would have to be removed in order not to obstruct the passage of air later. the use of such anchoring pins not only saves with certainty the eventual necessary post-processing, but also practically the inspection of the foamed Blocks, as through holes can only be missing or complete if the Form shows a most noticeable damage, which in turn is inevitable would be automatically recognized when cutting the shape. Incidentally, be on in this way eliminates disadvantages that have hitherto resulted from the fact that the Pins were introduced into the mold by means of perforated plates, with the result that Raising the price of the press and relatively long retooling times. Here had to be done for å each Grid its own perforated plate must be provided, and it was relatively cumbersome if through holes had to be made with a cross-section that differs from that of for which the grid was intended differed. Anchoring pins, however, are independent of any grids, and they allow in a very convenient way to change the cross-section of the passage openings and their shape.

The invention further proposes to design the foam mold so that it consists of several mold units, with the result that in a single operation several adapter blocks can be produced at the same time.

The advantage of this measure is the reduction in manufacturing costs, since this is essentially determined by the dwell time of the foaming mold in the press will.

The production of several individual panels in a single shot saves additional investments for the acquisition of further presses. Besides there is a simplification in the storage and handling, and of each individual copy the same number of pieces are automatically produced.

Another advantage is the negative mold made of castable plastics manufacture, which is lower cost and simplicity compared to metal molds result in handling. In addition, the compact zone has a smaller thickness has, so that advantageously only a little has to be ground off to obtain a sufficiently rough surface to maintain this. improves adhesion and enlarges the tolerances for the adhesive application.

In a further embodiment of the invention, it is proposed to manufacture the foaming mold by inserting anchoring pins of suitable length into the Holes of the original positive is stuck so that when pouring the negative form with their anchoring ends be embedded in the casting compound. It represents a simpler procedure that Negative form made from anchoring pins instead of the shaped pins, which are generally can be arranged in a standard grid. The use of anchor pins offers, as already mentioned above, a multitude of advantages.

It is advisable to cast on the original form, i.e. to manufacture the Negative form, to be carried out under vacuum and the corners and edges before pouring to apply casting resin to the original positive by means of a brush. By this measure the inclusion of vesicles is avoided.

The invention is exemplified below using a negative mold explained, which can be used in a polyurethane foaming process. That Polyurethane # foaming offers a way of making production cheaper of assembly blocks and blocks with integrated connections while improving the quality.

However, the invention is not restricted to these applications.

There are other uses beyond the manufacture from protective caps for control blocks with integrated connections to manufacture pneumatic switching elements are sufficient.

The polyurethane foam process is a good way to make molds cheaper very favorable conditions. During the foaming there is only one comparative low closing pressure of approx. 5 bar is required for the negative mold, and there will be only low temperature requirements.

The maximum temperature is 600C, and step inside the mold low flow forces. Furthermore, polyurethane is very resistant to Glycerine and mineral oil including gasoline as well as vegetable oil and ozone. It's cheap mechanical Properties: Sufficient strength and elasticity and freedom from tension, low Temperature influences especially at low temperatures, no age-related embrittlement. This results in requirements for the stability of the foam mold which are comparative to those can be done easily, that is to say at low cost. In particular the actual foring-giving parts can easily be made of castable plastics can be produced, which has the advantage of being less than metal molds Thickness of the compact zone of the Ir.te, rralschaums results. A small thickness of the compact zone is advantageous in that only a little has to be sanded away to make a porous Surface. The latter can be desirable for adhesive connections, in which they have greater tolerances in the adhesive application and improved adhesion brings itself.

As a negative form in a polyurethane foaming process, DE-PS 31 24 o20 a universal form known. The advantage of this arrangement lies in the Risk-free and in the precision of those present in the foamed panels Hole positions. The disadvantage lies in the relatively long set-up times and the increase in cost the press through the complex perforated plate and the many pins. Additionally must A separate perforated plate is provided for each grid (e.g. System 1000, M 5, etc.) and the use of elements with different basic grids on one and same Block is only on one side without special measures a block equipped on both sides is possible.

After all, it also prepares troubles when there are through holes with a larger cross-section than corresponds to the grid used have to.

In order to remedy these disadvantages, the invention is now with a Form structure worked, in which the holes in the channel plates by pins are generated, which are fixed in the mold plate. For this purpose, rivets are used appropriate length inserted into the holes of the original positive and when casting the negative form embedded with their heads in the casting compound.

Experiments showed that throttles and ES vectors for about 1 to 6 bar with a smallest diameter of at least 0.5 mm by inserting appropriate Pins can be foamed directly into the panels. A shape with such a Pen easily survived a series of 50 pieces.

Volumes for the purpose of supply air distribution or for extension the times of delay valves can be foamed without difficulty, if a (e.g. multiple) contiguous canal system is provided for this. In this case, the width of the channels should not exceed the plate thickness, and the jetties should a minimum width of 2.5 mm and one Adhesive fillers allow a proportion of at least 25%.

The removal of the foamed sheets from the mold with the channels and pins are done at least in the case of the previous formats with the help of the conical Edge of the frame plate as well as probably by short-term effective release agent-related "Gluing" the foam sheet to the base plate of the press.

The production of the master model from which the negative form is cast, does not offer any particular difficulties: milling the channels and drilling the holes expediently takes place by optical guidance from the drawing on the wet rod of about 2: 1 on an engraving machine. - A pneumatic remote control to lower the cutter with the possibility of an automatic for drilling holes proves to be helpful.

Delrin plates turned out to be the most suitable starting material, since it allows a high rate of advance, no substantial drag when guiding the pantograph and leads to clean surfaces and edges of the Channels leads. Another amenity of note is that Delrin will be with the later Pouring the negative forms with a polyurethane casting resin (2 components) no Release agent required.

While for the original process, raster forms on special paper with the smallest possible length changes with humidity and temperature differences were used, you will use forms of the connection diagrams for the new technology Insert assembly outlines for the switching elements used. For these forms Thanks to their smaller format, larger relative length changes are permitted: However, they must be mounted on a base that is still as length-invariant as possible will.

The casting of the original form has to be done under vacuum to avoid the formation of bubbles to avoid. At critical points, casting resin may have to be mixed with a Brushes are applied to prevent air pockets.

Molds can be repeatedly cast from a master model: Most likely over a hundred copies should be possible. The cost of a cast is each Depending on the format, around DM 80 to DM 120. Expected based on previous experience a minimum service life of 200 to 300 foam sheets is required for a mold.

The present considerations relate primarily to manufacturability of panels of various thicknesses and formats. The following illustration gives some of the most important points.

The initial attempts were from panel thicknesses between 6 and 8 mm. The limitation is due to the flow behavior of the foam compound when it is introduced into the shape and during the subsequent "rising" during foaming. Opposite to the production of conventional parts, such as housings, with similar wall thicknesses special difficulties arise due to the relatively high ribs of the form: the liquid has only a restricted passage available (e.g. plate thickness 6 - channel trough 4 = 2 min), and step at the same time rapid changes in cross-section.

The inevitably increased flow velocities and turbulence involve the risk of air inclusions.

Based on current experience, the following statements are possible: A format 160 x 220 mm with a panel thickness of 6 mm (channel depth 4 mm) is included negligible reject rate possible. The prerequisite is that the casting of below and along one long side takes place to keep the flow velocity low to keep. Here it is essential to adhere precisely to the setting values that have been determined however a prerequisite. Nevertheless, a panel thickness of 7 mm is essential Advantages: the flow rate is reduced by 33%, and for assembly blocks with connection socket strips on the face there is no second Plate thickness more required. After now aluminum plate material with a thickness of 7 mm was found could be, this solution no longer stands in the way.

In all likelihood, this can result in the maximum format at least 200 x 300 mm (approximately A4) can be enlarged without the setting of the Machine and the external conditions become particularly critical.

The interest in larger plate formats is justified by that the dwell time in the press is a significant part of the plate cost. So one would achieve a remarkable reduction in costs by at least one for blocks of smaller dimensions, all individual panels in a single operation could foam.

In particular, there would be no further investment in the form of additional investments Pressing required. Furthermore, there would be a simplification in storage and Handling of the forms resulted, and of each individual plate would automatically be the same many pieces made. - Especially with regard to the simultaneous foaming Incidentally, the introduction of as many individual panels as possible in a single shot affects the introduction a normalized plate thickness of 7 mm positive by the shape and the insertion the pins (if still necessary, see below!) is simplified.

A plate thickness over 10 to 12 mm leads to significantly extended Cycle times. Assembly blocks fitted on one side with connection strips on the front are therefore often equipped with a special bottom plate: Lies namely the lowest channel level at the level of the lower row of sockets, so would be a thickness of 14 mm is required for the bottom plate, which means that the one specified above Value would be exceeded. Because of this, most of it is on the underside The surface is recessed so deep that the remaining thickness is only approx. 7 mm. This should preferably be done with uniform, prefabricated parts, since Later, when gluing, in turn, supporting documents are required.

The previous statements concern plates with channels only on one Page; how far the circumstances change, if of the same in many cases interesting possibility of bilateral channel plates being made use of currently no experience. It is believed that the minimum thickness of 10 mm should hardly be enough for the last-mentioned maximum format. But there the fat one the zone with no channels can easily be increased up to 6 mm, It should be noted that two-sided channel plates of the maximum format mentioned are included a total thickness between 10 and 12 mm should be possible.

The sealing system according to the invention is also for Nultipol connection parts suitable. Per 22-fold Sultipol connection g can be each 22 sockets and plug nipples with the corresponding O-rings and 44 Seeger rings through 44 simple ones Replace press-fit nipples like parts 207 339 or 215 579, with these press-fit nipples are inserted when spraying or pressing the connecting strips. Both sides of a multi-pin coupling are identical apart from the numbering of the connections and yet they can only be plugged together in one way.

There are already 22-way connecting parts in the form of the female headers P and I, which is most likely characterized by an inexpensive seal Connect and seal an elastomer in the proposed type. So could E.g. the 96 double plug nipples, which are still required today, each with 2 O-rings, 5 retaining plates and 1o special screws for connecting the universal connection plate with the step switch control insert FS-10 and the supply / display module and for connecting the functional plug-in board only 5 such # seals need to be replaced. The same applies to the connection of program boards (e.g. on the programmable insertion device control), which require 22 or 44 double plug nipples and other accessories.

In view of the perspectives that have just been opened up, however, we must not forget be that particular in development of a new system of switching elements still many other conditions should be met in order to design and to facilitate the manufacture of mounting blocks with integrated connections. Such a task can only be achieved in close and long-lasting cooperation between the development departments for switching elements and integration technology.

Finally, it should be pointed out that it would be wrong to use the foaming technique to limit the manufacture of channel plates, a first foray out of the original Scope of application is already done by on the one hand the storage volume in the storage / display module for step switch control and on the other hand a housing for a control block with integrated connections made of integral polyurethane foam were manufactured.

Both solutions prove to be particularly beneficial in terms of molding costs are very economical and contain not only remarkable strength, but also complete freedom from corrosion.

In order to be able to amortize the mold costs for housings even better, Efforts have already been made to determine the formats of control circuits to unify with integrated connections at least in groups, so that one housing can be used for several and different types of circuits can.

Tests with temperatures down to -28 ° C have shown that no noticeable embrittlement occurs, which of course also applies to the channel plates: The test pieces showed only insignificant impressions (without cracks or splinters) on after being thrown on stone slabs while cooled; as well the glued areas remained intact.

Claims (5)

Negative mold for the production of adapter blocks and processes for their Manufacturing claims t negative mold for manufacturing adapter blocks for applications in fluid technology by introducing a foamable material and foaming it and curing to form a structural molding obtained by pouring an original positive of the adapter block with a castable plastic, characterized in that that the negative form for the creation of connecting holes anchored pins which are embedded in the plastic with anchoring ends. 2. Negative form according to claim 1, characterized in that that it is suitable for the simultaneous production of several adapter blocks. 3. A method for producing the negative form according to claim 1 or 2 by molding an original positive, characterized in that one in holes of the Urpositivs anchoring pins of suitable length, so that they can be used when pouring the negative mold with its anchoring ends are embedded in the casting compound. 4. The method according to claim 3, characterized in that the casting the negative form takes place under vacuum. 5. The method according to claim 3 or 4, characterized in that before casting compound is applied to the corners and edges of the original positive.