DE2326536A1 - METHOD AND DEVICE FOR THE CASTING OF OBJECTS - Google Patents

Description

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TEL. (0311) 53SS53-56 TELEX: 524845 tipat CABLE ADDRESS: Garmaniapatent Munich * ^ * 9j * 5 ß K ^ β

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24th time 197 3 B 5416

Imperial Metal Industries (Kynoch) Limited Birmingham, UK

Method and device for casting objects

The invention relates to a method and an apparatus for casting objects, which consist of a crystalline, synthetic plastic material.

According to the invention there is a method for

Molding an article from a synthetic plastic material in having a lot of plastic material in one

a> temperature up to 30 ⁰ C above the crystalline ο

<° melting temperature of this material in the _o molten state and mechanically presses this amount into the cavity ο of a casting mold, which is at a temperature

- * half of the crystalline melting temperature is, whereby

the plastic material in contact with the surfaces

Deutsche Bank (Munich) Account 51/61070 Dresdner Bank (Munich) Account 3939844 Postscheck (Munich) Account 67043-804

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of the mold cavity is quenched and on at least some of the surfaces the mold cavity in the plastic material a molecular orientation is brought about, so that the tensile strength of the plastic material in the direction the molecular orientation is increased by at least 80%.

The synthetic plastic material is advantageous "

a crystalline polyolefin polymer.

Further, 'the invention comprises a method for the casting of a shotgun cartridge case of a crystalline polyolefin plastic material and is _s by bringing a lot of plastic material in a molten state at a temperature which is up to 30 C above the crystalline melting temperature of this plastic material that a mold is used which has a mold cavity having a base portion and a wall portion, and that mechanically the amount of plastic is pressed into the mold cavity ₉ initially through the base portion of the cavity, the mold being at a temperature lower than is the crystalline melting temperature, whereby the plastic material is quenched or cooled in contact with the surfaces of the mold cavity and a molecular orientation is induced in the plastic material at least at the wall portion of the mold cavity "in order to increase the tensile strength of the plastic material in the direction to increase the molecular orientation by at least 80%.

309850/0910

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According to the invention, the casting mold is advantageous
continuously cooled to keep them at a temperature below the crystalline melting point.

Preferably the crystalline polyolefin polymer is high density polyethylene. .

The amount of plastic material is also expedient
prepared to a temperature up to 5 to 15 ° C above their crystalline melting temperature, preferably in particular at a temperature of 5 ° above this melting temperature.

The invention provides an object that
synthetic plastic material and in the
Is prepared in that one brings a lot of plastic material in the molten state, namely
at a temperature up to 30 ⁰ C above the crystalline
Melting temperature of this material that one mechanically this. Amount of plastic material in the cavity of a mold
presses, which is at a temperature below the crystalline melting temperature, whereby the plastic material is cooled or quenched by contact with the surfaces of the mold cavity and a molecular orientation in the plastic material at at least some sections of the
Surface of the mold cavity is induced, in order to increase the tensile strength of the plastic material in the direction of the molecular orientation by at least 80%.

3 0 9 8 6 0/0910.

The invention is particularly applicable in the production of shotgun cartridge cases, which are manufactured in such a way that it brings a lot of plastic material in a molten state _s and at a temperature up to 30 ⁰ C above the crystalline melting temperature of the plastic material, that a Casting mold used which has a mold cavity which has a base portion and a wall portion, and that mechanically the amount of plastic material is pressed into the mold cavity, initially through the base portion thereof; The casting mold is at a temperature below the crystalline melting temperature, whereby the plastic material is quenched when it comes into contact with the surfaces of the mold cavity and a molecular orientation in the plastic material at least in the wall section of the mold cavity results to increase the tensile strength of the plastic material in the direction of orientation by at least 80 % increase.

Preferably, the plastic material is a high density polyethylene, which is prepared at a temperature of 5 C above its crystalline melting temperature and its tensile strength about halfway along the wall section
Wall section is.

2
the wall section about 984 kg / cm in the direction of the length of the

Finally, the invention provides a mold ■ for casting objects from synthetic plastic material; the mold consists of a mold body,

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in this accommodated cooling channels _{s a mold cavity 3} delimited by the body of _{an extension s provided} on the body s which delimits an interior ₉ which is open to the mold cavity ₃ temperature monitoring channels in the extension _{s of} a plate ₃ a recess in the plate 5 in the one injection nozzle a Spritsgießmaschine fits a provided on DER plate projection _s has the = same length as the extension and serves as a sliding seat for the extension "and passing through the plate and the projection channel _s of a connection of the recess to the mold cavity via the Creates the interior or the interior of the extension.

Advantageously, the casting mold has an ejector rod within the mold cavity _9, a sleeve _s that extends around the ejector rod and forms a mold core _s and an extension on the ejector _{rod s} that fits with a sliding fit into the channel going through the plate »

The invention also provides a method for the injection molding of synthetic plastics material using the aforesaid mold; This method consists of ₃ keeping the temperature of the mold body at a temperature below the crystalline melting temperature of the plastic material, inserting the injection nozzle of an injection molding machine into the recess of the plate and inserting the projection in the extension of the

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Detected mold body and thereby holds open the interior of the extension, then an amount of synthetic plastics material at a temperature of up to 30 C above the crystalline melting temperature of the injection nozzle injects through the channel in the plate into the interior space, for a time so _s thus remains the material can partially solidify in the channel, then pulls the injection nozzle from the recess and closes the injection mold by pushing the projection fully into the interior and thereby mechanically pressing the plastic material into the cavity of the mold _s whereby a molecular orientation in the plastic material is close to at least one- Part of the surface of the mold cavity gives ₉ so that the tensile strength of the plastic material in the direction of the molecular orientation is increased by at least 80%.

The invention is illustrated in the following with the aid of a schematic Drawings explained in more detail using an exemplary embodiment.

Fig. 1 is a cross section through a casting mold

for a shotshell case when the mold is fully open;

FIG. 2 is a section corresponding to FIG. which shows the partially closed shape;

Fig. 3 is a FIG. 1 corresponding section of the mold after the complete closing

made clear. _3Q96 5 _{0 / 031u}

Referring to FIG. 1, a mold 1 is provided "which has a body 2 (not shown) with cooling channels is provided which are supplied with a continuous flow of cooling water ο The casting mold 2 has a mold cavity 3 ₉ which is generally cylindrical, and a base = section 4 and a wall section 5 has. At the end of the base section 4 facing away from the wall section 5, the mold cavity is provided with a radially outwardly pointing depression 6 through which the edge of a shotgun shell can be poured.

The mold body 2 also has a tubular shape Extension 7, which is open to the base section 4 of the mold cavity 3 and points away from this section. The inner

8 of the tubular extension 7 is cylindrical and goes into the recess 6. The tubular extension is provided with temperature monitoring channels (not shown) and can be thermally insulated from the cooled casting mold body 2 by interposing an insulating ring

9 is attached to this, indicated by dashed lines is.

The mold body 2 is provided with an ejector rod

10, which extends into the mold cavity 3 and is provided within this cavity with a sleeve 11 which is intended to form a casting mold core and to define the inner surface of the shotgun shell. The sleeve 11 has a head portion 12 with a frustoconical x ¹ shape;

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from the top of this head section stands the ejector rod 10 before, which is reduced in diameter and provides a cylindrical axial extension 13, whereby the conventional Inner shape of the shotgun shell can be cast together with a fuse cavity. The sleeve owns also a wall portion 14, which is attached to the head portion 12 connects and tapers in the direction of the head portion. As a result, the wall section 5 tapers Casting mold 3 away from the base section 4 and provides a conical shape in the shot shell case to be produced rejuvenating wall. The ejector rod 10 is provided with a device (not shown) for sliding through the Base portion 4 of the mold cavity 3 and the tubular extension 7 provided around the cast shotshell shell to eject.

The mold 1 is also provided with a plate 16, which is shown in Fig..1 in the open position. the Plate 16 consists of a circular plate 17 which has a partially spherical depression on an upper side in the middle 18 is provided, in which the spray nozzle 19 of an injection molding machine (not shown) fits. Opposite the recess 18, the plate is provided with a cylindrical projection 20, which has the same length as the tubular extension 7 and fits with a sliding fit in the interior 8 of this extension. A cylindrical channel 21 is drilled through the plate 16 and the projection 20, which channel into the base of the recess 18 opens. The channel 21 is coaxial with the ejector rod

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and can slip fit extension 13 when protrusion 20 is within the tubular extension 7 is located. The cylindrical projection 20 can be embedded in a tube 22 made of insulating material (shown in phantom) in order to minimize any heat transfer between the tubular extension 7 and the projection 20 to reduce. The protrusion 20 may be sealed against the mold body 2 around the base surface of the shotgun shell and to limit their edge. The plate 16 is provided with filling channels, not shown.

During use, the casting mold body 2 is supplied with a constant flow of cooling water through its cooling channels in order to keep it at a temperature below the crystalline melting temperature of the polymer to be deformed. The selected temperature can, for example; Room temperature, 10 ° C or 0 ⁰ C. The röhrförmige extension 7 is maintained at a temperature which is up to a maximum 30 ⁰ C above the crystalline melting temperature of the polymer. The plate 16 is at a temperature below the crystalline melting temperature of the polymer.

For the injection molding of a shotgun shell case, the mold parts are partially closed, as shown in FIG Fig. 2 is shown so that the projection 20 is just inserted into the tubular extension 7 and the Spray nozzle 19 is received in recess 18. There is then molten polymer from the nozzle 19 into the mold

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injected, wherein the injected polymer is basically in the tubular extension 7, which is normally is maintained at a temperature not greater than that of the polymer. It will be the one for pouring the Correct amount of polymer injected into the sleeve.

After a dwell time of a few seconds while which can partially solidify the polymer located in the channel 21 of the cold plate, the nozzle 19 is withdrawn and the mold is completely closed, as shown in FIG. When fully closed the mold is the molten polymer from the tubular extension 7 into the relatively cold mold body 2 pressed, which is at a temperature below the "crystalline melting temperature is located. This causes the polymer to grow at a speed that increases with the injection quenched and cooled along the wall section 5 of the mold cavity, the polymer in the longitudinal direction of the Mold is molecularly oriented. In the base section 4 of the mold cavity 3, there is less orientation because there the polymer cools more slowly and is not displaced to such an extent; in this area of finished cartridge case, a molecular orientation to the extent required for the Wall section is required. When the casting mold is closed, the extension 13 comes into working contact with the channel 21 of the plate 16 so that a seal is achieved, with which higher Press down on the polymer in the mold.

309850/0910

Can be practiced with the solidified polymer plug is expelled in the channel 21. This is illustrated in FIG. 3. When the mold is completely closed, the polymer becomes solidified very quickly in the wall section 5 of the mold cavity .3, while the solidification of the polymer in the base section U through the cold ejector rod 10 and their Extension-13 as well as by the relatively cold end surface of the.-itself therewith located in contact projection 20 is effected. A complete cartridge case is thus formed, which is provided with an edge which is formed by the recess 6.

~ v After a typical example of the mold body 2 at a temperature of 10 ° C, the tubular extension 7 and the edge is held of fuel injected by the nozzle 19 polymer at 135 C at a temperature of 10 ⁰ C and the temperature sixteenth Under these conditions, a cartridge case made of high density polyethylene is produced with a crystalline melting temperature of 130 ⁰ C, wherein the tensile strength at mid-length along the wall portion about 981 kg / cm in the direction of the length of the wall portion. Such a cartridge case can be compared favorably with conventional cartridge cases produced by injection molding, ie with those in which there is no substantial molecular orientation; namely, the invention increases the tensile strength of the sleeve wall in the direction of the molecular orientation, ie, along the length of the sleeve, by three to four times. In this specific example, the temperature of the polyethylene

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lens 5 ° C above its crystalline melting temperature. When using a polymer ^{temperature of 30 0} C above the crystalline melting temperature of this polymer, d.lr. when using a polyethylene using a
At a temperature of 160 ^° C., an increase in tensile strength of 80% was achieved. The temperature of the polymer is preferably between 5 and 15 ° above its crystalline melting temperature.

To complete the injection molding process
the mold parts are shown in FIG. 1
Position opened and the ejector rod 13 is actuated to eject the molded sleeve from the mold body 2.

The previous description was based on the injection molding of plastic shotgun cartridge cases; for the professional however, it will be understood that the invention can also be applied to injection molding other articles of synthetic plastics material can be used, especially when the material is crystalline in nature and it is desired that in parts a molecular orientation of the article is brought about in order to increase the strength.

309850/0910

Claims (3)

Claims 1.1 Procedure for casting an object from Synthetic plastic material, characterized in that there is a quantity of plastic material at one temperature brings this material into the molten state of up to 30 ° C above the crystalline melting temperature and mechanically injected into the cavity of a mold maintained at a temperature lower than. is the crystalline melting temperature of the plastic material, this material being in contact with the surfaces of the mold cavity and quenched in the plastic material adjacent to at least a portion of the surfaces of the mold cavity a molecular orientation is caused to increase the tensile strength of the plastic material in the direction of the Increase molecular orientation by at least 80%. 2. The method of claim 1 for casting a shotgun shell from a crystalline polyolefin plastic material, characterized in that a casting mold with a mold cavity is used which has a base section, and has a wall portion, wherein the plastics material is initially injected through the base portion. ' 3. The method according to claim 1 or 2, characterized in that the amount of plastic material at a Temperature is brought from 5 to 15 ° C above its crystalline melting temperature. 309850/0910 4. The method according to one or more of the preceding Claims, characterized in that the casting mold is continuously cooled in order to keep it at one temperature to be kept below the crystalline melting temperature. 5. The method according to one or more of the preceding claims, characterized in that the synthe-. table plastic material is a crystalline polyolefin polymer. 6. The method according to claim 5, characterized in that that the crystalline polyolefin polymer is high density polyethylene - - ■ 7. The method according to claim 6 for producing a shotgun shell, characterized in that the amount of plastic material brought to a temperature of 5 ⁰ C above its crystalline melting temperature and the tensile strength in the middle of the wall section to about 984 kg / cm in the direction of the length of the wall section is increased. 8. Device ^for carrying out the method according to one or more of the preceding claims, characterized by a casting mold body (2), cooling channels provided in this, through a mold cavity (3) delimited by the casting mold body, an extension (7>) provided on the casting mold body defining an interior space that is open to the mold cavity through in the extension ■ 30 98 50 / 0-9 10 housed temperature control channels, through a plate (16), a recess (18) provided in the plate, in which fits an injection nozzle of an injection molding machine through a projection (20) provided on the plate, the same Length as the extension (7) and fits with a sliding fit in this, with a through the plate and the projection Channel (21) extends, which establishes a connection from the recess to the mold cavity via the interior of the extension. 9. Device according to Änspuch 8, characterized by an ejector rod (10) extending within the mold cavity is located, through a sleeve (11) surrounding the ejector rod, which forms a mold core, and by an extension (13) provided on the ejector rod and slidingly fitted in the channel (21) extending through the plate fits. 10. Apparatus according to claim 8 and 9, characterized in that the mold body (2) is kept at a temperature below the crystalline melting temperature of the plastic material, that an injection nozzle (19) of an injection molding machine in the recess (18) of the plate (16 ) uses the projection (20) with the extension (11) of the casting mold body (2) in working contact while keeping the interior of the extension open, then an amount of synthetic plastic material at a temperature of up to 30 ⁰ C above the crystalline melting temperature from the injection nozzle through the channel (21) of the plate into the 30 98 50/0910 Interior (8) injected, lingering for a while so that the material can partially solidify in the channel, then the
Removes the injection nozzle from the recess and closes the mold by pushing the projection completely into the interior of the extension and thereby mechanically pressing the amount of plastic into the mold cavity (3). 3 0 9 8 B 0/0 9 1 0 fr L e r s e i f e