DE8000989U1 - DEVICE FOR PRODUCING AN INJECTION MOLDING PRODUCT - Google Patents

Description

Yamato Kogure, 5821-663 Masagocho, Niigata, Japan

Process and device for injection molding of resin and products manufactured therefrom, processes for embedding a wax mold into a plaster mold

The invention relates to an injection molding process for resins using a plaster of paris mold, an injection molded product, a device for carrying out the method and a method of embedding a wax mold in a plaster of paris mold.

The invention thus relates to methods of manufacture of resin articles, such as dental prosthetic goods or industrial test articles and their products, especially using a plaster cast mold.

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Bremen Office / Bremen Office Postfach / P. O. Box 10 7127 Hollerallee 32, D-2800 Bremen Telephone: (0421) »349071 Telecopier / Telecopier: Rank Xerox Telegr. / Cables: Diagram Bremen Telex: 244 958 bopatd

Accounts Bremen: Bremer Bank, Bremen (BLZ 290 80010) 100144 900 nk, j

• • PSchAHembuie · ■ ·· (BLZ 200 100 20) 1260 83-202

Munich Office: Postfach / P. O. Box 14 0108 Schlotthauerstraße 3, D-8000 Munich 5 Telephone: (089) 65 23 21 TelekopVTelecop .: (089) 2215 69 R X. Telegr. / Cables Telepatent Munich Telex: 523937 jus d (code: forbo)

BOEHMERT & ΒΘΕΗ-MERT.

So far, the step of filling the synthetic resin in the manufacturing process, artificial teeth in dental Embedding prosthetic goods, typically done by manual operation. The resulting product such a manual production method has poor dimensional accuracy due to uneven pressure polymerization, whereby the manufacture of an article with an exact fit is impossible.

Instead of such a manual operation, a resin molding process using plaster of paris molds is available has been proposed, wherein the casting device can be applied to the plaster of paris mold. Nonetheless The casting devices for plaster molds and those for metal molds are basically in the injection conditions different from each other. The following problems are encountered with this type of molding apparatus: Injection molding is used in molding machines in general as a process in which the plastic material is fed into a heated one with the aid of a screw Cylinder is guided and by external heat supply as well as internal frictional heat by rotation of the screw is plasticized. The molten material thus formed is introduced into the metal mold by mechanical energy and filled, pressurized, and cooled to a molded article having the desired quality. So the plastic material is through external mechanical energy transferred from the solid to the liquid state; into the mold with the help of external kinetic energy and converted back into the solid state by absorption of the energy by the mold returned. In this way the process is great as well as the quality of the finished article influenced by the external casting conditions. Actual-

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Lending, molded products can have defects due to inadequate defects Filling, glow wire evaporation (flashing), flow lines, shooting out, welding lines, burn marks, Air bubbles, cloudiness, cold defects, tensions, throws, cavities, deviations from the standard, standard defects between spray operations as well as standard defects between welds. The injection molding conditions Cylinder heating temperatures for plasticizing the material, rotational speeds of the screw, the Amount of material that is stored in the injection cylinder for injection into the mold, measuring cycles, screw back pressure, Injection pressure for filling and pressing into the mold, injection speed, injection time, cooling temperature for the absorption of thermal energy and cooling time. These conditions are critical and for the manufacture of molded articles is indispensable. For example, the properties of the plastic material go lost by destruction of the same if the cylinder temperature is too high. If excess metering speeds are used, the resin remains in the cylinder too long, which destroys the material is effected. If the injection energy is too large, the resin may come out of the mold parting line due to of the applied pressure seep out. If the injection energy is too low, the gloss that the Resin is peculiar, which sometimes creates cold marks. If the cooling time is too short, it can cast product may be inaccurately shaped and thrown. Accordingly, specialists are necessary for the operation, i.e. that the products of the casting process are checked and adjusted by visual inspection of the personnel got to. The casting conditions influence each other; a cast product can only be manufactured

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if it is known how the properties of the plastic material change under given conditions change the entire process, and you must also know what is going on in the mold.

Since the casting conditions are not constant, but always change to a lesser or greater extent, the Product quality for each injection cannot be maintained without difficulty. In fact, the Properties of the plastic material due to changes in hydraulic pressure, oil temperature and casting temperature and change the heating temperature. Since the casting device is itself under the effect of these changes remains unchanged, fluctuations or discrepancies in product quality in the absence of such Changes, except for plasticizing factors, for air leakage from the resin, material contamination, mixing of regenerated Attributed to articles, compounding material mixing and viscosity of regenerated articles. Experimental It could be confirmed that these factors are responsible for the majority of fluctuations in the products and that these factors are extremely difficult to subject to effective quality control.

Optimal injection molding should be done so that an optimal amount of uniformly plasticized, molten material is obtained Resin is filled into the injection mold with an injection energy adapted to the mold, wherein the injection energy is maintained until the filling channel and / or a gate is closed has taken place and the product has cooled for a suitable cooling time interval at a suitable cooling temperature has been. The problem then is this

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Control factors. The state functions of the plastic materials have three parameters, namely plastic pressure / plastic capacity and plastic temperature. It has been proposed to provide a probe in the mold for measuring the resin temperature and the thus measured Return temperature to heating devices at the entrance of the entry gate. Such a control practically involves great difficulties in view of the fact that the response to the control signal at high resin injection speed, which can be on the order of less than a second, should be carried out. The resin capacity can be made constant by keeping the closed state constant will. The increase in the filling quantity until the cavity is filled with resin can be indirectly caused by the increase in pressure can be measured in the resin. The basis for a control is therefore the resin pressure. In other words, as in Figure 8 shown, which shows the relationship between the internal mold pressure and casting time, are such defects as flow lines, Shoot out, weld lines, burn marks, bubbles, turbidity, cold marks, tension and throwing something that occurs during filling (time A in the drawing); Defects such as insufficient filling, glow evaporation (flashing), throwing, inaccuracy and standard errors between sprayings do not occur during maintaining the pressure (time C) and defects such as throwing or shots occur during cooling to (time D). Thus, in this way, the majority of the defects become during filling evoked. Accordingly, the basic requirement for resin injection molding is resin printing.

Accordingly, it is the object of the invention to provide a

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drive for injection molding of resin under optimal conditions, preferably using a plaster mold to deliver, the relationship between injection speed, internal pressure of the mold and the held Pressure on the one hand and between the diameter and length of the filling channel and the air outlet openings is clarified and The appropriate technical measures are used to make synthetic resin injection molded articles of the desired physical Establish properties and dimensional accuracy.

According to the invention, the object is achieved by an injection molding process solved, which is characterized by the following steps:

Providing a vent in the plaster of paris mold; Measuring the pressure of the injected resin in the plaster mold by pressure measuring means; Controlling the injection conditions such as the injection speed one of of the molding device to be injected into the mold according to the measured pressure to reduce the internal pressure in the plaster of paris mold according to a predetermined optimal pattern, stored in the memory of a computer, below to change the point of destruction of the product to be poured.

The injection molded product according to the invention is characterized in that that it was made by a process of any one of the preceding claims.

The device according to the invention for carrying out the method is characterized by an injection mold with a filler channel and a vent, one of which at least one is changeable in its dimensions by a control, an injection device with by the

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Control of controllable injection speed and a mold internal pressure measuring device, connected to a die Control computer operating the control based on a previously saved pattern of optimal dimensions the filling channel, the vent opening, the injection speed and the internal mold pressure actuated. Furthermore, a method for embedding a Wax mold supplied in a plaster mold, characterized in that that the wax mold is embedded in the plaster of paris mold by means of vacuum degassing.

The invention thus relates to a method and an apparatus for injection molding resin.

As the resin is pressurized and suddenly at high speed through an injection port into a The mold is filled, the air in the mold is compressed and the internal pressure of the mold is momentarily high, whereby the resistance within the mold also increases. This momentary pressure build-up in the mold slows it down the rate of filling the resin into the mold, which is at a rate of less than 1 second takes place. This induces the resin to cool down. The time it takes for the resin to cool in the injection mold, is inversely proportional to the distance covered by the resin and the thickness of the resin product, so that the filling must be done before the resin cools and hardens. Applying excessive pressures to the mold without considering the above leads to an increased pressure in the mold and deteriorates the physical properties as well as the stability of the resin. Injection molding can even become impossible when the product has both thick and thin sections

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Iv It is therefore to provide the same for carrying out a first purpose of the invention, a method I "and an apparatus'! Wherein the optimum ratio between p Injektionsgeschwin- speed, pressure, and vent can be achieved.

!, A second purpose of the invention is to provide a method t and to provide a device thereof for carrying out: which overcomes the situation, the abrupt Druckji increase in the mold that is encountered during the injection molding% to bypass through a vent, I whereby this ventilation opening is blocked in the next moment by ί hardened resin and that for as long as! Resin filled into the mold begins to harden and

to dwindle. The relationship between vent, . The filling opening and the injection holding pressure must therefore be clarified will.

Furthermore, when the injection molded product has a considerable thickness, dimensional accuracy can only be obtained when the holding pressure is applied immediately: because the resin once inserted into the injection mold is instantaneous : is subject to cooling and shrinking. The problem then is to control this and deal with the situation that, although the pressure decreases due to shrinkage, this can be compensated for by the addition of resin can, whereby there is no way to refill resin if the filling channel is completely hardened by curing ; has been stuffed before the injection molded article has assumed a fully stable shape. It is therefore the third purpose of the invention, a method and a pre

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direction to solve this problem by clarifying the dependencies to be clarified between the thickness and the diameter as well as the length of the filling channel.

A fourth purpose of the invention is to provide a method and an apparatus for carrying out the same to create whereby the physical properties and accuracy can be achieved if the injection molded Product has both thick and thin sections. It doesn't make sense to just shrink, that occurs during injection molding, the filling of the injection mold before the resin cures must be done. As such, the filling and injection must be carried out in a very short time using an increased injection speed occur. Nonetheless, the air resistance offered by the thin section is provided when the air in the thick portion is compressed into the thin portion, thereby causing the resin to flow is slowed down during loading and causes cooling to occur and the injection-filling effect decreases. Therefore, an article can be produced with too little filling capacity or the physical properties and the accuracy cannot be achieved. On the other hand, a reckless increase in the injection speed leads and the pressure to uneven quality as well as to the destruction of the plaster of paris mold. In this case it exists technical problem to be solved is that the relationship between the vent opening and the diameter as well the length of the feed channel must be taken into account. This makes it possible to harden the resin, whereby the vent opening is sealed according to its dimension and accuracy, and thereby the stabilization of the resin to contract or to shrink

BOEHMERT & BOEHMERT.

same supports to assist in releasing air from the mold. At the same time, the Properties of the molded article favorably influenced.

It is a fifth purpose of the invention to create a recess in a plaster of paris mold so that the outer Shape of the wax mold to be embedded in the plaster of paris mold is faithfully maintained.

All of these objects are achieved by the invention, wherein a wax mold, a fill opening, gate and a vent opening be attached in a desired manner in a plaster of paris mold, then plaster of paris in the plaster of paris mold is injected, then the air bubbles in the plaster of paris are removed by vacuum degassing, the plaster of paris mold for removal the wax mold is heated and resin is injected from an injection molding machine after washing. At the time of injection, the air in the plaster of paris mold is let through a vent with a diameter determined by a calculation considering the correlation between filler opening, Gate diameters and ranks as well as the internal pressure in the plaster mold was set during the filling of the Resin removed in the same. At the same time we aer resin pressure with the help of one located in the filling channel Pressure sensor measured until the resin has been filled to the last part of the cavity, cooled and solidified is. In addition, a curing pressure, within the maximum allowable pressure range in the plaster of paris mold, can be insufficient or to be too much to be found out. A control is used to control the hydraulic equipment to control the injection molding machine in such a way that this curing pressure until the injection molding gate is sealed is maintained.

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The invention thus relates overall to a method for producing resin articles using an injection mold, which comprises the steps of: measuring the resin injection pressure into the plaster of paris mold by means of pressure measuring devices, Controlling the injection conditions of an injection molding machine in accordance with the desired optimal correlation pattern between the .Durchmessern of a filling channel and a vent, this pattern in advance was saved in the memory of a computer. With this construction, molded products can be molded with sufficient Resistance in all areas of the same as well as with uniform injection molding properties and improved Dimensional accuracy can be obtained according to the invention.

Further features and advantages of the invention result from the claims and from the following description, in the exemplary embodiments on the basis of the drawing are explained. It shows:

1 shows a longitudinal section of a device according to the invention for injection molding, showing injection molding of a molded product having a uniform thickness;

2 shows a longitudinal section of a device according to the invention for injection molding, wherein the injection molding of a product is shown with a thick section A and a thin section B;

Fig. 3 perspective views injection molded 5 cast products;

6 shows a planar section through the device according to the invention, with the inside the box mold with cooling and

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Heating devices is shown; and

7 shows a longitudinal section of a further preferred embodiment of the invention Apparatus showing the injection molding of dental prosthetic goods with thin palatal surfaces is;

8 shows a characteristic representation of the dependency of the internal pressure of a Injection mold from the state of the art;

9 shows a characteristic curve of the curing pressure in a controllable injection mold;

Fig. 10 is an ideal characteristic curve of the internal pressure of a controllable plaster cast mold according to the invention;

11 is another characteristic curve of the internal pressure of an injection mold another preferred embodiment of the invention.

Figure 1 shows an injection molding device according to the invention, wherein a plastic product to be molded (a) in a mold cavity 1 has an approximately constant thickness.

A wax mold 6 is housed in a known manner between a lower 2 and an upper mold box 3, wherein a filling channel 4 and a vent opening 5 are provided are facing in opposite directions of the assembled surfaces of the lower and upper flasks 2, 3 extend.

Plaster of paris is injected into the hermetically sealed casting molds, and air bubbles are created from the plaster of paris by means of vacuum defoaming removed. After the plaster of paris has hardened, will

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the wax is removed from this by heating, whereby a plaster mold 7 is formed. Near the injection port 8, which leads to a filling channel 4, there is a feeler pin / 9 of an internal pressure measuring and control device (not shown) for internal printing. An injection nozzle of an injection molding device (shown indicated), the capable of injecting at a very high speed (maximum injection speed 0.1 seconds) the injection port 8 for pressure injection of ultra-hard resin into the plaster mold at an injection speed of 0.01 to 10 seconds and an injection pressure of 30 to

1200 kg / cm is set at the same time in the plaster mold 7 compressed air, which causes a momentary increase in the internal pressure and the resistance is increased in the plaster mold. This pressure is easily released through the vent 5, creating an abrupt An increase in the internal pressure is avoided. After the casting pressure has been completely relieved, the ventilation opening is opened 5 hermetically sealed. The numerical values at which an optimal correlation occurs should be in a computer memory stored, including the thickness of the molded product and other conditions in the area of the Diameter or the perimetric length of the vent opening 5 from 0.1 to 5 mm and the diameter or the perimetric length of 0.5 to 20 mm of the sprue 4 are taken into account. It is believed that an abrupt An increase in the pressure present in the mold can be avoided by venting via the vent opening 5 can, the latter being sealed in the next instant by hardened resin, the shrinkage at Hardening of the injected resin takes place after the injection is complete. Because of this, a hold pressure must be applied immediately can be used for a holding time of 0.05 to 60 seconds

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to compensate for this dwindling. At this time the ventilation opening 5, which was used to reduce the pressure in the mold, must be completely sealed.

In the embodiment of Figure 1, in which the cast Product has a uniform thickness, the casting process does not encounter any significant difficulty. Nevertheless, in the case when the product has a larger thickness, the shrinkage of the product is when the latter is held in the injection mold and cooled, the higher the temperature, the greater the temperature the resin has been heated. As a countermeasure to this shrinkage, the feeler pin 9 is for measuring the inner Pressure and provided for control on the filling channel 4, (with the destruction pressure of the plaster mold in the computer stored in advance) so that an appropriate amount of resin is poured into the mold to compensate for resin shrinkage can be delivered according to the decrease in internal pressure. It should be noted that if the filling channel 4 is completely clogged by hardened resin before the injected resin is completely and is permanently shaped, the control function of the feeler pin 9 cannot be exercised. In view of this fact must the optimal ratio between the diameter and length of the filling channel 4 and the thickness of the cast product stored in the memory of a computer so that the optimal proportions of the computer to prevent a Clogging can be determined by solidification of the sprue.

In Figure 2 a further embodiment of the invention is shown, wherein the cast product is a non-uniform Thickness and accordingly a thicker

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section A and a thinner section B, which must be cast at the same time. In this case it helps nothing to merely consider shrinkage during pouring; curing the resin should do not occur until the resin is fully injected into the mold. For this reason, an increased injection speed, compared to the embodiment shown in Figure 1, necessary. First is the air compressed in the thicker section A and held in the thinner section B, the air pressure grows and slows down the resin flow during injection molding while cooling the injected resin, which results in a smaller injection effect and the physical properties of the cast product will be deteriorated. An increase in the injection pressure and thus the injection speed can overcome the resistance in the mold. This can destroy the plaster of paris. The vent 5 is essential to prevent such an increase in pressure in the mold. In addition, should the vent opening 5 has such a diameter and Have length so that they are sealed by the injected resin even after realizing the above-described effect will.

The diameters of the filling channel 4 and the vent opening 5 are according to the size of the to be cast Products changed to compensate for the outlet pressure and to add the appropriate material properties of resin to maintain for shrinkage. For this purpose a correct correlation between the filling channel is established 4 and the vent 5 required which it allows the resin to cure in such a way that it

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ventilation opening 5 seals, so that the secondary pressure on ;: Dismantling is prevented.

ί The physical properties and the dimensional accuracies can be achieved with a product that wel-!>; ches has both thick and thin sections if this numerical values., corresponding to one already in advance Correlation stored in a control device for optimal injection molding conditions for the special molding process be communicated.

In the injection molding of industrial products as well as dental prostheses, if not many products are required and the injection molding is to take place in a plaster of paris mold, secured by the molding boxes, becomes the internal Pressure in the mold measured by the feeler pin 9 and adjusted to the physical properties and the Ensure dimensional accuracy of the cast product. The feeler pin 9 is directly connected to the filling channel 4 connected. By these means, a product with a thin section B, the thickness of which is 0.5 mm and with a thick section with a thickness of 20 mm, which otherwise had to be cast individually and then had to be connected to each other after casting, integrally and cast at the same time, such as shown in Figure 4, wherein injection molding at ultra high speed and without the risk of destroying the plaster mold, is carried out.

The pressure in the mold of the injection molding machine is controlled in the following manner. A pressure transducer or sensing device to measure the resin pressure, an injection mold or a cavity is

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Gate in the vicinity of the filling channel 4, as already described, arranged. The resin pressure is measured with the help of an oscilloscope or another recording device (not shown) measured from the time the molten resin is injected into the mold from the nozzle of the molding machine until the resin has been completely filled into the cavity 1 and solidified by cooling. on In this way, the desired curing pressure c is found, which is within a tolerance range between the upper and lower limits a and b due to insufficient filling or overfilling as indicated in Figure 9, is located. The hydraulic system of the injection molding device is used until the filling channel 4 is sealed controlled so that the pressure in the mold can be kept in the range of this curing pressure by a controller can.

It should be noted that in the case of the above described Structure a device for supplying variable hydraulic pressure attached to the injection devices can be around a closed loop, suitable for releasing the resin pressure within the mold so that the internal pressure in the mold for each injection can be controlled by this controller, such as a servo valve or a proportional solenoid valve, where this control takes place, until the filling channel 4 is sealed so that the internal pressure within the mold is within the, as indicated in Figure 10, the curing pressure is located.

Alternatively, the device for supplying variable hydraulic pressure can have the construction mentioned above the injection devices of the injection molding machine

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may be applied and, as shown in Figure 11, an intended one Program control for the injection speed according to the respective casting configuration, to the pressure of each section reaches the hardness pressure, can be carried out and the curing pressure is maintained for so long until the vent is sealed, invalidating the previous program, when the curing pressure P is reached.

According to the present invention, the resin is made at high speed from the sprue with a diameter or perimetric length of 0.5 mm and a perimetric length of 20 mm in resin injection molding using a plaster mold 7 and for a pressure hold time of 0.05 to 60 seconds using the injection molding conditions injection speed from 0.01 to 10 seconds

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speed and 30 to 1200 kg / cm injection pressure.

The internal mold pressure tends to increase abruptly and is through the vent 4 with a diameter of 0.1 mm and a perimetric length of 5 mm reduced. After the mold 7 has been filled with resin, the vent opening 5 is cooled by Resin is sealed and an amount of resin is further introduced to compensate for the shrinkage of the molded product. After filling, the filling channel 4 is cooled and hardened. The feeler pin 9 of the control device is connected directly to the filling channel and measures the internal pressure in this sequence of process steps to control. In this way, by controlling the internal pressure of the plaster of paris mold, an optimal ratio

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set between filling channel 4 and vent opening 5 in order to obtain dimensional accuracy and the desired properties of the injection molded product.

Nevertheless, when the filler channel 4 is hardened, the thick portion of the filled mold will still be cool and shrink because this thicker section is too thick, giving the desired properties and accuracy cannot be achieved. Therefore, as shown in Fig. 6, a cooling pipe 10 is already circumferentially arranged in advance of the thick portion embedded, while a heating pipe 11 is embedded where heating is necessary, to improve the general physical properties and accuracy of the molded product.

During the production of the plaster of paris mold, the plaster of paris is mixed with water and the resulting Mixing carried out as known. During the investment, the plaster of paris is injected in vacuo and at the same time placed under vibration before the hardening reaction, creating a good smooth inner surface of the plaster cast for improved accuracy of the cast product is achieved.

FIG. 7 shows a cross section of the casting mold when the casting method according to the invention is used, which is applied to a dental prosthesis is applied (such as artificial teeth). In this figure is the thickness of the section of the cast Product, corresponding to the upper palatal surface 12 of the mouth, less than 0.5 mm. Due to the In human physiology, it is normal for foreign or foreign substances that come into the mouth to

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as a physiological action an expulsion of the same occurs to the body by repelling the foreign substance out to defend the human body. Accordingly, this section must be very thin. In this regard it should be noted that the artificial teeth obtained by conventional methods so far are often attached to the thin portion broke, as the latter cannot effectively withstand the pressure of chewing, which is why artificial teeth with one thin section, but sufficient resistance could not be realized so far. Recently is a Synthetic resin having satisfactory properties in this connection has been developed. Such a synthetic resin must be heated between about 280 ° C to 400 ° C or higher and shows poor flow properties during the Injection filling. In order to compensate for the disadvantages of such a resin, injection molding is used in an injection time of about 0.1 seconds, otherwise the desired physical properties and Dimensional accuracy cannot be achieved. The product made by conventional methods is water-absorbing and consequently flexible, so that the accuracy is not good. It was with the conventional one Injection molding process not possible, artificial teeth with physiologically ideally thin sections of less than 5 mm, as shown in FIG. 7, using the known resins such as polycarbonate, polyallyate or polysulfone resins were injected into a plaster of paris mold and filled, neither with regard to the quality of the product. nor "from the human-physiological point of view. The injection molding process according to the invention of ideal dental Prostheses has been made possible by injection molding equipment with very high injection speeds, which the feeler pin 9 of devices for measuring and

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Controlling the internal pressure of the mold and the cooling and
Heating means of the plaster mold, operable according to the ratio between the parameters of the sprue and the vent opening 5, has. The invention enables uniform properties of the material in the plaster of paris form and accuracy of the cast product to be achieved.

The features of the invention disclosed in the above description and in the following claims can be used both individually and in any combination for the implementation of the invention in its various Embodiments are essential.

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REFERENCE LIST
(LISO? OP REFERENCE NUMERALS)

1 cavity 1 2 cast molds, upper; Molding box ? 3 mold, lower; Molding box ?; 4 filling channel 5 Vent 5 6 wax mold 6th 7 plaster mold, plaster mold 7th 8 injection port 8th 9 feeler pin 9 10 cooling pipe 10 11 heating pipe 11th 12 palatal surface 12th "13 13th rfbfc · c = desired curing pressure 14th 3ib £> a = upper pressure cartridge 45 $ & b = lower pressure cartridge 46 $ 5iP = curing pressure 09 18th 18th 19th 19th 20th 20th 21 21 22nd 22nd 23 23 24 24 25th 25th 26th 27 27 28 28 29 29 30th 30th

Claims (2)

Claims 1 to 4 1. Device for producing an injection molded product, characterized by an injection mold with a filling channel (4) and a vent opening (5), of which at least one (r) in his or her dimensions can be changed by a controller; an injection device with an injection speed controllable by the controller; and a mold internal pressure measuring device 2. Apparatus according to claim 1, characterized in that at an injection speed of 0.01 to 10 seconds and an internal pressure, held for 0.05 to 60 seconds 2 den, a filling channel diameter of 30 to 1200 kg / cm from 0.2 to 20 mm and a vent opening from 0.5 to 5 mm diameter with a length of at least 30 mm 422 Bremen / Bremen Office: P.O. Box / P. O. Box 10 7127 HoUerallee 32, D-2800 Bremen Telephone: (0421) * 34 90 Facsimile / Telecopier: Rank Xerox Telegr. / Cables: Diagram Bremen Telex: 244 958 bopatd Accounts Bremen: Bremer Bank, Bremen, (BLZ 290 80010) 100144 900 ΊρςΰέρΗί Etapk! ßregrep; (PtZ? ΪΟ 700 5Oj U12002: ¹ PSchA Hamburg ·· ·· (BLZ 200 100 20) 1260 83-202 Munich Office / Munich Office: Postfach / P. O. Box 14 01 08 Schlotthauerstraße 3, D-SOOO Munich 5 Telephone: (089) 65 23 21 Telekop./Telecop .: (089) 2215 69 R X. 400 Telegr. / Cables: Telcpatent Munich Telex: 523937 jus d (code: forbo) 4 ■ ta are. ϊ | 3. Device according to claim 1 or 2, characterized ¹ 'indicates that a heating device (11) at least in I sections of the plaster mold (7) is provided. I 4. Device according to one of the preceding claims, I characterized in that a cooling device (10) Pj, in at least one section of the casting mold (7) 4 is seen.