DE2206588A1 - Injection moulding technique - for two-part mouldings - Google Patents

Abstract

The moulding block has three cavities, connected to a common sprue. In the first operation material is injected via two shorter sprues to two parts of the moulding, any material flowing in to the third and longer sprue being discarded. The two part-mouldings are then extracted and placed together in the third cavity, there being a space between the two parts which butt together at a common shoulder. In the second injection operation, material flows along the third sprue to unite the two part-mouldings together, while at the same time it also flows along the two other shorter sprues to produce two more part-mouldings, to enable the process to be repeared.

Description

"Injection molding process and device" Procedure for Compression molding of hollow parts or objects are known per se. For example, U.S. Patent No. 2,219,57, a process in which the top of a bottle is in a Mold is pressed while the lower part is made in a separate mold will. After removing the two parts, the same are outside of the mold with one another tied together. A binding agent softens the two pressed parts and creates a connection between the mating upper and lower portions of the Bottle, which is essentially a three-step process will be produced.

In U.S. Patent No. 3,475,530 is a method of making hollow Plastic articles described. This is a hollow plastic frame in a stamp insert manufactured and side surfaces are then attached to the frame while the same is still in the stamp insert. By injecting a certain amount Melted plastic in the mold is removed from the frame and cover plates formed chamber filled at the junctions of the parts, the cover plates attached to the frame defining the hollow structure. After hardening the assembly is removed from the mold. One along the connecting lines provided ripple improves the connection between the injected liquid Plastic and the frame or the cover plates.

In U.S. Patent No. 2,819,494 is a method of making Cast parts described with the help of mutually overlapping inlet openings. Plastic parts are manufactured in a single injection process in which several parts movable with respect to one another are created. The inlet openings at the parts overlap, so that the parts to be assembled are separated on top of each other by compression molding can be produced. The patent description refers here to the manufacture of a clasp whose outer frame is made by there is an opening made of injected plastic, and a pivotable one in the clasp frame lying tip, which is produced by injection molding via a second inlet opening. After removing the two parts from the molds, the tip is in the clasp frame pivotable. This is a two-step manufacturing process executed in a single injection molding device, but the device is different different from that of the present invention in that the two parts are not interrelated are connected.

The present invention relates to a mold with at least three cavities in which at least two interfitting parts in corresponding Cavities are produced. The parts are removed from the mold and pressed into one another to give a hollow structure and inserted into a hollow mold to then in a second step by injecting a certain amount of a liquid Plastic to be joined together. During the connection the parts will be at the same time, further output parts are hergeeteXt.

A preferred embodiment of the present invention relates focus on the production of a hollow body from two preformed by injection molding Parts with three cavities and the subsequent connection of the output parts to it an end product consisting of a single piece, the previously known devices and methods relate to the formation of hollow bodies in molds and separate ones Operations in the same form. A disadvantage of the first mentioned invention of US patent no. 2,219,576 is that the two parts are outside the mold must be connected to each other with the help of suitable solvents to the bottle or to yield the hollow object. According to the present invention the parts are produced in the same, multi-cavity compression mold and connected to each other.

A disadvantage of the invention of U.S. Patent No. 3,475,530 results because the frame is made in a mold, but the top surfaces in another, whereupon the two parts by injecting plastic between them the top surfaces and the frame are joined together so that the hollow object is actually completed in a third die. This procedure includes accordingly three work steps.

An advantage of the present invention is that the two separate parts making up the hollow object in a single machine are produced in hollow compression molds, from which they are then removed be assembled, and in a third cavity in the same mold inserted and connected in it, while at the same time in the second, the connection of the first created parts manufacturing operation two more separate parts for the production of a further, hollow object in the other cavities of the Mold are generated.

The third of the aforementioned U.S. patents, No. 2,819,494 a process for the production of plastic parts that can move into one another with the aid of hollow Molds with separate inlet openings. In contrast, the present one allows Invention the production of two parts while simultaneously two previously produced Parts can be joined together into a single piece. A distinctive one The feature of the present invention is that at the same time a set of parts is manufactured while a previously manufactured set of parts is in the same operation is assembled to the end product.

An object of the present invention is therefore a method for Manufacture finished, hollow plastic objects to create.

Another object of the invention is to produce hollow plastic articles as a whole to create with the method according to the invention.

It is also an object of the invention to provide hollow plastic articles To create in injection molding with compression molds in which at least three cavities are provided are. All but one of these cavities are used for compression molding of parts that be taken out of the cavities, assembled manually, and in the remaining cavity can be used in the next step to a single object to be put together, while at the same time new parts in which his operation are produced, which then become one in the next operation single object can be joined together.

In a preferred embodiment of the invention, hollow Body made by injection molding, with during a second injection molding process two interlocking parts, compression-molded in the previous operation, in a third Cavity by injecting plastic into one of the two nested Divide defined channel to be combined into one piece, whereupon the channel with liquid inststoff is filled, the protruding rib-like projections on each of the Parts melts and thus the stimuli merges into a single object while At the same time, two more parts to be joined in the next step in others Cavities of the same shape can be produced in the same ãprisgußvorgang.

The present invention thus enables simultaneous manufacture two compression molded parts that are taken out of their molds, put together and inserted in a third cavity in the same reßfor, in order to become a single one in a second operation hollow object to be united while simultaneously having two new parts in the same mold getting produced.

For example, a three cavity mold is for injection molding purposes Mistake. Two of these cavities are used to make the two halves of one hollow object, while the third cavity to unite the two it is used for the first plastic injection molded halves. You two created first Parts fit into one another and shake a cavity enclosed by them. at The union of a two parts in the third cavity becomes molten plastic defined by grooves in one of the mating parts in either part Channel introduced into which several rib-like projections emanating from the parts protrude. These projections melt on contact with the; molten plastic and thus result in a liquid-tight connection between the two, the cavity 4 defining parts.

In the two-step manufacturing process the two parts initially by press molding and then from the hollow spaces taken from the mold. As previously mentioned, the parts are nested and inserted into the third cavity for their connection e. A single mold is required for the entire manufacturing process.

The connection between the two halves is an essential feature of the present invention. i suitable feed system consists of several inlet openings, which are placed around the cavity in which the parts are assembled. the Inlet openings are placed so that an even distribution of the scented Plastic in the channel defined by the two parts ensures that the Design of the two mating parts is another feature of the present Invention. The rusetende section must, for example, have a flat approach exhibit, the one close to a corresponding approach on the receiving section of the other half is present. The two surfaces must lie one inside the other when the two parts are pressed together connect to each other, so that when injecting liquid plastic into the channel the plastic does not penetrate into the cavity enclosed by the two halves can. Such a fit of the parts is achieved inden the external dimensions of the part to be inserted is slightly larger than the internal dimensions of the receiving part Partly held, so that when the two parts are pressed together a tight seal arises, which prevents the penetration of plastic into the hollow interior.

Another characteristic feature of the present invention emerges from joining the part to be inserted and the female part. On the outside of the part to be inserted, a groove is provided with a corresponding groove in the inner wall of the female part fits together, sodap when joining the two parts, the two channel sections form a single channel between the part to be inserted and the receiving part. Several in the radial direction projections protruding into the channel from the part to be inserted and from the female part Part will run out when liquid or molten plastic is introduced liquefied or melted in the channel, so that after hardening of the plastic results in a single, coherent connection of the two parts.

A major advantage over known devices and methods results according to the invention from the possibility of having a single injection molding machine Simultaneously manufacture parts and assembled parts in the same operation to assemble into a finished item.

Another advantage over known methods results themselves from the use of the same plastic for the manufacture and connection of the two parts, so that on the one hand the connection seam and the parts form a unit form, and that on the other hand a single injection molding machine for the entire manufacturing process can be used.

Another advantage over known methods results from the fusible projections extending into the connecting channel and the when liquid or molten plastic is supplied, surrounded by the same and are at least partially melted, with an intimate connection between the part to be used and the receiving part.

These and other objects and advantages of the present invention will become explained in the following description with reference to the drawings.

Figure 1 is a perspective view of a partially cutaway Article with the structure according to the invention.

Figure 2 is a plan view of a portion of the three cavities and inlet ports and supply channels for plastic in the mold.

Figure 3 is a perspective view of the die showing the Manufacture of an insertable and a female part in the mold.

Figure 4 is a partially cutaway elevation along that of Figure 2 with 4-4 and represents a female made in the mold Part.

Figure 5 is a partially cut away side view of the insert hollow body along the line denoted by 5-5 in Figure 2.

Figure 6 is a side view of the assembled assembly to be deployed or female parts, each with a plurality of rib-like projections is provided.

Figure 7 is a perspective view of the three cavities containing Die and shows the nested, inserted into the third cavity Share with the feeding system to the third cavity, in which the two parts become can be combined into one unit.

Figure 8 is a partial side view of the third cavity used receiving and to be inserted parts with the feed channel for the liquid plastic in the annular space defined by the two parts and serves to explain the resolution of the projections by liquefied plastic and the resulting connection.

Figure 9 shows a shape of rib-like projections in cross section, as they are attached in the channel used to connect the two parts.

Finally, FIG. 10 shows a different shape of the rib-like projections.

The outside 4 of the hollow plastic body designated by 2 in FIG can be formed in various shapes and, for example, the shape of a Accept fuel tanks for motorcycles. Suitable inlet ports 6 and 6A as well a supply line 8 can after the production of the tank according to the invention be used in the injection molding process, with inlet opening 6 being a can act compression molded internal or external thread.

As can be seen from Figure 2, the injection mold 10 consists essentially molten from three cavities 20, 50, 40 and a main inlet port 12 for supplying molten material Plastic to the cavities. Main inlet opening 12 branches into supply channels 13, 14, 15, wherein the supply channel 13 is again in the same type of cavity 20 opening sections -13a, 13b branched. As can be seen most clearly from Figures 3 and 4, cavity 20 is used to produce the receiving Part of the hollow Plastic body 2, while cavity 30, which extends over sections 14a and 14b and feed channel 14 contains plastic supplied, is used to produce the part to be used. The feed channel 15 emanating from the main inlet opening 12 leads to a set similar sections 15a and 15b, the inlet port 17 and branches 17a and 17b or a further inlet opening 18 with branches 18a and 18b etc. the introduction of plastic into cavity 40 enables a system of these feed channels ends in small outlet openings 42, which are equally spaced on the outer circumference of the Cavity 40 are attached and effective in the manner described below will.

Figure 3 is a perspective view of the two plastic parts 22,32 by a first injection of plastic through main inlet port 12 and feed channels 13, 14 and 15 can be obtained. In the first step of the Injection molding device, the two parts 22 and 32 are in the cavities 20 and 30 generated while at the same time a certain amount of plastic in the empty cavity 40 flows in. When the first parts 22, 32 are manufactured, this is simultaneous Amount of plastic obtained in the empty cavity 40 together with that in the supply channels discard solidified plastic material as waste.

The female part 22 shown in Figure 4 consists of one Body 21 with an annular projection 23 inside. One trained as a deepening Channel 25 is attached between the annular projection 23 and the bottom portion 24 From recess 25 go in the radial direction of several ribs 26, which extend over the the entire length of the recess 25 extend. In the bottom section are equally spaced several radial grooves 29 attached, all in a vertical slot 31 open, which in turn with recess 25 in connection stands. Depressions 29 and slot 31 correspond to the small channels 42 in cavity AQ, as can be seen particularly clearly from FIG. This from channels and inlet openings The purpose of the existing system is to distribute the plastic in the correct manner To supply chamber space 38, so that no empty areas through in the chamber space premature filling of one of the inlet openings remain. The melted plastic must be at each inlet port of the chamber in which the two parts are connected will arrive at the same time.

The illustrated in Figure 5, to be used section 32 of the to be produced Object is placed in cavity 30 by injecting molten plastic over it Feed channels 14> 14a and 14b made. The section to be used consists of a side wall 27, a bottom surface 37 and a top section 41. One around the circumference of the outer side wall 27 extending groove 35 contains a plurality of in Radially extending extensions 36.

FIG. 6 shows the two sections 22 produced by injection molding and 32 in the assembled state. The outer circumference of the section to be inserted 32 is slightly larger than the inner diameter of the receiving portion 22, so that when pressing the section 32 into the recess of the receiving section 22 the surface 41 of the section 32 to be inserted with the annular projection 23 terminates at the receiving section 22. The diameter of section 32 is chosen in such a way that, on the one hand, the parts no longer fit together after they have been pressed together solve each other, but that on the other hand liquid plastic in the supply system can flow. When the upper section 41 rests against the projection 23, the outer or inner surfaces of the two parts a liquid-tight seal, so that the plastic entering chamber space 38 not in the cavity 39 can arrive. When the floor surface 37 is flush with the floor section 24 Insert recess 25 in the receiving section 22 on groove 35 of the Section 32 aligned. When the two parts are put together, they are located the ribs 26 emanating from section 22 over the projections 36 to be inserted Part 32 within the chamber space 38. In the assembled state represents the outer edge 27 of the section 32 to be inserted a closure for the different, in the same Spaced slots 31 in the inner surface of the female part 22 After assembling the two parts, the same are in the third cavity 40 is used in the manner shown in FIG.

Well 29 and groove 31 on the female part 22 must with the associated small channels 42 for the introduction of plastic into the cavity 40 appear in their position in the right way. The one with the feeding system communicating small channels 42 are used for the introduction of liquid or molten plastic in the chamber space formed by recess 25 and groove 35 38, with the inflow from the main inlet channel 12 starting and via supply channels 18a, 18b, 18c and 18d is going on. The small channels 42 are recessed 29 and slot 31 in connection, the tight connection between sections 22 and 32 prevents the liquid plastic from entering the chamber space 38 as well penetrates into the cavity 39 defined by the two parts.

In operation, liquid plastic is in main inlet port 12 of the Press mold 10 initiated. The plastic is distributed in the feed channels 13, 14 and 15, the former having two feed channels for producing the two separate parts 22 and 32 are used, while the supply channel 15 is more fluid plastic is introduced into the initially empty, accessible line of the cavity 40. To Opening the mold, the two parts 22 and 32 are removed and the in the feed channels solidified, adhering to the parts 22 and 32 material removed. The material remaining in cavity 40 is treated as waste. the the two sections 22 and 32 are then pressed into one another, so that the upper section 41 with the annular projection 23 produces a liquid-tight seal and no liquid plastic in the cavity defined by the two parts 39 can pass.

The two assembled parts are then inserted into cavity 40 so that that the recesses 29 in the bottom portion 24 of the part 22 on the small channels 42 are aligned. The injection mold is then reassembled and more fluid Plastic is injected into the three cavities 20, 30, and 40 through the supply channel 12. The two nested parts are made by the introduction of liquid plastic through the small channels 42 in recess 29, slot 31 and the recess 25 and groove 35 formed chamber space 38 intimately connected to one another. Simultaneously the cavities 20 and 30 are filled with liquid plastic, the two parts 22, 32 to be connected to one another result in the next operation.

After opening the mold, the hollow object 2 (Figure 1) removed with the two simultaneously produced parts 22 and 32, the latter Parts are then nested to complete the entire manufacturing process to be repeated in the next operation.

Figure 8 shows a partial cross section of the in half 11 of the Press mold 10 inserted hollow plastic body 2. The cavity 40 forming half 11 is attached to the bottom part 9 of the injection mold 10. The figure shows a part of the nested parts 22, 32 and the supply of liquid plastic Via feed channel 17 and the small channels 42 in chamber space 38. The two parts 22, 32 rest against one another on the annular projection 23, whereby the passage of molten plastic in cavity 39 is prevented. The one in the radial direction extending projections 26 and 36 are at least partially injected from the hot Plastic melted and thus strengthen the connection between the two parts. The heat given off by the liquid plastic is enough to melt the thin ribs 26 or

of the extensions 36, so that a monolithic connection results.

To simplify the illustration, the two parts 22 and 32 are shown omitted in Figure 7 so that the figure essentially has the two above the small Channels 42 fitted nested parts in cavity 40 shows.

In the practical implementation of the procedure with in the same Mold provided cavities for the production of two parts and for connection the same can be done with the second work step, i.e. the assembly of the first Apparently, the parts manufactured in the process are not carried out at the beginning of the operation. The operation can be started in several ways, for example by several Sets of parts are injection molded and used to connect provided cavity can be used until perfect after a few injection processes Parts are obtained that form a first finished end product by plastic injection can be joined together, but it is more appropriate a suitably shaped Insert plastic piece in the supply line to the cavity 40 and the inflow of molten plastic into this cavity when first manufactured Parts 22 and 32 block. After the first injection, the mold will be opened and the two pressing parts are in the cavity after removal of the blocking plug 40 used, where they in the next step with simultaneous production of two new parts 2, 32 connected to one another by plastic injection to form the end product will.

The resulting end product need not necessarily be hollow Be an object, i.e. although the above description refers to a hollow object relates, other plastic articles can be produced, which expediently can be assembled from two or more parts. So it may prove necessary various parts of the plastic article to be manufactured from polymer material with to make different colors. The inventive method can also Use on objects in which different colored parts are inserted into one another and should be connected to each other.

There is no need for the binder injected into channel 25 necessarily to be the polymer or plastic material from which the to be connecting parts are made. However, the binder has ribs 26 and the extensions 36 to melt and an intimate connection with the parts after cooling of the total amount.

The principle of the invention was based on a two-half, an article defining a single cavity described, but the invention can also advantageous for connecting several individual parts to form a single end object be used. The entire manufacturing process does not necessarily need to be to be carried out in a single injection molding machine, i.e. it can under certain Depending on the circumstances, it may be useful to manufacture the individual parts in several injection molds, insert them into another injection molding machine and in the same to the end product connect to. It however, is an essential feature of the present Brfin manure that the entire manufacturing process is carried out in two steps being done by injecting plastic from a single injection machine In the same injection process, parts inserted in a mold are joined together to form the end product and other starting parts are made in other molds.

A secure, interlocking fit between the bottom portion 24 and the receiving portion 22 is another essential feature of the present Invention. In the preferred embodiment, the fit is made by chamfering the outer wall 51 of the receiving part 22 and the wall 52 of the Part 24 created (Figure 8). In addition, a projection 53 is provided on part 22, on which a corresponding approach attached to the bottom section 24 rests. Of the The inner diameter of the wall 51 is slightly larger than the outer diameter of the wall 52. When the mold is closed, projection 54 is therefore pressed against projection 53 and wall 51 then rests against wall 52 in the manner shown in FIG flat bottom portion 55. Apart from the four depressions 29 there is a good contact between walls 51 and 52 outside the flat bottom portion 55. In a preferred embodiment of the invention, wall 52 is somewhat longer than the inside of the wall 51 between projection 53 and the other end of the Wall 51. When closing the mold before the two parts are finally joined Wall 52 is then slightly pressed together and the connection between the projection 53 and approach 54 improved.

Various polymer materials and plastics can be used in the individual operations are used and the material making the connection does not need to be identical to the other plastics, but results special Advantages of using a single polymer material or plastic for the manufacture of the parts and their final assembly.

The ribs 26 provided in recess 25 can have various shapes have, but they may only have a thin, light layer of hot melted binder Oppose the fusible surface. You shown in Figure 9, the projections have the shape of prisms 61 with a triangular cross-section. Next to it is the one in figure 10 shown rib shape 71 with a rectangular cross-section is expedient, the The sharp edges 72 melt just as easily as the triangular ribs 61. In the frame the invention, no particular restrictions are to be provided for the projections, since they only have to be thin enough to be at least partially molten binder to be dissolved.

The method according to the invention is suitable for various plastic materials and is particularly suitable for thermoplastic materials commonly used for injection molding used types. These are, for example, polyvinyl chloride, polystyrene, Acrylonitrile-butadiene-styrene copolymers, polyethylene, nylon, polysulfone polymers and the like with and without reinforcing fibers.

Claims (4)

P A T E N T A N S P R Ü C H E S Hollow plastic body made of two parts by injecting molten plastic into one between the two parts provided channel (38), characterized in that at least one of the parts (22, 32) has a hollow, annular projection (23) and that at least one of the parts (32, 22) with an annular recess (25) for receiving the projection (23) is provided, so that a channel (38) for the introduction of molten plastic arises between the two parts (22, 32). 2. Process for the production of a hollow plastic body, characterized by the following operations: Making at least two separate, mating ones Divide (22, 32), nesting of the two parts (22, 32), so that at least one Chamber space (38) is created between the surfaces of the two parts, insertion the parts in the cavity (40) of a die (10), and injecting molten Plastic in the channel or the chamber space to connect the two in the mold inserted parts into a hollow plastic body (2). 3. The method according to claim 2, characterized in that the joined Parts (22, 32) are pressed together after being inserted into the injection mold (10). 4. The method according to claim 2, with a mold which is in a for Injection molding in different cavities suitable machine can be used, marked by injecting liquid plastic through a system of feed channels (12, 13, 14, 15) to the cavities (20, 30, 40) in a first step, in a first open body (22) in a first cavity (20) of the plurality of cavities containing mold (10) and a second open, with the first open body zubammeneassender and with it a hollow structure (2) resulting body (32) in one second cavity (30) of the multiple cavity containing compression mold are produced, Removal of the first and second body from the cavities, nesting the two open bodies (22, 32), with a channel-like chamber space (38) between the compressed bodies is created, inserting the nested Body in a third cavity (40) of the mold (10) in the second operation, Injection of liquid plastic through a system of feed channels (12, 13, 14, 15) into the cavities (20, 30, 40), with plastic in the chamber space (38) penetrates and the two nested bodies located in the cavity (40) (22, 32) connects together into a single hollow object while simultaneously two new bodies (22, 32) are formed in the other cavities (20 and 30, respectively).