Injection-molded plastic part, method for producing the molded part, insert for carrying out the method, and injection mold for carrying out the method.

Abstract

A molded plastic injection molded part is proposed which is designed as a one-piece hollow body and has a molded part wall (65, 75, 105) that defines a molded part cavity (66, 106), wherein the molded part (61, 71, 81, 91, 101, 111, 121, 131) comprises at least one hollow molded part curvature section (63, 73, 103, 113). The molded part (61, 71, 81, 91, 101, 111, 121, 131) has a plastic-encapsulated insert (62, 72, 82, 92, 102, 112, 122, 132, 142, 152, 162, 172) in the molded part curvature section (63, 73, 103, 113), which is designed as an insert hollow body, such that the molded part wall (65, 75, 105) at the molded part curvature section (63, 73, 103, 113) is at least partially connected to a composite of the insert (62, 72, 82, 92, 102, 112, 122, 132, 142, 152, 162, 172) and is formed from the plastic.Furthermore, a method for manufacturing the molded part, as well as an insert and an injection molding tool for carrying out the method, are proposed.

Description

[0001] The invention is based on a molded part made of plastic injection molding, a method for producing the molded part, an insert and an injection molding tool for carrying out the method.

[0002] During plastic injection molding of a molded part, a plastic is liquefied and the liquid plastic melt is injected under pressure into an injection mold. The injection mold has a cavity that determines the shape and surface structure of the molded part to be produced. The cavity represents a negative mold of the molded part. In the injection mold, the liquid plastic transforms into a solid state through cooling and / or crosslinking and solidifies. Finally, the finished molded part is removed from the injection mold. In this way, molded parts can be produced cost-effectively in large quantities. The molded parts can have almost any shape and surface structure. This also includes molded parts that are designed as hollow bodies and have a molded part wall that defines a molded part cavity. Such hollow molded parts can also have a curved section.

[0003] In plastic injection molding, the molded part is created by injecting liquid plastic melt into a cavity of an injection mold on a plastic injection molding machine. The plastic melt fills the cavity completely or partially. The plastic melt solidifies on the mold wall, while it is still a liquid core inside. To produce a hollow molded part, a fluid is injected into the cavity under pressure using fluid injection technology. This displaces the still liquid plastic melt inside the cavity and creates a hollow space. The fluid can be a gas or a liquid, e.g. water. If the cavity was only partially filled when the plastic melt was introduced, the displacement of the liquid plastic melt by the fluid ensures that the molded part is completely formed.If the cavity contains excess plastic melt, this can either be conveyed back into a screw cylinder of the plastic injection molding machine via a hot runner using the fluid or be pressed into a collecting cavity adjacent to the cavity.

[0004] If the molded part is free of curvatures, the position and size of the cavity can be adjusted during production by adjusting the position of the injectors for the plastic melt and the fluid, as well as by adjusting the process parameters, so that the molded part has a desired wall thickness throughout. However, if the molded part includes one or more curved sections, the liquid plastic melt is displaced in this curved section of the molded part in such a way that the wall thickness in an inner curved section of the molded part, which faces a geometric center of curvature of the molded part, is smaller than in an outer curved section of the molded part, which faces away from the geometric center of curvature of the molded part. The position of the created cavity is shifted inward.Because the radius of curvature in the inner mold part curved section is smaller than the radius of curvature in the outer mold part curved section, the flow velocity of the fluid injected into the cavity is greater inside than outside when displacing the liquid plastic melt. As a result, more plastic melt is removed in the inner mold part curved section than in the outer mold part curved section. The smaller the radius of curvature in the inner mold part curved section, the more plastic melt is removed there, and the more critical the wall thickness of the mold part becomes in this inner mold part curved section. In this case, the wall thickness may fall below a specified limit.If a static load is applied to the finished molded part after its production, resulting in tensile, compressive, or transverse stresses in the molded part, the molded part cannot withstand the load due to the insufficient wall thickness at the inner curved section of the molded part. The result is that the molded part breaks or cracks.

[0005] In addition, when manufacturing a molded part with a curved section, there may be a requirement that the wall thickness in an outer molded part curved section, which is facing away from a geometric molded part curvature center, has a certain specified value, which must not be undercut for reasons of stability.

[0006] The invention is based on the object of providing a hollow molded part with a molded part curved section as well as a method, an insert and an injection molding tool for producing the molded part, wherein the molded part has a predetermined minimum wall thickness in the molded part curved section, which is not undercut.

[0007] This object is achieved by a molded part having the features of claim 1. The molded part is characterized in that it is equipped with an insert in the region of the curved section of the molded part. This dimensionally stable insert is designed as a hollow body. It is therefore referred to as a hollow insert body. During production of the molded part, the insert is inserted into the cavity of the injection mold and over-molded with plastic. The insert is positioned in the cavity in such a way that it forms a bond with the over-molded plastic in the curved section of the molded part and, together with the plastic, forms the molded part wall. The molded part wall delimits the molded part cavity. In the curved section of the molded part, the molded part wall consists entirely or partially of the bond of insert and the plastic, which is injected into the cavity of the injection mold as a liquid plastic melt during production using the plastic injection molding process.In all other areas of the molded part apart from the insert, the molded part wall is formed from the plastic that is injected into the cavity during plastic injection molding, without these other areas of the molded part enclosing the insert. The insert and plastic are bonded together during production, resulting in a single-piece molded part.

[0008] In the following, the term plastic always refers to the plastic that is injected into the cavity of the injection mold during the production of the molded part by means of plastic injection molding and with which the insert is overmolded.

[0009] Since the molded part is designed as a hollow body, the molded part wall has an inner side facing the molded part cavity and an outer side facing away from the molded part cavity. Furthermore, the molded part has a curved part section comprising an inner side with a small radius of curvature and an outer side with a larger radius of curvature. The inner side of the curved part section faces a geometric center of curvature of the molded part, while the outer side of the curved part section faces away from the geometric center of curvature of the molded part. If the shape of the molded part wall in the curved part section corresponds at least approximately to part of a circle, the geometric center of curvature of the molded part corresponds to the center of this circle. The radius of curvature corresponds to the radius of this circle.To conceptually distinguish the inside of the molded part's curved section from the inside of the molded part's wall, the inside of the molded part's curved section is referred to as the inner molded part's curved section, and the outside of the molded part's curved section is referred to as the outer molded part's curved section. The radius of curvature on the outside of the molded part's curved section is smaller than on the outside of the molded part's curved section. The smallest radius of curvature on the molded part's curved section is referred to as the inner radius of curvature, and the largest radius of curvature on the molded part's curved section is referred to as the outer radius of curvature.

[0010] The insert can be overmolded with plastic only on the inside facing the molded part cavity. Alternatively, the insert can be overmolded with plastic on both the inside and the outside facing away from the molded part cavity.

[0011] The wall thickness of the molded part wall at the curved section corresponds to the sum of the insert wall thickness and the thickness of the plastic layer that forms on the inside of the insert and, if applicable, the outside of the insert during molding. Thus, the wall thickness of the molded part wall corresponds to at least the insert wall thickness. This applies even if the liquid plastic melt is almost completely displaced by the fluid in the inner curved section of the molded part during molding. The insert wall thickness is not exceeded because the insert does not change its shape during overmolding with plastic.

[0012] According to an advantageous embodiment of the invention, the molded part wall is formed in the entire molded part curved section by the composite of insert and plastic.

[0013] According to a further advantageous embodiment of the invention, the molded part is produced by means of a combination of plastic injection molding and fluid injection technology.

[0014] According to a further advantageous embodiment of the invention, the insert is overmolded with plastic exclusively on its inner side facing the molded part cavity. The outer side of the insert facing away from the molded part cavity is free of the plastic that is injected into the injection mold during the production of the molded part.

[0015] According to a further advantageous embodiment of the invention, the insert is overmolded with plastic on its inner side facing the molded part cavity and on its outer side facing away from the molded part cavity. In this case, the insert is embedded in the plastic.

[0016] According to a further advantageous embodiment of the invention, the molded part has an inner molded part curved section, which faces the geometric molded part curvature center, and an outer molded part curved section, which faces away from the geometric molded part curvature center. The insert is overmolded with plastic in such a way that the molded part wall is formed by a composite of the insert and the plastic only in the inner molded part curved section. In this case, the insert can have a distance from the molded part wall in the outer molded part curved section. Alternatively, the molded part wall is formed by a composite of the insert and the plastic only in the outer molded part curved section. In this case, the insert can have a distance from the molded part wall in the inner molded part curved section.

[0017] According to a further advantageous embodiment of the invention, the molded part curved section is L-shaped, U-shaped, C-shaped, Y-shaped or T-shaped.

[0018] According to a further advantageous embodiment of the invention, the molded part has a first rectilinear molded part section extending along a first molded part axis L1. Furthermore, the molded part has a second rectilinear molded part section extending along a second molded part axis L2. The curved molded part section is located between the first molded part section and the second molded part section. The molded part cavity extends continuously through the first molded part section, the curved molded part section, and the second molded part section.

[0019] According to a further advantageous embodiment of the invention, the molded part has a third rectilinear molded part section extending along a third molded part axis L3. The molded part curved section is T-shaped or Y-shaped. The molded part curved section is arranged between the first molded part section, the second molded part section, and the third molded part section. The insert also has a T-shape or Y-shape.

[0020] According to a further advantageous embodiment of the invention, an angle α between L1 and L2 is between 5° and 180°, including the limits. The following applies: 5° ≤ α ≤ 180°.

[0021] According to a further advantageous embodiment of the invention, the radius of curvature at the inner curved section of the molded part is greater than or equal to 0.5 mm. This applies in particular to the inner radius of curvature, which is the smallest radius at the curved section of the molded part. The smaller the inner radius of curvature of the molded part, the more pronounced the edge or corner formed at the curve or deflection of the molded part.

[0022] According to a further advantageous embodiment of the invention, the insert consists of a material which is dimensionally stable under the influence of the temperature and pressure prevailing in the injection mold.

[0023] According to a further advantageous embodiment of the invention, the insert consists of a fiber-reinforced plastic material, wherein the fibers are glass, aramid, carbon or natural fibers.

[0024] According to a further advantageous embodiment of the invention, the insert consists at least partially of metal.

[0025] According to the method according to the invention with the features of claim 15, the molded part is produced using a plastic injection molding machine equipped with an injection molding tool. This injection molding tool has a cavity designed as a hollow mold, which represents a negative mold of the molded part and comprises a cavity curved section corresponding to the molded part. The cavity is delimited by a cavity surface, which is part of the injection molding tool. The injection molding tool also has an inlet for the liquid plastic melt and an injector for a fluid. The dimensionally stable insert, which is designed as a hollow insert body, is inserted into the cavity curved section of the injection molding tool. This is done in such a way that the insert at least partially rests against the cavity surface at the cavity curved section and also leaves the cavity free so that the plastic melt can spread.The insert is thus arranged in the curved cavity section without completely filling the curved cavity section. The injection mold is then closed. Liquid plastic melt is then introduced into the cavity under pressure at the inlet, with the plastic melt entering the curved cavity section from the at least one inlet and spreading there. Since the insert does not completely fill the curved cavity section, spreading of the plastic melt in the curved cavity section is possible.A fluid is then introduced into the liquid plastic melt in the cavity in such a way that at least one continuous molded part cavity extending through the molded part's curved section is created in the plastic melt using fluid injection technology. The plastic melt forms the hollow molded part's curved section at the cavity's curved section and the insert arranged there, wherein the insert forms a bond with the plastic melt and forms the molded part wall in this area. The solidifying plastic melt also forms the molded part wall. This process produces a hollow molded part by plastic injection molding, which is reinforced in a molded part's curved section by an insert overmolded with plastic, such that the wall thickness of the molded part wall in the molded part's curved section corresponds at least to the wall thickness of the insert.

[0026] According to a further advantageous embodiment of the method according to the invention, the insert, together with the solidified plastic melt, forms a circumferentially surrounding composite molded part wall in the molded part curved section.

[0027] According to a further advantageous embodiment of the method according to the invention, the insert lies exclusively on the cavity surface on the inner cavity curvature section and leaves the outer cavity curvature section free, such that the insert together with the solidified plastic melt forms a composite molded part wall on the inner molded part curvature section and this is formed integrally with the remaining molded part wall, which consists exclusively of the solidified plastic melt.

[0028] According to a further advantageous embodiment of the method according to the invention, the insert lies exclusively on the cavity surface on the outer cavity curvature section and leaves the inner cavity curvature section free, such that the insert, together with the solidified plastic melt, forms a composite molded part wall on the outer molded part curvature section and this is formed integrally with the remaining molded part wall, which consists exclusively of the solidified plastic melt.

[0029] According to a further advantageous embodiment of the method according to the invention, the insert is overmolded with plastic melt on its outer side facing the cavity surface and on its inner side facing away from the cavity surface.

[0030] According to a further advantageous embodiment of the method according to the invention, the insert is positioned and held in the cavity by positioning pins. These positioning pins are movably arranged on the injection mold. In a first position, the positioning pins protrude above the cavity surface. They ensure that the insert is spaced from the cavity surface and that plastic can be injected into the space between the insert and the cavity surface. To demold the molded part from the cavity, the positioning pins are moved to a second position, where they are flush with the cavity surface.

[0031] According to a further advantageous embodiment of the method according to the invention, the insert is overmolded with plastic melt exclusively on its inner side facing away from the cavity surface.

[0032] According to a further advantageous embodiment of the method according to the invention, the insert is L-shaped, U-shaped or C-shaped.

[0033] According to a further advantageous embodiment of the method according to the invention, the insert is T-shaped or Y-shaped.

[0034] According to a further advantageous embodiment of the method according to the invention, the insert is one-piece.

[0035] According to a further advantageous embodiment of the method according to the invention, the insert has several insert parts from which it is composed.

[0036] According to a further advantageous embodiment of the method according to the invention, the plastic melt displaced from the cavity with the fluid is pressed into a collecting cavity which adjoins the cavity.

[0037] According to a further advantageous embodiment of the method according to the invention, the plastic melt displaced from the cavity with the fluid is pressed back into a screw cylinder of the injection molding machine via a hot runner at the inlet. This makes the displaced plastic melt available for another cycle.

[0038] The insert according to the invention with the features of claim 27 is characterized in that it is designed as a hollow insert body and consists of a material that is dimensionally stable under the influence of the temperature and pressure prevailing in the injection mold. The insert thus retains its shape during the implementation of the method according to the invention.

[0039] According to a further advantageous embodiment of the insert according to the invention, the insert has a wall thickness predetermined by the minimum wall thickness of the molded part.

[0040] According to a further advantageous embodiment of the insert according to the invention, it is L-shaped, U-shaped, C-shaped, Y-shaped or T-shaped.

[0041] According to a further advantageous embodiment of the insert according to the invention, it consists of a fiber-reinforced plastic material, wherein the fibers are glass, aramid, carbon or natural fibers.

[0042] According to a further advantageous embodiment of the insert according to the invention, it consists at least partially of metal.

[0043] The injection molding tool according to the invention with the features of claim 32 is characterized in that it is equipped with at least one hold-down device by which the insert is held at the position predetermined for it in the injection molding tool.

[0044] According to a further advantageous embodiment of the injection mold according to the invention, the hold-down device is designed as a positioning pin that is movably arranged in the injection mold. In a first extended position, the positioning pin protrudes above the cavity surface and, in a second retracted position, is flush with the cavity surface.

[0045] Further advantages and advantageous embodiments can be found in the following description, the drawing and the claims. drawing

[0046] The drawings illustrate exemplary embodiments of the subject matter of the invention. They show: Fig. 1 non-inventive hollow molded part in L-shape in sectional view, Fig. 2 first embodiment of a hollow L-shaped molded part with insert in sectional view, Fig. 3 second embodiment of a hollow L-shaped molded part with insert in sectional view, Fig. 4 non-inventive hollow molded part in T-shape in sectional view, Fig. 5 third embodiment of a hollow T-shaped molded part with insert in sectional view, Fig. 6 fourth embodiment of a hollow T-shaped molded part with insert in sectional view, Fig. 7 non-inventive hollow molded part in L-shape in sectional view, Fig. 8 fifth embodiment of a hollow L-shaped molded part with insert in sectional view, Fig. 9 sixth embodiment of a hollow L-shaped molded part with insert in sectional view, Fig. 10 non-inventive hollow molded part in T-shape in sectional view, Fig. 11 seventh embodiment of a hollow T-shaped molded part with insert in sectional view, Fig. 12 eighth embodiment of a hollow T-shaped molded part with insert in sectional view, Fig. 13 first embodiment of a cavity of an injection molding tool for producing a molded part, Fig. 14 second embodiment of a cavity of an injection mold for producing a molded part, Fig. 15 embodiment of an injection molding tool with an insert lying against the cavity surface for producing a molded part according to Fig. 2, Fig. 16 Injection mold according to Fig. 15 with an insert which has a distance to the cavity surface, for producing a molded part according to Fig. 3. Description of the embodiments

[0047] In the Fig. 1, Fig. 4, Fig. 7 and Fig. 10 shows hollow molded parts made of plastic injection molding not according to the invention with at least one curved molded part section without inserts. Fig. The molded part 1 shown in Figure 1 has a first straight molded part section 2, a molded part curved section 3, and a second straight molded part section 4. The molded part curved section 3 is located between the first straight molded part section 2 and the second straight molded part section 4. The first straight molded part section 2 is elongated and extends along a first geometric molded part longitudinal axis L1. The second straight molded part section 4 is also elongated and extends along a second geometric molded part longitudinal axis L2. L1 and L2 are perpendicular to one another. The molded part wall 5 of the molded part 1 delimits a molded part cavity 6, which extends continuously through the first straight molded part section 2, the molded part curved section 3, and the second straight molded part section 4.The molded part wall 5 has an inner side 7 facing the molded part cavity 6 and an outer side 8 facing away from the molded part cavity 6. The wall thickness of the molded part wall 5 is the same and constant in the first straight molded part section 2 and in the second straight molded part section 4. In the molded part curved section 3, however, the wall thickness is different. In an inner molded part curved section 9, which faces a geometric molded part curvature center 10, the wall thickness is less than in an outer molded part curved section 11 and than in the first and second straight molded part sections 2, 4. The reason for this different wall thickness is the production of the molded part 1 by plastic injection molding, with the molded part cavity 6 being created using fluid injection technology.The fluid flowing through the liquid plastic melt in the cavity of the injection mold removes more liquid plastic melt at the inner mold part curved section 9 than at the outer mold part curved section 11 and than in the straight mold part sections 2, 4. Less plastic melt is removed at the outer mold part curved section 11 because the speed of the flowing fluid is lower there at the inner mold part curved section 9 and than in the straight mold part sections 2, 4. The mold part curved section 3 has an inner radius of curvature on the mold part wall outer side at the inner mold part curved section 9. This inner radius of curvature corresponds to the radius r of the circle 12, which at least approximately describes the course of the outer side of the molded part wall at the inner molded part curvature section 9 at the transition from the first straight molded part section 2 to the second straight molded part section 4.The geometric molded part curvature center 10 corresponds to the center of this circle 12. Furthermore, the molded part curved section 2 has an outer radius of curvature on the molded part wall outer side at the outer molded part curved section 11. This outer radius of curvature corresponds to the radius r of the circle 13, which at least approximately describes the course of the molded part wall outer side at the transition from the first straight molded part section 2 to the second straight molded part section 4. The inner radius of curvature is significantly smaller than the outer radius of curvature. The radii of curvature on the molded part wall inner side in the molded part curved section are larger than the inner radius of curvature and smaller than the outer radius of curvature.

[0048] In Fig. 4 shows a second molded part 21 not according to the invention, which, in contrast to the molded part according to Fig. 1 has a T-shape. In addition to the first straight molded part section 22 with longitudinal axis L1 and the second straight molded part section 24 with longitudinal axis L2, the molded part 21 has a third straight molded part section 32 with longitudinal axis L3. Between these three straight molded part sections 22, 24, and 32 is the molded part curved section 23. Due to the T-shape, the molded part 21 comprises two inner molded part curved sections 29a and 29b, both of which face their respective geometric molded part curvature centers 30a and 30b. The wall thickness of the molded part wall 25 is smaller in the region of the inner molded part curved sections 29a, 29b than in the straight molded part sections 22, 24 and 32. The outer molded part curved section 31 runs in a straight line in the molded part 21 shown, since the longitudinal axis L2 of the second straight molded part section 24 and the longitudinal axis L3 of the third straight molded part section 32 coincide or enclose an angle of 0°.However, since the flowing fluid in the outer curved section of the molded part 21 is produced using a combination of plastic injection molding and fluid injection technology, the flowing fluid has a lower velocity in the outer curved section than in other sections 22, 24, 29a, 29b, 32 of the molded part, the least amount of liquid plastic melt is displaced in this area. The wall thickness of the molded part wall 25 is therefore greatest in this area. The inner radius of curvature of the two inner curved sections 29a, 29b is identical.

[0049] In the Fig. 7 and Fig. 10 shows two further molded parts 41 and 51 not according to the invention, which essentially correspond to the two molded parts 1 and 21 in the Fig. 1 and Fig. 4. The molded part 41 in Fig. 7 differs from the molded part 1 in Fig. 1 only because the inner radius of curvature is smaller. The comparison with Fig. 1 shows that due to the smaller inner radius of curvature in the molded part 41, the wall thickness of the molded part wall 45 at the inner molded part curvature section 49 is even smaller than in the molded part 1 in Fig. 1. The same applies to the molded part 51 in Fig. 10: it differs from the molding 21 in Fig. 4 only in that the inner radius of curvature is smaller, which is why the wall thickness of the molded part wall 55 is smaller at the inner molded part curvature sections 59a, 59b.

[0050] In the Fig. 2, Fig. 3, Fig. 8 and Fig. 9 shows L-shaped molded parts according to the invention. They differ from the molded parts in the Fig. 1 and Fig. 7 in that they are equipped with an insert. This insert is designed as a hollow body and also has an L-shape. It is located at the curved section of the molded part. With regard to the straight molded part sections 2, 4, the molded parts in the Fig. 2, Fig. 3, Fig. 8 and Fig. 9 with the molded parts in the Fig. 1 and Fig. 7. Therefore, the same reference numbers are given for the straight molded part sections. In the first embodiment of a molded part 61 according to the invention in Fig. 2, an insert 62 designed as a hollow insert body is embedded in the plastic at the curved section 63 of the molded part such that the insert 62 forms the outer side 68 of the molded part wall at the curved section 63. The plastic from which the two straight molded sections 2, 4 are made is located on the inner side of the insert facing the molded part cavity 66. The inner radius of curvature of the molded part 61 in Fig. 2 corresponds to the inner radius of curvature of the molded part 1 in Fig. 1. Due to the insert 62, the wall thickness of the molded part wall 65 at the inner molded part curved section 69 is significantly greater than the wall thickness at the corresponding position in the molded part 1 in Fig. 1. The molded part wall 65 is formed at the molded part curvature section by the insert and the plastic on the inside of the insert.

[0051] Fig. 3 shows a second embodiment of a molded part 71 according to the invention with an insert 72. The molded part 71 differs from the molded part 61 in that the insert 72 is overmolded with plastic on its inside and outside. The insert 72 is thus embedded in the plastic. The molded part wall 75 is formed at the molded part curved section 73 by the insert 72 and the plastic on the inside and outside of the insert. The insert 72 does not form the molded part wall outer side 78 at the molded part curved section 73, since the insert is covered by the plastic on its outside.

[0052] The molded part 81 in Fig. 8 is similar to the molded part 61 in Fig. 2. It differs from the molding 61 in Fig. 2 in that the inner radius of curvature of the inner curved section 89 of the molded part is smaller. The insert 82 of the molded part 81 has a correspondingly small inner radius of curvature on its outer side. Furthermore, the molded part 61 and the molded part 81 are identical.

[0053] The molding 91 in Fig. 9 is similar to the molded part 71 in Fig. 3. It differs from the molding 71 in Fig. 3 in that the inner radius of curvature of the inner curved section 99 of the molded part is smaller. The insert 92 of the molded part 91 has a correspondingly small inner radius of curvature on its outer side. Furthermore, the molded part 71 and the molded part 91 are identical.

[0054] In the Fig. 5, Fig. 6, Fig. 11 and Fig. 12 shows T-shaped molded parts according to the invention. They differ from the molded parts in the Fig. 4 and Fig. 10 in that they are equipped with an insert. This insert is designed as a hollow body and also has a T-shape. It is located at the curved section of the molded part. With regard to the straight molded part sections 22, 24, and 32, the molded parts in the Fig. 5, Fig. 6, Fig. 11 and Fig. 12 with the molded parts in the Fig. 4 and Fig. 10. Therefore, the same reference numbers are given for the straight molded part sections. In the embodiment of a molded part 101 according to the invention in Fig. 5, the insert 102, designed as a hollow insert body, is embedded in the plastic at the curved section 103 of the molded part in such a way that the insert 102 forms the outer side 108 of the molded part wall at the curved section 103. The plastic from which the three straight molded sections 22, 24, 32 are made is located on the inner side of the insert facing the molded part cavity 106. The inner radius of curvature of the molded part 101 in Fig. 5 corresponds to the inner radius of curvature of the molded part 21 in Fig. 4. Due to the insert 102, the wall thickness of the molded part wall 105 at the inner molded part curved sections 109a, 109b is significantly greater than the wall thickness at the corresponding positions in the molded part 21 in Fig. 4. The molded part wall 105 is formed at the molded part curved section 103 by the insert 102 and the plastic on the inside of the insert 102.

[0055] Fig. 6 shows a further embodiment of a molded part 111 according to the invention with an insert 112. The molded part 111 differs from the molded part 101 in that the insert 112 is overmolded with plastic on its inside and outside. The molded part wall 115 is formed at the molded part curved section 113 by the insert 112 and the plastic on the inside and outside of the insert 112. The insert 112 does not form the molded part wall outer side 118 at the molded part curved section 113, since the insert is covered by the plastic on its outside.

[0056] The molded part 121 in Fig. 11 is similar to the molded part 101 in Fig. 5. It differs from the molding 101 in Fig. 5 in that the inner radius of curvature of the inner curved sections 129a, 129b of the molded part is smaller. The insert 122 of the molded part 121 has the correspondingly small inner radius of curvature on its outer side. Furthermore, the molded part 101 and the molded part 121 are identical.

[0057] The molded part 131 in Fig. 12 is similar to the molded part 111 in Fig. 6. It differs from the molded part 111 in Fig. 6 in that the inner radius of curvature of the inner curved sections 139a, 139b of the molded part is smaller. The insert 132 of the molded part 131 has the correspondingly small inner radius of curvature on its outer side. Furthermore, the molded part 111 and the molded part 131 are identical.

[0058] Fig. Figure 13 shows a first embodiment of a cavity 140 of an injection molding tool in cross-section and in longitudinal section. A possible associated injection molding tool is shown in Fig. 15 and Fig. 16. The cavity 140 is circular in cross-section and has an L-shape in longitudinal section. It is generally suitable for producing L-shaped molded parts that have an external shape such as that shown in the Fig. 1, Fig. 2, Fig. 3, Fig. 7, Fig. 8 and Fig. 9. The cavity represents a negative form of the Fig. 13. The cavity is delimited by a cavity surface 141, which is part of the associated injection molding tool. The cavity has a first straight cavity section 143, a second straight cavity section 144, and a cavity curved section 145 between the first and second cavity sections. The cavity curved section 145 comprises an inner cavity curved section 146, which faces a geometric cavity curvature center 147, and an outer cavity curved section 148, which faces away from the geometric cavity curvature center 147. An insert 142 with a circular cross-section is arranged in the cavity curved section 145. The outer diameter of the insert 142 is substantially smaller than the inner diameter of the cavity 140. The insert 142 is arranged in the cavity 140 such that it rests against the cavity surface 141 only in the region of the outer cavity curvature section 148.In the region of the inner cavity curvature section 146, the insert 142 is spaced from the cavity surface 141. In . Fig. 13 does not show the plastic that is introduced into the cavity 140 to form a molded part. Fig. 13, a molded part can be produced in which the molded part wall in an outer molded part curved section is formed by a composite of the insert 142 and the injected plastic and in which the molded part wall in an inner molded part curved section is formed only by the injected plastic.

[0059] All of the aforementioned molded parts have a circular cross-section. The molded part cavity also has a circular cross-section. The aforementioned inserts, which are designed as hollow bodies, also have a circular cross-section.

[0060] In Fig. Figure 14 shows a second embodiment of a cavity 150 in cross-section and in longitudinal section. The cavity 150 has different cross-sections in different sections. In longitudinal section, the cavity has a Y-shape. The cavity 150 comprises a first straight curved section 153, a second straight curved section 154, a third straight curved section 155, and a cavity curved section 156 that connects the straight curved sections 153, 154, and 155. The cross-section of the first straight curved section 153 is circular. The cross-section of the second straight curved section 154 is oval. The cross-section of the third straight curved section 155 is hexagonal. In the cavity curvature section 156, the cross sections of the straight cavity sections 153, 154, 155 merge into one another. An insert 152 is arranged in the cavity curvature section 156 of the cavity 150.This insert 152 also has a Y-shape with three straight sections and one curved insert section. The cross-section of the insert 152 in the straight sections is adapted to the shape of the corresponding straight cavity sections 153, 154, 155. The insert 152 is arranged in the cavity 150 such that there is essentially an equal distance on all sides between the outer side of the insert 152 and the cavity surface 151. For this purpose, the injection mold (not shown) which encloses the cavity is equipped with hold-down devices. These are also not shown in the drawing. When plastic melt is introduced into the cavity 150 and a cavity is created using a fluid, the insert 152 is embedded in the plastic on its inner and outer sides.This creates a Y-shaped molded part (not shown), which has different cross-sections in different sections according to the cavity 150 and the insert 152.

[0061] The Fig. 15 and Fig. 16 shows an embodiment of an injection mold 160 with a device 163 for supplying a liquid plastic melt and for supplying a fluid. The opened injection mold is shown with a view of the cavity 161 with the cavity curved section. Fig. 15, an insert 162 is arranged in the cavity 161, which rests with its outer side against the cavity surface. The cavity 161 and the insert 162 are basically suitable for forming a molded part according to Fig. 2. In Fig. 16, an insert 172 is arranged in the cavity 161, the outer diameter of which is smaller than the diameter of the cavity 161. The cavity 161 and the insert 172 are basically suitable for forming a molded part according to Fig. 3 to produce.

[0062] All molded parts shown in the drawing are manufactured using a combination of plastic injection molding and fluid injection technology.

[0063] All features can be essential to the invention both individually and in any combination. Reference numbers 1 molded part 2 First straight molded section 3 Molded part curvature section 4 Second straight molded section 5 molded wall 6 molded part cavity 7 Moulded wall inside 8 Moulded wall exterior 9 Inner molded part curvature section 10 Geometric molded part curvature center 11 Outer molded part curvature section 12 Circle 13 Circle 21 molded part 22 First straight molded section 23 Molded part curved section 24 Second straight molded section 25 molded wall 29a Inner molded part curved section 29b Inner molded part curved section 30a Geometric molded part curvature center 30b Geometric molded part curvature center 31 Outer molded part curvature section 32 third straight molded section 41 molded part 45 molded wall 49 inner molded part curvature section 51 molded part 55 molded wall 59a inner molded part curved section 59b inner molded part curvature section 61 molded part 62 inserts 63 Molded part curved section 65 molded wall 66 molded part cavity 68 Moulded wall exterior 69 Inner molded part curvature section 71 molded part 72 inserts 73 Molded part curved section 75 molded wall 78 Moulded wall exterior 81 molded part 82 inserts 89 inner molded part curvature section 91 molded part 92 inserts 99 inner molded part curvature section 101 molded part 102 inserts 103 Molded part curved section 105 molded wall 106 molded part cavity 109a inner molded part curvature section 109b inner molded part curvature section 111 molded part 112 inserts 113 Molded part curved section 118 Moulded wall exterior 121 molded part 122 inserts 129a inner molded part curvature section 129b inner molded part curvature section 131 molded part 132 inserts 139a inner molded part curvature section 139b inner molded part curvature section 140 cavities 141 Cavity surface 142 inserts 143 first straight cavity section 144 second straight cavity section 145 Cavity curvature section 146 inner cavity curvature section 147 geometric cavity curvature center 148 outer cavity curvature section 150 cavities 151 Cavity surface 152 inserts 153 first straight cavity section 154 second straight cavity section 155 third straight cavity section 156 Cavity curvature section 160 injection mold 161 Cavity 162 inserts 163 Device for supplying a liquid plastic melt and a fluid 172 inserts

Claims

[1] Moulded part made of plastic injection moulding, which is designed as a one-piece hollow body and has a moulded part wall (65, 75, 105) which delimits a moulded part cavity (66, 106), wherein the molded part (61, 71, 81, 91, 101, 111, 121, 131) comprises at least one hollow molded part curved section (63, 73, 103, 113), wherein the molded part (61, 71, 81, 91, 101, 111, 121, 131) has, in the molded part curved section (63, 73, 103, 113), an insert (62, 72, 82, 92, 102, 112, 122, 132, 142, 152, 162, 172) overmolded with plastic, which insert is designed as a hollow insert body, such that the molded part wall (65, 75, 105) at the molded part curved section (63, 73, 103, 113) is at least partially formed by a composite of the insert (62, 72, 82, 92, 102, 112, 122, 132, 142, 152, 162, 172) and the plastic. [2] Moulded part according to claim 1, characterized bythat the molded part wall (65, 75, 105) in the entire molded part curved section (63, 73, 103, 113) is formed by the composite of insert (62, 72, 82, 92, 102, 112, 122, 132, 152, 162, 172) and plastic. [3] Moulded part according to claim 1 or 2, characterized by that the molded part (61, 71, 81, 91, 101, 111, 121, 131) is manufactured by means of a combination of plastic injection molding and fluid injection technology. [4] Moulded part according to one of the preceding claims, characterized by that the insert (62, 82, 102,122, 162) is overmolded with plastic exclusively on its inner side facing the molded part cavity (66, 106). [5] Moulded part according to one of the preceding claims, characterized by that the insert (72, 92, 112, 132) is overmolded with plastic on its inner side facing the molded part cavity and on its outer side facing away from the molded part cavity. [6] Moulded part according to one of the preceding claims, characterized by that the molded part (61, 71, 81, 91, 101, 111, 121, 131) has an inner molded part curved section (69, 89, 99, 109a, 109b, 129a, 129b, 139a, 139b) which faces a geometric molded part curvature center (10), and an outer molded part curved section which faces away from the geometric molded part curvature center (10), that the insert is over-molded with plastic in such a way that the molded part wall is formed only in the inner molded part curved section by a composite of the insert and the plastic, or that the molded part wall is formed only in the outer molded part curved section by a composite of the insert and the plastic. [7] Moulded part according to one of the preceding claims, characterized by that the molded part curved section is L-shaped, U-shaped, C-shaped, Y-shaped or T-shaped. [8] Moulded part according to one of the preceding claims, characterized by that the molded part (61, 71, 81, 91, 101, 111, 121, 131) has a first straight molded part section (2, 22) which extends along a first molded part axis L1, that the molded part (61, 71, 81, 91, 101, 111, 121, 131) has a second straight molded part section (4, 24) which extends along a second molded part axis L2, that the molded part curved section (63, 73, 103, 113) is located between the first straight molded part section (2, 22) and the second straight molded part section (4, 24), and that the molded part cavity (66, 106) extends continuously through the first straight molded part section (2, 22), the molded part curved section (63, 73, 103, 113) and the second straight molded part section (4, 24). [9] Moulding according to claim 8, characterized bythat the molded part (101, 111, 121, 131) has a third straight molded part section (32) which extends along a third molded part axis L3, that the molded part curved section (103, 113) is T-shaped or Y-shaped and that the molded part curved section (103, 113) is arranged between the first straight molded part section (2, 22), the second molded part section (4, 24) and the third molded part section (32). [10] Moulded part according to claim 8 or 9, characterized by that for an angle α between L1 and L2: 5° ≤ α ≤ 180°. [11] Moulded part according to one of the preceding claims, characterized by that a radius of curvature at the inner molded part curvature section is greater than or equal to 0.5 mm. [12] Moulded part according to one of the preceding claims, characterized bythat the insert (62, 72, 82, 92, 102, 112, 122, 132, 142, 152, 162, 172) consists of a material which is dimensionally stable under the influence of the temperature and pressure prevailing in the injection mould. [13] Moulded part according to one of the preceding claims, characterized by that the insert (62, 72, 82, 92, 102, 112, 122, 132, 142, 152, 162, 172) consists of a fiber-reinforced plastic material, wherein the fibers are glass, aramid, carbon or natural fibers. [14] Moulded part according to one of the preceding claims, characterized by that the insert (62, 72, 82, 92, 102, 112, 122, 132, 142, 152, 162, 172) consists at least partially of metal. [15] Method for producing the molded part (61, 71, 81, 91, 101, 111, 121, 131) according to one of the preceding claims by means of a plastic injection molding machine, wherein the plastic injection molding machine has an injection molding tool (160) with a cavity (140, 150, 161) designed as a hollow mold, which represents a negative mold of the molded part (61, 71, 81, 91, 101, 111, 121, 131) and comprises a cavity curvature section (145) corresponding to the molded part (61, 71, 81, 91, 111, 121, 131), wherein the cavity (140, 150, 161) is delimited by a cavity surface (141, 151) which is part of the injection mold (160), wherein the injection molding tool (160) is equipped with at least one inlet (163) for a liquid plastic melt and with at least one inlet for a fluid, characterized by following procedural steps - inserting the dimensionally stable insert (62, 72, 82, 92, 102, 112, 122, 132, 142, 152, 162, 172) designed as a hollow insert body into the cavity curved section (145) of the injection mold (160), such that the insert (62, 72, 82, 92, 102, 112, 122, 132, 142, 152, 162, 172) at least partially bears against the cavity surface at the cavity curved section (145) and, moreover, leaves the cavity (140, 150, 161) free so that the plastic melt can spread, - Closing the injection mold (160), - introducing liquid plastic melt under pressure at the inlet (163) into the cavity (140, 150, 161), wherein the plastic melt passes from the at least one inlet (163) into the cavity curvature section (145), - Introducing a fluid into the liquid plastic melt in the cavity (140, 150, 161) in such a way that at least one continuous mold cavity (66, 106) extending through the molded part curved section (63, 73, 103, 113) is created in the plastic melt by means of fluid injection technology and the plastic melt forms the hollow molded part curved section (63, 73, 103, 113) on the cavity curved section (145) and the insert (62, 72, 82, 92, 102, 112, 122, 132, 142, 152, 162, 172) arranged there, wherein the insert (62, 72, 82, 92, 102, 112, 122, 132, 142, 152, 162, 172) forms a bond with the plastic melt and forms the molded part wall (65, 75, 105) in this area, and the plastic melt otherwise forms the molded part wall (65, 75, 105). [16] Method according to claim 15, characterized bythat the insert (62, 72, 82, 92, 102, 112, 122, 132, 142, 152, 162, 172) together with the solidified plastic melt in the molded part curved section (63, 73, 103, 113) forms a circumferentially surrounding composite molded part wall. [17] Method according to claim 15, characterized by that the insert rests exclusively on the cavity surface on the inner cavity curvature section and leaves the outer cavity curvature section free, such that the insert together with the solidified plastic melt forms a composite molded part wall on the inner molded part curvature section and this is formed integrally with the remaining molded part wall, which consists exclusively of the solidified plastic melt. [18] Method according to one of claims 15 to 17, characterized bythat the insert (72, 92, 112, 132, 152, 172) is overmolded with plastic melt on its outer side facing the cavity surface and on its inner side facing away from the cavity surface. [19] Method according to claim 18, characterized by that the insert (62, 72, 82, 92, 102, 112, 122, 132, 142, 152, 162, 172) is positioned and held in the cavity (140, 150, 161) by positioning pins which are arranged on the injection mold (160) and protrude in a first position above the cavity surface (141, 151), and that the positioning pins are moved into a second position in which they are flush with the cavity surface (141, 151) before the molded part is removed from the injection mold. [20] Method according to one of claims 15 to 17, characterized bythat the insert (62, 82, 102, 122) is overmolded with plastic melt exclusively on its inner side facing away from the cavity surface. [21] Method according to one of claims 15 to 20, characterized by that the insert (62, 72, 82, 92, 142, 162, 172) is L-shaped, U-shaped or C-shaped. [22] Method according to one of claims 15 to 20, characterized by that the insert (102, 112, 122, 132, 152) is T-shaped or Y-shaped. [23] Method according to one of claims 15 to 22, characterized by that the insert (62, 72, 82, 92, 102, 112, 122, 132, 142, 152, 162, 172) is one-piece. [24] Method according to one of claims 15 to 22, characterized by that the insert has several insert parts. [25] Method according to one of claims 15 to 24, characterized by that the plastic melt displaced from the cavity with the fluid is pressed into a collecting cavity which is connected to the cavity. [26] Method according to one of claims 15 to 24, characterized by that the plastic melt displaced from the cavity with the fluid is pressed back into a screw cylinder of the injection molding machine via a hot runner at the inlet. [27] Insert for carrying out the method according to one of claims 15 to 26, characterized by that the insert (62, 72, 82, 92, 102, 112, 122, 132, 142, 152, 162, 172) is designed as a hollow insert body and consists of a material which is dimensionally stable under the influence of the temperature and pressure prevailing in the injection moulding tool. [28] Insert according to claim 27, characterized by that the insert (62, 72, 82, 92, 102, 112, 122, 132, 142, 152, 162, 172) has a wall thickness predetermined by the minimum wall thickness of the molded part. [29] Insert according to claim 27 or 28, characterized by that the insert is L-shaped, U-shaped, C-shaped, Y-shaped or T-shaped. [30] Insert according to one of claims 27 to 29, characterized by that it is made of a fiber-reinforced plastic material, the fibers being glass, aramid, carbon or natural fibers. [31] Insert according to one of claims 27 to 30, characterized by that it is at least partly made of metal. [32] Injection moulding tool for a plastic injection moulding machine for producing a moulded part according to one of claims 1 to 14 with a method according to one of claims 15 to 26, characterized by that the injection molding tool is equipped with at least one hold-down device, by means of which the insert (62, 72, 82, 92, 102, 112, 122, 132, 142, 152, 162, 172) according to one of claims 27 to 31 is held at the position predetermined for it in the injection molding tool (160). [33] Injection moulding tool according to claim 32, characterized byin that the hold-down device is designed as a positioning pin which is movably arranged in the injection molding tool (160), wherein the positioning pin projects beyond the cavity surface (141, 151) in a first extended position and is flush with the cavity surface (141, 151) in a second retracted position.

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