Projectile injection method with S-PIT for angled pipes

Abstract

Method for manufacturing an angled pipe section or pipe, comprising the steps of: a) Provision of a system (1) for the manufacture of an angled pipe section or pipe, comprising: a form (2) with a cavity (20) that defines the outer contour of the angled pipe section or pipe, with a first section (201) having a longitudinal axis (H1) to form a first pipe section (41), and a second section (202) angled to it with a longitudinal axis (H2) to form a second pipe section (42) with a longitudinal direction at least partially along the longitudinal axis (H2), an injector (3) comprising: a core (30) with a passage channel (31) along the longitudinal axis (H1) for the passage of a fluid, wherein the core (30) has an opening (32) for the fluid to exit from the passage channel (31), wherein the core (30) is suitable to form a cavity in the first section (201) to form the first pipe section (41); the normal vector of the opening (32) is arranged transversely or obliquely relative to the longitudinal axis (H1), so that the fluid exits through the passage channel (31) and over the opening (32) of the core (30) obliquely or transversely to the longitudinal axis (H1) in order to drive a solidification area (5) of the plastic covering the opening, formed locally in the area of ​​the opening, in order to form a cavity, wherein the injector (3) is arranged in the first section (201) of the cavity (20) such that a space corresponding to the wall of the tube section or tube is formed between the inner wall of the mold and the outer wall of the core (30). b) Introducing liquid plastic into the cavity (20), wherein the liquid plastic fills the first section (201) and at least part of the second section (202); c) Formation of a cavity and the first section (41) of the tube section by the core (30). d) Formation of at least one area of ​​solidified plastic (5) within the cavity (20) in the area of ​​the opening (32) of the core (30); and e) Introducing a fluid into the passage channel (31) and through the opening (32) f) Driving the area of ​​solidified plastic (5) to displace still molten plastic material from the second section of the cavity (20) wherein fluid introduced via the opening (32) moves the area of ​​solidified plastic (5) through the still molten plastic to form the cavity in the plastic part to be produced within the second section of the cavity (202).

Description

TECHNICAL AREA

[0001] The invention relates to a method for manufacturing an angled pipe section or pipe. STATE OF THE ART

[0002] Pipes with a short end section and a main pipe section running at a right angle to it are manufactured using various techniques. The cavity of the end section can be created using a slide. The cavity of the main pipe section can be created using standard fluid injection techniques, such as gas injection or water injection. First, molten plastic is injected into the cavity. Since the melt initially solidifies at the edge of the cavity, after a short cooling period the still-liquid melt can be removed from the central area of ​​the main pipe section, for example, by blowing out the melt with a gas or removing the plastic with a liquid.

[0003] However, the methods used are relatively space-consuming, as systems using valve technology and, for example, fluid or projectile injectors require considerable installation space.

[0004] The publication DE 10 2010 015 453 B3 discloses a device and method for injection molding a molded part forming a closed cavity.

[0005] Document WO 2010 / 007 142 A2 discloses a forming device for producing a hollow molded part, which has a displacement device suitable for propelling a projectile by means of a fluid.

[0006] Furthermore, the publication DE 103 39 859 B3 describes a method and a device for manufacturing a plastic component which has an inner cavity.

[0007] In addition, a molding device for producing pipes with undercut internal geometry, preferably with internal thread, and a method for producing pipes with undercut internal geometry, preferably with internal thread, by injection molding are known from the publication DE 10 2015 225 247 A1. TASK OF INVENTION

[0008] Based on this, the object of the present invention is to provide a method for manufacturing a pipe or pipe section that allows for space-saving use and ensures reliable manufacturing. TECHNICAL SOLUTION

[0009] This problem is solved by providing a method according to claim 1. Advantageous embodiments result from the features of the dependent claims.

[0010] For the method according to the invention, a system for producing an angled pipe section or tube is provided. The system for producing an angled pipe section or tube comprises: a mold with a cavity that defines the outer contour of the angled pipe section or tube, with a first section and a second section angled thereto; an injector comprising: a core with a through-channel for the passage of a fluid, the core having a longitudinal axis, wherein the core has an opening for the fluid to exit from the through-channel. The normal vector of the opening is arranged transversely or obliquely relative to the longitudinal axis, so that the fluid passes obliquely through the through-channel and over the opening of the core.exits transversely to the longitudinal axis to drive a solidification area of ​​the plastic covering the opening, formed locally in the area of ​​the opening, in order to form a cavity, wherein the injector is arranged in the first section of the cavity such that an interval corresponding to the wall of the pipe section or pipe is formed between the inner wall of the mold and the outer wall of the core.

[0011] The latter means that the core of the injector, among other things, acts as a valve, ensuring that the cavity is created in the first pipe section. The second direction (H2) corresponds at least partially to the longitudinal direction of the second pipe section in the area behind the pipe angle, while the longitudinal axis (H1) of the core of the injector corresponds to the longitudinal axis of the first pipe section in the area before the pipe angle. The pipe angle thus corresponds to the angle between the longitudinal axis of the first section of the cavity and the longitudinal axis of the second section of the cavity.

[0012] The opening (or the normal vector of the opening, which is perpendicular to the plane defined by the edge of the opening and lies in particular on the line H2) is inclined, for example at an angle of 90° to the longitudinal axis H1 of the channel, core, or first pipe section. In particular, the projectile (initially) forms in the area of ​​the opening and covers it after the plastic has solidified.

[0013] The resulting projectile detaches from the injector as soon as fluid is introduced into the cavity via the opening behind the solidification area.

[0014] The core may have a chamfer at the edge of the opening to allow the projectile to be releasably attached to the core.

[0015] The injector preferably has a geometry that enables the formation and subsequent release (upon introduction of the fluid) of the solidified projectile. The section of the core extending furthest into the tube serves as a launching ramp for the projectile formed during the process.

[0016] The core is specifically designed to be removable within the cavity. After the plastic material injected into the space between the core and the inner wall of the cavity (which defines the first section) has hardened, the core can be removed, thus exposing the cavity of the first pipe section.

[0017] The core must be designed in such a way that it can be pulled out of the component without damaging it, i.e., the core is free of undercuts with respect to its longitudinal axis.

[0018] The inventive method using the above-mentioned system for producing an angled pipe section or pipe comprises the following steps: a) Provision of a system as described above; b) Introducing liquid plastic into the cavity; c) Formation of at least one area of ​​solidified plastic (projectile) within the cavity in the area of ​​the core opening, particularly at the core; d) Introducing a fluid into the passage channel and through the opening to drive the area of ​​solidified plastic to displace still molten plastic material from the second section of the cavity, wherein The fluid introduced in step d) through the opening moves through the area of ​​solidified plastic to form the cavity in the plastic part to be produced within the second section of the cavity, through the still molten plastic.

[0019] In step c), the projectile preferably displaces molten plastic from the second section. The pipe wall in the first section, on the other hand, is formed by the slide (core) keeping the cavity clear until the plastic introduced between the core and the inner wall of the cavity has sufficiently solidified.

[0020] The process is in particular a projectile injection process, in which the displaced plastic is collected in a secondary cavity or forced back into a plastic injector (backpressure process).

[0021] The emerging projectile is launched at an angle (e.g., 90°) relative to the core's axis, corresponding to the angle of the bend in the tube being manufactured. The core fulfills the functions of a slide in the first section, while simultaneously acting as both the emerging projectile and a fluid injector. This reduces installation space and eliminates work steps, as conventional slide techniques and the integration of a projectile injector require more space. Furthermore, the emerging projectile does not need to be deflected under the present invention, thus saving additional installation space.

[0022] Projectile injection processes offer the advantage of high accuracy and consistency with regard to the wall thickness of the product being manufactured. According to the invention, a projectile injection process is implemented using a projectile injector as described in the present invention.

[0023] Using the described method, pipes with an angle and (short) connecting piece or pipes with a bend can be reliably manufactured.

[0024] By using a solidification zone that forms within the plastic itself as a projectile to create the cavity in the plastic part, the melt-extrusion process is significantly improved compared to pure fluid injection methods. This process enables the production of very smooth, uniform, and thin wall thicknesses in the tubular components.

[0025] Reducing component wall thickness results in material savings and a reduction in manufacturing time (cooling time). Gravity effects causing plastic to run, as occurs in fluid injection processes, are prevented. Furthermore, the process limits can be extended to significantly larger pipe diameters.

[0026] Compared to projectile processes, the cycle time for manufacturing the plastic component is significantly reduced, as at least the additional step of inserting a projectile into the cavity can be eliminated. The projectile essentially consists of the same plastic material inserted into the cavity as the tube. Therefore, all the ejected material, including the projectile, can be reused in subsequent manufacturing processes.

[0027] Furthermore, in contrast to conventional projectile methods, in the method according to the invention the projectile is still relatively hot during the ejection process and thus flexible to a certain extent. In this way, changes in pipe cross-section can be replicated. Continuous transitions can be formed in the areas between different pipe diameters. Overall, the result of the ejection of the liquid plastic material is improved due to the soft cap structure, as the relatively flexible projectile adapts to the pipe geometry.

[0028] The use of the plastic cap formed around the injector surface as an ejector piston or projectile for the fluid injection process is made possible primarily by a suitable injector geometry or design. This determines the projectile shape. Crucially, however, it is also essential that the fluid supplied through the injector opening cannot escape uncontrollably, but rather that the cap only breaks off at predetermined breaking points after a specific pressure has built up. The projectile is then propelled through the molten material.

[0029] The fluid used can be gas, but also a liquid. The fluid is introduced under the solidification area or under the cap to at least partially lift and detach the cap from the injector. The projectile or cap is then moved through the cavity along a controlled, predetermined path by the introduced fluid. The geometry of the injector is therefore particularly important for the gas distribution or gas flow under the projectile before it is ejected from the injector surface. Uncontrolled detachment of the solidification area or the detachment of randomly formed, solidified areas should be prevented as far as possible.

[0030] The inventive method is particularly suitable for the production of tubular components with rather small curvatures and correspondingly small deflections of the projectile as well as continuous, not too abrupt changes in cross-section.

[0031] In particular, the area of ​​solidified plastic formed in step b) is developed as a solidification zone adjacent to and / or near the injector opening, and, in particular, it seals this opening after the plastic has hardened. This means that the solidification zone lies as a layer on the injector surface and covers the opening to a certain extent. With this arrangement, the pressure is increased when the fluid is introduced under the solidification layer until the layer breaks at predetermined fracture points. Subsequently, the solidified layer is propelled as a projectile through the inner pipe area bounded by the solidified pipe walls.

[0032] Preferably, the solidification area is used as a projectile to form the cavity of the plastic part by introducing the fluid in step c). The shape of the projectile can be largely determined by the geometry of the injector. Other parameters important for the projectile shape are the arrangement of the predetermined breaking points, through which the introduced fluid first flows out after a certain pressure has built up under the cap (possibly assisted by suitable cooling of the injector), and / or process parameters such as the solidification time.

[0033] In particular, the area of ​​solidified plastic formed in step b) is designed as a cap-like region that closes the injector opening. The solidified area can thus be configured as a kind of cap over the injector, for example, resting against the injector surface. The injector geometry determines the shape of the cap. Equipment or process engineering measures can be taken to ensure the intended breaking points are positioned appropriately. The cap should break off at predetermined points, especially at its ends, when a specific fluid pressure is applied.

[0034] In particular, the fluid supplied via the injector opening in step c) initially detaches the solidification zone from the injector before the solidification zone is moved through the molten plastic or before the displacement process begins. Acting as a projectile, the solidification zone displaces the liquid or still sufficiently soft plastic within the solidified walls that have formed near the cavity walls, thus creating a defined channel or cavity in the injection-molded plastic part. The walls of the pipe being produced can be relatively thin and have a high surface quality thanks to the use of this projectile. Furthermore, the flexibility of the still-soft projectile allows for the production of pipes with varying cross-sections.

[0035] As an additional measure, the injector can be cooled at least locally during solidification in step b) to form the defined solidification area.

[0036] Preferably, the fluid is introduced in step c) after a period of time during which a projectile-like solidified layer has formed over the injector. This period of time depends on the apparatus design and other process variables, such as injector geometry, measures for creating the intended fracture points, cooling parameters, type of plastic material, etc. BRIEF DESCRIPTION OF THE FIGURES

[0037] Further features and advantages of the invention will become clear with reference to the specific embodiments shown in the accompanying figures and their description. These show: Fig. 1 a system for manufacturing a pipe or pipe section; Fig. 2. Top-down representation of a system corresponds to the Fig. 1 for the manufacture of a pipe or pipe section; Fig. 3. One by means of the system from Fig. 1 and the tube product produced according to the inventive method, which is partially cut open to allow a view of the inner contour. DESCRIPTION OF A PREFERRED EXECUTION EXAMPLE

[0038] In the Fig. 1 and Fig. Figure 2 shows a system 1 for manufacturing a pipe section. The system 1 has a shape 2 with a cavity 20. The cavity 20 has a first section 201 and a second section 202, which in this example is arranged perpendicular to the first section 201 and is angled along its course. The principal axes (longitudinal axes) H1 of the first section 201 and H2 of the second section 202 form a right angle.

[0039] In the first section 201, an injector 3 is arranged. This injector has a core 30. The core 30 is partially hollow, i.e., it is equipped with a flow channel 31 through which fluid can flow. The flow channel 31 extends in approximately the same direction as the main axis H1 of the first section 201. Furthermore, the core 30 has an opening 32 connected to the flow channel 31. The opening 32 points substantially in the direction of the longitudinal axis of the second section 202, i.e., fluid flowing out of the core 3 via the opening 32 is deflected and exits the opening 32 approximately in the direction of the main axis H2 of the second section. The edge of the opening 32 can be formed with a chamfer 320 for this purpose.

[0040] In a first manufacturing step for producing a pipe section using a variation of the so-called injection molding technique, liquid plastic is introduced into the cavity 20. This can be accomplished by a plastic injector, which introduces the plastic through a nozzle into the first section 201 and / or the second section 202. The liquid plastic fills the area outside the projectile injector 3 in the first section 201, and also at least part of the cavity of the second section 202. The liquid plastic then forms a projectile-like area of ​​solidified plastic / a solidification area 5 in the region of the opening 32.

[0041] In the next step, a fluid at a predetermined pressure is introduced from the outside into the flow channel 31. The fluid flows towards the opening 32 and exerts pressure on the solidification zone 5. This pressure drives and moves the solidification zone 5. This phase is in the Fig. Figure 2 shows that the direction of movement of the solidification area 5 corresponds to the main direction H2 (longitudinal direction) of the second section 202. Through this movement, the solidification area 5 displaces and removes the liquid melt present in the center of the cavity 20, thus forming the cavity of the tube section in the second section 202. The displaced plastic can be collected in a secondary cavity or forced back into the plastic injector if it is located opposite the original position of the solidification area 5. With this method, it is not necessary to attach a projectile to the injector before inserting it into the cavity 20, as this is formed by solidification during the process.

[0042] A pipe section 4 produced by the process is in the Fig.Figure 3 shows the pipe section comprising a first section 41 and a second section 42 arranged at right angles to it. The cavity in the first section was formed by the core 30. The outer wall in this section is formed externally by the inner contour of the cavity 20 and internally by the outer contour of the core 30. The second section 42 extends at a 90° angle, its cavity formed by the solidification zone 5 as described above. The solidification zone 5 was moved to the right from position 42a along axis H2 by means of fluid introduced into the core via the flow channel.

[0043] Overall, the process and the equipment make it possible to reliably and precisely produce pipes with a bend or angle. Such pipe constructions save installation space and have various applications, for example in automotive manufacturing.

Claims

[1] Method for producing an angled pipe section or pipe, comprising the steps of: a) Provision of a system (1) for the manufacture of an angled pipe section or pipe, comprising: a form (2) with a cavity (20) that defines the outer contour of the angled pipe section or pipe, with a first section (201) having a longitudinal axis (H1) to form a first pipe section (41), and a second section (202) angled to it with a longitudinal axis (H2) to form a second pipe section (42) with a longitudinal direction at least partially along the longitudinal axis (H2), an injector (3) comprising: a core (30) with a passage channel (31) along the longitudinal axis (H1) for the passage of a fluid, wherein the core (30) has an opening (32) for the fluid to exit from the passage channel (31), wherein the core (30) is suitable to form a cavity in the first section (201) to form the first pipe section (41); the normal vector of the opening (32) is arranged transversely or obliquely relative to the longitudinal axis (H1), so that the fluid exits through the passage channel (31) and over the opening (32) of the core (30) obliquely or transversely to the longitudinal axis (H1) in order to drive a solidification area (5) of the plastic covering the opening, formed locally in the area of ​​the opening, in order to form a cavity, wherein the injector (3) is arranged in the first section (201) of the cavity (20) such that a space corresponding to the wall of the tube section or tube is formed between the inner wall of the mold and the outer wall of the core (30). b) Introducing liquid plastic into the cavity (20), wherein the liquid plastic fills the first section (201) and at least part of the second section (202); c) Formation of a cavity and the first section (41) of the tube piece by the core (30). d) Formation of at least one area of ​​solidified plastic (5) within the cavity (20) in the area of ​​the opening (32) of the core (30); and e) Introducing a fluid into the passage channel (31) and through the opening (32) f) Driving the area of ​​solidified plastic (5) to displace still molten plastic material from the second section of the cavity (20) wherein fluid introduced via the opening (32) moves the area of ​​solidified plastic (5) through the still molten plastic to form the cavity in the plastic part to be produced within the second section of the cavity (202). [2] Method according to claim 1, wherein the system (1) characterized by is that the core (30) is arranged in the cavity (20) in a way that allows it to be pulled out. [3] Method according to one of the preceding claims 1 and 2, wherein the method is an injection method, wherein the displaced plastic is collected in a secondary cavity or forced back into a plastic injector. [4] Method according to any one of the preceding claims 1 to 3, characterized by , that the area of ​​solidified plastic (5) formed in step b) is formed as a solidification area adjacent to and / or near the opening (32) and in particular closes it after the plastic has hardened. [5] Method according to any one of the preceding claims 1 to 4, characterized by , that the area formed in step b) of solidified plastic (5) is formed as a cap-like area closing the opening (32). [6] Method according to any one of the preceding claims 1 to 5, characterized by , that the fluid supplied via the opening (32) in step c) tears the area of ​​solidified plastic (5) away from the injector before the area is moved through the cavity as a projectile. [7] Method according to any one of the preceding claims 1 to 6, characterized by , that the injector (3) is cooled to form a defined solidification area (5) within the polymer melt during solidification in step b). [8] Method according to any one of the preceding claims 1 to 7, characterized by, that the introduction of the fluid in step c) is carried out after a period of time in which a projectile-like solidification layer (5) has formed over the injector (3).

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