Method for manufacturing a plastic sleeve, plastic sleeve and support system

Abstract

The invention relates to a method for producing a plastic sleeve, a plastic sleeve and a bearing system, wherein the method (100) comprises: active heating (101) of a profiled mold surface of an injection mold to a predetermined injection temperature by means of a temperature regulating device; after heating the profiled surface of the mold to the injection temperature, injection (103) of a polymer melt into the mold; active cooling (105) of the profiled mold surface to a predetermined cooling temperature by means of a temperature regulating device; ejection (107) of a shape-stable plastic sleeve (200) from the mold, wherein a surface profile is formed on the outer surface of the plastic sleeve (200) by the mold, the surface profile having a plurality of lateral gripping elements (201) with a maximum lateral height of 0.5 mm.

Description

Technical Field

[0001] The invention relates to a method for manufacturing a plastic sleeve, a plastic sleeve, and a support system. Background Technology

[0002] Elastomer supports are typically achieved by a simple interference fit between the elastomeric bushing and the metal housing. However, when a plastic outer sleeve (particularly made from PA6 or PA66 compounds or mixtures thereof) is used in conjunction with a metal housing cavity, the high coefficient of thermal expansion of the plastic poses a challenge. For example, at high operating temperatures above 70 °C, not only does the interference fit increase significantly, but it also exceeds the glass transition temperature of the polyamide compound, resulting in noticeable stress relaxation. If the operating temperature subsequently drops significantly below 0 °C, the required tight fit is often no longer guaranteed, especially after stress relaxation has occurred.

[0003] Prior art knows of support systems that establish a form fit between a plastic outer sleeve and a metal housing. If the housing is made of, for example, aluminum, the inner surface of the aluminum housing can be bored to have a rough, serrated profile. Each tooth can grip within the plastic after the plastic outer sleeve is pressed in, resulting in a high extrusion force when extruded in the direction opposite to the pressing direction.

[0004] However, if a steel insert with a KTL coating (electrophoretic coating) is used, a solution from, for example, GB 2370338B is known, in which the end ring, after being pressed in, encloses the receiver to establish a form fit. However, this variation has a limitation: the ring must first be pressed past the receiver. Here, the interference is limited to a degree that allows the ring to be pressed past without damage. Furthermore, the insert must be pressed in just enough to push the ring out of the receiver's end and engage there without play. Since the insert on the end face opposite the ring also has an undercut structure such as a flange or ring, care must be taken regarding the receiver length, the plastic sleeve length, and the tolerance chain of the relative positions of the two rings. Otherwise, either undesirable play will occur between the ring and the receiver, or the ring will not be pushed far enough past the receiver to engage at all.

[0005] Furthermore, solutions are known, for example, through DE 10 2011 080 452 A1, DE 10 2020 104 160 A1, DE 10 2020207 154 B4, DE 10 2020 214 302 B4, EP 2 456 995 B1, and DE 10 2021 205 347 B3, in which the receiving element itself has snap-fit ​​structures such as holes or slots, into which corresponding protruding snap-fit ​​structures on the outer sleeve engage. In principle, the snap-fit ​​connection in the receiving element represents a snap-fit ​​connection similar to the convex ring on the back of the receiving element. However, for this solution, grooves that are sometimes difficult to manufacture must still be provided in the receiving element. Another disadvantage of this solution is the need for equally fine tolerance chain coordination. Summary of the Invention

[0006] In this context, one object of the present invention is to provide a solution for securing a plastic sleeve made of polyamide into a accommodating element with a KTL coating without a strict tolerance chain.

[0007] Therefore, according to a first aspect of the invention, a method for manufacturing microstructured plastic sleeves is proposed.

[0008] The proposed method includes: actively heating the contoured mold surface of the injection mold to a predetermined injection temperature using a temperature control device; injecting polymer melt, particularly molten polyamide, into the mold after the contoured mold surface has been heated to the injection temperature; actively cooling the contoured mold surface to a predetermined cooling temperature using a temperature control device; and ejecting a shape-stabilized plastic sleeve from the mold, wherein a surface contour is formed on the outer surface of the plastic sleeve by the mold, the surface contour having a plurality of gripping elements with a maximum side height of 0.5 mm.

[0009] This invention is based on providing a plastic sleeve made of polyamide, having a Shore hardness of about 80 to 85 Shore D for pure polyamide, or 85 to 90 Shore D for polyamide with glass reinforcement. Accordingly, this plastic sleeve is harder than the KTL coating with a Shore hardness of 50 to 80 Shore D typically used in receptacles for receiving plastic sleeves. Therefore, the difference in hardness between the plastic sleeve and the KTL coating allows for the gripping elements formed on the outer surface of the plastic sleeve to be gripped in, snapped onto, or clamped to the KTL coating.

[0010] However, if the gripping elements protrude too much, they will undergo plastic deformation when pressed into the KTL coating of the receiver, thereby losing their gripping ability. Therefore, according to the present invention, the gripping elements are designed to have a maximum side height of 0.5 mm.

[0011] By using temperature-controlled devices, such as temperature-controlled molds, it is possible to manufacture such small structures with sharp edges. Since the extrusion force depends largely on the number of gripping elements (e.g., teeth or toothed structures), a large number of gripping elements can be formed on the surface through the overall small geometry of the gripping elements, resulting in unexpectedly high extrusion pressure. Because the polyamide is harder than the KTL coating, the teeth of the plastic sleeve can bite into the KTL.

[0012] It can be specified that the surface profile has a large number of gripping elements with a maximum side height of 70 µm, preferably 30 µm.

[0013] If the corresponding gripping elements protrude too much, they may lose their gripping ability due to plastic deformation caused by being pressed into elements with KTL coating (e.g., steel holes). Therefore, the protrusion of the gripping elements should not be significantly greater than the thickness of the KTL coating. For typical KTL layer thicknesses of 15 to 35 μm, a maximum lateral height of twice the KTL thickness, i.e., 70 µm, is preferred, with a lateral height of 30 µm having proven to be particularly robust.

[0014] It can be further specified that the polymer is composed of polyamides, wherein the polyamides preferably include glass fibers.

[0015] Having a Shore hardness of about 80 to 85 Shore D for pure polyamide or 85 to 90 Shore D for polyamide with glass reinforcement, combined with the Shore hardness of the KTL coating of 50 to 80 Shore D, a sufficient hardness difference can be set between the plastic outer sleeve and the KTL coating, so that the gripping element can bite into the KTL coating.

[0016] It can be further specified that the injection temperature of the mold surface that imparts the contour is between 120 °C and 200 °C, preferably between 140 °C and 160 °C, and / or the cooling temperature is between 40 °C and 100 °C, preferably between 60 °C and 80 °C.

[0017] In particular, cooling temperatures between 60 °C and 80 °C have proven to be especially advantageous for the shortest processing time, as the plastic sleeve can be removed directly from the mold and further processed within this temperature range.

[0018] It can be further specified that the mold has an external sliding strip for parting or a large-area lateral slider, so as to demold the side of the plastic sleeve from the side of the mold without damaging the side.

[0019] According to a second aspect, the present invention relates to a plastic sleeve, wherein the plastic sleeve is manufactured by one possible embodiment of the proposed method.

[0020] Due to the proposed method, the proposed plastic sleeve has a Shore hardness of approximately 80 to 85 Shore D for pure polyamide, or 85 to 90 Shore D for polyamide with glass reinforcement. Accordingly, this plastic sleeve is harder than the KTL coating with a Shore hardness of 50 to 80 Shore D typically used in receivers of plastic sleeves. Therefore, the hardness difference between the plastic sleeve and the KTL coating allows the gripping element formed on the outer surface of the plastic sleeve based on the proposed method to grip in or snap onto or clamp with the KTL coating.

[0021] It can be specified that the plastic sleeve has a surface profile on its outer surface consisting of a large number of gripping elements, the maximum lateral height of which is up to 0.5 mm, preferably up to 70 µm, and particularly preferably up to 30 µm.

[0022] If the corresponding gripping elements protrude too much, they may undergo plastic deformation due to being pressed into elements with a KTL coating (such as steel holes), subsequently losing their gripping ability. Therefore, the degree to which the gripping elements protrude should not be significantly greater than the KTL coating thickness. Corresponding to a typical KTL layer thickness of 15 to 35 μm, a maximum lateral height preferably equal to twice the KTL thickness, i.e., 70 µm, is derived, of which a lateral height of 30 µm has proven to be particularly robust.

[0023] It can be further specified that the plastic sleeve has a serrated geometry formed on its outer surface, wherein the corresponding teeth of the serrated geometry are formed to have a first angle in a first direction and a second angle in a second direction, wherein the second angle is greater than the first angle.

[0024] A serrated geometry with a gentle angle in the pressing direction and a locking angle in the opposite direction has proven particularly well-suited for gripping in KTL coatings.

[0025] It can be further specified that the second angle is greater than 70°, preferably 90°.

[0026] The second serration geometry, with an angle greater than 70°, preferably 90°, determines the extremely stable and correspondingly robust shape of the serrations, resulting in a particularly high load-bearing capacity for the corresponding plastic sleeve. Furthermore, the exceptionally steep teeth act as barbs, leading to high-pressure output in the direction opposite to the pressing direction.

[0027] It can be further specified that the plastic sleeve has a uniform serrated geometry formed on its outer surface, wherein the corresponding teeth of the serrated geometry are formed to have a first angle in a first direction and a second angle in a second direction, wherein the second angle is the same size as the first angle.

[0028] The identical first and second angles determine a uniform tooth flank, which results in lower pressing force compared to sawtooth profiles with different first and second angles. Therefore, the corresponding support can be pressed out more easily during maintenance. This is particularly possible in receiving holes with a KTL coating without significant damage to the KTL. If the KTL is damaged, corrosion can damage the receiving hole.

[0029] It can be further specified that the corresponding tips of the gripping elements, particularly the teeth of the serrated geometry, are spaced at most 5 mm, preferably 1 mm, particularly preferably 0.2 mm apart, and / or the gripping elements, particularly the serrated geometry, are formed on at least 40% of the cylindrical outer surface of the plastic sleeve, preferably at least 70% of the outer surface, particularly preferably at least 90% of the outer surface of the plastic sleeve, and / or the ratio between the cylindrical integral segment and the toothed segment of the plastic sleeve is less than 0.4, preferably less than 0.9, and / or the plastic sleeve is made of polyamide, preferably glass fiber reinforced polyamide, and has an average roughness Rz of up to 70 µm.

[0030] In particular, the plastic sleeve may be composed of PA6, PA66, or a mixture of PA6 and PA66. PA66 is characterized by its particularly easy flowability during injection molding, while maintaining strength and stiffness even at typical high operating temperatures up to 90 °C under elastomer support in the chassis. A mixture of PA66 and a small amount of PA6 combines the good high-temperature properties of PA66 with the good flowability of PA6; thus, in variable-temperature processes, it is particularly effective to mold gripping elements with sharp edges according to the invention.

[0031] It can be further specified that the sawtooth geometry includes a plurality of teeth that transition into each other in a spiral shape.

[0032] Multiple helical teeth that transition into each other can be manufactured by simply turning a die and together form a thread-like structure that grips well and results in high pressure output.

[0033] According to a third aspect, the present invention relates to a support system.

[0034] The proposed support system includes one possible embodiment of the proposed plastic sleeve and a receiving element forming a receptacle, wherein the receiving element is coated with a plastic layer, particularly KTL paint, on the inner surface defining the receptacle, and wherein the plastic sleeve is arranged in the receptacle and engaged with the plastic layer by a plurality of gripping elements, thereby gripping the plastic sleeve in the receiving element.

[0035] Because of the plastic sleeve according to the invention, which is held extremely firmly in the receiving element, the support system is particularly robust.

[0036] In particular, in the proposed support system, the proposed plastic sleeve enables a tight tolerance chain to be maintained so that the snap-fit ​​component formed by the support system can be engaged into the corresponding undercut structure without the need for machining the receiving part for making the snap-fit ​​component, thereby achieving a robust, safe and economical fixation.

[0037] It can be stipulated that the height of the gripping element is equal to the thickness of the KTL layer.

[0038] By using a gripping element whose height is equal to the thickness of the KTL layer, deformation of the gripping element by the containing element, such as the metal substrate, is avoided.

[0039] It can be specified that, in the support system, the Shore hardness of the gripping element of the plastic sleeve is higher than the Shore hardness of the plastic layer of the receiving element. This ensures that the gripping element can bite into or grip in the plastic layer of the receiving element, especially in the KTL coating of the receiving element, because the harder gripping element can cause plastic deformation of the softer coating. Attached Figure Description

[0040] Other features, details, and advantages of the invention will become apparent from the following description of the embodiments taken in conjunction with the accompanying drawings. In the drawings: Figure 1 One possible implementation of the proposed method is shown. Figure 2 The first possible implementation of the proposed plastic sleeve is shown. Figure 3 A second possible implementation of the proposed plastic sleeve is shown. Figure 4 A third possible implementation of the proposed plastic sleeve is shown. Figure 5 A fourth possible implementation of the proposed plastic sleeve is shown. Figure 6One possible implementation of the proposed support system is shown.

[0041] List of reference numerals

[0042] 100 methods

[0043] 101 Heating Steps

[0044] 103 Injection Procedure

[0045] 105 Cooling Steps

[0046] 107. Ejection Steps

[0047] 200 Plastic Sleeve

[0048] 201 Grip Components

[0049] 203 Flange

[0050] 300 Support System

[0051] 301 Retaining element

[0052] 303 Retainer Detailed Implementation

[0053] exist Figure 1 The diagram illustrates a method 100 for manufacturing a plastic sleeve.

[0054] Method 100 includes a heating step 101, in which the contoured mold surface of the injection mold is actively heated to a predetermined injection temperature by means of a temperature control device.

[0055] In addition, method 100 includes an injection step 103, wherein the polymer melt is injected into the mold after the surface of the mold with the given contour is heated to the injection temperature.

[0056] In addition, method 100 includes a cooling step 105 in which the mold surface to which the contour is given is actively cooled to a predetermined cooling temperature by means of a temperature regulating device; and an ejection step 107 in which a shape-stabilized plastic sleeve is ejected from the mold, wherein a surface contour is formed on the outer surface of the plastic sleeve by means of the mold, the surface contour having a plurality of gripping elements with a maximum side height of 0.5 mm.

[0057] exist Figure 2 The image shows a plastic sleeve 200, which has a surface profile on its outer surface consisting of a plurality of gripping elements 201, with a side height Hz of a maximum of 0.5 mm, preferably a maximum of 70 µm, and particularly preferably a maximum of 30 µm.

[0058] The top of the gripping element 201 has a maximum distance Dz of 5 mm. exist Figure 3 The image shows a plastic sleeve 200 with a surface profile composed of multiple gripping elements 201, and... Figure 1 In contrast, these gripping elements extend at a gentler angle in the pressing direction, as indicated by arrow x, and form a steeper locking angle in the opposite direction to the pressing direction.

[0059] exist Figure 4 The image shows a plastic sleeve 200 with a surface profile consisting of multiple gripping elements 201, the toothed sides of which are angled at 90°, thus providing particularly high extrusion force or locking action.

[0060] exist Figure 4 The image shows a plastic sleeve 200 with a surface profile composed of multiple gripping elements 201, whose toothed flanks extend uniformly, thereby, for example, engaging with... Figure 4 Compared to providing a lower extrusion force, the plastic sleeve 200 can be extruded without damage, for example, for maintenance.

[0061] exist Figure 5 The plastic sleeve 200 is shown as a cylindrical integral segment (Sg) on ​​which a surface profile (Sg) is formed, the surface profile forming at least 15 tooth tips staggered from each other in the axial direction. In addition, a flange 203 is formed on the plastic sleeve 200 here.

[0062] The ratio between the height of the integral section (Sg) and the height of the surface profile (Sg) should be less than 0.9, and in particular less than 0.4.

[0063] exist Figure 6 The support system 300 is shown. The support system 300 includes, for example, according to... Figure 2 The plastic sleeve 200 and a receiving element 301 forming a receiving member 303, wherein the receiving element 301 is coated with a plastic layer, particularly coated with KTL paint, on an inner surface defining the receiving member 303, and wherein the plastic sleeve 200 is arranged in the receiving member 303 and engaged in the plastic layer by means of a plurality of gripping elements 201, thereby gripping the plastic sleeve 200 in the receiving element 301.

[0064] The present invention is not limited to one of the above embodiments, but can be modified in many ways.

[0065] All features and advantages derived from the specification and drawings, including structural details, spatial arrangements and method steps, may be essential to the present invention, whether individually or in a variety of combinations.

Claims

1. A method (100) for manufacturing a plastic sleeve (200), wherein, The method (100) includes: - The mold surface of the injection mold, which is given a contour, is actively heated (101) to a predetermined injection temperature by means of a temperature control device. - After heating the contoured surface of the mold to the injection temperature, the polymer melt is injected (103) into the mold. - The contoured mold surface is actively cooled (105) to a predetermined cooling temperature using a temperature control device. - Eject the shape-stable plastic sleeve (200) from the mold (107). The mold forms a surface profile on the outer surface of the plastic sleeve (200), the surface profile having a plurality of gripping elements (201) with a maximum side height of 0.5 mm.

2. The method (100) according to claim 1, Its features are, The surface profile has a large number of gripping elements (201) with a maximum side height of 70 µm, preferably 30 µm.

3. The method (100) according to any one of the preceding claims, Its features are, The polymer is composed of polyamides, wherein the polyamides preferably include glass fibers.

4. The method (100) according to any one of the preceding claims, Its features are, The injection temperature of the mold surface that imparts the contour is between 120 °C and 200 °C, preferably between 140 °C and 160 °C, and / or the cooling temperature is between 40 °C and 100 °C, preferably between 60 °C and 80 °C.

5. The method (100) according to any one of the preceding claims, Its features are, The mold has an external sliding strip or a large-area lateral slider to demold the side of the plastic sleeve from the side of the mold without damaging the side surface.

6. A plastic sleeve (200), in, The plastic sleeve (200) is manufactured by the method (100) according to any one of claims 1 to 5.

7. The plastic sleeve (200) according to claim 6, Its features are, The plastic sleeve (200) has a surface profile on its outer surface consisting of a large number of gripping elements (201), the maximum lateral height of which is up to 0.5 mm, preferably up to 70 µm, and particularly preferably up to 30 µm.

8. The plastic sleeve (200) according to claim 7, Its features are, The plastic sleeve (200) has a serrated geometry formed on its outer surface. The teeth of the sawtooth geometry are formed to have a first angle in a first direction and a second angle in a second direction, wherein the second angle is greater than the first angle.

9. The plastic sleeve (200) according to claim 8, Its features are, The second angle is greater than 70°, preferably 90°.

10. The plastic sleeve (200) according to claim 9, Its features are, The plastic sleeve (200) has a uniform serrated geometry formed on its outer surface. The teeth of the sawtooth geometry are formed to have a first angle in a first direction and a second angle in a second direction, wherein the second angle is the same size as the first angle.

11. The plastic sleeve (200) according to any one of claims 8 to 10, Its features are, The gripping element (201), particularly the teeth of the sawtooth geometry, has a maximum spacing of 5 mm between the corresponding tooth tips, preferably 1 mm, particularly preferably 0.2 mm, and / or The gripping element (201), particularly the serrated geometry, is formed on at least 40% of the cylindrical outer surface of the plastic sleeve, preferably on at least 70% of the outer surface, and particularly preferably on at least 90% of the outer surface of the plastic sleeve, and / or The ratio between the cylindrical integral section and the toothed section of the plastic sleeve is less than 0.4, preferably less than 0.9, and / or The plastic sleeve is molded from polyamide, preferably glass fiber reinforced polyamide, and has an average roughness Rz of up to 70 µm.

12. The plastic sleeve (200) according to any one of claims 8 to 11, Its features are, The sawtooth geometry comprises multiple teeth that transition into each other in a spiral pattern.

13. A support system (300), in, The support system (300) includes: - The plastic sleeve (200) according to any one of claims 6 to 12, - A receiving element (301) forming the receiving member (303), The receiving element (301) has a plastic layer coated on the inner surface defining the receiving member (303), particularly coated with KTL paint. The plastic sleeve (200) is arranged in the receiving element (303) and engaged in the plastic layer by a plurality of gripping elements (201), such that the plastic sleeve (200) is snapped into the receiving element (301).

14. The support system (300) according to claim 13, Its features are, The height of the gripping element (201) is at most equal to the thickness of the KTL layer.

15. The support system (300) according to claim 13 or 14, Its features are, The Shore hardness of the gripping element (201) of the plastic sleeve (200) is higher than that of the plastic layer of the receiving element (301), and in particular higher than that of the KTL coating of the receiving element (301).

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