Abstract
A plastic component is provided that leads to an initial friction reduction with a friction partner. At least part of the surface of the plastic component, which interacts with a surface of a friction partner, is provided with a plurality of structures. The structures are composed of at least one structure type. Between two adjacent structure types, a distance is formed in the range of 10 microns to 1 mm. A width of the structure types is in the range of 10 microns to 100 microns. A height or depth of the structure types is in the range from 1 micron to 100 microns.
Claims
1. A thermoplastic plastic component comprising a surface structure to reduce friction, wherein, after an injection molding process, at least a portion of a surface of the plastic component has a plurality of structure types arranged in a straight line, wherein a distance between two adjacent straight lines of the structure types is in a range of 10 microns to 1 mm, wherein a width of the structure types arranged in the straight line is in a range of 10 microns to 1 mm, and wherein a height or depth of the structure types arranged in the straight line is in the range of 1 micron to 100 microns.
2. The thermoplastic plastic component according to claim 1, wherein the distance, the width or the height of the structure types arranged in the straight line, or the distance, the width or the depth of the structure types arranged in the straight line are constant within the surface of the plastic component (10).
3. The thermoplastic plastic component according to claim 1, wherein the distance, the width or the height of the structure types arranged in the straight line, or the distance, the width or the depth of the structure types arranged in the straight line vary within the surface of the plastic component.
4. The thermoplastic plastic component according to claim 1, wherein the structure types on the surface of the plastic component are raised or recessed.
5. The thermoplastic plastic component according to claim 1, wherein the structure type is a solid line or several lines juxtaposed in the straight line or several spots juxtaposed in the straight line.
6. The thermoplastic plastic component according to claim 1, wherein the structure types on the surface of the plastic component are oriented at an angle of 90 to +90 with respect to a load direction of the plastic component.
7. The thermoplastic plastic component according to claim 1, wherein a distribution of the structure types on the surface of the plastic component is homogeneous or statistical.
8. A method for producing a surface structure in at least a portion of a surface of a thermoplastic plastic component in an injection molding process, the method comprising: forming, with a pulsed laser, a surface structure of a negative surface structure of the plastic component in a surface of an insert for a tool for manufacturing the plastic component in an injection molding process, and molding the plastic component with the insert thereby forming the surface structure on the surface of the plastic component, which includes several structure types each arranged in a straight line, wherein a distance between two adjacent straight lines of the structure types in at least a part of the surface of the injection molded plastic component is in a range of 10 microns to 1 mm, wherein a width of the structure types arranged in the straight line in at least a portion of the surface of the injection molded plastic component is in the range from 10 microns to 1 mm, and wherein a height or depth of the structure types arranged in the straight line in at least a part of the surface of the injection molded plastic component is in the range from 1 micron to 100 microns.
9. The method according to claim 8, wherein, when forming the negative surface structure in the tool for producing the plastic component in the injection molding process in at least a part of the surface of the plastic component, the pulsed laser is controlled such that the distance, the width or the height of the structure types arranged in the straight line or the distance, the width or the depth of the structure types arranged in the straight line vary or are constant at the surface of the plastic component.
10. The method according to claim 8, wherein the structure types arranged in the straight line have an orientation which is aligned in a flow direction of the thermoplastic plastic in the injection molding process.
11. The method according to claim 8, wherein the pulsed laser is controlled such when forming the negative surface structure of the insert that the structure type is a solid line.
12. The method according to claim 8, wherein the pulsed laser is controlled such when forming the negative surface structure of the insert that the structure type is a plurality of lines juxtaposed in the straight line.
13. The method according to claim 8, wherein the pulsed laser is controlled such when forming the negative surface structure of the insert that the structure type is a plurality of spots juxtaposed in the straight line.
14. The method according to claim 8, wherein the pulsed laser is controlled such when forming the negative surface structure in the insert that the structure types on the surface of the plastic component are oriented at an angle of 90 to +90 with respect to a load direction of the plastic component.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:
[0038] FIG. 1 is a schematic representation of an arrangement with which structures are written in an insert for an injection mold by means of a pulsed laser;
[0039] FIGS. 2A to 2F illustrate several variants of the orientation of the structures on the surface of a plastic component with respect to a load direction with another friction partner;
[0040] FIGS. 3A to 3B illustrate possible combinations and arrangements of two different structure types on the surface of a plastic component;
[0041] FIGS. 4A to 4B illustrate the formation of the line structures on the surface of a plastic component, wherein the line structures may be protrusions or dimples;
[0042] FIGS. 5A to 5B illustrate the formation of a further structure type, which is formed as a spot and may also be formed on the surface of a plastic component in the form of a protrusion or a dimple;
[0043] FIG. 6 is a schematic representation of the tool in section, incorporating the insert designed according to the invention;
[0044] FIG. 7 is a schematic assignment of the plastic component structured according to the present invention with respect to a friction partner;
[0045] FIGS. 8A to 8B illustrate the state of a plastic component, which is provided with an additive, in the initial state and in the retracted state;
[0046] FIGS. 9A to 9B illustrate the state of a plastic component, which is also provided with an additive, and which has formed a surface structure on the surface, and the corresponding state, also in the retracted state; and
[0047] FIG. 10 is a function of the friction force dependent on the number of load cycles for a plastic component with or without surface structuring.
DETAILED DESCRIPTION
[0048] FIG. 1 shows a schematic view of an arrangement with which microstructures can be introduced in the surface 4 of an insert 2 for an injection mold (not shown here) for manufacturing a plastic component 10 (see FIG. 7). For the structuring of the surface 4 of the insert 2, a pulsed laser 7 is used. Preferred in this context is a pulse duration of the laser 7 between 10 and 20 picoseconds and that the pulsed laser beam 9 striking the surface 4 has a high light intensity. In order to write the dimples (not shown here) in the surface 4 of the insert 2 (in the molded plastic component 10, microstructured protrusions 15 are formed as a result; see FIGS. 4A and 5A) or to remove material from the surface 4 of the insert 2 (in the molded plastic component 10, consequently microstructured dimples 16 are formed; see FIGS. 4B and 5B), a relative movement between the surface 4 of the insert 2 and the pulsed laser beam 9 striking the surface 4 of the insert 2 must exist. One way to achieve this is a scanning device 5 with which the pulsed laser beam 9 is deflected in the X-direction X and in the Y-direction Y on the surface 4 of the insert 2 so as to write the dimples (not shown here). How the pulsed laser beam 9 is to be deflected on the surface 4 of the insert 2 is controlled by a controller 8. It is also possible that with the pulsed laser 7, a direct structuring of a plastic component may be carried out. In this case, material is accordingly removed from the surface of the plastic component with the laser 7 so that structures 13 required for friction reduction can form on the surface 4 of the plastics component 10.
[0049] FIG. 2A to 2F show different variants of the arrangement of the structures 13 on the surface 12 of the thermoplastic plastic component 10. The structures 13 on the surface 12 of the thermoplastic plastic component 10 may be solid lines 17 and/or a juxtaposition of individual lines 17 and/or a series of separate spots 18 (see FIG. 3A). A spot 18 in the sense of the invention is understood to be a geometric shape which substantially has a circular shape and is not too large. The structures 13 on the surface 12 of the thermoplastic plastic component 10 are substantially arranged along a straight line L. The straight lines L are spaced at a distance a from each other. It is also conceivable that the distance a between the straight lines L of the individual structures 13 may be varied. The distance a is thus not constant across the part of the surface 12 of the plastic component 10 that is at least structured. By varying the distance a between the straight lines L of the structures 13, the initial frictional value can thus also be specifically set.
[0050] In FIG. 2A to 2F, different orientations of structures 13 (of a single structure/structure type) are shown with respect to a load direction 19 with a further friction partner (not shown here).
[0051] The structure type 14 used in FIG. 2A to 2F is formed as a line 17. In the embodiment of the surface structure 11 illustrated in FIG. 2A, the lines extend 17 toward the load direction 19. The embodiment of the surface structure 11 shown in FIG. 2B is designed such that the lines 17 of the surface structure 11 extend perpendicular to the load direction 19. In the embodiment shown in FIG. 2C, the lines 17 of the surface structure 11 extend at an angle to the load direction 19. In the embodiment shown in FIG. 2D, the surface structure 11 is designed such that individual lines 17 of the surface structure 11 are oriented along a preferred direction 30 corresponding to the straight line L. The individual lines 17 are mutually spaced apart along the straight line L. According to a further embodiment, as shown in FIG. 2E, the lines 17 of the surface structure 11 are inclined at an angle and with respect to the load direction 19. The individual lines 17 of the surface structure 11 intersect there. In the embodiment illustrated in FIG. 2F, the surface structure 11 of the plastic component 10 is designed such that the individual lines 17 are inclined analogous to the representation shown in FIG. 2E, also at an angle and with respect to the load direction 19. The individual lines 17 of the surface structure 11 shown here are mutually spaced apart along the straight line.
[0052] In FIGS. 3A and 3B, combination structures are shown, which means that the surface structures 11 of the thermoplastic plastic component 10 are composed of a combination of at least two different structure types 14. In the embodiment shown in FIG. 3A, a structure type 14 is formed with lines 17. The other structure type 14 is comprised of a plurality of spots 18, which are arranged linearly juxtaposed along the straight line L. The structure types 14 are arranged on the surface 12 of the plastic component 10 such that they are in contact with one another. The lines 17 are arranged at an angle to the load direction 19 and the juxtaposed spots 18 are arranged at an angle to the load direction 19. In the representation shown in FIG. 3B, two different structure types 14 are also formed on the surface 12 of the plastic component 10. As already mentioned in the description of FIG. 3A, a structure type 14 in the shape of lines 17 is formed; the other structure type 14 is designed in the shape of a series of spots 18. Both structure types 14 are arranged parallel to each other in the embodiment shown in FIG. 3B, and are oriented toward the load direction 19.
[0053] The embodiment shown in FIG. 3A represents an advantageous combination of the different structure types 14 because the structure types 14 made up of the lines 17 and the juxtaposition of the spots 18 are in contact with one another and are inclined at an angle in each case of or with respect to the load direction 19. In comparison to the representation shown in FIG. 3B, this does not lead to any catching in the loading of the plastic component 10 in the load direction 19 labeled with respect to a friction partner (not shown here). Although in FIGS. 3A and 3B only two possible embodiments of the combination of two different structure types 14 are shown, this is not intended to be a limitation of the invention. A variety of alignments and orientations of the different structure types 14 with respect to the load direction 19 are conceivable. Precisely by configuring the surface structure 11 on the surface 12 of a thermoplastic plastic component 10 in different ways, it is possible to achieve the optimum adaptation of the plastic component 10 with respect to the desired initial friction (with the first load cycles).
[0054] FIGS. 4A and 4B illustrate the formation of structure types 14, which are formed as lines 17 on the surface 12 of the plastic component 10. In FIG. 4A, the line 17 (or part of a line) is a protrusion 15 which has a width B and a height H. The width of the line 17 can range from 10 microns to 100 microns. The height of the line 17 can be in the range of 1 microns to 100 microns. In the embodiment shown in FIG. 4, the line 17 is formed as a dimple 16 starting from the surface 12 of the plastic component 10. The dimple 16 thereby has a depth T, which is in the range of 1 microns to 100 microns. The width B of the dimple 16 is in the range of 10 microns to 100 microns.
[0055] FIG. 5A and FIG. 5B show the structure type 14, which is formed as a spot 18 in the shape of a protrusion 15 or a dimple 16 with respect to the surface 12 of the plastic component 10. As already illustrated in the description of FIGS. 3A and 3B, the individual spots 18 can be arranged juxtaposed in a line.
[0056] The spots 18 are substantially circular and have a width B which is in the range between 10 microns and 100 microns. If the spot 18 is formed as a protrusion 15, it has a height H which is in the range from 1 micron to 100 microns. In the event that the spot 18 is formed as a dimple 16, it has a depth T which is analog in the range between 1 micron and 100 microns. The structure types 14, which can form, e.g., a line 17 or a series of spots 18, which may extend over a certain part of the surface 12 of the plastic component 10, can be designed according to the invention such that within the structure 13, the parameters, such as the distance a of the structures 13 to one another, the width B, the height H or the depth T along the structure, may vary. The variation of these parameters ranges within the above described range of values.
[0057] The structures 13, which are formed in the surface 12 of a plastic component 10, result from the fact that in an insert 2 (see FIG. 6) for an injection mold 1 (see FIG. 6) for the manufacture of a plastic component 10, these structures 13 are introduced into the insert 2 in a negative mold. The plastic component 10 can then be molded in an injection molding process, together with the surface structure 11. Possibly, the injection molding process may be supplemented with a variothermal process. The individual structures 13 can be utilized in meaningful combinations. The only thing to be considered is that a catching of the two structures 13 during the movement in respect of the load direction 19 should be avoided.
[0058] FIG. 6 shows a schematic view of the injection mold 1, with which an injection molded component can be produced. The insert 2 is introduced in the injection mold 1. Between the insert 2 and the injection mold 1 is a free space 24, which can be filled during the injection molding process with the plastic (thermoplastics) used for the injection molding process. The structures produced with the pulsed laser 7 in the surface 4 of the insert 2 for the injection mold 1 are dimples 26 (line, series of lines, or series of spots), which alternate. The dimples 26 in the surface 4 of the insert 2 thus represent the negative mold of the plastic component (not shown) that is ultimately produced.
[0059] FIG. 7 shows a schematic view of the interaction of the plastic component 10 produced according to the invention with a friction partner 20. The plastic component 10 injection-molded with the aid of the insert 2 has a line 17, a series of lines 17 and/or a series of spots 18, which are in contact with the friction partner 20. The lines 17, the series of lines 17 and/or the series of spots 18 reduce the initial friction (stiction) between the plastic component 10 and the friction partner 20.
[0060] FIGS. 8A and 8B show the position of a conventional plastic component 10 in a starting position and in the retracted state (after a specified number of load cycles). For reducing the friction with a friction partner 20, which is guided along a load direction 19 across the surface 12 of the plastic component 10, the plastic component 10 is provided with a slip additive 41. The slip additive 41 is substantially homogeneously distributed in the base material 40 of the plastic component 10. In the position illustrated in FIG. 6A, the initial friction has an increased value since the slip additive 41 is not yet released on the surface 12 of the plastic component 10. In the position shown in FIG. 6B, a lubricating film 42 is formed on the surface 12 of the plastic component 10 after a plurality of load cycles (retracted state). With this design of the lubricating film 42, a reduction in friction is thus achieved, which levels off to a specified constant value (see FIG. 8).
[0061] In the embodiment shown in FIGS. 9A and 9B, the plastic component 10 is formed of the base material 40 and the added slip additive 41. According to the invention, in the representation in FIG. 7A, the surface structure 11 is formed on the surface 12 of the plastic component 10, which ensures a low adhesive initial friction between the plastic component 10 and the friction partner 20 along the load direction 19. As can be seen in FIG. 7B, after a certain number of load cycles, the surface structure 11 is abraded and a lubricating film 42 has formed on the surface 12 of the plastic component 10. By means of this lubricating film 42, a friction value is also set which ultimately reaches a value which corresponds to the range value of a plastic component 10, which, analogous to the embodiment in FIGS. 6A and 6B, at least before the start of the load cycle, has not formed a surface structure 11.
[0062] FIG. 10 illustrates the course of the friction force in dependence with the load cycles between the friction partners 20 and the plastic component 10. The dashed line 51 displays the friction force dependent on the number of load cycles, which occurs in a plastic component 10 that has formed a surface structure 11 in accordance with the invention. The solid line 52 reflects the course of the friction force as a function of the number of load cycles for a conventional plastic component 10 (without the inventive surface structure 11). From FIG. 10, it can be clearly seen that the initial friction is reduced in a plastic component 10 with a surface structure 11 according to the invention. After a certain number of load cycles, the friction force aligns with the friction force of the conventional plastic component 10. In both cases, a lubricating film 42 (see FIGS. 6B and 7B) forms on the surface 12 of the plastic component 10 after a certain number of load cycles so that in both cases (conventional plastic component 10 and plastic component 10 with a surface structure 11 on the surface 12), the same friction conditions can be achieved after a certain number of load cycles.
[0063] The plastic component 10 with the surface structure 11 is formed of a thermoplastic. The friction partner 20 can also be a thermoplastic. Another type of material, such as for example glass or a metallic component, is also conceivable. Usually, the plastic component 10 and the friction partner 20 are made of a thermoplastic. The materials of the plastic component 10 or of the friction partner 20 may be the same or different. Normally, two different materials are provided since mutually identical materials for the plastic component 10 and the friction partner 20 exhibit increased friction.
[0064] Especially in practice, two types of loading between the plastic component 10 and the friction partner can 20 occur. For example, there may be a few or only one load cycle between the plastic component 10 and the friction partner 20. This may be the case, e.g., when removing a cap from a disposable product. As is apparent from the illustration in FIG. 8, in this case, the surface structure 11 can lower the operating force and possibly avoid an additive. Wear of the structure 13 on the surface 12 of the plastic component does not interfere.
[0065] However, a more frequent application is that many load cycles are executed between the plastic component 10 and the friction partner 20. This is the case, e.g., with lancing devices or inhalers. In the first application, these products often exhibit a slightly more sluggish operation. The structuring according to the invention can counteract this sluggishness and achieve a more uniform operating force of all duty cycles.
[0066] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.
