EP2276617A1

EP2276617A1 - Process for production of a fastener and fastener for an elongated object

Info

Publication number: EP2276617A1
Application number: EP09734431A
Authority: EP
Inventors: Markus Kumpf; Michael Schmidt; Frank Rosemann
Original assignee: Newfrey LLC
Current assignee: Newfrey LLC
Priority date: 2008-04-25
Filing date: 2009-04-15
Publication date: 2011-01-26
Also published as: JP5498480B2; JP2011518685A; WO2009130146A1; DE102008021021A1

Abstract

For molding a fastener (10) for an elongated object, where the fastener (10) has a section which forms an object holder (12), and a fastening section (11), a mono- sandwich injection molding process is used, where a given quantity of a first synthetic material component and a second synthetic material component are fed into a melting and injection cylinder and then are continuously pressed, one after the other, by the cylinder into a mold cavity forming the fastener (10) in a stratification such that the first synthetic material component reaches the mold cavity before the second synthetic material component and forms a surface part (O) in the region of the object holder (12) and the second synthetic material component forms a core part (K) connected substance-lockingly with the surface part (O), which comprises the object holder (12) and the fastening section (11).

Description

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PROCESS FOR PRODUCTION OF A FASTENER AND FASTENER FOR AN

ELONGATED OBJECT

The invention relates to a process for production of a fastener for an elongated object by use of a sandwich injection molding process, in particular of the mono- sandwich type. The invention also relates to a fastener for an elongated object produced according to the process, which has an object holder and a fastening section. The so-called mono-sandwich injection molding process for production of stratified objects from synthetic material is disclosed in, among other sources, DE 2,353,818 A1. In this process, two unlike components of synthetic material are fed, in a suitable stratification, into a melting and injection cylinder and then pressed, one after the other, into the cavity of an injection mold by the latter. Here the component first pressed into the cavity forms a skin or thin layer on the walls of the cavity, on the inner side of which the following second component rests. A sandwich part is produced, the surface of which is formed wholly or partially of the component first injected and the core of which consists of the second component.

The mono-sandwich injection molding process was developed in order to be able to use high-grade synthetic material as sparingly as possible and only at those places at which high-grade material is required for the sake of appearance or for some other reason. Thus, the process is used to produce for example high-quality parts of synthetic material for the interior of motor vehicles, such as handles or the like, in which the core region consists of a hard synthetic material for obtaining the static properties necessary for function and the visible and graspable outer region consists of a soft synthetic material.

For fasteners for fastening tubes, cables or the like, it is disclosed in DE 3,708,864 C2 that a holding region for mounting the fastening element on a supporting member may be produced from a harder synthetic material and a bearing region for accommodation of the elongated object with an inlay of a softer synthetic material may be provided. Here the inlay may be connected with the bearing region of the fastener in the so-called two-component injection molding process. In this process, in contrast to the mono-sandwich injection molding process, first the part consisting of the harder component is molded and then, by repositioning of the injection-molded piece, by displacement of a tool part into a new position or by withdrawal of a core of the cavity for subsequent injection, the second component is procured. These measures make the tools for the two-component injection molding process costly and the cycle times longer than in the single-component injection molding process.

The object of the invention is to indicate a process for production of a fastener for elongated objects, consisting of two components of synthetic material, which is low-cost and permits short cycle times. In addition, the process is designed to improve adhesion between the sections of the fastener consisting of unlike synthetic material components.

According to the invention, this object is accomplished by use of a sandwich injection molding process for production of a fastener for an elongated object, where the fastener has a section that forms an object holder, and a fastening section, where in addition a given quantity of a first synthetic material component for forming a surface part and a second synthetic material component for forming a core part are fed into a melting and injection cylinder and then are continuously pressed, one after the other, out of the cylinder into a mold cavity forming the fastener, in a stratification such that the first synthetic material component reaches the mold cavity before the second synthetic material component and forms a surface part in the region of the object holder and the second synthetic material component forms a core part, which is connected substance-lockingly with the surface part and comprises the object holder and the fastening section.

According to the process according to the invention, substantially only the object holder is formed in the sandwich structure, while the fastening section consists substantially exclusively of the core part component, in order to be able to withstand high holding forces in fastening. Here, the second synthetic material component for formation of the core part preferably is a hard component. The first synthetic material component preferably is a soft component, which stabilizes the object held in the holder and increases resistance to displacement.

Use according to the invention of a kind of mono-sandwich injection molding process for molding fasteners in addition has the advantage that the molding tools required are simpler and less costly and the time needed for a molding cycle is hardly any longer than that for the single-component injection molding process. Further, it has been found that the formation of grooves or small cavities in the wall of the mold cavity results in thicker, raised zones, which in the case of soft surface components can be utilized for obtaining damping and elasticity properties. In contrast to the conventional two-component injection molding process, with the process according to the invention improved adhesion between the core part and the surface part is also obtainable and the material requirement needed for formation of the surface part is smaller, since the surface part can be designed very thin and a greater wall thickness can be obtained at only particular places provided therefor. Moreover, the surface part in the form of a thin skin can cover fairly great sections of the fastener, in order to lend the latter surface properties differing from the properties of the core part. According to an additional proposal of the invention, it is advantageous when the gate is located at an end of the object holder far from the fastening section. In this - -

way, it can be reliably obtained that the surface part is formed only in the region of the object holder. For formation of the surface part, it is also advantageous when the gate is designed as a constricted film gate. In some designs of the mold cavity it may be advantageous to provide a plurality of selectively operative gates. If the object holder has a curved wall with reinforcing ribs projecting outward on its outer side and intersecting each other, which are formed substantially by the core part, according to the invention a gate may be provided at the point of intersection of the reinforcing ribs.

In a fastener that has a fastening section designed as a sleeve for the accommodation of a bolt where one end of the sleeve is closed off by a bottom, it is advantageous when the gate is located on the bottom of the sleeve. In this way, a ring-shaped section is formed at the opposite, open end of the sleeve, as surface part.

Advantageous embodiments of fasteners that can be produced by the process according to the invention at especially low cost and with advantageous properties are indicated in Claims 7 to 26.

The invention is described in detail below by exemplary embodiments which are represented in the drawing, wherein

Figure 1 shows a perspective representation of a first fastening element with a parallelepiped fastening section, Figure 2, a side view of the fastener of Figure 1 , partially sectioned,

Figure 3, a second fastener with a sleeve-like fastening section, Figure 4, a side view of the fastener of Figure 3, partially sectioned, Figure 5, a perspective view of a third fastener with a sleeve-like fastening region closed at one end, Figure 6, a side view of the fastener of Figure 5, partially sectioned, Figure 7, a perspective view of a fourth fastener with a sleeve-like fastening region and holding fingers,

Figure 8, a side view of the fastener of Figure 7, partially in section, Figure 9, a side view of a fifth fastener, partially sectioned, and Figure 10, a schematic representation of a device for performing a mono- sandwich injection molding process.

The mono-sandwich injection molding process is generally known and before description of the examples will be briefly explained by the injection molding device represented schematically in Figure 10. The device comprises a main injection unit 100 and a charging unit 101. The injection unit consists essentially of a filling funnel 102, a heated screw cylinder 103 with enclosed screw and a path-measuring system 104, by which the path covered by the screw in the cylinder 103 can be measured. The charging unit has substantially the same design and comprises a filling funnel 105 and a screw cylinder 106 with enclosed screw. The feed channels of the injection unit 100 and the charging unit 101 are connectable by a three-way valve 107. In addition, the injection unit

100 is connectable by the valve 107 to a mold cavity of an injection mold 108.

For molding an injection part with two unlike synthetic material components, the funnel 102 of the injection unit 100 is filled with the component for the core part and the funnel 105 of the charging unit 101 is filled with the component for the surface part. In both units, the components are melted by heating. Before the injection operation, a defined quantity of the surface component is conducted through the charging unit 101 by the appropriately switched three-way valve 107 into the front nozzle region of the screw cylinder 103 of the injection unit 100, owing to which the core component 109 found therein is pushed back and in the screw cylinder 102 a plug is formed from the surface component 1 10. Then the three-way valve 107 is switched in such a way that the feed channel of the charging unit 101 is closed off and the feed channel of the injection unit 100 is opened to the cavity of the injection mold 108. By operation of the screw of the injection unit 100, first the surface component 110 and then the core component 109 are then injected into the mold cavity. There the surface component 110 first spreads out primarily into the regions of the mold cavity near the point of injection and reaches the regions of the mold cavity further from the point of injection only when the quantity of surface component previously loaded into the injection unit 100 is sufficient to do so. Spread of the surface component can thus be selectively influenced by the load quantity of the surface component and by the design of the mold cavity. When the load quantity of the surface component has been consumed, the remaining sections of the mold cavity, including their surfaces, will be filled exclusively by the core component.

Use of the mono-sandwich injection molding process has hitherto been limited to parts of simple design. With the invention, such process is for the first time used for molding fasteners with a complicated design, as is to be shown by the following examples.

Figures 1 and 2 show a first fastener 10, which has a central fastening section 1 1 and two object holders 12 located in symmetrical arrangement on opposite sides of the fastening section 1 1. The fastening section 1 1 consists of a parallelepiped hollow body, which on its underside 13 has an opening for the introduction of a fastening bolt. At the top and on the two sides turned toward the object holders 12, the fastening section 11 is closed by walls 14, 15. On the two other sides, walls 16 are in each instance pierced by two longitudinal parallel slots 17. In the inside of the fastening section 11 , locking ribs 18 are formed on the walls 15, which extend in the direction of the upper wall 14 and act to hold the fastening section 1 1 on a threaded bolt. The holders 12 each have a circular cylindrical, continuously curved wall 19, which extends over an angle of about 280°. The axes of curvature of the walls 19 lie in a plane that intersects the longitudinal axis of the fastening section 1 1 at right angles. The opposite peripheral ends 20, 21 of each curved wall 19 are provided with surfaces 22, 23 broadened in the radial direction and extending substantially radially, which limit a wedge-shaped feed slot 24 narrowing toward the axis of curvature, through which an object to be held, for example a tube, can, with widening of the curved wall 19, be pressed into the holder 12.

The curved wall 19 has on its concave inner side in the center region a flat rib 25 extending in the peripheral direction, by which an increase in the wall thickness in this region is produced. In addition, a plurality of ribs 26, projecting inward and extending parallel to the axis of curvature, are provided, which serve for support of the object to be held. The ribs 26 are higher than the rib 25 and extend beyond the rib 25.

The curved walls 19 are connected with the fastening section 11 by two parallel crosspieces 27. The crosspieces 27 extend over the entire axial length of the curved walls 19 and are tied to the walls 15 of the fastening section 11 , the ends of which project over them. The thickness of the crosspiece 27 in the regions bridging the intermediate spaces between the curved walls 19 and the walls 15 is kept small for reasons relating to injection technology, as will be explained below. At the two peripheral ends 21 of the walls 19 farther from the fastening section 11 is in each instance formed a film gate 28, which extends over the axial length of the walls 19 and has the form of a thin-walled rib with a bead-like thickened end. The film gate 28 produces a more uniform flow front over the width and hence better distribution of in particular the surface component. On the outside the curved walls 19 are in addition provided with a reinforcing rib 29, which extends in approximately the center from the lower crosspiece 27 downward to the contact plane defined by the lower end of the fastening section 11. It can be seen from the sectional representation in Figure 2 how the formation of a core part K and a surface part O has been obtained by molding the fastener 10 with use of a mono-sandwich injection molding process. The core part K forms the inner core of the object holder 12 and the fastening section 1 1 completely. The surface part O surrounds the core part K in the region of the holder 12 and forms the ribs 26 projecting inward. In addition, the surface part O forms a thicker bead primarily at the radially inner edges of the surfaces 22, 23. This definition of the core part K and surface part O was obtained by control of the injection molding process and by the geometric design of the fastener 10. The determining factor, for one thing, was the position and design of the film gates 28 at the outer ends of the curved walls 19, owing to which uniform distribution of the synthetic material component injected first for the surface part O was produced. The central rib 25 in addition also contributes substantially to spread of the surface component into the axial marginal zones of the holder 12. Further, it has been found that the surface component fills the ribs 26 almost completely, and is also no longer forced out of the latter by the following component of the core part. Owing to metering of the quantity of the surface component and the constricted cross section of the crosspiece 27, by which entry of the surface component into the fastening section 11 is hindered, it is in addition obtained that the fastening section 11 consists exclusively of the component of the core part.

Hard synthetic material, for example a polyamide, is selected for the core part in the fastener 10. For the surface part, on the other hand, a soft synthetic material, for example TPE, which has rubber elastic properties, is selected so that, owing to the ribs 26 and the thickenings at the edge of the surfaces 22, 23, vibration-damping support of the object held by the holder 12 is obtained. On the outside of the fastener 10, the layer of soft synthetic material component makes for good haptics and for stable bracing at the support part.

Figures 3 and 4 show a fastener 30, which is like the fastener 10 in its basic construction, but which differs from it by the following features, considered in detail below. The fastener 30 has a sleeve-like fastening section 31 and two object holders 32, 33, which have diameters differing from one another. The two holders 32, 33 in each instance have a curved wall 34, 35, which extends over an angle of more than 280°. In each instance, one end of the walls 34, 35 is connected by two parallel crosspieces 36, 37 with the fastening section 31. The crosspieces 37 run approximately tangential to the curved walls 34, 35 and at an angle of 30° to the longitudinal axis of the fastening section 31. The crosspieces 36 have a first section parallel to the crosspieces 37 and a section substantially perpendicular to the longitudinal axis of the fastening section, by which they are connected to one end of the respective wall 34, 35. On the inner side, the curved walls 34, 35 in each instance have in the center a flat rib 38, raised inward, which extends in the peripheral direction and is limited in the axial direction on both sides by two steps located spaced apart. In addition, the two walls 34, 35 have on their inner side a plurality of ribs 39, extending axially and projecting inward, which are higher than the rib 38. The curved wall 34 is in addition provided on the outer side in its center with a reinforcing rib 40. The curved wall 35 has a reinforcing rib 45 on the outer side, in a peripheral section of about 90° adjoining the crosspiece 37. The two outer peripheral ends of the walls 34, 35 are provided with wide faces 41 , 42 extending substantially radially, which are formed by shoulders 43, 44 extending radially outward. For injection molding of the fastener 30, the melted synthetic material components are injected, one after the other, through gates at the shoulders 43, 44 into the corresponding mold. Via the laterally stepped rib 38, this results in good distribution of the component for formation of the surface part over the walls of the object holders 32, 33 and virtually complete filling of the ribs 39. Overflow of the surface component into the fastening section 31 is effectively prevented by the arrangement of the crosspieces 35, 37, since they leave the curved walls 34, 35 at an acute angle against the direction of flow. First, the core component following the surface component penetrates through the crosspieces 36, 37 into the cavity for the fastening section 31 and fills it up. The design described of the fastener 30 thus results, in the mono-sandwich injection molding process, in holders 32, 33 formed in sandwich structure and a fastening section 31 consisting substantially of only the core component. Here, in addition to the acute-angled arrangement, the smaller width of the crosspieces 36, 37 in the axial direction in comparison to the axial length of the curved walls 34, 35 also contributes to this distribution of the two components.

In the fastener 50 represented in Figures 5 and 6, a cylindrical sleeve 51 , closed off at the upper end by a bottom 52, forms the fastening section. In the vicinity of the lower open end of the sleeve 51 , the latter has two crosspieces 53, 54, arranged spaced apart and perpendicular to the central axis of the sleeve 51 , which have the shape of rectangular plates, in the center of which is found the sleeve 51. At two opposite ends, the crosspieces 53, 54 are in each instance connected with an object holder 55. The holders 55 correspond in their design, except for the differences indicated below, to the holders 12 of the fastener 10. Differing from these, the object holders 55 do not have a film gate and have at their outer side at the bottom in the center a rib 56 projecting outward and extending in the direction of the axis of curvature. The open end 58 of the sleeve 51 projects on the underside of the lower crosspiece 54 by a small amount from the latter and with its face forms a contact surface 57, which lies in a plane touching the ribs 56. - -

The fastener 50 is designed so that it can be molded by a mono-sandwich injection molding process from a central gate lying on the bottom 52. In this connection, it has been found that, owing to the smooth contour of the sleeve 51 extending in the direction of flow and the arrangement of the crosspieces 53, 54 at the sleeve end 58 located opposite the point of injection, the sleeve 51 is formed substantially only by the second core component, while however at the lower sleeve end 58, projecting from the crosspiece 54, a uniformly formed ring is produced from the surface component, which forms the contact surface 57. In addition, the surface component forms the ribs 56 and also the inner-lying ribs 59 of the object holder 55 as in the fastener 10. In this way, a fastener is procured in which the contact surface 57 and the ribs 56 serving for support consist of a soft surface component, in order to obtain an elastically yielding and protective support of the fastener on the part holding it.

In Figures 7 and 8 is shown a fastener 60, which has a fastening section in the form of a cylindrical sleeve 61 closed at one end. To the sleeve 61 are fastened, in approximately the center by means of two plate-like crosspieces 62 extending radially, two object holders 63, 64. The two holders 63, 64 have a substantially semi- cylindrical groove 66, formed of a curved wall 65. The central axes of the groove 66 lie in a plane common to the central axis of the sleeve 61 and parallel to the crosspieces 62. Formed on the edges of the groove 66 are walls 67, 68 parallel to each other, which extend upward from the groove 66 and at their upper edges bear springy holding fingers 69. The holding fingers 69 project into the interspace between the walls 67, 68 and extend in the direction of the groove 66, so that an object inserted in the groove 66 can be held in it by the holding fingers 69. Owing to the walls 68, which are adjacent to the sleeve 61 , the holders 63, 64 are connected with the crosspieces 62. On their outer side, the curved walls 65 in each instance have a rib 70 projecting downward and extending centrally and in the longitudinal direction of the groove 66. The rib 70 intersects, at right angles, a central reinforcing rib 71 , which extends under the wall 65 to under the walls 67, 68. The lower front edges of the ribs 70 and the reinforcing ribs 71 of the two holders 63, 64 lie in a common plane with the lower edge of the sleeve 61. In addition, these ribs 72, prolonged upward, are formed at the edges of the groove 66. In the groove 66 of the holder 64 are in addition provided raised beads 73, which extend in the longitudinal direction of the groove 66.

For molding the fastener 60, the two synthetic material components are injected at the intersections of the ribs 70 with the reinforcing ribs 71 into the corresponding mold cavity. Here, the first component for formation of the surface part is distributed substantially on the surfaces of the curved wall 65 and the ribs 70, 71 , 72 formed thereon, while the ribs 72 and the beads 73, because of their small cross sections, are formed almost exclusively from the surface component. After the surface component has reached these regions of the fastener, its previously prepared volume is exhausted, so that the upper regions of the object holders 63, 64, with the holding fingers 69, the crosspieces 62 and the sleeve 61 located in their center, are formed exclusively by the following component for the core part. The effect of the soft component provided for the surface part is therefore substantially limited to the contact surfaces for the objects to be held in the region of the groove 66 and to the contact surfaces formed by the ribs 70, 71 for the support part to be connected with the fastener. The sleeve 61 for the accommodation of a fastening bolt and the crosspieces 62 and the holding fingers 69, which are designed for the accommodation and transmission of the holding forces, are formed of a hard core component.

Figure 9 shows a fastener 80, which is designed for fastening two lines or comparable objects to each other. The fastener 80 has two object holders 81 , 82 spaced apart, which are connected together by a connecting crosspiece 83. The holders 81 , 82 are substantially like the holders 55 of the fastener 50. For molding the fastener 80, the two synthetic material components are simultaneously injected into the mold cavity in the sequence prescribed by the injection molding process and at like delivery speed at two gates 84, 85. Here, the quantity of the first, soft synthetic material component is sized so that the surfaces of the two object holders 81 , 82 and of the connecting crosspiece 83 are coated with a skin of the first component of synthetic material forming the surface part O. In the center of the connecting cross- piece 83, the surface component brought from both sides forms a continuous wall 86, which separates the core parts K1 , K2 of the holders 81 , 82, formed from the hard core component, from each other. Owing to the wall 86, an elastically yielding connecting point is procured between the two holders 81 , 82, which decouples the holders from each other and can dampen any vibration transmission. In addition, the flexibility of the wall 86 can contribute to facilitating assembly of the fastener 80.

It is essential for molding of the fastener 80 that the synthetic material components be fed at the same time and in like quantity per unit of time, so that the wall 86 is formed in the center of the connecting crosspiece 83.

Claims

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1. Process for molding a fastener for an elongated object by use of a sandwich injection molding process, where the fastener has a section that forms an object holder, and a fastening section, where a given quantity of a first synthetic material component for forming a surface part and a second synthetic material component for forming a core part are fed into a melting and injection cylinder and then are continuously pressed, one after the other, out of the cylinder into a mold cavity in a stratification such that the first synthetic material component reaches the mold cavity before the second synthetic material component and forms a surface part in the region of the object holder and the second synthetic material component forms a core part, which is connected substance-lockingly with the surface part and comprises the object holder and the fastening section.

2. Process according to Claim 1 , characterized in that the first synthetic material component is a soft component and the second synthetic material component is a hard component.

3. Process according to either of the preceding claims, characterized in that the gate is located at an end of the object holder far from the fastening section.

4. Process according to any of the preceding claims, characterized in that the gate is designed as a constricted film gate.

5. Process according to any of the preceding claims, characterized in that the fastening section is a sleeve closed off by a bottom, the gate being located on the bottom of the sleeve.

6. Process according to Claim 1 , characterized in that the object holder has a curved wall with reinforcing ribs projecting outward on its outer side and intersecting each other, a gate being located at the point of intersection of the reinforcing ribs. - -

7. Fastener for an elongated object with a section forming an object holder and a fastening section, where the object holder and the fastening section form an integral core part that consists of a second synthetic material component, and the object holder has a surface part consisting of a first synthetic material component, and where the fastener is molded in one piece with use of a sandwich injection molding process, in which the two synthetic material components are fed into a melting and injection cylinder in a given stratification and then are pressed, one after the other, by the cylinder into a mold cavity forming the fastener.

8. Fastener according to Claim 7, characterized in that the object holder has a curved wall with a recess for accommodation of the elongated object, where the surface part forms the inner surface of the recess in the form of a layer covering the core part.

9. Fastener according to Claim 8, characterized in that the curved wall of the object holder has on the inner side a plurality of ribs projecting inward, which are formed of the surface part.

10. Fastener according to either of Claims 8 or 9, characterized in that the outer surface of the curved wall of the object holder is formed of the surface part in the form of a layer covering the core part.

11. Fastener according to Claim 10, characterized in that the curved wall of the object holder has on the other side a plurality of reinforcing ribs projecting outward, which are formed of the surface part.

12. Fastener according to any of Claims 8 to 11 , characterized in that the central region of the curved wall extending in the direction of curvature has a greater wall thickness than the marginal regions adjoining the central region, a gate being located at one end of the curved wall.

13. Fastener according to Claim 12, characterized in that the gate is designed as a constricted film gate, which extends over the axial width of the curved wall.

14. Fastener according to any of Claims 8 to 13, characterized in that the recess of the curved wall has a radial slip-in opening and on the object holder there is designed a springy holding finger, which consists substantially of the first synthetic material component of the core part and extends from outside in the direction of the opening and the recess, in order to hold an object found in the recess in the recess.

15. Fastener according to any of Claims 8 to 14, characterized in that the curved wall of the object holder has reinforcing ribs projecting outward on the outer side and intersecting each other, which are formed substantially of the core part, where the point of intersection of the reinforcing ribs forms a gate.

16. Fastener according to any of Claims 7 to 15, characterized in that the fastening section is connected with the object holder by crosspieces, the crosspieces form a narrow region, by which spread of the surface part in injection molding is limited.

17. Fastener according to Claim 16, characterized in that the gate is located at an end of the curved wall far from the fastening section and the crosspiece forms a narrow region, by which spread of the surface part in injection molding is limited.

18. Fastener according to Claim 16, characterized in that the gate is located at an end of the curved wall far from the fastening section and the crosspiece is connected to the curved wall at an acute angle of less than 90° against the direction of flow of the synthetic material components in injection molding.

19. Fastener according to any of Claims 16 to 18, characterized in that the axial length of the crosspiece is smaller than the axial length of the curved wall.

20. Fastener according to any of Claims 16 to 19, characterized in that the fastening section is connected by two parallel crosspieces with the object holder. - -

21. Fastener according to any of Claims 8 to 20, characterized in that a curved wall is in each instance located in symmetrical arrangement on opposite sides of the fastening section.

22. Fastener according to any of Claims 8 to 21 , characterized in that the fastening section is a sleeve for the accommodation of a bolt, the longitudinal axis of the sleeve running transverse to the axis of curvature of the curved wall.

23. Fastener according to Claim 22, characterized in that the sleeve is closed off at one end by a bottom.

24. Fastener according to Claims 22 and 23, characterized in that the gate is located on the bottom of the sleeve.

25. Fastener according to any of Claims 22 to 24, characterized in that at least one plate-like crosspiece surrounding the sleeve is located in the vicinity of the open end of the sleeve, while a ring-shaped section of the open end projects from the crosspiece and has an end region made of the second synthetic material component.

26. Fastener according to any of Claims 7 to 21 , characterized in that the fastening section is a parallepiped hollow body with inner-lying locking ribs for the accommodation of a bolt.

27. Fastener according to any of Claims 7 to 26, characterized in that the first synthetic material component is a soft component and the second synthetic material component is a hard component.