Plastic glider for suspending curtains therefrom, and method and injection mold for manufacturing such a glider

Abstract: A method for manufacturing at least one plastic curtain glider (201) comprising a body (206) and a substantially U-shaped eye (203,204,205) which has two legs (203,204) connected with the body (206) and an arch portion (205) connecting the legs (203,204) with each other at the ends remote from the body (206), the glider being manufactured by means of an injection molding process in an injection mold which is provided with at least one injection mold cavity (100) containing at least one glider cavity (101), the plastic being injected into the glider cavity (101) from such a position that plastic streams (A,B,C,D,E,F) formed in the glider cavity (101) during the injection do not meet each other in the arch portion (205) of the U-shaped eye (203,204,205). The invention also relates to an injection mold for use in the method and to a glider and glider strip obtained by means of the method, using the injection mold.

Description: The invention relates to a method for manufacturing at least one plastic glider comprising a body and a substantially U-shaped eye which has two legs connected with the body and an arch portion connecting the legs with each other at the ends remote from the body, the body having a section intended for slidable cooperation with a curtain rail, the substantially U-shaped eye being intended for hooking in a curtain hook, the glider being manufactured by means of an injection molding process in an injection mold which is provided with at least one injection mold cavity containing at least one glider cavity. The invention also relates to a plastic glider manufactured in an injection mold cavity, which glider comprises a body and a substantially U-shaped eye which has two legs connected with the body and an arch portion connecting-the legs with each other at the ends remote from the body, the body having a section intended for slidable cooperation with a curtain rail, the U-shaped eye being intended for hooking in a curtain hook. The invention further relates to an injection mold for manufacturing such a plastic glider, which injection mold is provided with at least one injection mold cavity, which injection mold cavity contains at least one glider cavity, each glider cavity comprising a body cavity and a U-shaped eye cavity, the eye cavity comprising two leg cavities connected with the body cavity and an arch portion cavity connecting the leg cavities with each other at the ends remote from the body cavity, a plastic supply channel discharging into each glider cavity. It is a drawback of the method known e.g. from EP-A-0 601 663, plastic glider and injection mold that the gliders are injected therein via the body, that is to say at a point located diametrically opposite the arch portion of the U-shaped eye. As a result thereof, the plastic flows into the glider cavity of the injection mold symmetrically inwards and the U-shaped eye cavity is filled simultaneously via both leg cavities. Both plastic streams meet each other in the arch portion cavities, and exactly there a so-called flow joint therefore results. Such a flow joint forms a weak portion in the eventually molded product. It is a drawback of the known method, injection mold and the glider obtained therewith that the flow joint is located exactly at the point where the load of the glider is highest. The fact is that the curtain hooks which are hooked into the U-shaped eyes rest exactly on the arch portion of the U-shaped eye. In particular the glider located at the end of the curtain, which glider is often pulled to open and close the curtain, is loaded very heavily. In practice, this often leads to fracture of the U-shaped eye of the gliders. To limit this problem, concessions were often made in the past to the plastic from which the gliders are manufactured. A relatively strong plastic was used therefor, such as for instance pure polyamide. It is a drawback of this plastic, however, that the friction coefficient thereof is rather high, so that the glider is not smoothly movable along the curtain rail. It is an object of the invention to provide a glider without the above-described drawbacks. It is also an object of the invention to provide a method and an injection mold by means of which such a glider can be manufactured. According to the invention the method of the type described in the opening paragraph is characterized in that the plastic is injected into the glider cavity from such a position that plastic streams formed in the glider cavity during the injection do not meet each other in the arch portion of the U-shaped eye. According to the invention the plastic glider of the type described in the opening paragraph is characterized in that the or each flow joint, that is to say the or each joint formed owing to two plastic streams in the injection mold cavity touching each other there, is not located in the arch portion. The injection mold of the type described in the opening paragraph is further characterized according to the invention in that the plastic supply channel discharges into the glider cavity such that during the filling of the glider cavity the plastic divides into at least two plastic streams, the positioning of the plastic supply channel being selected such that the or each flow joint, that is to say the or each joint formed owing to two plastic streams in the injection mold cavity touching each other there, is not formed in the arch portion cavity. By means of the method and the injection mold a plastic glider is obtained in which no flow joint is located in the portion of the plastic glider which, in use, is critically loaded. As a result thereof, in the arch portion of the U-shaped eye, too, the glider will show an optimum plastic structure and, as a result thereof, an optimum strength. The strength profit made therewith is such that the glider can be manufactured from a mixture of polyamide with a number of components which reduce the friction coefficient, but which have the result that the strength decreases with respect to the pure polyamide hither used. The gliders manufactured from the polyamide mixture have the advantage that the gliders can be moved along the curtain rail with much less resistance. According to a further elaboration of the invention the injection point of each glider is located in one of the legs of the glider. According to a further elaboration of the invention the injection mold is therefore characterized in that one plastic supply channel discharges into each glider cavity, the plastic supply channel discharging into a leg cavity near the body cavity. With such a positioning of the plastic supply channel it is ensured that no flow joint is formed in the arch portion of the U-shaped eye. The invention also relates to a glider strip provided with a number of gliders according to the invention obtained with the method according to the invention, using an injection mold according to the invention, the gliders being connected with each other by a strip, such that the bodies of the gliders connected with the strip are in alignment. Further elaborations of the invention are described in the subclaims and will be specified below with reference to the drawing. Fig. 1 shows a partial top view of an injection mold cavity of a glider strip according to the prior art; Fig. 2 shows a top view of an exemplary embodiment according to the invention of the injection mold cavity of two glider strips with the associated plastic supply channels; Fig. 3 shows a detail of the injection mold cavity represented in Fig. 2; Fig. 4 shows a front view of a plastic glider according to the invention; Fig. 5 shows a side view of the plastic glider represented in Fig. 4; and Fig. 6 show a cross-sectional view on the line VI-VI from Fig. 4. In the injection mold cavity according to the prior art partly represented in Fig. 1 it is clearly visible that a plastic supply channel 2 discharges into the glider cavity 1, that is to say into the portion of the body cavity 6 remote from the U-shaped eye cavity 3, 4, 5. The plastic supplied via the plastic supply channel 2 flows via the body cavity 6 to the U-shaped eye cavity and forms the U-shaped eye via both legs 3, 4 from two sides. Both plastic streams meet each other in the arch portion cavity 5 of the U-shaped eye cavity and form a flow joint there. From the arch portion cavity 5 the plastic flows further into the strip cavity 7 to form a plastic strip at which a number of gliders is formed. As a result of the above-described flow pattern, these known gliders have a flow joint in the region which, in use, is loaded most heavily, that is to say the arch portion of the U-shaped eye. By means of the exemplary embodiment according to the invention of the injection mold cavity represented in Fig. 2 a glider 201 is obtained in which the flow joints G, H are located in regions in the plastic glider 201 which are loaded less heavily than the arch portion 205. For clarity's sake, for the description of the exemplary embodiment of the invention reference numerals will be used which correspond to the reference numerals used in Fig. 1, although increased by 100. The injection mold cavity 100 represented in Fig. 2 is provided with a number of glider cavities 101. Connected to these glider cavities 101 are plastic supply channels 102. Furthermore, the glider cavities 101 have plastic discharge channels 108 connected to, which lead to a strip cavity 107 in which a plastic strip 207 is formed at which a number of plastic gliders 201 are formed. As visible in more detail in Fig. 3, each glider 201 has a body 206 which, in the present exemplary embodiment, has two bridge portions 206a, 206b. Furthermore, the glider is provided with a substantially U-shaped eye 203, 204, 205 which has two legs 203, 204 and an arch portion 205 connecting the legs 203, 204 with each other to form the eye. During the filling of the glider cavity 101 with plastic the plastic flows from the plastic supply channel 102 into the glider cavity 101 and divides there into two streams A, B. Stream B flows to the body cavity 106 and, in turn, divides into two streams C, D which fill the bridge portion cavities 106a and 106b, respectively. Stream C then divides into two streams E, F. Stream E meets stream A in the leg cavity 104 near the body cavity 106 and forms a flow joint G there. Stream F meets stream D in the body cavity 106 and forms a flow joint H there. It may be clear that both flow joints G, H are not located in the most heavily loaded arch portion 205 of the plastic glider 201. From the flow joint H the plastic flows via the plastic discharge channel 108 to the strip cavity 7 and then fills the strip cavity 107 to form the strip 207. Figs. 4, 5, 6 once more show in detail the plastic glider 201 obtained by means of the method and the injection mold according to the invention. When indicating the different parts of the plastic glider 201, reference numerals are used which correspond to the reference numerals referring in Fig. 3 to cavities in an injection mold, although increased by 100. The injection point is located at position 209 indicated in Figs. 4, 5. The discharge point 210 of the plastic discharge channel 108 is also represented in Figs. 4 and 5. The plastic used is a plastic having polyamide as main component and additives ensuring that a lower friction coefficient is obtained, so that the gliders are easily movable along a curtain rail. The additives also ensure a substantial prolongation of life. It may be clear that the invention is not limited to the described exemplary embodiment, but that various modifications are possible within the scope of the invention. Thus, the body which, in the present exemplary embodiment, is built up of two bridge portions 206a, 206b may also be of massive design and therefore consist of only one part. In that case the plastic glider will only contain one flow joint located approximately between the flow joints G and H as indicated in Fig. 3. In that case the flow joint is therefore located in the body 206 of the glider 201.

Claims: A method for manufacturing at least one plastic glider (201) comprising a body (206) and a substantially U-shaped eye (203, 204, 205) which has two legs (203, 204) connected with the body (206) and an arch portion (205) connecting the legs (203, 204) with each other at the ends remote from the body (206), the body (206) having a section intended for slidable cooperation with a curtain rail, the U-shaped eye (203, 204, 205) being intended for hooking in a curtain hook, the glider (201) being manufactured by means of an injection molding process in an injection mold which is provided with at least one injection mold cavity (100) containing at least one glider cavity (101), characterized in that the plastic is injected into the glider cavity (101) from such a position that plastic streams (A, B, C, D, E, F) formed during the injection into the glider cavity (101) do not meet each other in the arch portion (205) of the U-shaped eye (203, 204, 205). A plastic glider manufactured in an injection mold cavity, which glider (201) comprises a body (206) and a substantially U-shaped eye (203, 204, 205) which has two legs (203, 204) connected with the body (206) and an arch portion connecting the legs with each other at the ends remote from the body, the body (206) having a section intended for slidable cooperation with a curtain rail, the U-shaped eye (203, 204, 205) being intended for hooking in a curtain hook, characterized in that the or each flow joint (G, H), that is to say the or each joint (G, H) formed owing to two plastic streams (A, E; D, F) in the injection mold cavity touching each other there, is not located in the arch portion (205). A plastic glider according to claim 2, characterized in that the injection point (209) of each glider (201) is located in one of the legs (203) of the glider (201). A plastic glider according to claim 2 or 3, characterized in that the body comprises two bridge portions (206a, 206b), a first flow joint (G) being located in a leg (204) of the U-shaped eye (203, 204, 205) near the body (206), and a second flow joint (H) being located in the body (206). A plastic glider according to claim 2 or 3, characterized in that the body (206) comprises a single massive plastic portion, a single flow joint being located in the body (206). A plastic glider according to claim 2, characterized in that the glider (206) is manufactured from a mixture of polyamide and a number of additives which reduce the friction coefficient of the material. An injection mold, provided with at least one injection mold cavity (100), which injection mold cavity (100) is provided with at least one glider cavity (101), each glider cavity (101) comprising a body cavity (106) and a U-shaped eye cavity (103, 104, 105), the eye cavity (103, 104, 105) comprising two leg cavities (103, 104) connected with the body cavity (106) and an arch portion cavity (105) connecting the leg cavities with each other at the ends remote from the body cavity (106), a plastic supply channel (102) discharging into each glider cavity (106), characterized in that the plastic supply channel (102) discharges into the glider cavity (101) such that during the filling of the glider cavity (101) the plastic divides into at least two plastic streams (A, B, C, D, E, F), the positioning of the plastic supply channel (102) being selected such that the or each flow joint (G, H), that is to say the or each flow joint (G, H) formed owing to two plastic streams (A, E; D, F) in the injection mold cavity touching each other there, is not formed in the arch portion cavity (105). An injection mold according to claim 7, characterized in that one plastic supply channel (102) discharges into each glider cavity (101), the plastic supply channel (102) discharging into a leg cavity (103) near the body cavity (106). An injection mold according to claim 7 or 8, characterized in that each glider cavity (101) also has a plastic discharge channel (108) connected thereto, the plastic discharge channel (108) being connected to the body cavity (106). A glider strip, provided with a number of gliders (201) according to any one of claims 2-6, obtained by means of the method according to claim 1, using an injection mold according to any one of claims 7-9, the gliders (201) being connected with each other by a strip (207), such that the bodies (206) of the gliders (201) connected with the strip (207) are in alignment.

Inventors: TER BRAAK BART, TER BRAAK, BART
Applicants: GOELST ROLF EDWARD, GOELST, ROLF EDWARD
Application year: 2001
Main classification: B29C45
IPC codes: B29C45, A47H15