A METHOD AND A FORMER MEMBER FOR TAPERING AN END PORTION OF AN EXTRUDED TUBULAR PLASTIC MEMBER SAID FORMER BEING USED AS A SALES UNIT

Abstract: One end portion of an extruded tubular screw or nail anchoring member (12), which is made from plastic material, is tapered by deforming the end portion to the desired shape. The deformation of the end portion is obtained by exposing it to a radial compression and by maintaining the radial compression for a period of time, which is sufficient to obtain a permanent character of the deformation. The compression is preferably obtained by pressing the respective end portion of the tubular member into a tapered passage (15) of a former member, which is preferably in the form of a holder (13). This holder (13) may be adapted to receive a plurality of tubular anchoring members (12) so as to form a sales package or unit.

Description: A METHOD AND A FORMER MEMBER FOR TAPERING AN END PORTION OF AN EXTRUDED TUBULAR PLASTIC MEMBER SAID FORMER BEING USED AS A SALES UNIT The present invention relates to a method and a former member for tapering an end portion of an extruded tubular plastic member, which is adapted to be inserted in a bored hole, such as a screw or nail anchoring member. The most commonly used tubular members for anchoring nails and screws in holes bored or drilled in panels or walls are made by ex¬ trusion of a tubular string with the desired cross-sectional shape, and by cutting the string into suitable lengths forming the anchoring members. A tubular anchoring member made in this manner, has necessarily the same cross-section along its total length . When such a tubular anchoring member is used for mounting a screw, such a wood screw, in a wall or panel, the anchoring member is pushed into a hole which has been bored or drilled in the wall or panel, and in order to obtain a reliable fastening of the screw, the diameter of the hole must substantially correspond to the outer diameter of the tubular anchoring member. The insertion of a tubular anchoring member in such a bored hole would, of course, be facilita- ted, if one end of the anchoring member was tapered . It is known to taper one end portion of tubular anchoring members which have been made by extrusion of plastic material , by exposing the end portions of the otherwise finished tubular members, to a cutting or grinding operation . Such an additional , separate manufacturing process will, however, substantially increase the production costs, but may also cause a disadvantageous axial splitting of the tapered end portions, for example when the tubular members have a cross-sectional shape with radially outer portions comprising thin , connecting wall parts . The present invention provides a method by means of which it is possible to taper an end portion of an extruded tubular plastic member substantially simpler and cheaper than by using the above known method, and without any risk of splitting the end portion to be tapered . The method according to the invention is characterized in that the said end portion of the tubular member is deformed to the desired tapered shape by exposing it to a radial compression, and that the radial compression is maintained until the deformation of the end portion has obtained a permanent character. The radial compression of the end portion of the tubular member may take place in connection with the extrusion and prior to cutting the tubular member from the extruded tubular string, or at any desired time after such cutting. I n the first mentioned case, the compression or deformation may, for example, be made by means of die parts movable away from and towards each other so as to compress the respective end of the tubular member, before it has been cooled to room temperature, and if the die parts are cooled so that they also cool the end portion of the tubular member being compressed, the deformation or tapering made will soon become permanent. Thus, by the method according to the invention the tapering may be obtained without a further manufacturing step involving manual labour. As explained below, the tapering of the tubular member may also be made after cooling and cutting from the extruded string, without an addit¬ ional manufacturing step being necessary. When the end portion of the tubular member is tapered by deformation its adjacent free end will be at least partly closed . Therefore, the risk that bore meal penetrates into the inner hollow space of the tubular member when the tubular member is inserted into a hole bored or drilled in a wall, is reduced. The presence of bore meal in the tubular tapering member would make it difficult to fasten the screw in the anchoring member. Especially when the tapering member is made after cutting the same from the extruded string, the radial compression of the end portion of the tubular member is preferably performed by inserting the end portion into a passage defined in a former member by an inner peri¬ pheral surface with a taper corresponding to the desired taper of the end portion of the tubular member. The deformation thereby imparted to the end portion of the tubular member will then become permanent after a certain period of time, even by room temperatu re. This period of time, which is dependent i . a . on the type of plastic material, from which the tubular member has been made, normally amounts to some hours . If desired, this period of time may be very substantially reduced, if the end portion of the tubular member is heated, while it is positioned within the former member, for example by heating the latter. The former member used may have any appropriate form allowing a suitable tapering of the end portion of the tubular member. As an example, the tapered end portion of the tubular member may have an elliptical, or another elongated cross-section . However, it is preferred to use a former member, wherein the peripheral surface of the pas- sage defines a surface of revolution, the diameter of the passage and the outer end thereof exceeding the outer diameter of the tubular member in its non-deformed condition, and the diameter of the pas¬ sage at the inner end thereof being substantially smaller than the outer diameter of the non-deformed tubular member. The increased cross-section of the outer end of the passage facilitates insertion of the tubular member therein . The inner peripheral surface of the passage may be a surface of revolution with any suitable shape, for example with convexly or concavely curved generatrices . The passage is, however, preferably in the form of a truncated cone. Furthermore, axially and/or peripherally extending grooves or chan¬ nels may be formed in the inner peripheral su rface of the passage. These grooves or channels may, for example, be provided to increase a sufficient friction between the inner su rface of the passage and the end portion of the tubular member so as to prevent the tubular member to move out from the passage due to resiliency of the plastic material from which the tubular member is made. When the passage is through-going, this may, alternatively, be prevented by pressing the end portion to be tapered through the passage so that the adjacent end su rface of the tubular member is located slightly outside the passage at the narrow end thereof. The very short length of the tubular member extending from this narrow end of the passage may then distend radially and serve to retain the tubular member in the desired position in relation of the former member. In an especially preferred embodiment the former member comprises a plurality of passages for receiving a corresponding number of tubular screw or nail anchoring members . The former member may then be a holder for the tubular members, and be part of a sales package for such tubular members . Thus, the former member or holder with tubular members received in the passages thereof may constitute a sales unit. This means that tubular screw anchoring members which have been manufactured in a conventional manner by extrusion may obtain a tapered shape at one of their end portions, while they are positioned in a holder or package, in which they are distributed to the consumers . Such a holder may, for example, be a modified em- bodiment of a grid-like holder which is presently commonly used as a holder for extruded screw anchoring members . As mentioned above the wide end opening of each of the passages formed in the holder may have a diameter exceeding the outer diameter of the tubular members . This feature substantially facilitates manual as well as mechanical mounting of the tubular members in the tapered passages of the holder or sales package. It should be understood that the passage or passages of the former member or holder need not be th rough-going, but may be in the form of funnel-shaped pockets having a totally or partly closed bottom wall at its inner narrow end. The present invention also relates to a former member for tapering an end portion of an extruded tubular plastic member, which is adapted to be inserted in a bored or drilled hole in a wall or panel , such as a screw or nail anchoring member, and the former member according to the invention is characterized in that at least one passage is defined therein by an inner peripheral surface having a taper corresponding to the desired taper of the end portion of the tubular member. The former member may be made from any suitable material, provided that the part or parts defining the inner peripheral surface of the passage is made from a material which is harder and less deformable than the material from which the tubular member is made. As an example, the former member may be made from metal or wood . However, when the former member is intended to be used as a holder for a plurality of tubular members forming part of a sales unit, the former member is preferably made from a hard, die cast plastic material . The invention will now be fu rther described with reference to the drawings, wherein Fig. 1 shows a sectional view of a former member according to the invention and an extruded tubular screw anchoring member which is being inserted into a passage thereof, Fig. 2 shows the former member of Fig . 1 when the end portion of the tubular anchoring member has been fully inserted into the pas¬ sage, Fig. 3 is a side view and partially sertional view of a former member according to the invention used as a sales package or holder for a plurality of tubular screw anchoring members, Fig. 4 is a top plan view of the holder or sales unit shown in Fig . 3, Fig . 5 is a bottom plan view of the holder or sales unit shown in Fig. 3, and Fig. 6 illustrates a tubular screw anchoring member with an end portion , which has been tapered by using the method according to the invention, and which is being pushed into a hole bored or drilled in a wall . The method according to the invention is diagrammatically illustrated in Figs . 1 and 2, which show a former tool or a socket 10 having an inner frusto-conical surface defining 1 a through-going passage 11 . This simple tool or former member 10 may be used for tapering one end portion of a tubular screw or nail anchoring member 12, which has been made from plastic material by extrusion . The outer diameter of the tubular member does not exceed, and is preferably somewhat smaller than the diameter of the broader end of the passage 11 (vide especially Fig . 1 ) , and the outer diameter of the tubular member exceeds the diameter of the narrow end of the passage 11 (vide especially Fig . 2) . The socket or former member 10 may be made from any desired material, having a suitable hardness, such as wood, metal, or plastic material . When one end portion of the plastic tubular member 12 is inserted into the passage 11 as illustrated in Figs . 1 and 2, this end portion will be compressed and deformed radially so as so attain a tapered shape corresponding to the shape of the inner surface of the passage 11 . It has been found, that the deformation of the tubular plastic member attains a permanent character after a certain residence time in the socket or former member 10. The neces¬ sary residence time is several hours at room temperature, but may be substantially reduced by heating of the deformed portion of the tubular anchoring member. Tapering of end portions of tubular screw anchoring members in accordance with the method described above may be performed in immediate connection with the extrusion process, and the extruded tubular anchoring members 12 may be inserted into the former mem¬ bers or sockets 10 mechanically or manually. It is also possible to taper the end portions of the tubular members at any desired later time after the extrusion . As indicated above, the method according to the invention may be performed as an additional manufacturing step. However, it is also possible to utilize the method according to the invention without involving a cost-increasing additional manufacturing step. Figs. 3-5 illustrate a holder 12 for tubular screw anchording members 12. This holder 13, which may be used as a sales package for the tubular members, comprises an outer rectangular frame 14 encircling a plurality of sockets 15 defining through-going frusto-conical passages therein for receiving the tubular anchoring members 12. These pas¬ sages have substantially parallel axes extending at substantially right angles to the plane of the frame 14. The sockets 15 are intercon- nected and connected to the frame 14 by means of connecting parts 16. The holder or sales package 13 may, for example, be made as an integral part by die casting from hard plastic material, such as knockproof polystyrene. OMP The extruded tubular nail or screw anchoring members 12 may be manually or mechanically inserted into the sockets 15 of the holder 13 so that one end 17 of each tubular member extends a small distance, such as 1 -2 mm, from the narrow end of the socket 15. When the tubular members 12 have been inserted into the sockets 15 in this manner, the extending ends 17 will tend to expand radially in an attempt to reassume their original shape. The narrow opening of each of the through-going passages defined in the sockets 15 is preferably encircled by an inner, sharp edge, which may cooperate with the extending end 17 of the tubular member 12, so as to safely retain the tubular member in the respective socket 15, even when the tubular member is exposed to incidental shocks during storage and shipment. When the sales package or holder 13 with the tubular anchoring members 12 mounted therein arrives to the consumer, any desired of the tubular members 12 may be removed from the holder 13 by excer- ting an inwardly directed axial pressure to the extending end 17 of the tubular member. When a tubular member 12 is removed from the holder 13 it has obtained a tapered end portion which has been shaped during its residence time in the socket 15 of the holder 13. As illustrated in Figs . 3 and 5, the radial deformation of the tubular anchoring members 12 taking place when they are received in the holder 13 causes, that the respective end portion of the tubular mem¬ ber is at least partly closed . When such a tubular anchoring 12 is later to be used, it may be inserted into a bored or drilled hole 18 in a wall 19 as shown in Fig . 6. The tapered end portion of the tubular member facilitates this insertion, but the fact that the inner end portion of the tubular member is partly closed also reduces the risk that bore meal 20, which is present within the hole 18, penetrates into the inner space of the tubular member 12. As indicated in Fig . 6, the bore meal 20 will instead tend to be positioned around the tapered end portion of the tubular member, which contributes to a good fastening, when a screw, such as a wood screw (not shown) is later screwed into the anchoring member 12 positioned in the hole 18. While the present invention has especially been described above with reference to tubular nail and screw anchoring members, it should be understood that the method and former member according to the invention could also be used in connection with the tapering of other extruded tubular members, which are adapted to be inserted in a bored or drilled hole, for example tubular plastic pins used for inter- locking structural members, such as furniture parts . O PI

Claims: CLAIMS 1 . A method of tapering an end portion of an extruded tubular plastic member, which is adapted to be inserted in a bored hole (18) , such as a screw or nail anchoring member (12) , characterized in that the said end portion of the tubular member (12) is deformed to the desired tapered shape by exposing it to a radial compression, and in that the radial compression is maintained until the deformation of the end portion has obtained a permanent charac¬ ter. 2.. A method according to claim 1 , characterized in that the radial compression of the end portion is performed by inserting the end portion into a passage (11 ) defined in a former member (10, 13) by an inner peripheral surface with a taper corresponding to the desired taper of the end portion of the tubular member. 3. A method according to claim 2, characterized in using a former member (10, 13) , wherein the inner peripheral surface of the passage defines a surface of revolution, the diameter of the passage at the outer end thereof exceeding the outer diameter of the tubular member (12) in its non-deformed condition, and the diameter of the passage at the inner end thereof being sub¬ stantially smaller than the outer diameter of the non-deformed tubular member. 4. A method according to claim 2 or 3, characterized in that the passage (11 ) is in the form of a truncated cone. 5. A method according to any of the claims 2-4, characterized in that the passage (11) is through-going, and in that the end portion to be tapered is pressed th rough the passage so that the adjacent end surface (17) of the tubular member is located slightly outside the passage. 6. A method according to any of the claims 3-5, characterized in that the former member (13) comprises a plurality of tubular member receiving passages (15) , and is used as a holder for the tubular members (12) received in the passages so as to form a sales unit. 7. A former member for tapering an end portion of an extruded tubular plastic member, which is adapted to be inserted in a bored hole (18) , such as a screw or nail anchoring member (12) , characterized in that at least one passage (11 ) is defined in the former member (10,13) by an inner peripheral surface having a taper corresponding to the desired taper of the end portion of the tubular member (12) . 8. A former member according to claim 7, characterized in that the passage (11 ) is a through-going passage extending between a wide end opening and a narrow end opening, the latter being defined by a sharp edge portion . 9. A former member according to claim 7 or 8, characterized in that the passage (5) is in the form of a truncated cone. 10. A former member according to any of the claims 7-9, characterized in that it comprises a plurality of tubular member receiving passages (15) and is adapted to be used as a holder (13) * for the tubular members (12) , so as to form a sales unit. 11 . A sales unit comprising a holder (13) having a plurality of pas- sages or openings (15) therein , and a corresponding number of extruded tubular screw or nail anchoring members (12) , which are - • made from plastic material and received in the respective passages (15) , characterized in that each of the passages has a tapered shape and receives one end portion of the respective tubular anchoring member. - UR O

Inventors: MORTENSEN LOUIS AACKERSBERG, MORTENSEN, LOUIS, AACKERSBERG
Applicants: EXPANDET SCREW ANCHORS, EXPANDET SCREW ANCHORS A/S
Application year: 1982
Main classification: B29C17
IPC codes: B29C57