A MECHANICAL FASTENING MEANS FOR THE TUBE MEMBERS OF AN ASSEMBLY CONSISTING OF BENT AND COLLARED TUBE ELEMENTS

Abstract: A mechanical fastening means for the tube members of a furniture element assembled of bent and collared tube members. A problem to be solved is the reliable attachment of tubular members at an accurate relative angle to each other without welding. At the bending point of tube members there is used as a fastening means a cylindrical collar (6) made by the extraction of tube material. The fastening means comprises a nut member (1) fitted within the tube and provided with a threaded hole, a screw member (2) provided with threaded dowels pointing in opposite directions, and a spacer sleeve (3) mountable on top of said screw member and fitted between the collars (6) of the tubes to be joined and in engagement (4, 6) with screw member (2) in a manner that, when said spacer sleeve (3) is turned, the tightening or fastening rotating motion is transmitted to screw member (2).

Description: A mechanical fastening means for the tube members of an assembly consisting of bent and collared tube elements. Finnish Patent application Nr. 803801 has described a method for making a furniture element constructed of bent tubes. This solutio is based on welding attachment / whereby the element will be an assembly that cannot be dismounted. Storing and transporting of such element demands a lot of space and incurs expenses. On the other hand, e.g.DE publication Nr. 2 426 973 discloses the use of a screw nut element for joining tube elements together, but no use has been made of a cylindrical collar worked in the tube in order to improve the joint stiffness and presicion of installation. An object of the present invention is to provide a mechanical fastening element by means of which the collared tubes can be readily assembled and dismounted as necessary. This object is achieved as set forth in the appended claim 1. One preferred embodiment of the invention is illustrated in the accompanying drawings, ' in which fig. 1 shows a fastening means of the invention as a perspective exploded view and fig. 2 shows an assembly construed by means of the fastening means. The fastening means comprises a nut member 1 , a screw member 2 as well as a spacer sleeve 3. The nut member is fitted inside the tube and provided with a threaded hole/holes which sets in the middle of a collar 6 in the tube. The screw member 2 is engaged with nut 1 and the spacer sleeve 3 is pushed on top of said screw member, producing between spacer sleeve 3 and screw member 2 an engagement transmitting torque in the rotational direction of said screw, e.g. by means of a groove 4 and a dowel 5. Thereafter, the free end of said screw member is fitted with the other tube member to be secured, with a nut member 1 therein for engagement with the free end of screw 2. When the pairwise registered screw/nut members have right- handed/left-handed threading, the nut members 1 are urged against each other as spacer sleeve 3 is turned. A torque can be trananitted to the screw by means of a key by way of a keylevel 7, groove 4 and dowel 5 in engagement with the latter. As the cylindrical portion 3a of a spacer sleeve matches the inner diameter of collar 6 and the outer portion matches the outer dia¬ meter of said collar, this will result in a situation in which the spacer sleeve 3 supports collar 6 from the inside and the entire front face of a collar meets the shoulder 3b of a spacer sleeve and, by virtue of the force exerted by screw 2, said nut member 1 squeezes collar 6 on the tube side from inside the tube over a considerably large part of the tube face. Since the face of a nut member corresponds to the curvature of tube in the joint portion, the result -will be a strongand solid joint holding the tubes together. It should be noted that the angle between the planar faces of collars 6, if it is anything else but 180°, always imparts tensile stress to the screw if a tube is attenpted to be re-positioned by means of an external force in any direction. This is due to the fact that the assembly situation is arranged so that the center distance of the tubes to be joined is at its minimum.

Claims: Claims 1. A mechanical fastening means for the tube'members of an assembly put together by bent and collared tubes, comprising a screw member and a nut member which is fitted inside the tube and to which is secured a screw that connects the tubes to be joined, c h a r a c t e r i z e d by a spacer sleeve (3) inserted on top of said screw member (2) between collars (6) of the tubes to be joined, the turning motion tightening screw member (2) being transmitable through said sleeve. 2. A fastening means as set forth in claim 1, f h a r a c t er- i z e d in that a nut -member (1) , fitted inside the tube, as the tube inner face matching configuration on those sides by which the screw members (2) engage it through the collar and one of the threaded holes in nut member (1) is right-handed and the other left-handed, said holes being positioned so as to settle -in the center of collars (6) when nut member (1) is tightly urged against the inner wall of a tube. 3. A fastening means as set forth in claim 1, c h a r a c t er ¬ i z e d in that said screw member (2) consists of a right- and left-handed thread and that screw member (2) and spacer sleeve (3) are so connected that they are movable relative to each other making angular movement in the direction of their longitudinal axes and being simultaneously movable so that the central axes, when they are parallel or in angular position, are capable of moving radially relative to each other in all directions to certain extent, while at the same time the screw member (2) is in engagement with spacer sleeve (3) wherein it is capable of moving radially and axially relative to the spacer sleeve. 4. A fastening means as set forth in claims 1-3, c h ar a c te r¬ i z e d in that said spacer sleeve (3) is provided with a cylindrical portion (3a) precision-fitted within collar (6) and a thicker central portion (3b) against which the straight-cut end face of a collar strikes and the inner hole of spacer sleeve (3) is so designed (4) that turning of the spacer sleeve transmits a rotating motion to said screw member (2) fitted therein but the radially and axially effectad movement is not obstructed.

Inventors: LARIKKA LEO, LARIKKA, LEO
Applicants: LARIKKA LEO, LARIKKA, LEO
Application year: 1982
Main classification: F16B7
IPC codes: F16B7, F16B12