GB1355574A - Annular expanding ring structure for forming ring-shaped grooves or recesses in tube-shaped bodies - Google Patents

Abstract

1355574 Tube expanding LYNG INDUSTRIER A S LEKSVIKARMATUR 14 Oct 1971 [22 Oct 1970] 47858/71 Headings B3J and B3Q [Also in Division B5] The cross-section of a pipe is altered using an annular, radially expanding ring structure divided into a number of segments E (Fig. 1) arranged to undergo movement between a radially inner and a radially outer position, the segments E being divided into two sets 66, 79, each of the segments being supported for movement in mutually synchronized fashion along a straight path, lying, for each set in parallel with one of two identical conical surfaces 58, 60 having common axes and a common base circle, the base circle lying in the central plane of the ring structure. Adjacent segments E are maintained in mutual surface contact in all positions during movement from the radially inner to the radially outer position, with the contact area varying from a minimum in the inner position to a maximum in the outer position. The segments E are arranged for projection from, and withdrawal into, a cylindrical body 2, 4. A pistonrod 6 (Fig. 1) supports a pair of pistons 16, 18 and is attached via a pair of bosses 8, 10 to two cylindrical bushings 2, 4. The piston-rod 6 includes a ring-shaped, stepped shoulder 54 aligned with a cavity defined between the bushings 2, 4 and the pistons 16, 18. The shoulder 54 supports a ring-shaped guide flange 56 which, together with the bushings and pistons, defines guide seats for the segments E (see also Fig. 3), the latter comprising two sets of eight segments. Each segment E is formed as a frustrum in cross-section (see Fig. 4c, not reproduced) but is rectangular in plan (see Fig. 4a, not reproduced), and includes a T-shaped guide that slides in the associated guide seat 62 or 64 (Fig. 3). As shown, the segments form a curved recess in a pipe, but could be shaped to form a right-angled recess and flange. Operation.-With the segments E withdrawn into the bushings 2, 4 as shown in Fig. 3, the end of a plastics pipe is heated, inserted in a socket mould (see Fig. 5, not reproduced), and drawn over the bushings from the left in Fig. 1. A step 17 in bushing 2 expands the pipe end. Pressurized fluid is fed to a channel 21 in the pistonrod 6, flows through ports 24 and 26 into cavities 28, and 30, and forces the pistons 16, 18 toward one another. The segments E slide over the guide seats 62, 64 to project from the bushings 2, 4, and shape the pipe. After shaping, pressurized fluid is fed to a channel 23 in the piston-rod 6, flows through ports 32 and 34 into cavities 36 and 38, and forces the pstons 16, 18 apart so that the segments E withdraw into the bushings 2, 4, and the shaped pipe can be removed. The expanding ring structure can be used as a mandrel for casting tubular articles, and is applicable to plastics or metallic pipes.