Patent GB-704751-A (GB)
Title: Improvements in a method for extruding metal sections
Inventor: BRIDGE ARCHIBALD CLAUDE
IPC: B21C35/03
Filed: 1950-03-03
Abstract: 704,751. Extruding. CRITTALL-LUXFER, Ltd., [formerly CRITTALL-LUXFER ALUMINIUM WINDOWS, Ltd.]. Feb. 27, 1951 [March 3, 1950], No. 5487/50. Classes 83 (2) and 83 (4) Making pipes; stretching.-A method of cold percussion extrusion of metal sections comprises extruding a section on each forward stroke of the arm wherein a thin discard left on the unobstructed face of the die is severed from the extruded section during the return stroke of the ram and approximately simultaneously with the severing, whilst the section still possesses high ductility, holding the extruded section by means of a mechanical grab and applying thereto a tensile force parallel to the direction of extrusion. A machine for extruding metal tubing by this method comprises a press frame 1, a ram 2 reciprocated by toggles 3 actuated by eccentric rods 4 and gears 5, driven by a motor not shown. The ram has a slug receiving chamber 8 and a mandrel 9. A die 10 projects axially from the frame 1 and is a sliding fit within the chamber 8. A knife 15 for severing the discard from an extruded section is carried on a member 14 operated by a pivoted lever 11 linked to the toggles 3. A cam shaft 16 carries a cam 17 formed with a cam track 18 in which slides a roller 19- on a slide 19a pinned to a pivoted slug feeding member 20 which holds a slug in a forkat oneend by a spring-loaded finger 20a. The feeding member' carries a roller 22 which engages a face cam 23 and a projection 24 engages in a slotted gate 25. When the cam shaft 16 is driven the feedings member is rocked about its pivot 21 into alignment with a loading slide 27. Quadrants 28 operated by a piston and cylinder 31 control the delivery of the slugsto a spring-loaded plate 32 which is pushed away by the feeding member so that the slug drops into the fork. The finger 20a engages a stop 27a on the magazine 27 to allow the slug' to enter the fork and the finger grips the slug when the feeding member is swung back towards the die. The feeding member is also pivoted about a transverse pin 21a carried by the pivot 21 and rotation about pin 21a is effected by the ram during its forward movement so that the finger 20a and that end of the feeding member passes over the die. The feeding member is brought back again on the reverse movement of the ram by the roller 22 riding over the face cam 23. The extruded section is straightened immediately after extrusion by means of a grab 34 actuated by a . fluid cylinder 36. Between the cylinder 36 and the point of extrusion is a cylinder 38 which actuates toggles 40, 41. The free end of the toggle 40 is pivoted to a slidable bracket 42 which carries the cylinder. 36 and the toggle 41 is pivotally anchored to the frame 44. The grab 34 is formed in two parts, the lower part 34a being carried by the bracket 42. Operation of the cylinder 38 straightens the toggles so that the bracket 42 moves in its slide 45 and the extruded section is straightened by tension. A tubular guide behind the die is supplied with compressed air for assisting the extraction of the extruded section. In the extruding operation as the ram moves forward the knife 15 is raised and, as the chamber 8 and mandrel 9 contact the slug 26, the ram pushes the feeding member 20 forward and extrusion occurs. On the reverse movement of the ram the cam 23 returns the feeding member and the discard is severed by the knife 15. During this time the cam shaft 16 actuates a selector valve to operate the grab and stretching cylinder 38 and supply compressed air to the extrusion guide 47. Towards the end of the ram's return stroke the cam track 18 rocks the feeding member to receive a further slug from the magazine. The grab and stretching means may be electrically operated. Specification 704,826 is referred to.