Patent GB-1445542-A (GB)
Title: Light-alloy piston for rotary piston internal combustion engines
IPC: A43D49/00
Filed: 1974-04-01
Abstract: 1445542 Shoemaking FORTUNA-WERKE MASCHINENFABRIK AG 1 April 1974 [11 April 1973] 14397/74 Heading A3B A method for roughening and/or pounding the lasting margin of a lasted shoe 13 (Fig. 3) uses a pot-shaped tool 11 whose working face 12 or WS (Fig. 4) machines around the margin such that one face zone corresponding to the width B of the margin is in contact with the shoe, and the axis of rotation of the tool 11 cuts an imaginary base plane corresponding to the shoe bottom with an adjustable angle of inclination at an axis of rotation reference point RB, the tool being guided such that the connecting line between the point RB and a surface point F of the zone of the tool in contact with the shoe is aligned tangentially to an imaginary working line AL which determines the lasting margin of the shoe, the line AL comprising a semi-circle at both toe and heel. these being joined by straight lines. The semi-circles are formed about toe and heel pivots DS and DF respectively. these pivots lying on an advance line VL. The point RB is moved about a second axis of rotation reference point DB approximately half the tool diameter away, the point DB being moved to and fro along the line VL. The machining is preferably started with the point DB1 in approximate agreement with the toe pivot DS and with the point RB1 chosen such that the angle of incidence α (Fig. 4) is equal to 90 + Sin<SP>-1</SP> (H/V) where H is the half diameter of the toe semi-circle of the line AL and V is the distance between the points RB and DB. Operation around the shoe is continued by increasing α by increments of 90 and by movement of the point DB along the advance line VL, as indicated in Fig. 4. The initial angle of incidence α may be determined automatically by a control magnitude representing the size of the shoe. An apparatus for carrying out the method includes a supporting circular disc I mounted in a holding frame 5 by three guide rollers 2-4, one of which 2 is held by spring tension against the edge of the disc I and is coupled to an electric motor 9 via a gear 10. The transmission of torque from the roller 2 to the disc 1 is by frictional connection only. The working tool 11 is mounted on a plate 15 by means of a spindle 14 and is driven via a belt 17 by an electric motor 16. Both the spindle 14 and the motor 16 pass through a recess 18 in the disc 1, the plate 15 being mounted on the latter such that it is inclined to it at an angle of 5-60 and such that the axes of rotation of the tool 11 and the disc 1 intersect at a point 21. The disc 1 is attached to a stirrup 22 on which is fixed a tube 23 which carries slip rings 24, 25 to allow electrical connection for the motor 16. A potentiometer including a slip contact 28 and a stationary resistance path 29 allows indication of the instantaneous position of rotation of the disc 1. The holding frame 5 is mounted on the ends of arms 36, 37 which are attached to a frame 33 linked vertically movably by arms 34 to a machine frame 35, whereby the axis of rotation of the disc 1 and the tilting axis 40 (Fig. 3) are set perpendicularly such that they intersect in a plane corresponding approximately to the bottom of the shoe. The frame 5 is linked to an angle arm 45 which runs on a threaded spindle 44 driven via a gear 43 by a motor 42. The gear 43 may be coupled to a potentiometer 42a to indicate the instantaneous pivot position of the holding frame 5. The shoe 13 is held by a heel mandrel 47 and a toe support 48 in a pivot frame 49 which has a pivot drive 50 to enable tilting of the shoe in a longitudinal direction. A potentiometer 51 may be applied to allow indication of the position of tilting. The shoe may be moved longitudinally along a sliding path 52.