Patent GB-507235-A (GB)
Title: Improvements in or relating to apparatus for duplicating three-dimensional objects
IPC: B23Q35/00
Filed: 1937-10-04
Abstract: 507,235. Photo-electrically controlled copying-apparatus. JACKSON, L. MELLERSH. (Buggie & Co., H. H.) Oct. 4, 1937, No. 26829. [Class 40 (iii)] Apparatus for duplicating threedimensional objects comprises an optical unit having means for projecting a beam of light towards an object or pattern to be scanned, to produce an image on the surface of the object with a sharply defined contour line, and having a lightsensitive cell system supported in fixed angular relation to the projector with the line of sight of the cell intersecting the contour line of the image ; means supporting the object and optical unit for relative movement towards and away from each other ; means controlled by the cell for effecting the said movement, to maintain the point of intersection of the line of sight of the cell with the contour line on the surface of the object being scanned, and a tool operable upon a work blank and controlled by the cell in accordance with the pattern. The tool and the optical unit are traversed in unison across the blank and the pattern respectively. The invention is shown as applied to a machine for making a mould for bottles by controlling a cutting-tool under the influence of a photoelectric device which scans the surface of a solid pattern. Fig. 1 shows the apparatus diagrammatically. A pattern A, preferably covered with reflecting paint, and a work blank B are supported on a carriage C which can reciprocate horizontally and is adapted to be fed downwardly step by step. A cutting tool D is mounted so as to engage the inner surface of the blank, and an optical unit E comprising a photo-electric cell and a projector is located oppositely to the outer side of the pattern. The optical unit is movable relatively to the pattern by fluid-pressure-actuated means controlled by the cell, which means correspondingly moves the tool relatively to the blank, but in opposite phase. The optical system, Fig. 7, comprises a projector G, which casts on the pattern a sharp contour line, an image of which is focused by lenses 112 on a semicircular or straight aperture in a plate 115 in a tube F set at an angle to the projector so that the line of sight I intersects the adjacent edge of the beam from the projector at a predetermined point. Light passing through the aperture falls on a photo-electric cell 113. The photoelectric cell system F, 113 and the'projector G are fixedly supported in relation to each other on a quadrant 102, which is adjustably pivoted on a yoke 101. The arrangement is such that as the optical system moves transversely with respect to the pattern, the cell scans the images of the contour lines projected on the surface, and the light passing through the aperture in the plate 115 is varied accordingly. When the amount of reflected light received by the cell diminishes, the effect produced by the cell is such that the cell recedes and the tool D is fed into the work, and vice versa. Thus, the point of intersection of the line I with the projected image closely follows the contour of the pattern at a constant level, and correspond. ing movements are imparted to the tool D, until the end of a transverse movement of the carriage is reached. The carriage is then lowered through a predetermined distance, and the same operations are repeated at a lower level, and so on until the whole surface of the pattern has been scanned. The control produced by the cell 113 is effected through an electromagnet K, Fig. 1, which operates a valve L to control the supply of fluid from a pressure supply pipe M (connected to a pump V) to cylinders O, O<1>, the pistons in which are connected to the optical unit E and the tool D. When light falls on the cell 113, the supply pipe M is connected to 0, and the exhaust side of 0<1> is connected to a return pipe S ; conversely, when the cell is rendered non-conductive, the valve L changes the connections to the cylinders 0, 0<1>, the appropriate movements of the optical unit and of the tool being thus produced. The tool is maintained substantially normal to the work throughout the cutting operation by mounting the pattern and the work on face-plates (not shown) on the carriage C, which plates are oscillated by means of a belt D<1> and pulleys connected to the plates. The required movements of the belt are obtained by connecting it to opposed pistons P', P<2> in cylinders C<1>, C<2>, which are connected alternately to fluid pressure supply and exhaust through a four-way valve X and a pilot valve W. The valve W is automatically rotated by the pattern face-plates at the end of each oscillation of the latter, to change the flow of fluid through the valve X to the cylinders C<1>, C<2>. Rotation of the face-plates also effects transverse feed of the carriage C by means of a cam E<1> secured to the plates so as to rotate therewith. The cam acts on one end of an arm E<2> pivoted on the carriage and having its other end bearing against a fixed abutment E<3>. The return of the carriage is effected by a spring E'. The face-plates and the carriage are held stationary during periods when the tool is being fed into the work, a valve F<1> being provided for this purpose to prevent flow of exhaust fluid from the cylinders O, O<1> to the return line S until movement of the tool into the work is completed. Step-by-step vertical movement of the pattern A and the work B is effected by means of a piston P<3> connected to a slide G<1> which supports the carriage C. Opposite ends of the piston P<3> slide in cylinders C<3>, C<4> connected to a manuallyoperated valve H<2>, through which pressure from a supply line M<3> is admitted to the cylinders as required. The valve H<2> communicates through a valve J<2> with a two-chamber measuring-valve K<2>. When the pilot valve W is rotated at the end of the travel of the carriage C in each direction, it moves the piston of the valve J<2> in one direction or the other, allowing a predetermined volume of fluid to pass from one of the chambers of the valve K<2> to the cylinder C<3>, and connecting the cylinder C<4> to an exhaust line S<2>; thus, equal increments of downward movement of the carriage occur after each complete horizontal scanning and cutting movement. A machine embodying the features diagrammatically shown in Fig. 1 is fully described and shown in the Specification. Details of the machine include means for securing the work-piece and the pattern to the face-plates; constructions of the various valves and their operating-devices : means for mounting the carriage for horizontal and vertical movement ; means for varying the increments of downward movement of the carriage by adjustment of the valve K<2>; means for mounting the cutting-tool and driving it by a pivotally mounted motor operating through a belt and sets of pulleys adapted to give variable speeds; and means for moving the optical unit and tool simultaneously, comprising a transverse rock-shaft operatively connected to the pistons in the cylinders O, O<1>. A modification is also described, in which the optical system includes two oppositely inclined projectors which cast beams intersecting each other at. the surface of the pattern, light reflected from the pattern being received by a suitably inclined photoelectric cell. Specification 465,447 is referred to.